Window bitblt

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Dec 5th, 2011, 04:07 AM
cheesebrother

Window bitblt

I've got a cool idea for my game (not really unique, i don't know why i didn't think of it before). What it is is that when you press the "Menu" button on the form a menu appears. The thing which i'd like to do would be to have the whole window fade a bit and then the menu, on a picturebox, would appear with the faded window behind it (by this i mean the contents of the window, of course). So to do this i think that there are two basic steps, one is to somehow get the window into a picturebox which would appear over everything and then draw the faded effect on the picturebox. It's prettymuch like a bitblt from window.hdc to picture1.hdc. How would i make this image, getting all the controls, pictureboxes and their contents... Everything into a picturebox?
Dec 5th, 2011, 05:26 AM
reacen

1 Attachment(s)

Re: Window bitblt

I'm sure LaVolpe will be the one to resolve this (as always) just wait for him :bigyello:

But meanwhile I have a piece of code that can help take screenshots of your window. (Tested on windows xp)

Please use attached file for the example.
Dec 5th, 2011, 10:07 AM
LaVolpe

Re: Window bitblt

This is actually much simpler than taking screenshots. With Windows 2000 and above you can make your entire form semi-transparent.

1. Create a menu in your form's menu editor (Ctrl+E), sample code calls it mnuButton
:: Add the sub menu items to that menu. Make menu visible = false
2. In your button's click event copy & pasted the following

Code:

Dim lStyle As Long ' set layered window attribute & fade window 50% lStyle = GetWindowLong(Me.hWnd, GWL_EXSTYLE) SetWindowLong Me.hWnd, GWL_EXSTYLE, lStyle Or WS_EX_LAYERED ' 128 below = 50%. Set value = (255 * (Percent/100)) SetLayeredWindowAttributes Me.hWnd, 0&, 128, LWA_ALPHA ' show popup menu PopupMenu mnuButton ' remove layered attribute SetWindowLong Me.hWnd, GWL_EXSTYLE, lStyle ' tell window it needs to be repainted InvalidateRgn Me.hWnd, 0&, 1& ' call this to repaint, not Me.Refresh else menus that fade out will leave artifacts on form SetWindowPos Me.hWnd, 0&, 0&, 0&, 0&, 0&, SWP_FRAMECHANGED Or SWP_NOMOVE Or SWP_NOSIZE Or SWP_NOZORDER

Here are the API declarations

Code:

Private Declare Function SetWindowLong Lib "user32.dll" Alias "SetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long Private Declare Function GetWindowLong Lib "user32.dll" Alias "GetWindowLongA" (ByVal hWnd As Long, ByVal nIndex As Long) As Long Private Declare Function SetLayeredWindowAttributes Lib "user32.dll" (ByVal hWnd As Long, ByVal crKey As Long, ByVal bAlpha As Byte, ByVal dwFlags As Long) As Long Private Declare Function SetWindowPos Lib "user32.dll" (ByVal hWnd As Long, ByVal hWndInsertAfter As Long, ByVal x As Long, ByVal y As Long, ByVal cx As Long, ByVal cy As Long, ByVal wFlags As Long) As Long Private Declare Function InvalidateRgn Lib "user32.dll" (ByVal hWnd As Long, ByVal hRgn As Long, ByVal bErase As Long) As Long Private Const SWP_NOMOVE As Long = &H2 Private Const SWP_NOSIZE As Long = &H1 Private Const SWP_FRAMECHANGED As Long = &H20 Private Const SWP_NOZORDER As Long = &H4 Private Const GWL_EXSTYLE As Long = -20& Private Const WS_EX_LAYERED As Long = &H80000 Private Const LWA_ALPHA As Long = &H2&
Dec 5th, 2011, 10:43 AM
cheesebrother

Re: Window bitblt

Wow, that's really neat! I'd love to use it in some places but it isn't what i'm hoping to do here. Sorry for not being clear. When i said "fade" i meant that black gets mixed in with the window, not that it fades to semitransparent. You've probably seen it in some games where you hit esc and the menu appears. It doesn't cover the whole screen so what it doesn't cover just goes dark. Anothing misunderstanding was the meaning of "menu". by that i mean four or five buttons, new, open, save, exit... not a popupmenu. Anyway i'm glad you misunderstood me because i like the code a lot.

reacen's getting at it with the screenshot thing. I guess the second question i've got is how to darken the picture after i've got in safe and sound in a picturebox.
Dec 5th, 2011, 11:33 AM
LaVolpe

Re: Window bitblt

So what exactly is suppose to "go dark"? The entire screen, including your app (except the picturebox to be displayed later)? Just your app? Is your app full screen? Maybe more details could be helpful
Dec 5th, 2011, 12:27 PM
cheesebrother

1 Attachment(s)

Re: Window bitblt

My app is a sizable form. It can be whatever size. What i want is the space inside the form to go dark. I'll make it crystal clear with an image i doctored up in photoshop. When the menu appears the space inside the form goes dark and the normal picturebox is in the middle with menu buttons on it.
Dec 5th, 2011, 01:13 PM
LaVolpe

Re: Window bitblt

Ok, here's a really short example and has some logic issues you'll need to figure out.

1. Include a picturebox (named picClientCapture below) which is hidden and exists on your form, not in some other container
2. Include a picturebox to hold your "menu" (named picMenu below)
3. Behind the button that is suppose to do this, add this code

Code:

Dim tmpPicColor As PictureBox Dim wDC As Long, Cx As Long, Cy As Long Set tmpPicColor = Me.Controls.Add("VB.Picturebox", "picClientColorXYZ") With picClientCapture .BorderStyle = 0 .Appearance = 0 .AutoRedraw = True .ZOrder vbBringToFront .Move 0, 0, Me.ScaleWidth, Me.ScaleHeight End With With tmpPicColor .BorderStyle = 0 .Appearance = 0 .AutoRedraw = True .Move 0, 0, Me.ScaleWidth, Me.ScaleHeight .BackColor = vbBlack ' change to whatever 'blend' color you desire End With Cx = ScaleX(Me.ScaleWidth, Me.ScaleMode, vbPixels) Cy = ScaleY(Me.ScaleHeight, Me.ScaleMode, vbPixels) wDC = GetDC(Me.hWnd) BitBlt picClientCapture.hdc, 0, 0, Cx, Cy, wDC, 0, 0, vbSrcCopy ReleaseDC Me.hWnd, wDC ' below change 168 to higher value for more 'blend' color ' 168 = (66%/100)*255 AlphaBlend picClientCapture.hdc, 0, 0, Cx, Cy, tmpPicColor.hdc, 0, 0, Cx, Cy, &H10000 * 168 Me.Controls.Remove tmpPicColor Set tmpPicColor = Nothing picClientCapture.Visible = True picMenu.ZOrder vbBringToFront picMenu.Visible = True

Here are the declarations

Code:

Private Declare Function GetDC Lib "user32.dll" (ByVal hWnd As Long) As Long Private Declare Function ReleaseDC Lib "user32.dll" (ByVal hWnd As Long, ByVal hdc As Long) As Long Private Declare Function AlphaBlend Lib "msimg32.dll" (ByVal hdcDest As Long, ByVal xDest As Long, ByVal yDest As Long, ByVal WidthDest As Long, ByVal HeightDest As Long, ByVal hdcSrc As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc As Long, ByVal Blendfunc As Long) As Long Private Declare Function BitBlt Lib "gdi32.dll" (ByVal hDestDC 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 dwRop As Long) As Long

Logic issues:
1. If the form is resized, your effect is broken. You may want to set the backcolor of the form while the "menu" is displayed. If you do, set it at the end of the sample routine above. Don't forget to set the backcolor back to normal just before the 'menu' is removed. Here's a simple formula to figure out the right color

Code:

' sample call to the following function looks like this: ' pass to the BackColorToBlendColor the same values you used for the blend color & percentage value Me.BackColor = BackColorToBlendColor(Me, vbBlack, 168) Private Function BackColorToBlendColor(formObject As Object, BlendColor As Long, Level As Long) As Long Dim lColor As Long Dim dstLevel As Long Dim R1 As Long, R2 As Long, G1 As Long, G2 As Long, B1 As Long, B2 As Long lColor = formObject.BackColor If lColor < 0& Then lColor = GetSysColor(lColor And &HFF&) dstLevel = 255 - Level R1 = BlendColor And &HFF G1 = (BlendColor And &HFF00&) \ &H100& B1 = (BlendColor And &HFF0000) \ &H10000 R2 = lColor And &HFF G2 = (lColor And &HFF00&) \ &H100& B2 = (lColor And &HFF0000) \ &H10000 R1 = ((R1 * Level) + (R2 * dstLevel)) \ 255 G1 = ((G1 * Level) + (G2 * dstLevel)) \ 255 B1 = ((B1 * Level) + (B2 * dstLevel)) \ 255 BackColorToBlendColor = RGB(R1, G1, B1) End Function

2. This is more difficult to fix and should be avoided. If your form is resizable and the form size is not large enough to show all of its controls when the code captures its appearance, then resizing the form will not show the now-unhidden-controls as 'blended'

3. Any animation on your form will no longer be animating to the user; animation still occurring behind the capture picbox

4. Not an issue, but for memory easing, after your 'menu' is removed, resize picClientCapture to 1x1 so it uses very little resources

Oops, forgot to include this API if you will be using the BackColorToBlendColor function:

Code:

Private Declare Function GetSysColor Lib "user32.dll" (ByVal nIndex As Long) As Long
Dec 5th, 2011, 01:22 PM
jcis

Re: Window bitblt

Windows does something similar in shut down screen when placing the mouse over the button, this fades to black and white, not exatly the same since you need to darken the Form.

I think it could be easier to do if your screen behind (not your menu) is captured as picture and then using a PictureBox that would cover all your Form, then bliting the picture onto that, finally fading the picture in the Picbox and not the real controls, like a trick i mean, the user shouldn't see the difference. This Picbox should be made visible before your Menu opens and invisible when it closes.

I say this because fading the real Form with its controls will be much harder, VB controls how thay are drawn and refreshed messing with that may requiere harder approaches like subclassing.

How to exatly fade the Picture darker in progression i don't know but there are things to try, like alphablending with a dark pic, or using BitBlt with bSrcAnd (joins 2 pics together), making the dark pic a bit darker before each fade step.

EDIT: didn't see last Lavolpe's post before posting :)
Dec 5th, 2011, 01:31 PM
cheesebrother

Re: Window bitblt

That's pretty good, thanks. I'm wondering if it wouldn't be possible to fire the blending sub when the form resizes. I tried doing that but it had and error "Me.Controls.Remove tmpPicColor". Is that why that won't work?
Dec 5th, 2011, 01:37 PM
LaVolpe

Re: Window bitblt

No. If you did, it would flicker like mad.

Theoretically, when the "menu" is displayed your users shouldn't be able to resize the form anyway; should they? Not until a menuitem has been selected or menu canceled.

So why the flicker? Because before a capture of the client area (your form), the previous capture, if any, would need to be removed; new capture done & displayed dark. This removal and replacement loop would cause a visible flicker. If the previous capture wasn't removed, the area of that capture would become progressively darker with each additional call the routine. Also your menu would now be captured. A possible work around would be to cache a capture (large enough for all controls), but that could require trying to capture controls that are not visible due to the form size. This is problematic in itself. Simply suggest preventing form resizing while your menu is displayed
Dec 5th, 2011, 01:42 PM
cheesebrother

Re: Window bitblt

Right. I guess the best way would to just fill in new areas with the same grey as the form's backcolor darkened. Thanks for the help lavolpe!
Dec 5th, 2011, 01:44 PM
LaVolpe

Re: Window bitblt

Quote:

Originally Posted by cheesebrother

Right. I guess the best way would to just fill in new areas with the same grey as the form's backcolor darkened. Thanks for the help lavolpe!

That's what that BackColorToBlendColor function I gave you will do. See "Logic Issues #1 & #2" in post 7
Dec 5th, 2011, 01:54 PM
LaVolpe

Re: Window bitblt

Here are a couple more things to think about.

1. You could resize the picClientCapture to a screen size. If you do, set picClientCapture.BackColor to the return value of BackColorToBlendColor:
picClientCapture .Move 0, 0, ScaleX(Screen.Width, vbTwips, Me.ScaleMode), ScaleY(Screen.Height, vbTwips, Me.ScaleMode)

You may or may not like how this will affect partially visible controls at time of the capture

2. While your picClientCapture & your menu are visible, users can still tab to your 'hidden' controls, the ones behind picClientCapture. This could be an issue you want to address
Dec 5th, 2011, 02:06 PM
jcis

Re: Window bitblt

Nice code Lavolpe. I'm trying to make it fade progressively, like windows shut down, this seems to do the trick, what do you think?

By Replacing this..

Code:

' below change 168 to higher value for more 'blend' color ' 168 = (66%/100)*255 AlphaBlend picClientCapture.hdc, 0, 0, Cx, Cy, tmpPicColor.hdc, 0, 0, Cx, Cy, &H10000 * 168 Me.Controls.Remove tmpPicColor Set tmpPicColor = Nothing picClientCapture.Visible = True picMenu.ZOrder vbBringToFront picMenu.Visible = True

with this..

Code:

Dim ColorVal As Long, i As Long ' (should be added where sub begins) For i = 1 To 20 picClientCapture.Visible = False ColorVal = ColorVal + 1 AlphaBlend picClientCapture.hdc, 0, 0, Cx, Cy, tmpPicColor.hdc, 0, 0, Cx, Cy, &H10000 * ColorVal picClientCapture.Visible = True DoEvents Sleep 30 Next picMenu.ZOrder picMenu.Visible = True Me.Controls.Remove tmpPicColor Set tmpPicColor = Nothing Me.BackColor = vbButtonFace

Sleep API declaration is required:

Code:

Private Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

Maybe it's not very "clean" using sleep but couldn't find another way to pause the thing to make it fade.
Dec 6th, 2011, 03:14 AM
cheesebrother

Re: Window bitblt

Quote:

2. While your picClientCapture & your menu are visible, users can still tab to your 'hidden' controls, the ones behind picClientCapture. This could be an issue you want to address

Yes, i anticipated that and disabled all the controls behind picClientCapture. Thanks again for the help. I should do good enough on my own from here.