How To Draw Transparent Bitmap With Bitbit?

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hi everyone i used this code in C# for draw bitmap on Control,Unfortunately, the Drawed background color is gray But my Bitmap is Transparent.Can you help me please?

try
                {
                    hdcDest = grpDest.GetHdc();
                    hdcSrc = grpSrc.GetHdc();
                    hBitmap = bmp.GetHbitmap();

                    hOldObject = SelectObject(hdcSrc, hBitmap);
                    if (hOldObject == IntPtr.Zero)
                        throw new Win32Exception();
                   
                    if (!BitBlt(hdcDest, 0, 0, Width, Height,
                        hdcSrc, 0, 0,SRCCOPY))
                        throw new Win32Exception();
                }
                finally
                {
                    if (hOldObject != IntPtr.Zero) SelectObject(hdcSrc, hOldObject);
                    if (hBitmap != IntPtr.Zero) DeleteObject(hBitmap);
                    if (hdcDest != IntPtr.Zero) ReleaseHdc(hdcDest);
                    if (hdcSrc != IntPtr.Zero) ReleaseHdc(hdcSrc);
                }

Posted 14-Feb-15 0:06am

Silent Boy

Updated 14-Feb-15 0:09am

v2

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Vladimir Svyatski · Answer 1 · 2015-02-14T00:25:00

Solution 1

You may have to use the AlphaBlend function.

Posted 14-Feb-15 0:25am

Vladimir Svyatski

Silent Boy · Answer 2 · 2015-02-14T08:59:00

Solution 2

Doesn't matter i found this,a transparent bitbit.

[System.Runtime.InteropServices.DllImportAttribute ("msimg32.dll")]
       public  static extern bool TransparentBlt (IntPtr hdc, int nXOriginDest, int nYOriginDest, int nWidthDest, int hHeightDest, IntPtr hdcSrc, int nXOriginSrc,  int nYOriginSrc, int nWidthSrc, int nHeightSrc, uint crTransparent);

Posted 14-Feb-15 8:59am

Silent Boy

Comments

Vladimir Svyatski 16-Feb-15 7:48am

Well, this one is not exactly drawing 32 bit bmp. It emulates transpanency making pixels with certain color transparent. How do you display properly a pixel with alpha = 128 using this function? Didn't AlphaBlend work? And by the way, why don't you just leverage GDI+ drawing functions like DrawImage here? You're in .NET. I find original GDI useful in .NET only if you're to draw text on controls, because the text drawn with GDI+ differs in size.

Silent Boy 17-Feb-15 10:14am

Yes Sir, AlphaBlend doesn't Work For Me And Dot Net Controls Have Many flickers.I Used SetStyle ,DoubleBuffer And CreateParams Function For Free flicker and Nothing Changed.BitBit is free flicker Drawing But Only Problem is Transparent Color.