drawing with alpha blending on compactramework C#

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This code taken from HERE

using (Graphics gxSrc = Graphics.FromImage(constantAlphaImage)) { gxSrc.Clear(Color.Transparent);******//it do not work, it no is Transparent, is white******

if (checkBox1.Checked)

                    {
                        //On a Image Object I can draw a FillRectangle. 

                        gxSrc.FillRectangle(new SolidBrush(Color.Green),  (Corrimiento  15),  (Corrimiento  15), 50,50);
                    }

                    IntPtr hdcDst = gxBuffer.GetHdc();
                    IntPtr hdcSrc = gxSrc.GetHdc();

                    BlendFunction blendFunction = new BlendFunction();
                    blendFunction.BlendOp = (byte)BlendOperation.AC_SRC_OVER;   
                    blendFunction.BlendFlags = (byte)BlendFlags.Zero;           
                    blendFunction.SourceConstantAlpha = (byte)vScrollBar1.Value;// Constant alpha factor
                    blendFunction.AlphaFormat = (byte)0;                        // Don't look for per pixel alpha

                    PlatformAPIs.AlphaBlend(hdcDst, 36, 36, 100, 100, hdcSrc, 0, 0, 128, 128, blendFunction);

                    POINT [] ArrayPoiter = new POINT[3];


                    gxBuffer.ReleaseHdc(hdcDst);    
                    gxSrc.ReleaseHdc(hdcSrc);     
                }

Here is the file modificated from the website

Our problem is that by Alphablend we can draw square with alphablend the background of this drawing is not transparent. Or by ImagingImage we can load png with transparent background but we cant draw anything. Take a look to the example in the link above.

asked 33 secs ago

Arturo D. Gentili

1

drawing with alpha blending on compactramework C#