[VB6] GDI+ Usage & Samples

Good catch. I don't use that function any longer as I've written a more efficient and much faster routine to create such sourceless GDI+ bitmaps. I won't be updating this project with that routine which can be found in my AlphaImage Control project linked in my signature below.

The problem appears to be writing memory beyond intended bounds. That offending line should be changed to:
CopyMemory BHI.bmiColors(0), pal(8), .biClrImportant - 8

What was happening is that by copying 8 more bytes of data to the .bmiColors memory location than that location could hold, corruption of the following 8 bytes of memory on the stack occurs. This could be where the Depth variable resided? Anyway, I think you'll find the above patch suitable.

Quote:

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Originally Posted by LaVolpe

This project is a teaser to get one's feet wet. For a fully functional usercontrol that is based almost entirely on GDI+, see my alpha image control project.

If you have questions on how to do something with GDI+ that the attached project does not do, please post your question in the Graphics portion of the forum. I do not want, nor intend that this posting become a proxy "GDI+ Forum"

If you have questions about this project then by all means ask away. There may be a few logic errors in the project; as we find those I'll continue to update. Jump to bottom to determine when last updated.

GDI+ is a very handy tool and many coders stay away from it because it appears difficult, at first. So, the classes in this project are aimed at easing you along a bit. GDI+ has 100's of functions and the project herein only touches a small percentage of them. But should be enough for you to get your feet wet without being overwhelmed.

A great site for descriptions of the GDI+ API functions.

I do plan on updating this project from time to time. Things I have knowledge on and have not yet added to the project include GDI+ paths, strings, and regions. The project does include a very complete image processing class, a rendering class, and a pens/brushes class to get you started.

If you want the absolute minimal code to read and display an image at actual size, see post #8 below

Attachment 75528

Some advantages of using GDI+
:: Load/Save PNGs and TIFFs, even multi-page TIFFs
:: Load and display animated GIFs
:: Alphablending - images, lines, shapes, everything. GDI+ does not use standard RGB colors. All colors are ARGB which includes level of alphablending.
:: Built-in niffty options like rotation, mirroring, on-the-fly pixel transformations and more
:: No manual premultiplication of alpha values
Some disadvantages of GDI+
:: Crashes easy if not used properly. Objects created around other objects (i.e., images) are not actually stand-alone. GDI+ requires the source data to remain present until the GDI+ object is destroyed.
-- Here is the MS KB Article link: http://support.microsoft.com/kb/814675
-- The workaround is to create a DIBSection, then create a GDI+ bitmap from it and destroy the DIBSection
-- But that workaround won't allow access to other images in a multi-image formats (GIFs, TIFFs) and 32bpp become pARGB.
:: In IDE, can crash easily too -- like subclassing, you cannot just hit End or terminate your app from the debug window while GDI+ is running.
:: As mentioned above, a little complicated for new users
:: Does not support all older GDI functions. For example, you can't create an XOR pen with GDI+
:: Requires extra steps to setup for drawing; but like anything new to you, just takes a little getting used to

___________________________________________________________________________
Last Edited: Jan 21, 2010 8:50 PM GMT/Zulu
:: Modified primarily for TIFF saving
-- Can now save multiple images with/without attributes applied
-- TIFF images can be saved in 1,4,8,24,32 bit depths - dependent upon source image depth
:: Added another optional rendering quality setting when drawing: PixelOffsetMode
:: Removed requirement of cGDIpRenderer to be passed token class during its function calls.
-- Now entire class can be passed it one time via its AttachTokenClass method
:: Single page TIFFs no longer cache their original source data; more memory savings
Jan 19, 2010 2:20 AM GMT/Zulu
:: Revamped quite a bit
-- To reduce memory usage, PNG, BMP, & JPG no longer cache original data
-- CloneImage routine still had some shortcomings when trying to clone without applying image attributes; fixed
-- Fixed logic error reported by Jonney when cloning rotated images
:: Added additional image types: imageIconPNG & imageCursorPNG to distinguish between PNGs loaded from ico/cur resources
Jan 14, 2010 19:10 PM GMT/Zulu
:: Found 2 memory leaks, one each in 2 different functions; fixed
:: Changed logic when loading new images
-- If new image then all attributes are reset automatically (were not before). Optional load flag prevents this.
-- If multi-image format displays another image within same source; attributes remain (no change from previous logic)
:: CreateCloneWithAttributes renamed to CreateClone. WithAttributes now an optional parameter
:: ImageType property distinguishes between icons and cursors now
:: Reorganized and cleaned up some routines
:: Demo reworked a tad
-- You can now apply multiple attributes to the same image and see results
-- Included sample of saving a multi-page TIFF
Jan 12, 2010 01:10 AM GMT/Zulu
:: Added a little more functionality to the cGDIpImage class
-- GetPixel, SetPixel, ExtraTransparentColor (similar functionality of TransparentBLT)
:: Mirroring was off, had my constants swapped around, fixed
:: When SaveAsOriginalFormat was applied for 32bpp alphablended bitmaps, was saved as 24bpp vs 32pp, fixed
:: Updated demo a bit
-- included SaveAsOriginalFormat, TransparentBLT examples
-- included option to view any image in a multiple image format
-- included option to view image info: size, depth, type
Jan 11, 2010 01:30 AM GMT/Zulu
:: Jonney helped identify a logic error when deciding whether 32bpp images use the Alpha channel and how it is used. Thanx Jonney
...

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AWESOME!

Too bad you don't in your online documentation explain how to use HGraphics. Render Class can create HGraphics from Image Class and a number of other sources. And while the Render Class can directly Render the Image Class to a DC for viewing, what it can't do is render an HGraphics to DC. Sure it can convert a DC to HGraphics, but not the other way. So after getting an HGraphics and using that for the Draw Rectangle command, I have NO WAY TO DISPLAY THE DRAWN RECTANGLE! Please help. Thanks in advance.

Sorry for my English, I translate with google!
Good evening everyone, I'm new to this forum and do not know English well.
I wanted to complete my little project for my collection of coins and I would, at this point, transfer images with a transparent background on word 2010.
I would have my picture (picture3.hdc) in transparency would save it in png transparent and then transfer it into word (only know the way through file:

Code:

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Set Img = wApp.Selection.InlineShapes.AddPicture (FileName: = IMAGEFILE, LinkToFile: = false, SaveWithDocument: = True)

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where Filename = image.png).
How do I save a picture3.hdc file.png?
I could give a hand please?
I tried but I can not save the picture, I am only the background color!!
To explain better, I hope, I have a picturebox with an image with a white background and I would like to send a word in transparency ('cause word on the sheet there' a background image and you should see below, I have transformed my picturebox in a transparent picturebox.hdc (with mask), and now I would like to save it in png with transparent background.
Can you help me with the command line that I include in my project?
thank you very much

Hello; I am not so clever person. So I need your help: I want to display PNG data from a vCard in a picturebox. I already decoded the base64 data into an byte array. I would prefer to convert the data into a StdPicture to load it easily into the picturebox or imagebox.
Please can you provide me the minimal code for this? I need a function like this:

Private Function GetPictureFromPNGArray(PNG() as Byte) as StdPicture

Ciao LaVolpe,
first of all, thanks for this well done work, you saved me tons of hours about writing code to manage GDI+ from VB6!!

Your classes works very well for my pourposes. However I need something it seems to be not present at all in this classes: create a Bitmap/Image in memory.

At the moment, sources for creating cGDIpImage objec are: File, Stream, StdPicture and Dib handle. But there is no way to create a in-memory-bitmap like in C# i can do with the code:

Code:

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Bitmap bitmap = new Bitmap(100, 100);

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Suppose I've a .png with a round button shape inside (100x100px), and a .png with the floppy image(48x48px). Both .png are 32bbp and have transparence and AlphaChannel for a drop shadow effect. I need to obtain a single image, with the result of a paste operation between the two .pngs. This I can do with your class in this way:

1) load the two .pngs in two cGDIpImage objects via .LoadPicture_FileName() method
2) create a cGDIpRenderer object via .CreateGraphicsFromImageClass() method from first cGDIpImage object (the button image)
3) use the .RenderImageClassToHGraphics() method to paste then floppy object over the button object
4) save to new .png or use it with a PictureBox standard control

This works fine. But: if I need to get a 300x300px image as result of the merge operation, with button and floppy centered, I need a new image (not existing as .png file!!) of 300x300px, wich I use as starting point for cGDIpRenderer object, where I can paste over the button and floppy objects. Well, this new image of 300x300px should be created as new memory bitmap, then saved to .png file using .SaveAsPNG() method, preserving transparence and AlphaChannel.

I've been able to create a in-memory bitmap using this code:

Code:

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Public Function Create(Width As Integer, Height As Integer)

  Dim pbmi As BITMAPINFO

  'Memorizza dimensioni
  m_Width = Width
  m_Height = Height

  'Prepara informazioni per la generazione del bitmap
  With pbmi.bmiHeader
    .biBitCount = 32
    .biCompression = BI_RGB
    .biPlanes = 1
    .biSize = Len(pbmi.bmiHeader)
    .biWidth = m_Width
    .biHeight = m_Height
    .biSizeImage = m_Height * m_Width * 4&
  End With

  'Crea in memoria un DC compatibile con lo schermo
  m_hDC = CreateCompatibleDC(0)

  'Crea un BMP compatibile con il DC creato
  m_hBMP = CreateDIBSection(m_hDC, pbmi, DIB_RGB_COLORS, m_hDIBS, ByVal 0&, ByVal 0&)

  'Azzera contenuto
  FillMemory ByVal m_hDIBS, (m_Width * m_Height * 4&), 0

End Function

Public Sub Dispose()

  'Scarica oggetti
  If (m_hBMP <> 0) Then DeleteObject m_hBMP
  If (m_hDC <> 0) Then DeleteDC m_hDC

End Sub

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and after creating the in-memory 300x300 surface bitmap I can use the

Code:

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.LoadPicture_DIBhandle(m_hBMP , mclsToken)

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method to create theh cGDIpImage object I can work with, starting from a bitmap created in memory and not loaded from file.

The problem is that this in-memory bitmap has the background setted to black (I mean due to the fact all BMP bytes are filled to 0). So, when I display the result in a PictureBox or save to a .png file, the background around the button is not transparent, but black. If I FillMemory with &H255 the background becomes white, of course.

At the moment my workaround is to load a file .png that is completely transparent in a "surface" cGDIpImage object, stretch it to the size I need, load others .png files, .RenderImageClassToHGraphics() to paste loaded .png over the "surface" object, then finally save it back to .png file (preserving transparence and AlphaChannel) or paste into Picturebox (with alphablend to the PictureBox background color).

It would be perfect if you can suggest me the code to obtain an ARBG, completely transparent, cGDIpImage object created directly in memory, giving only then Width and Height parameters.

Thanks a lot!

With GDIP you can create a 32bit blank image with this line of code:
GdipCreateBitmapFromScan0 Width, Height, 0&, PixelFormat32bppPARGB, ByVal 0&, hImage

In the cGDIpImage class, you may want to create a new function where you pass the width,height and assign the hImage of the GdipCreateBitmapFromScan0 to the m_Image(0) variable in that class. Once you have a class you can render from GDIP to GDIP via the RenderImageClassToHGraphics after first calling CreateGraphicsFromImageClass and passing the destination class.

So logic could be:
1) modify then cGDIpImage class to add new function to create a blank 32bit bitmap as suggested above. Set that class' m_ImageType to imageBitmap and other properties as appropriate, i.e, m_Size, m_OrigColorType
2) call cGDIpRenderer.CreateGraphicsFromImageClass to get a graphics handle for that blank bitmap
3) call cGDIpRenderer.RenderImageClassToHGraphics, passing the source image class and the hGraphics handle
4) call cGDIpRenderer.DestroyHGraphics when done drawing

These classes were designed to get one started with GDI+, just intended as an outline to be learned from & eventually moved on to one's own classes & implementation.

Quote:

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Originally Posted by LaVolpe

With GDIP you can create a 32bit blank image with this line of code:
GdipCreateBitmapFromScan0 Width, Height, 0&, PixelFormat32bppPARGB, ByVal 0&, hImage

In the cGDIpImage class, you may want to create a new function where you pass the width,height and assign the hImage of the GdipCreateBitmapFromScan0 to the m_Image(0) variable in that class. Once you have a class you can render from GDIP to GDIP via the RenderImageClassToHGraphics after first calling CreateGraphicsFromImageClass and passing the destination class.

So logic could be:
1) modify then cGDIpImage class to add new function to create a blank 32bit bitmap as suggested above. Set that class' m_ImageType to imageBitmap and other properties as appropriate, i.e, m_Size, m_OrigColorType
2) call cGDIpRenderer.CreateGraphicsFromImageClass to get a graphics handle for that blank bitmap
3) call cGDIpRenderer.RenderImageClassToHGraphics, passing the source image class and the hGraphics handle
4) call cGDIpRenderer.DestroyHGraphics when done drawing

These classes were designed to get one started with GDI+, just intended as an outline to be learned from & eventually moved on to one's own classes & implementation.

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Great!!! You are the man LaVolpe!!! :)

So, new function to create in-memory bitmap could be:

Code:

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Public Function LoadPicture_Memory(Width As Long, Height As Long, ImageFormat As ImageColorFormatConstants, TokenClass As cGDIpToken) As Boolean

    If TokenClass Is Nothing Then Exit Function
    If TokenClass.Token = 0& Then Exit Function
    If Width = 0 Then Exit Function
    If Height = 0 Then Exit Function
   
    Dim lResult As Long
    Dim hImage  As Long

    If m_Token Is Nothing Then
        Set m_Token = TokenClass
        TokenClass.AddUser Me
    End If
   
    'Tenta creazione del Bitmap in memoria
    GdipCreateBitmapFromScan0 Width, Height, 0&, ImageFormat, ByVal 0&, hImage
    If hImage <> 0 Then
      m_Image(0) = hImage
      m_ImageType = imageBitmap
      m_Size.nWidth = Width
      m_Size.nHeight = Height
      m_Attr = 0
      m_Alpha = 0
      m_TransColor = 0
      m_Angle = 0
      m_Lightness = 0
      m_GrayScale = attrGrayNone
      m_Mirror = attrMirrorNone
      m_OrigColorType = ImageFormat
    End If

    LoadPicture_Memory = (hImage <> 0)

End Function

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Then, calling

Code:

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.LoadPicture_Memory(300, 300, PixelFormat32bppARGB, mclsToken)

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will do the trick!

Image created by GdipCreateBitmapFromScan0 (handle in m_Image(0)) will be automatically disposed by

Code:

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GdipDisposeImage m_Image(0)

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in pvCleanUp function.

So, what's the difference to use PixelFormat32bppPARGB and PixelFormat32bppARGB values as PixelFormat for the new in-memory bitmap?? The resulting .png file seems to be the same..

Thanks once more for this huge work you've made and released as free usable code!

Quote:

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So, what's the difference to use PixelFormat32bppPARGB and PixelFormat32bppARGB values as PixelFormat for the new in-memory bitmap?? The resulting .png file seems to be the same..

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Very slight pixel modification due to rounding during premultiplication. However, theoretically faster internal GDI+ usage, especially if intending to render to an old-fashioned GDI device context

Enjoy.

Edited: One flaw with your new function. ImageFormat should be restricted to 24 bit or higher. Honestly can't recall whether GDI+ allows creating of blank 16bit or not? However, anything less than 16bit requires a palette and your code doesn't currently support that. If GDI+ doesn't support creation (via Scan0 method) of specific bit depths, it uses the next higher depth it does support, or defaults to 32bit as a last resort

Quote:

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Originally Posted by LaVolpe

Very slight pixel modification due to rounding during premultiplication. However, theoretically faster internal GDI+ usage, especially if intending to render to an old-fashioned GDI device context

Enjoy.

Edited: One flaw with your new function. ImageFormat should be restricted to 24 bit or higher. Honestly can't recall whether GDI+ allows creating of blank 16bit or not? However, anything less than 16bit requires a palette and your code doesn't currently support that. If GDI+ doesn't support creation (via Scan0 method) of specific bit depths, it uses the next higher depth it does support, or defaults to 32bit as a last resort

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Ok, I mean.

Last (stupid) question, regarding plain BMP (24 bit) and VB6 StdPicture object.

If I use the code

Code:

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Dim thePic as StdPicture
set thePic = LoadPicture("background.bmp")

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I get the bitmap inside StdPicture object; then I can pass it to control's .Picture property to show it. Fine.

But if bmp is a set of contiguos icons of 32x32 size, and I'd like to create an array of n 32x32 StdPicture objects, each one with his own n-icon graphics from original bmp, how can I do this without any .hDC available??

I'm trying to use the .Render method of the StdPicture object, but it requires .hDC. More, if I create a new instance of StdPictures, Width, Height, Handle all equals 0.

I tried to create in-memory bitmap 32x32 and convert it to StdPicture via OleCreatePictureIndirect() and I get correct properties values, but Render method fails.

Have you some suggestions??

Thanks a lot!

I'm surprised that .Render method of stdPicture would fail on a valid stdPicture object?

As far as an array of stdPicture objects, that can be done a few ways. Using a VB control called PictureClip I believe? You could also do this with these classes or using a hidden picturebox (autoredraw=true & sized to 32x32).

The logic for these classes, looks like this:
1) Use your new function to create a memory 32x32 (24 bit) bitmap
2) Load the bitmap that has the strip of 32x32 images into a separate image class
3) Using cGDIpRenderer, draw the current 32x32 block, offsetting x,y as needed, to the blank image
4) in that image class, Save the 32x32 image to a bitmap array that you can send to OleCreatePictureIndirect
5) now blank out that memory bitmap using cGDIpRenderer.EraseHGraphics
6) repeat steps 3-5 for each 32x32 block
7) destroy the created Graphics object & unload your classes

The logic for VB's picbox is very similar
1) PicboxBuffer: autoredraw=true, sized to 32x32 inside width (or 32x32 without borders)
2) Set PicboxBuffer.Picture = Nothing
3) BitBlt or stdPicture.Render a 32x32 block, offsetting x,y as needed, to PicboxBuffer.hDC
4) Set PicboxBuffer.Picture = PicboxBuffer.Image
5) cache PicboxBuffer.Picture to a new stdPicture object
6) repeat steps 2-5 for each 32x32 block
7) Clean up: Set PicboxBuffer.Picture = Nothing: PicboxBuffer.AutoRedraw = False, etc

The above is air-code. Hopefully I didn't miss an obvious (or subtle) step anywhere. Sounds like you are a good coder & can fill in any blanks I may have missed.

Edited: I just glanced over a comment you made and shouldn't have. You don't want to use an .hDC? Sounds like this is a class-based issue then? Just FYI: You always have an hDC to render to, just need to create one via GDI API calls. Of course that usually means you have to create a bitmap (GDI calls) & move it in & out of the hDC as needed. Using the 1st idea above avoids those extra steps since the classes have the necessary code to get what you want.

Quote:

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Originally Posted by rebo

Hello; I am not so clever person. So I need your help: I want to display PNG data from a vCard in a picturebox. I already decoded the base64 data into an byte array. I would prefer to convert the data into a StdPicture to load it easily into the picturebox or imagebox.
Please can you provide me the minimal code for this? I need a function like this:

Private Function GetPictureFromPNGArray(PNG() as Byte) as StdPicture

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It seems you ignore me here. :mad:

Quote:

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Originally Posted by rebo

It seems you ignore me here. :mad:

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Don't be mad. I took over a year off from this forum. When I came back I was ignoring all posts that were 1+ years old ;)

You have two issues:
1) VB6 does not support PNG as a stdPicture. The PNG will have to be converted to a bitmap/jpg for use in the stdPicture object
2) The classes in this project do not directly support saving any images to a stdPicture object

So, workarounds.
1) Consider using my AlphaImage control. It accepts base64 and can also save to various formats, including saving to a stdPicture object. However, that control was an attempt to replace VB's image control. So all you have to do is simply add it to a form and use it as is.
2) There are several examples of sending a byte array to the OleCreatePictureIndirect API. If you search for that API in the VB forum, you will find examples. So, what you can do is send the PNG array to the cGDIpImage class' LoadPicture_Stream function to create an image. Then call the SaveAsBMP or SaveAsJPG method and pass the array returned from those functions to the OleCreatePictureIndirect API to create a stdPicture

Thank you very much! :wave:

Thanks for your reply!

Quote:

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Originally Posted by LaVolpe

I'm surprised that .Render method of stdPicture would fail on a valid stdPicture object?

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You can try by yourself.. creating a new StdPicture you won't get a valid bitmap behind the object.. you have to get a reference from an existing .Picture from PictureBox or use LoadImage() function.. really strange!

Quote:

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Originally Posted by LaVolpe

As far as an array of stdPicture objects, that can be done a few ways. Using a VB control called PictureClip I believe? You could also do this with these classes or using a hidden picturebox (autoredraw=true & sized to 32x32).

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Oh, that was only an example.. I don't really need a PictureClip control, or, at least, I don't need only that kind of solution.. For example, I'm implementing some code for 9patch images: starting from 256x256 .png button I've to create some other buttons in different sizes (100x80, 180x120, 90x45..) and each one, once created with your classes and pasted over a graphic background (a photo for example), I need to keep it in memory, in the form of StdPicture object, so is very easy to assign it to the corresponding PictureBox control on the form.

Quote:

---

Originally Posted by LaVolpe

The logic for these classes, looks like this:
1) Use your new function to create a memory 32x32 (24 bit) bitmap
2) Load the bitmap that has the strip of 32x32 images into a separate image class
3) Using cGDIpRenderer, draw the current 32x32 block, offsetting x,y as needed, to the blank image
4) in that image class, Save the 32x32 image to a bitmap array that you can send to OleCreatePictureIndirect
5) now blank out that memory bitmap using cGDIpRenderer.EraseHGraphics
6) repeat steps 3-5 for each 32x32 block
7) destroy the created Graphics object & unload your classes

The logic for VB's picbox is very similar
1) PicboxBuffer: autoredraw=true, sized to 32x32 inside width (or 32x32 without borders)
2) Set PicboxBuffer.Picture = Nothing
3) BitBlt or stdPicture.Render a 32x32 block, offsetting x,y as needed, to PicboxBuffer.hDC
4) Set PicboxBuffer.Picture = PicboxBuffer.Image
5) cache PicboxBuffer.Picture to a new stdPicture object
6) repeat steps 2-5 for each 32x32 block
7) Clean up: Set PicboxBuffer.Picture = Nothing: PicboxBuffer.AutoRedraw = False, etc

The above is air-code. Hopefully I didn't miss an obvious (or subtle) step anywhere. Sounds like you are a good coder & can fill in any blanks I may have missed.

Edited: I just glanced over a comment you made and shouldn't have. You don't want to use an .hDC? Sounds like this is a class-based issue then? Just FYI: You always have an hDC to render to, just need to create one via GDI API calls. Of course that usually means you have to create a bitmap (GDI calls) & move it in & out of the hDC as needed. Using the 1st idea above avoids those extra steps since the classes have the necessary code to get what you want.

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However the code to create 9-path images and all the other graphics will be the best to be keept in common classes/modules, without the need of a form and a hidden PictureBox control. That's the reason why I said "no .dHC", I don't (want to) have a PictureBox to use for graphics pourposes, and if I can load sources images from files, I need a "destination surface" in memory, and I've to create it from scratch.. Your classes can manage this (now with GdipCreateBitmapFromScan0) but I don't want to bother GDI+ to create a plain 24bit bitmap for raster operation, so I developed the following code to create an in-memory bitmap using the standard GDI APIs, and convert it back to StdPicture object I cas store in a Collection for faster later use.

Code:

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Option Explicit

Private Declare Function OleCreatePictureIndirect Lib "olepro32.dll" (lpPictDesc As PICTDESC, RefIID As GUID, ByVal fPictureOwnsHandle As Long, IPic As Any) As Long
Private Declare Function CreateCompatibleDC Lib "gdi32.dll" (ByVal hDC As Long) As Long
Private Declare Function DeleteDC Lib "gdi32.dll" (ByVal hDC As Long) As Long
Private Declare Function DeleteObject Lib "gdi32.dll" (ByVal hObject As Long) As Long
Private Declare Function GetObjectType Lib "gdi32.dll" (ByVal hGDIObj As Long) As Long
Private Declare Function GetObject Lib "gdi32.dll" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
Private Declare Function SelectObject Lib "gdi32.dll" (ByVal hDC As Long, ByVal hObject As Long) As Long
Private Declare Function CreateDIBSection Lib "gdi32.dll" (ByVal hDC As Long, pBitmapInfo As BitmapInfo, ByVal un As Long, ByRef lplpDIBS As Long, ByVal handle As Long, ByVal dw As Long) As Long
Private Declare Function FillMemory Lib "kernel32.dll" Alias "RtlFillMemory" (ByRef Destination As Any, ByVal Length As Long, ByVal Fill As Byte) As Long
Private Declare Function FillRect Lib "user32.dll" (ByVal hDC As Long, lpRC As RECT, ByVal hBR As Long) As Long
Private Declare Function CreateSolidBrush Lib "gdi32.dll" (ByVal crColor As Long) As Long

Private Const OBJ_BITMAP As Long = &H7
Private Const PICTYPE_BITMAP As Long = &H1

Private Const BI_RGB = 0
Private Const DIB_RGB_COLORS = 0

Private Type GUID
  Data1 As Long
  Data2 As Integer
  Data3 As Integer
  Data4(7) As Byte
End Type

Private Type PICTDESC
  cbSize As Long
  picType As Long
  hImage As Long
  xExt As Long
  yExt As Long
End Type

Private Type BitmapInfoHeader '40 bytes
  biSize As Long
  biWidth As Long
  biHeight As Long
  biPlanes As Integer
  biBitCount As Integer
  biCompression As Long
  biSizeImage As Long
  biXPelsPerMeter As Long
  biYPelsPerMeter As Long
  biClrUsed As Long
  biClrImportant As Long
End Type

Private Type RGBQUAD
  rgbBlue As Byte
  rgbGreen As Byte
  rgbRed As Byte
  rgbReserved As Byte
End Type

Private Type BitmapInfo
  bmiHeader As BitmapInfoHeader
  bmiColors As RGBQUAD
End Type

Private Type RECT
  nLeft  As Long
  nTop    As Long
  nWidth  As Long
  nHeight As Long
End Type

Private Type BITMAP
  bmType As Long
  bmWidth As Long
  bmHeight As Long
  bmWidthBytes As Long
  bmPlanes As Integer
  bmBitsPixel As Integer
  bmBits As Long
End Type

Public Function CreateStdPicture(Width As Long, Height As Long, Optional BackgroundColor As OLE_COLOR = vbBlack) As IPicture

  Dim pbmi      As BitmapInfo
 
  Dim hDC      As Long
  Dim hBMP      As Long
  Dim hDIBS    As Long
  Dim hOldBMP  As Long
  Dim hBrush    As Long
  Dim tRECT    As RECT
 
  Dim lResult  As Long

  'Prepara informazioni per la generazione del bitmap
  With pbmi.bmiHeader
    .biSize = Len(pbmi.bmiHeader)
    .biBitCount = 24
    .biCompression = BI_RGB
    .biPlanes = 1
    .biWidth = Width
    .biHeight = Height
    .biSizeImage = ((((Width * .biBitCount) + &H1F) And Not &H1F) \ &H8) * Height
  End With

  'Crea in memoria un DC compatibile con lo schermo
  hDC = CreateCompatibleDC(0)

  'Crea un BMP compatibile con il DC creato
  hBMP = CreateDIBSection(hDC, pbmi, DIB_RGB_COLORS, hDIBS, ByVal 0&, ByVal 0&)
 
  'Azzera contenuto
  FillMemory ByVal hDIBS, pbmi.bmiHeader.biSizeImage, 0
 
  'Se colore diverso da nero, effettua un fill dell'area del BMP
  If (BackgroundColor <> vbBlack) Then
 
    'Seleziona il BMP nel DC
    hOldBMP = SelectObject(hDC, hBMP)
   
    'Colora il bitmap con il colore di sfondo
    With tRECT
      .nTop = 0
      .nLeft = 0
      .nWidth = Width
      .nHeight = Height
    End With
   
    'Crea un brush solido
    hBrush = CreateSolidBrush(BackgroundColor)
   
    'Riempie il bitmap con il brush creato
    lResult = FillRect(hDC, tRECT, hBrush)
   
    'Elimina il brush
    lResult = DeleteObject(hBrush)
   
    'Rilascia il BMP
    SelectObject hDC, hOldBMP
 
  End If
 
  'Distrugge il DC generato, mentre il BMP rimane valido e verrà automaticamente distrutto al momento della distruzione dell'oggetto
  'OLE generato tramite la GDIToPicture(), grazie all'automazione offerta dall'interfaccia IDispatch
  lResult = DeleteDC(hDC)
 
  'Converte in IPicture e ritorna l'oggetto
  Set CreateStdPicture = GDIToPicture(hBMP)

End Function

Public Function GDIToPicture(ByVal hGDIObj As Long) As IPicture
 
  Dim PicDesc  As PICTDESC
  Dim IPict    As IPicture
 
  Dim lObjType  As Long
  Dim lResult  As Long
 
  'Recupera tipologia di oggetto presente nell'handle passato
  lObjType = GetObjectType(hGDIObj)
 
  Select Case lObjType
     
      Case OBJ_BITMAP
        PicDesc.cbSize = 16
        PicDesc.picType = PICTYPE_BITMAP
       
      Case Else
        'Oggetto non riconosciuto
        Exit Function
       
  End Select
 
  'Imposta l'handle del DC
  PicDesc.hImage = hGDIObj
 
  'Tenta la conversione da BMP a StdPicture
  lResult = OleCreatePictureIndirect(PicDesc, IPictureGUID(), 1, IPict)
  If (lResult = 0) Then Set GDIToPicture = IPict
 
  'Scarica riferimento all'oggetto IPucture locale
  Set IPict = Nothing
   
End Function

Private Function IPictureGUID() As GUID
 
  'IPicture GUID {7BF80980-BF32-101A-8BBB-00AA00300CAB}
  With IPictureGUID
    .Data1 = &H7BF80980
    .Data2 = &HBF32
    .Data3 = &H101A
    .Data4(0) = &H8B
    .Data4(1) = &HBB
    .Data4(2) = &H0
    .Data4(3) = &HAA
    .Data4(4) = &H0
    .Data4(5) = &H30
    .Data4(6) = &HC
    .Data4(7) = &HAB
  End With
 
End Function

Public Sub RenderStdPicture(SourcePic As IPicture, DestPic As IPicture, Optional X As Long = -1, Optional Y As Long = -1, Optional Width As Long = -1, Optional Height As Long = -1, Optional xSrc As Long = -1, Optional ySrc As Long = -1, Optional WidthSrc As Long = -1, Optional HeightSrc As Long = -1)
 
  Dim hDC      As Long
  Dim hBMP      As Long
  Dim hOldBMP  As Long
 
  Dim tBITMAP  As BITMAP
  Dim lResult  As Long
 
  'Effettua render delle due StdPicuture
 
  'Verifica i valori x,y,width,height. I parametri devono essere espressi tutti in Pixel
  If (X = -1) Then X = 0
  If (Y = -1) Then Y = 0
  If (Width = -1) Then Width = HimetricToPixelX(SourcePic.Width)
  If (Height = -1) Then Height = HimetricToPixelY(SourcePic.Height)
  If (xSrc = -1) Then xSrc = 0
  If (ySrc = -1) Then ySrc = 0
  If (WidthSrc = -1) Then WidthSrc = HimetricToPixelX(SourcePic.Width)
  If (HeightSrc = -1) Then HeightSrc = HimetricToPixelY(SourcePic.Height)

  'Crea un DC per la StdPicture di destinazione
  hDC = CreateCompatibleDC(0)

  'Seleziona il BMP nel DC
  hOldBMP = SelectObject(hDC, DestPic.handle)
 
  'Effettua il render
  SourcePic.Render hDC, X, Y, Width, Height, PixelToHimetricX(xSrc), SourcePic.Height - PixelToHimetricY(ySrc), PixelToHimetricX(WidthSrc), -PixelToHimetricY(HeightSrc), 0&
   
  'Rilascia il BMP
  SelectObject hDC, hOldBMP
   
  'Distrugge il DC generato
  lResult = DeleteDC(hDC)
 
End Sub

Private Function HimetricToPixelY(Value As Long) As Long

  HimetricToPixelY = (CDbl(Value) / 1000) * 567 / Screen.TwipsPerPixelY

End Function

Private Function PixelToHimetricY(Value As Long) As Long

  PixelToHimetricY = (CDbl(Value) * 1000) / 567 * Screen.TwipsPerPixelY

End Function

Private Function HimetricToPixelX(Value As Long) As Long

  HimetricToPixelX = (CDbl(Value) / 1000) * 567 / Screen.TwipsPerPixelX

End Function

Private Function PixelToHimetricX(Value As Long) As Long

  PixelToHimetricX = (CDbl(Value) * 1000) / 567 * Screen.TwipsPerPixelX

End Function

---

What do you think about this way to deal with graphics resources?!?

In case you want to handle your graphics without any Controls - and store them in a
VB-Collection as StdPictures as a kind of global ImageCache...

I've managed that already in a combination of GDI+ based PNG-Loading - and then storing
the resulting DIBs (as 32Bit ones, including the AlphaChannel) in normal StdPictures.

That is managed in a small wrapper-class (cPngCacheGDIP), which when declared globally
(and then filled with PNG-resources at App-Startup) - would then be reachable throughout
your Application, to render its preloaded Alpha-Image-StdPictures "per Key".

The appropriate codebank-example is here:
http://www.vbforums.com/showthread.p...ely-per-WIA%29

Not sure if that is more like, what you are after?

Here's a variation of the above, which is using the base-mechanism (the cPngCacheGDIP),
in lightweight UserControl-encapsulations - but that's not as "pure VBClass-driven" anymore,
as the example in the above link.
http://www.vbforums.com/showthread.p...mage-Sprite%29


Olaf

Quote:

---

Originally Posted by minimega

What do you think about this way to deal with graphics resources?!?

---

There are various ways to deal with graphics. In my alpha image control, I don't use stdPictures at all, but since VB uses them, that control has a SaveAs option to create them if the user needs them.

I must stress that these classes were not designed to be a graphics factory for any serious projects. There were designed to get people comfortable with using GDI+, more or less: "Graphics 101 with GDI+", borrowing college terminology as a play on words.

Hey LaVolpe, just a note of appreciation - these classes are awesome for my purposes and are very much appreciated as they saved me tons of time. I've been using Freeimage in this particular application for several years now but I've decided to streamline the code and that my program doesn't really need to support 23+ image formats. And using GDI+ internally dumps the dependence on the Freeimage dll as well. Anyway, thanks again for the fine work!

Quote:

---

Originally Posted by rebo

Thank you very much! :wave:

---

I can't believe it. This guy was waiting for a response almost 2 years... No doubt it is a record of this forum :)
My respect, Rebo.

Can someone give me minimal code which will load and display an ICO file into a PictureBox? Thanks in advance!

Minimal code: Picture1.Picture = LoadPicture(path/filename)

Maybe you can more specific. To handle icons that O/S supports but VB doesn't

Code:

---

hIcon = LoadImage(0&, path/filename, IMAGE_ICON, desiredWidth, desiredHeight, LR_LOADFROMFILE)
If hIcon Then
    DrawIconEx Picture1.hDC, 0, 0, hIcon, targetWidth, targetHeight, 0, 0, DI_NORMAL)
    DestroyIcon hIcon
End If

---

LoadImage: https://msdn.microsoft.com/en-us/lib...=vs.85%29.aspx
DrawIconEx: https://msdn.microsoft.com/en-us/lib...=vs.85%29.aspx

EDIT: Fixed, thanks very much for this!

Here is the final code:

Code:

---

Private Declare Function LoadImage Lib "user32" Alias "LoadImageA" (ByVal hInst As Long, ByVal lpsz As String, ByVal dwImageType As Long, ByVal dwDesiredWidth As Long, ByVal dwDesiredHeight As Long, ByVal dwFlags As Long) As Long
Private Declare Function DrawIconEx Lib "user32.dll" (ByVal hdc As Long, ByVal xLeft As Long, ByVal yTop As Long, ByVal hIcon As Long, ByVal cxWidth As Long, ByVal cyWidth As Long, ByVal istepIfAniCur As Long, ByVal hbrFlickerFreeDraw As Long, ByVal diFlags As Long) As Long
Private Declare Function DestroyIcon Lib "user32.dll" (ByVal hIcon As Long) As Long
Private Const IMAGE_ICON As Long = 1
Private Const LR_LOADFROMFILE As Long = &H10
Private Const DI_NORMAL As Long = &H3

Private Sub Command1_Click()
Dim hIcon As Long
Picture1.Picture = Nothing
hIcon = LoadImage(0&, App.Path & "\1.ico", IMAGE_ICON, 0&, 0&, LR_LOADFROMFILE)
If hIcon Then
    DrawIconEx Picture1.hDC, 0, 0, hIcon, 0&, 0&, 0&, 0&, DI_NORMAL
    DestroyIcon hIcon
End If
End Sub

---

Sorry, this is a bit off-topic, but I'm having another issue now - the PictureBox content erases after I drag some window above it. How can I keep (redraw) the loaded icon?

Picture1.AutoRedraw = True

That was so simple... :bigyello: Thanks again!

You're welcome. GDI+ is overkill for most icon needs and GDI+ doesn't even handle icons as well as it should. Good old fashioned GDI works well enough for simple needs.

In " Private Sub pvModifyAttributes() ", If We set m_GrayScale > 0 and m_Lightness <>0, the clrMatrix(1,1) and clrMatrix(2, 2) will conflict ? If so, should we separate them into two Sub or Call GdipSetImageAttributesColorMatrix after new m_GrayScale?

Code:

---

Private Sub pvModifyAttributes()

    If m_GrayScale > attrGrayNone Then ' apply grayscale ratios
      '...
      ' grayscale the image
            clrMatrix(0, 0) = R: clrMatrix(1, 0) = R: clrMatrix(2, 0) = R
            clrMatrix(0, 1) = G: clrMatrix(1, 1) = G: clrMatrix(2, 1) = G
            clrMatrix(0, 2) = B: clrMatrix(1, 2) = B: clrMatrix(2, 2) = B
            clrMatrix(3, 3) = CSng((100! - m_Alpha) / 100!)  ' global blending; value between 0 & 1
            clrMatrix(4, 4) = 1! ' required; cannot be anything else
        End If
        If m_Lightness <> 0! Then ' add/subtract light intensity
            If clrMatrix(4, 4) = 0! Then
                clrMatrix(0, 0) = 1!: clrMatrix(1, 1) = 1!: clrMatrix(2, 2) = 1!
                clrMatrix(3, 3) = CSng((100! - m_Alpha) / 100!)  ' global blending; value between 0 & 1
                clrMatrix(4, 4) = 1! ' required; cannot be anything else
            End If
            clrMatrix(0, 4) = m_Lightness / 100! ' red added/subtracted brightness
            clrMatrix(1, 4) = clrMatrix(0, 4)    ' same for blue
            clrMatrix(2, 4) = clrMatrix(0, 4)    ' same for green
        End If
        '...

End Sub

---

Jonney, nope. Notice that clrMatrix(4, 4) is set to non-null when grayscale matrix was created. The lightness matrix section is only filling in those matrix items if clrMatrix(4, 4) is null. That should be the case for all the matrix sections. Only fill in the required items if they haven't already been filled in.

My alpha image control rewrote that logic, but fundamentally, it uses the same checks & balances.

Quote:

---

Originally Posted by LaVolpe

Jonney, nope. Notice that clrMatrix(4, 4) is set to non-null when grayscale matrix was created. The lightness matrix section is only filling in those matrix items if clrMatrix(4, 4) is null. That should be the case for all the matrix sections. Only fill in the required items if they haven't already been filled in.

My alpha image control rewrote that logic, but fundamentally, it uses the same checks & balances.

---

I miss the check. :D

I am troubleshooting why the alpha doesn't work： hGraphics bind to hImage.

Code:

---

GdipGetImageGraphicsContext hImage, hGraphics
imgAttributesHandle = pvModifyAttributes(Alpha,Lightness, TransColor,GrayScale)
GdipDrawImageRectRectI hGraphics, hImage, 0, 0, imgWidth, imgHeight, 0, 0, imgWidth, imgHeight, UnitPixel, imgAttributesHandle
If imgAttributesHandle Then GdipDisposeImageAttributes imgAttributesHandle
GdipDeleteGraphics hGraphics

---

Edited:
But this one is OK: hGraphics created by hdc.

Code:

---

Public Sub gdipStretchPicture(ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal Width As Long, ByVal Height As Long, hImage As Long, ByVal srcX As Long, ByVal srcY As Long, ByVal srcWidth As Long, ByVal srcHeight As Long, Optional ByVal srcUnit As GpUnit = UnitPixel)
 
  If hImage <> 0 Then
      Dim hGraphics As Long
      GdipCreateFromHDC hdc, hGraphics
      Dim Attributes As Long                              'Testing Code
      Attributes = pvModifyAttributes(70, 0, 0, 1)  'Testing Code
      GdipDrawImageRectRectI hGraphics, hImage, x, y, Width, Height, srcX, srcY, srcWidth, srcHeight, srcUnit, Attributes
      If Attributes <> 0 Then GdipDisposeImageAttributes Attributes
      GdipReleaseDC hGraphics, hdc
      GdipDeleteGraphics hGraphics
  End If
 
End Sub

---

What is TransColor? I assume that is what you are talking about. Remember that most color references in GDI+ are BGR vs RGB
How do you use it in your version of pvModifyAttributes? May need to see that code portion

Quote:

---

Originally Posted by LaVolpe

What is TransColor? I assume that is what you are talking about. Remember that most color references in GDI+ are BGR vs RGB
How do you use it in your version of pvModifyAttributes? May need to see that code portion

---

Please refresh the page, I have edited my writing.
I think this rung has problem. They overide each other?

Quote:

---

GdipGetImageGraphicsContext hImage, hGraphics
imgAttributesHandle = pvModifyAttributes(Alpha,Lightness, TransColor,GrayScale)
GdipDrawImageRectRectI hGraphics, hImage, 0, 0, imgWidth, imgHeight, 0, 0, imgWidth, imgHeight, UnitPixel, imgAttributesHandle
If imgAttributesHandle Then GdipDisposeImageAttributes imgAttributesHandle
GdipDeleteGraphics hGraphics

---

my usage is not correct I think. But why others like Lightness and GrayScale work? Only Alpha doesn't take effect.
Do we have to use GdipDrawImageRectRectI to apply the attribute for hImage, any other GDI+ API?

Code:

---

Private Function pvModifyAttributes(Optional Alpha As Long = 0, Optional ByVal Lightness As Long = 0, Optional ByVal TransColor As OLE_COLOR = 0, Optional ByVal eGrayScale As GrayScaleConstants = 0) As Long


' about attributes.
' The following are added to a GDI+ attributes handle:
'      eGrayScale, GlobalTranparency, GlobalLightness, ExtraTransparency
' Mirroring is done inside the GDI+ image itself
' Rotation is done via DC WorldTransformation on-the-fly when rendering
' So to determine if any attributes are in play, 3 variables must be checked:
'  Inplay = ((Me.ImageAttributesHandle=0& And Me.Rotation=0! And Me.Mirrored=attrMirrorNone) = False)
   
    Dim Attr As Long
    If Alpha <> 0 Or Lightness <> 0 Or TransColor <> 0 Or eGrayScale <> 0 Then
      Call GdipCreateImageAttributes(Attr)
    Else
      Exit Function
    End If
   
    Dim clrMatrix(0 To 4, 0 To 4) As Single
    Dim r As Single, g As Single, b As Single
    Const ColorAdjustTypeBitmap As Long = &H1&
   
    'ColorMatrix ClrMatrix ={
    '        1.0f, 0.0f, 0.0f, 0.0f, 0.0f,
    '        0.0f, 1.0f, 0.0f, 0.0f, 0.0f,
    '        0.0f, 0.0f, 1.0f, 0.0f, 0.0f,
    '        0.0f, 0.0f, 0.0f, 0.5f, 0.0f, //Alpha =0.5  (50% Transparency)
    '        0.0f, 0.0f, 0.0f, 0.0f, 1.0f };
   
        If eGrayScale > attrGrayNone Then ' apply grayscale ratios
            Select Case eGrayScale
            Case attrGrayNTSCPAL
                r = 0.299: g = 0.587: b = 0.114 ' standard weighted average
            Case attrGraySimpleAverage
                r = 0.333: g = 0.334: b = r    ' pure average
            Case attrGrayCCIR709
                r = 0.213: g = 0.715: b = 0.072 ' CCIR709
            Case attrGrayRedMask
                r = 0.8: g = 0.1: b = g    ' personal preferences: could be r=1:g=0:b=0 or other weights
            Case attrGrayGreenMask
                r = 0.1: g = 0.8: b = r    ' personal preferences: could be r=0:g=1:b=0 or other weights
            Case attrGrayBlueMask
                r = 0.1: g = r: b = 0.8    ' personal preferences: could be r=0:g=0:b=1 or other weights
            Case attrGrayBlueGreenMask
                r = 0.1: g = 0.45: b = g    ' personal preferences: could be r=0:g=.5:b=.5 or other weights
            Case attrGrayRedGreenMask
                r = 0.45: g = r: b = 0.1    ' personal preferences: could be r=.5:g=.5:b=0 or other weights
            End Select
            ' grayscale the image
            clrMatrix(0, 0) = r: clrMatrix(1, 0) = r: clrMatrix(2, 0) = r
            clrMatrix(0, 1) = g: clrMatrix(1, 1) = g: clrMatrix(2, 1) = g
            clrMatrix(0, 2) = b: clrMatrix(1, 2) = b: clrMatrix(2, 2) = b
            clrMatrix(3, 3) = CSng((100! - Alpha) / 100!)  ' global blending; value between 0 & 1
            clrMatrix(4, 4) = 1! ' required; cannot be anything else
        End If
        If Lightness <> 0! Then ' add/subtract light intensity
            If clrMatrix(4, 4) = 0! Then
                clrMatrix(0, 0) = 1!: clrMatrix(1, 1) = 1!: clrMatrix(2, 2) = 1!
                clrMatrix(3, 3) = CSng((100! - Alpha) / 100!)  ' global blending; value between 0 & 1
                clrMatrix(4, 4) = 1! ' required; cannot be anything else
            End If
            clrMatrix(0, 4) = Lightness / 100! ' red added/subtracted brightness
            clrMatrix(1, 4) = clrMatrix(0, 4)    ' same for blue
            clrMatrix(2, 4) = clrMatrix(0, 4)    ' same for green
        End If
        If Alpha <> 0! Then ' add global transparency
            If clrMatrix(4, 4) = 0! Then
                clrMatrix(0, 0) = 1!: clrMatrix(1, 1) = 1!: clrMatrix(2, 2) = 1!
                clrMatrix(3, 3) = CSng((100! - Alpha) / 100!) ' global blending; value between 0 & 1
                clrMatrix(4, 4) = 1! ' required; cannot be anything else
            End If
        End If
        If clrMatrix(4, 4) = 1! Then ' create attributes?
            If GdipCreateImageAttributes(Attr) = 0& Then
                If GdipSetImageAttributesColorMatrix(Attr, ColorAdjustTypeBitmap, 1&, clrMatrix(0, 0), clrMatrix(0, 0), 0&) Then
                    GdipDisposeImageAttributes Attr
                    Attr = 0&
                End If
            End If
        End If
        If TransColor Then
            If Attr = 0& Then Call GdipCreateImageAttributes(Attr)
            If Attr Then
                If GdipSetImageAttributesColorKeys(Attr, 1&, 1&, TransColor, TransColor) Then ' failure
                    If clrMatrix(4, 4) = 0! Then
                        GdipDisposeImageAttributes Attr
                        Attr = 0&
                    End If
                End If
            End If
        End If
       
        pvModifyAttributes = Attr
       
End Function

---

OK. I expose the return of pvModifyAttributes to my Image Class Public Property: Image.gdpiAttributes so that the attributes can be applied when calling gdipStretchPicture. My Image Class will take care Dispose.

Code:

---

Public Sub gdipStretchPicture(ByVal hdc As Long, ByVal x As Long, ByVal y As Long, ByVal Width As Long, ByVal Height As Long, hImage As Long, ByVal srcX As Long, ByVal srcY As Long, ByVal srcWidth As Long, ByVal srcHeight As Long, Optional ByVal srcUnit As GpUnit = UnitPixel,Optional Byval Attributes As Long =0)
 
  If hImage <> 0 Then
      Dim hGraphics As Long
      GdipCreateFromHDC hdc, hGraphics
      GdipDrawImageRectRectI hGraphics, hImage, x, y, Width, Height, srcX, srcY, srcWidth, srcHeight, srcUnit, Attributes
      GdipReleaseDC hGraphics, hdc
      GdipDeleteGraphics hGraphics
  End If

---

I see what you were trying to do by binding it to the image. The reason why the alpha doesn't work is because the pixel data is still on the image. You are rendering semi-transparency over the same image. You can't make an existing image less transparent by rendering something over it. Blending same images on each other, changing only transparency, should result in no change to the image.

It would be like taking a screen capture of the desktop. Then rendering another copy of the desktop over the 1st one, just at 70% transparency. You should see no difference after rendering. However, if the 70% version was rendered on some other image, then you'd see the semi-transparent blended into that other image.

Quote:

---

Originally Posted by LaVolpe

I see what you were trying to do by binding it to the image. The reason why the alpha doesn't work is because the pixel data is still on the image. You are rendering semi-transparency over the same image. You can't make an existing image less transparent by rendering something over it. Blending same images on each other, changing only transparency, should result in no change to the image.

It would be like taking a screen capture of the desktop. Then rendering another copy of the desktop over the 1st one, just at 70% transparency. You should see no difference after rendering. However, if the 70% version was rendered on some other image, then you'd see the semi-transparent blended into that other image.

---

I can't get sleep in whole night for this GDI+ matter.
Thanks for this analyst. I learned the lesson.
Thank you Sir.

@LaVolpe: Can you help me again, I need a basic example on how to load and display GIF image, first frame?

First frame is always displayed first. Simply load the image via GDI+ or VB's LoadPicture() which also supports GIF. Not sure I understand the problem.

Quote:

---

Originally Posted by LaVolpe

Fist frame is always displayed first. Simply load the image via GDI+ or VB's LoadPicture() which also supports GIF. Not sure I understand the problem.

---

tired with all kinds of strange questions.

Quote:

---

Originally Posted by Jonney

tired with all kinds of strange questions.

---

Gut feeling is that that is not the entire question or not stated completely

I want simple GDI+ API code which will load GIF image and display its first frame in a PictureBox, because LoadPicture loads it in poor quality.

GDIpLoadImageFromFile/GdipLoadImageFromStream will load a properly formatted GIF. VB's LoadPicture will do the same. Both will have the exact same quality at 100% scale. In any case, the 1st frame is always rendered initially.

After reading your edited comment:
You can extract the code from this project to do what you are asking. The steps would look like this:

1. Load image via GDIpLoadImageFromFile
2. Get picturebox DC into GDI+ graphics object via GDIpCreateFromHDC
3. Set bicubic scaling on the graphics object via GdipSetInterpolationMode
4. Get the image bounds via GDIpGetImageBounds
5. Render the image to the graphics object: GDIpDrawImageRectRect or GDIpDrawImageRectRectI
6. Destroy the GDI+ graphics & image objects

Using your topic, I wonder how I can save only one area (x, y, heigh, width) of the image using the code below

Quote:

---

Dim bData() As Byte, fn As Integer, bOk As Boolean
Dim tImage() As cGDIpImage

On Error GoTo ExitRoutine

bOk = cImage.SaveAsJPG(bData(), , True)
If bOk = False Then
MsgBox "Failed to save to the desired image format", vbInformation + vbOKOnly
Else
fn = FreeFile()
Open "c:\teste.jpg" For Binary As #fn
Put #fn, 1, bData()
Close #fn
MsgBox "File saved", vbInformation + vbOKOnly
End If

ExitRoutine:
If fn Then
Close #fn
If Err Then MsgBox Err.Description, vbExclamation + vbOKOnly
End If

---

LaVolpe: please correct that link on #1 post. the link isn't working for i see the GDIPlus API functions.
thanks for all

Lavolpe, I know this post is rather old (and dead) but I needed that routine (bonus code Post #8) to load png simply.
Post #21 as you stated contain a fix, but the solution was incompleted and bugged too (m_Size.nWidth, m_Size.nWidth instead of m_Size.nWidth, m_Size.nHeight) so I decided to provide missing code to make your bonus code fully work.
plz don't flame me. All the credit still go to you, thanks again.

Code:

---

Option Explicit

Private Const UNIT_PIXEL As Long = &H2&

Private Type GdiplusStartupInput
  GdiplusVersion          As Long
  DebugEventCallback      As Long
  SuppressBackgroundThread As Long
  SuppressExternalCodecs  As Long
End Type

Private Type RECTF
  nLeft As Single
  nTop As Single
  nWidth As Single
  nHeight As Single
End Type

Private Declare Function GdiplusStartup Lib "GdiPlus.dll" (Token As Long, inputbuf As GdiplusStartupInput, Optional ByVal outputbuf As Long = 0) As Long
Private Declare Function GdipLoadImageFromFile Lib "GdiPlus.dll" (ByVal mFilename As Long, ByRef mImage As Long) As Long
Private Declare Function GdipDeleteGraphics Lib "GdiPlus.dll" (ByVal mGraphics As Long) As Long
Private Declare Function GdipCreateFromHDC Lib "GdiPlus.dll" (ByVal hDC As Long, hGraphics As Long) As Long
Private Declare Function GdipDrawImage Lib "GdiPlus.dll" (ByVal mGraphics As Long, ByVal mImage As Long, ByVal mX As Single, ByVal mY As Single) As Long
Private Declare Function GdipDisposeImage Lib "GdiPlus.dll" (ByVal Image As Long) As Long
Private Declare Sub GdiplusShutdown Lib "GdiPlus.dll" (ByVal Token As Long)
Private Declare Function GdipGetImageBounds Lib "GdiPlus.dll" (ByVal nImage As Long, srcRect As RECTF, srcUnit As Long) As Long
Private Declare Function GdipDrawImageRectRectI Lib "GdiPlus.dll" (ByVal hGraphics As Long, ByVal hImage As Long, ByVal dstX As Long, ByVal dstY As Long, ByVal dstWidth As Long, ByVal dstHeight As Long, ByVal srcX As Long, ByVal srcY As Long, ByVal srcWidth As Long, ByVal srcHeight As Long, ByVal srcUnit As Long, Optional ByVal imageAttributes As Long = 0, Optional ByVal Callback As Long = 0, Optional ByVal callbackData As Long = 0) As Long

Public Function RenderPNG(FileName As String, hDC As Long, ByVal plngDestX As Long, ByVal plngDestY As Long) As Long
  Dim lngRetValue As Long
  Dim GDIsi As GdiplusStartupInput
  Dim gToken As Long
  Dim hGraphics As Long
  Dim hBitmap As Long
  Dim lngSuccess As Long
  Dim typPicSize As RECTF
 
  lngRetValue = 0

  On Error Resume Next
  GDIsi.GdiplusVersion = 1&
  lngSuccess = GdiplusStartup(gToken, GDIsi)
  'If Err Then
  '  Err.Clear
  '  Exit Function
  'ElseIf gToken = 0& Then
  '  Exit Function
  'End If
  On Error GoTo 0

  If (gToken <> 0) Then
    Call GdipCreateFromHDC(hDC, hGraphics)
    If hGraphics Then
      Call GdipLoadImageFromFile(StrPtr(FileName), hBitmap)
      If hBitmap Then
        'GdipDrawImage hGraphics, hBitmap, plngDestX, plngDestY
        Call GdipGetImageBounds(hBitmap, typPicSize, UNIT_PIXEL)
        Call GdipDrawImageRectRectI(hGraphics, hBitmap, plngDestX, plngDestY, typPicSize.nWidth, typPicSize.nHeight, 0, 0, typPicSize.nWidth, typPicSize.nHeight, UNIT_PIXEL, 0&, 0&, 0&)

        GdipDisposeImage hBitmap
        lngRetValue = 1
      End If
      GdipDeleteGraphics hGraphics
    End If
    GdiplusShutdown gToken
  End If
 
  RenderPNG = lngRetValue
End Function

calling is something like:
  'frmMain.Autorefresh = True
  RenderPNG strPath, frmMain.hDC, 0, 0
  frmMain.Refresh

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PolygonBlt isn't actually drawing a proper polygon, but a parallelogram. How would I draw an image as a polygon using an array of 4 POINTAPIs to set each corner's coordinate (like DrawPolygon, but drawing an image instead of a color). A parallelogram only lets me set 3 of the coordinates and GDI+ guesses the 4th, which is incorrect in my use case.

What you are asking, I don't believe there is an "easy" solution. Maybe there are free libraries out there that will do what you are asking. Without such a library/class, basically each pixel in the bitmap needs to be "stretched" proportionally to fill a dynamic shape/polygon. GDI+ offers a method of warping points to a polygon, but not a method to warp an image to other than a parallelogram (rectangle or otherwise). If you google "Free Image Transformation", you should see a project on CodeProject site. It isn't written in VB, but offers logic and a sample project. I do think you need an account to download the project.

Quote:

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Originally Posted by LaVolpe

What you are asking, I don't believe there is an "easy" solution. Maybe there are free libraries out there that will do what you are asking. Without such a library/class, basically each pixel in the bitmap needs to be "stretched" proportionally to fill a dynamic shape/polygon. GDI+ offers a method of warping points to a polygon, but not a method to warp an image to other than a parallelogram (rectangle or otherwise). If you google "Free Image Transformation", you should see a project on CodeProject site. It isn't written in VB, but offers logic and a sample project. I do think you need an account to download the project.

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Turns out I was wrong anyway. ParallelBlt worked just fine. Thank you though.

Hi there, what an amazing piece of code!

Sorry to bother you for this, but I noticed that saving a picture as a gif is not possible.

And for an old VB6 project I specifically need to convert png's to gif's...

Is there a simple way to add this feature to the existing code?

Any help would be greatly appreciated, thanks!

Hi there, what an amazing piece of code!

Sorry to bother you for this, but I noticed that saving a picture as a gif is not possible.

And for an old VB6 project I specifically need to convert png's to gif's...

Is there a simple way to add this feature to the existing code?

Any help would be greatly appreciated, thanks!

I was able to change the code a little bit so now it saves the png's to gif's, but how can I preserve transparency?

Not sure what code you are using to convert PNG to GIF. But if using GDI+ to create a GIF, the color format must be 8 byte, paletted image with transparency.

As for preserving transparency. That can be really difficult for PNG to GIF because of alphablending that most PNGs have. Typically, some sort of threshold is set to say if transparency is greater than x percent make the color transparent else make it opaque. One index of the 256 possible color indexes in that 8 byte format would be reserved for transparency. Every transparent pixel will be assigned that index. So you only have 255 possible colors for color reduction (if PNG has more than 255 colors) when transparency exists.

LaVolpe where can i see the GDIPlus functions declarations for VB6?