gdi

I have an HBITMAP containing alpha channel data. I can successfully render this using the ::AlphaBlend GDI function. However, when I call the ::GetPixel GDI function, I never get back values with an alpha component. The documentation does say that it returns the RGB value of the pixel. Is there a way to retrieve the alpha channel values for pixels in an HBITMAP ? I want to be able to detect when to use ::AlphaBlend, and when to use an old-school method for treating a particular colour in the source HBITMAP as transparent. HDC sourceHdc = ::CreateCompatibleDC(hdcDraw); ::SelectObject(sourceHdc,

How would I go about rotating a Bitmap in Windows GDI,C++? You can do it with GDI+ ( #include <gdiplus.h> ). The Graphics class has the RotateTransform method . That allows arbitrary rotations. Use Image::RotateFlip() if you only need to rotate by 90 degree increments, that's a lot more efficient. Sounds like you have to use PlgBlt . Take your rectangle's 4 corners as 2D Points, rotate them, then call PlgBlt. From MSDN Bitmap Rotation : To copy a bitmap into a parallelogram; use the PlgBlt function, which performs a bit-block transfer from a rectangle in a source device context into a

I have a ProgressBar control like the following two: The first is painted properly. As you can see, the second only has one 0, it's supposed to have two but the other cannot be seen because ProgressBar's ForeColor is the same as the TextColor . Is there a way I can paint the text in black when the ProgressBar below is painted in Lime and paint the text in Lime when the background is black? You can first draw the background and text, then draw the foreground lime rectangle using PatBlt method with PATINVERT parameter to combine foreground drawing with background drawing: using System; using

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Under Win32, it is a common technique to generate a monochrome bitmask from a bitmap for transparency use by doing the following: SetBkColor(hdcSource, clrTransparency); VERIFY(BitBlt(hdcMask, 0, 0, bm.bmWidth, bm.bmHeight, hdcSource, 0, 0, SRCCOPY)); This assumes that hdcSource is a memory DC holding the source image, and hdcMask is a memory DC holding a monochrome bitmap of the same size (so both are 32x32, but the source is 4 bit color, while the target is 1bit monochrome). However, this seems to fail for me when the source is 32 bit color + alpha. Instead of getting a monochrome bitmap in

I'm looking for a way to generate PDF files using the standard PrintDocument and Graphics (GDI) classes in .NET. As far as I know, the only way to do that is by printing to a PDF printer. The problem is that a PDF printer driver always asks for a filename, but I need to control the filename from my code. Using a PDF library like PDFSharp or DynamicPDF is not an option, because they all provide their own API for generating PDF files. I need this for an internal application, so dependencies are not a problem. My question is simple: is there a way to control a printer driver (Adobe Acrobat,