GDI / GDI+

[Adno]

Thanks Mark, but my aim is to use the transparency of the png and Alpha channel to define the transparency, perpixelvlue as it were. am goind all wrong about it? thanks

[Mark Salsbery]

I "think" you may be able to use a 32-bit ARGB DIBsection - I put together this test just to make sure the alpha channel stuff was working. (My "hdc" would be your "dcMem" and you wouldn't want to delete it or un-select your alpha bitmap like I have if you pass it to UpdateLayeredWindow())

Image TransparentSrcBitmap(L"clockbg.bmp");

LONG lImageWidth = TransparentSrcBitmap.GetWidth();
LONG lImageHeight = TransparentSrcBitmap.GetHeight();
WORD wBitsPerPixel = 32;

//LONG lBytesPerRow = (((lImageWidth * (long)wBitsPerPixel + 31L) & (~31L)) / 8L);
LONG lBytesPerRow = lImageWidth * 4;

BITMAPINFO bmi;
memset(&bmi, 0, sizeof(BITMAPINFO));
bmi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmi.bmiHeader.biWidth = lImageWidth;
bmi.bmiHeader.biHeight = lImageHeight;
bmi.bmiHeader.biPlanes = 1;
bmi.bmiHeader.biBitCount = wBitsPerPixel;
bmi.bmiHeader.biCompression = BI_RGB;
bmi.bmiHeader.biSizeImage = lBytesPerRow * lImageHeight;
//bmi.bmiHeader.biXPelsPerMeter = 0;
//bmi.bmiHeader.biYPelsPerMeter = 0;
//bmi.bmiHeader.biClrUsed = 0;
//bmi.bmiHeader.biClrImportant = 0;

HDC hdc = ::CreateCompatibleDC(0);

BYTE* pBitmapBits;
HBITMAP hBitmap = ::CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)&pBitmapBits, NULL, 0);

if (hBitmap)
{
memset(pBitmapBits, 0, bmi.bmiHeader.biSizeImage);

HGDIOBJ hOldBitmap = ::SelectObject(hdc, hBitmap);

Graphics DstGraphics(hdc);
DstGraphics.DrawImage(&TransparentSrcBitmap, 0, 0, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight());

//** Test - blt the memory dc to the screen to make sure alpha channel data carried over
BLENDFUNCTION bf;
bf.BlendOp = AC_SRC_OVER;
bf.BlendFlags = 0;
bf.SourceConstantAlpha = 0x7F; // Alpha multiplier applied overall - use 0xFF - 0x7F is a test
bf.AlphaFormat = AC_SRC_ALPHA;

HDC hClientDC = ::GetDC(*this);
::AlphaBlend(hClientDC, 50, 50, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight(),
hdc, 0, 0, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight(), bf);
::ReleaseDC(*this, hClientDC);
//** End Test

::SelectObject(hdc, hOldBitmap); //<-- Don't do this when using with UpdateLayeredWindow()

::DeleteObject(hBitmap); //<-- Don't do this when using with UpdateLayeredWindow()
}

::DeleteDC(hdc); //<-- Don't do this when using with UpdateLayeredWindow()

Sorry about all the strange extra variables - I cut and paste from assorted worki

[Adno]

thank you Mark very much for taking the time, it mean as lot me. but is not quite there is coming out pixalated, the alpha value is being replace by a black colour. program running image: http://img118.imageshack.us/img118/8953/testwindowhu9.png . . . Code: the main method. http://rafb.net/p/1Dfouz58.html thank you so much ....:-D

[Mark Salsbery]

No problem! Can you show your latest code? Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Mark Salsbery]

What's "image" and what's "program window" in your screenshot? Never mind I get it LOL I'd still like to see your updated code if you can :) Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Adno]

Code: the main method. http://rafb.net/p/1Dfouz58.html ^i posted here

[Mark Salsbery]

Try replacing int t = UpdateLayeredWindow(hwnd, NULL, NULL, &sz, hdc, &ptSrc, NULL, &bf, ULW_COLORKEY ); with int t = UpdateLayeredWindow(hwnd, NULL, NULL, &sz, hdc, &ptSrc, NULL, &bf, ULW_ALPHA ); You probably want to set bf.SourceConstantAlpha = 0xFF; (instead of 0x7F) too. Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Mark Salsbery]

And comment out these lines - they were there for testing only (leave in the BLENDFUNCTION since you're using that)... // comment these out HDC hClientDC = ::GetDC(hwnd); ::AlphaBlend(hClientDC, 50, 50, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight(), hdc, 0, 0, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight(), bf); ::ReleaseDC(hwnd, hClientDC);

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Adno]

thanks a million one more thing since i've got you here. will i be able to draw on this window? i.e: Graphics graphics(GetDC(hwnd)); Bitmap bitmap(L"clockbg.bmp"); graphics.DrawImage(&bitmap, 100,100); i did a quick test it dont seem to be working. my goal would be to be as great as you one day lol

[Mark Salsbery]

Lamefif wrote:

will i be able to draw on this window?

Absolutely not! Just kidding. The DIBSection bitmap is already in a DC which is associated with a Graphics object (DstGraphics). That's where you should draw. Example...

// redraw the image background
DstGraphics.DrawImage(&TransparentSrcBitmap, 0, 0, TransparentSrcBitmap.GetWidth(), TransparentSrcBitmap.GetHeight());

// draw some stuff on top of the background
Bitmap bitmap(L"clockbg.bmp");
DstGraphics.DrawImage(&bitmap, 100,100);

You have full access to the bitmap that IS your window. You can write directly to the pixel bytes, use GDI+ to draw, use GDI to draw, or any combination of those :) You may need to call UpdateLayeredWindow() again to see changes (i think the hdcSrc param can be NULL for updates). Mark

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder

[Adno]

Cheers Mark man i new i could do it. :->

[Mark Salsbery]

:beer:

"Posting a VB.NET question in the C++ forum will end in tears." Chris Maunder