public AlphaLayerControl(Graphics parentGraphics, Size size, byte alphaVal)
{
try
{
_alphaImage = new Bitmap(size.Width, size.Height, System.Drawing.Imaging.PixelFormat.Format16bppRgb565);
using (Graphics gx = Graphics.FromImage(_alphaImage))
{
IntPtr hdcDst = gx.GetHdc();
IntPtr hdcSrc = parentGraphics.GetHdc();
Win32.BlendFunction blendFunction = new Win32.BlendFunction();
blendFunction.BlendOp = (byte)Win32.BlendOperation.AC_SRC_OVER; // Only supported blend operation
blendFunction.BlendFlags = (byte)Win32.BlendFlags.Zero; // Documentation says put 0 here
blendFunction.SourceConstantAlpha = alphaVal; // Constant alpha factor
blendFunction.AlphaFormat = (byte)0; // Don't look for per pixel alpha
Win32.AlphaBlend(hdcDst, 0, 0, _alphaImage.Width, _alphaImage.Height, hdcSrc, 0, 0, _alphaImage.Width, _alphaImage.Height, blendFunction);
gx.ReleaseHdc(hdcDst); // Required cleanup to GetHdc()
parentGraphics.ReleaseHdc(hdcSrc); // Required cleanup to GetHdc()
}
}
catch
{
GC.Collect();
_alphaImage = new Bitmap(1, 1);
}
}
public AlphaLayerControl(Graphics parentGraphics, Size size, byte alphaVal)
{
try
{
_alphaImage = new Bitmap(size.Width, size.Height, System.Drawing.Imaging.PixelFormat.Format16bppRgb565);
using (Graphics gx = Graphics.FromImage(_alphaImage))
{
IntPtr hdcDst = gx.GetHdc();
IntPtr hdcSrc = parentGraphics.GetHdc();
Win32.BlendFunction blendFunction = new Win32.BlendFunction();
blendFunction.BlendOp = (byte)Win32.BlendOperation.AC_SRC_OVER; // Only supported blend operation
blendFunction.BlendFlags = (byte)Win32.BlendFlags.Zero; // Documentation says put 0 here
blendFunction.SourceConstantAlpha = alphaVal;// Constant alpha factor
blendFunction.AlphaFormat = (byte)0; // Don't look for per pixel alpha
Win32.AlphaBlend(hdcDst, 0, 0, _alphaImage.Width, _alphaImage.Height, hdcSrc, 0, 0, _alphaImage.Width, _alphaImage.Height, blendFunction);
gx.ReleaseHdc(hdcDst); // Required cleanup to GetHdc()
parentGraphics.ReleaseHdc(hdcSrc); // Required cleanup to GetHdc()
}
}
catch
{
GC.Collect();
_alphaImage = new Bitmap(1, 1);
}
}
