private Graphics CreateBuffer(IntPtr src, int offsetX, int offsetY, int width, int height)
{
//NativeMethods.POINT pVp = new NativeMethods.POINT();
if (width <= bufferWidth && height <= bufferHeight && compatDC != IntPtr.Zero)
{
virtualWidth = width;
virtualHeight = height;
Debug.WriteLineIf(DoubleBuffering.TraceInfo, "Reusing compatible DC");
if (compatGraphics != null)
{
Debug.WriteLineIf(DoubleBuffering.TraceInfo, " Disposing compatGraphics");
compatGraphics.Dispose();
compatGraphics = null;
}
//SafeNativeMethods.SetViewportOrgEx(compatDC, offsetX, offsetY, pVp);
Debug.WriteLineIf(DoubleBuffering.TraceInfo, " Create compatGraphics");
compatGraphics = Graphics.FromHdcInternal(compatDC);
compatGraphics.TranslateTransform(-targetX, -targetY);
return(compatGraphics);
}
int optWidth = bufferWidth;
int optHeight = bufferHeight;
Dispose();
Debug.WriteLineIf(DoubleBuffering.TraceInfo, "allocating new buffer: " + width + " x " + height);
Debug.WriteLineIf(DoubleBuffering.TraceInfo, " old size : " + optWidth + " x " + optHeight);
optWidth = Math.Max(width, optWidth);
optHeight = Math.Max(height, optHeight);
Debug.WriteLineIf(DoubleBuffering.TraceInfo, " new size : " + optWidth + " x " + optHeight);
IntPtr pvbits = IntPtr.Zero;
dib = CreateCompatibleDIB(src, IntPtr.Zero, optWidth, optHeight, ref pvbits);
compatDC = UnsafeNativeMethods.CreateCompatibleDC(new HandleRef(null, src));
oldBitmap = SafeNativeMethods.SelectObject(new HandleRef(this, compatDC), new HandleRef(this, dib));
//SafeNativeMethods.SetViewportOrgEx(compatDC, offsetX, offsetY, pVp);
Debug.WriteLineIf(DoubleBuffering.TraceInfo, " Create compatGraphics");
compatGraphics = Graphics.FromHdcInternal(compatDC);
compatGraphics.TranslateTransform(-targetX, -targetY);
bufferWidth = optWidth;
bufferHeight = optHeight;
virtualWidth = width;
virtualHeight = height;
return(compatGraphics);
}