8-bit paletted graphics in memory [resolved]

I already have some idea how to do this, but it is all theory. I have no real knowledge how to assign a palette to a graphic in a memory - I haven't done a non 32-bit image before either. So if anyone has a simple example code / tutorial to go with, I'll be grateful :) My search results this far have given far too complicated codes atm, but I continue searching once I'm awake again.

Here are two tools i've made for my quake modifications (which uses 8-bit palette).

In palette.zip there is a program for editing the palette.

In convert.zip there is a program that converts 8/16/24/32 bit images to 8 bit using the palette. I've made a dll file in C that searches for closest matching color from the palette, and because I'm not that good at C I didn't make the program load the palette file, I've added the palette to the code instead. You'll have to make it load it yourself.

Have fun!

Quote:

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Originally posted by cyborg
Here are two tools i've made for my quake modifications (which uses 8-bit palette).

In palette.zip there is a program for editing the palette.

In convert.zip there is a program that converts 8/16/24/32 bit images to 8 bit using the palette. I've made a dll file in C that searches for closest matching color from the palette, and because I'm not that good at C I didn't make the program load the palette file, I've added the palette to the code instead. You'll have to make it load it yourself.

Have fun!

---

It's slow....

Yes it is, but why would you want to convert 32-bit images to 8-bit in realtime?

I don't need to convert images at all, as I have to read 8-bit images to memory and then view them with the correct palette. I might have found a code that works for me, but I can't test it until I can get as far as reading the data properly - sure is complicated not to be able to debug well, but I've always found a way :)

It's really easy to read 8-bit images...

The colors in a 8-bit image are from 0 to 255 so the palette should have the Red, Green and Blue values for each 256 colors.
Just load the palette into an array like this:

VB Code:

Private Type ColorUDT
    Red As Byte
    Green As Byte
    Blue As Byte
End Type
 
Dim Palette(255) As ColorUDT

Then to get the color from the palette you just do something like this:
Palette(ColorFrom8BitImage).Red
Palette(ColorFrom8BitImage).Green
Palette(ColorFrom8BitImage).Blue

Btw...Check the function that loads LMP files in the Bmp2Lmp program i attached. It loads 8-bit images and displays them on the screen using a palette.

I know how to do it the slow way - I want to do it the fast Windows native way. Should be possible.

- I have byte array of the image
- I want to storage it in a form I can display instantly from the memory
- I want to be able to view it in a PictureBox or any other object that supports Picture

There is code there, but these aren't too clear on what they do. And there are tons of API calls. At the moment I have ended up creating a class module - the only thing missing is the _working_ code. I haven't seen anything that is exactly what I need so I'm trying to figure out how to do it from the codes that handle the memory storaged images. What really lacks with the examples I have found are the comments: they are like "'Create the picture" - not describing how it does the new picture and what the input values mean.

This is my current class module, at the moment untested. You are free to point out errors you might see. I'm pretty sure this won't work, but I keep up a small drop of hope.

VB Code:

Option Explicit
 
Private Const DIB_RGB_COLORS As Long = 0
 
'bitmap information
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
 
Private Type BMP_GUID
    Data1 As Long
    Data2 As Integer
    Data3 As Integer
    Data4(7) As Byte
End Type
 
Private Type BMP_PICTURE
    Size As Long
    Type As Long
    hBmp As Long
    hPal As Long
    Reserved As Long
End Type
 
'images in memory
Private Declare Function CreateBitmap Lib "gdi32" (ByVal nWidth As Long, ByVal nHeight As Long, ByVal nPlanes As Long, ByVal nBitCount As Long, lpBits As Any) As Long
Private Declare Function CreateCompatibleBitmap Lib "gdi32" (ByVal hDC As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long
Private Declare Function GetBitmapBits Lib "gdi32" (ByVal hBitmap As Long, ByVal dwCount As Long, lpBits As Any) As Long
 
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function GetObject Lib "gdi32" Alias "GetObjectA" (ByVal hObject As Long, ByVal nCount As Long, lpObject As Any) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hDC As Long, ByVal hObject As Long) As Long
 
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hWnd As Long) As Long
Private Declare Function ReleaseDC Lib "user32" (ByVal hWnd As Long, ByVal hDC As Long) As Long
 
Private Declare Function SetDIBits_8 Lib "gdi32" Alias "SetDIBits" (ByVal aHDC As Long, ByVal hBitmap As Long, ByVal nStartScan As Long, ByVal nNumScans As Long, lpBits As Any, lpbi As BITMAPINFO_8, ByVal wUsage As Long) As Long
 
Private Declare Function CreatePalette Lib "gdi32" (lpLogPalette As LOGPALETTE) As Long
Private Declare Function RealizePalette Lib "gdi32" (ByVal hDC As Long) As Long
Private Declare Function SelectPalette Lib "gdi32" (ByVal hDC As Long, ByVal hPalette As Long, ByVal bForceBackground As Long) As Long
 
Private Declare Function OleCreatePictureIndirect Lib "olepro32.dll" (PicDesc As BMP_PICTURE, RefIID As BMP_GUID, ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long
 
Private InUseScreen As Boolean, InUseImage As Boolean
Private ScreenDC As Long, PicDC As Long, DestDC As Long
Private PicBmp As Long, PicPrevBmp As Long, PicPal As Long, PicPrevPal As Long
Private Width As Long, Height As Long
'initial step: get screen DC as default DC
Private Sub Class_Initialize()
    Init GetDC(0)
End Sub
'last step: free memory
Private Sub Class_Terminate()
    If InUseImage Then ClearImage
    'free Dc
    Call ReleaseDC(0, ScreenDC)
    InUseScreen = False
End Sub
Public Sub ClearImage()
    Dim PrevBmp As Long
    'free image
    If InUseImage Then
        PrevBmp = SelectObject(PicDC, PicPrevBmp)
        Call DeleteObject(PicBmp)
        Call DeleteDC(PicDC)
        InUseImage = False
    End If
End Sub
'alternative step: change DC
Public Sub Init(hDC As Long)
    'do a proper clearing before filling up with new information (if required)
    If InUseScreen Then Class_Terminate
    'set default DC
    ScreenDC = hDC
    PicDC = CreateCompatibleDC(ScreenDC)
    'mark we have filled DC
    InUseScreen = True
End Sub
'step 3: view the image
Property Get Picture() As IPictureDisp
    Dim Pic As BMP_PICTURE, IPic As IPicture, IID_IDispatch As BMP_GUID
 
    'fill GUID info (whatever it is...)
    With IID_IDispatch
        .Data1 = &H20400
        .Data4(0) = &HC0
        .Data4(7) = &H46
    End With
 
    'fill picture info
    With Pic
        .Size = Len(Pic) ' Length of structure
        .Type = vbPicTypeBitmap ' Type of Picture (bitmap)
        .hBmp = PicBmp ' Handle to bitmap
        .hPal = PicPal ' Handle to palette (may be null)
    End With
    
    Call OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)
    
    'view picture in destination
    Set Picture = IPic
End Property
'step 1: image must be set
Public Sub SetImage(ByRef Info As BITMAPINFO_8, ByRef DataArray() As Byte)
    'do a proper clearing before new image
    If InUseImage Then ClearImage
    'create image
    PicBmp = CreateCompatibleBitmap(ScreenDC, Width, Height)
    PicPrevBmp = SelectObject(PicDC, PicBmp)
    'set image bits
    Call SetDIBits_8(PicDC, PicBmp, 0, Width, DataArray(0), Info, DIB_RGB_COLORS)
    'mark image to be in use
    InUseImage = True
End Sub
'step 2: palette must be set
Public Sub SetPalette(ByRef DataArray() As Byte)
    Dim BmpPal As BITMAPPALETTE
    'init palette
    BmpPal.palVersion = &H300
    BmpPal.palNumEntries = 256
    RtlMoveMemory VarPtr(BmpPal.palPalEntry(0)), VarPtr(DataArray(0)), 1024
    'create palette and set it in use
    PicPal = CreatePalette(BmpPal)
    PicPrevPal = SelectPalette(PicDC, PicPal, 0)
    Call RealizePalette(PicDC)
End Sub

I finally found this great code that resolves my problem:

VB Code:

Option Explicit
 
Private Const BI_RGB = 0&
Private Const CBM_INIT = &H4
Private Const DIB_RGB_COLORS = 0
Private Const SRCCOPY = &HCC0020
 
Private Type BITMAPINFOHEADER
    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_256
    bmiHeader As BITMAPINFOHEADER
    bmiColors(0 To 255) As RGBQUAD
End Type
 
Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function CreateDIBitmap Lib "gdi32" (ByVal hdc As Long, lpInfoHeader As BITMAPINFOHEADER, ByVal dwUsage As Long, lpInitBits As Any, lpInitInfo As BITMAPINFO_256, ByVal wUsage As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function StretchBlt Lib "gdi32" (ByVal hdc As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal dwRop As Long) As Long
 
Dim Pixels() As Byte          ' Pixel data.
Dim bm_info As BITMAPINFO_256 ' DIB bitmap info.
Dim hDIB As Long              ' Bitmap handle.
Dim wid As Integer            ' Size of the bitmap.
Dim hgt As Integer
 
' Create the DIB.
Private Sub CreateDIB()
Dim screen_hdc As Long
 
    With bm_info.bmiHeader
        .biSize = Len(bm_info.bmiHeader)
        .biWidth = wid          ' Width in pixels.
        .biHeight = hgt         ' Height in pixels.
        .biPlanes = 1           ' 1 color plane.
        .biBitCount = 8         ' 8 bits per pixel.
        .biCompression = BI_RGB ' No compression.
        .biSizeImage = 0        ' Unneeded with no compression.
        .biXPelsPerMeter = 0    ' Unneeded.
        .biYPelsPerMeter = 0    ' Unneeded.
        .biClrUsed = 256        ' # colors in color table that are used by the image. 0 means all.
        .biClrImportant = 256   ' # important colors. 0 means all.
    End With
    
    ' Get the screen's device context.
    screen_hdc = GetDC(0)
    
    ' Create the DIB.
    hDIB = CreateDIBitmap(screen_hdc, _
        bm_info.bmiHeader, CBM_INIT, Pixels(0, 0), _
        bm_info, DIB_RGB_COLORS)
End Sub
 
' Draw the DIB onto the form.
Private Sub DrawDIB()
Dim compat_dc As Long
 
    ' Create a compatible device context.
    compat_dc = CreateCompatibleDC(hdc)
    
    ' Select the DIB into the compatible DC.
    SelectObject compat_dc, hDIB
        
    ' Copy the compatible DC's image onto the form.
    StretchBlt Picture1.hdc, 0, 0, _
        Picture1.ScaleWidth, Picture1.ScaleHeight, _
        compat_dc, 0, 0, wid, hgt, _
        SRCCOPY
 
    ' Destroy the compatible DC.
    DeleteDC compat_dc
End Sub
 
' Initialize 256 shades of blue.
Private Sub SetColorTable()
Dim i As Integer
 
    For i = 0 To 255
        bm_info.bmiColors(i).rgbRed = 0
        bm_info.bmiColors(i).rgbGreen = 0
        bm_info.bmiColors(i).rgbBlue = i
        bm_info.bmiColors(i).rgbReserved = 0
    Next i
End Sub
' Create a drawing.
Private Sub SetPixels()
Dim X As Integer
Dim Y As Integer
 
    wid = 100
    hgt = 256
    ReDim Pixels(0 To wid - 1, 0 To hgt - 1)
    For Y = 0 To hgt - 1
        For X = 0 To wid - 1
            If Y Mod 20 = 19 Or X Mod 20 = 19 Then
                Pixels(X, Y) = Y
            Else
                Pixels(X, Y) = 255 - Y
            End If
        Next X
    Next Y
End Sub
Private Sub Form_Load()
    SetColorTable
    SetPixels
    CreateDIB
End Sub
 
Private Sub Form_Resize()
    Picture1.Move 0, 0, ScaleWidth, ScaleHeight
    Picture1.Refresh
End Sub
 
 
Private Sub Picture1_Paint()
    DrawDIB
End Sub

Simple and clear code and does exatly what I want. Well, not exactly (it doesn't provide Picture handling), but close enough to be usable :)