/// <summary>
/// Draws a bitmap to a Graphics context.
/// </summary>
/// <param name="dst">The Graphics context to draw the bitmap on to.</param>
/// <param name="dstRect">The clipping rectangle in destination coordinates.</param>
/// <param name="dstMatrix">The transformation matrix to apply. This is only used to transform the upper-left corner of dstRect.</param>
/// <param name="srcBitmapHandle">The handle to the bitmap obtained from Memory.AllocateBitmap().</param>
/// <param name="srcWidth">The full width of the bitmap.</param>
/// <param name="srcHeight">The full height of the bitmap.</param>
/// <param name="srcOffsetX">The left edge of the source bitmap to draw from.</param>
/// <param name="srcOffsetY">The top edge of the source bitmap to draw from.</param>
public unsafe static void DrawBitmap(
Graphics dst,
Rectangle dstRect,
Matrix dstMatrix,
IntPtr srcBitmapHandle,
int srcOffsetX,
int srcOffsetY)
{
if (srcBitmapHandle == IntPtr.Zero)
{
throw new ArgumentNullException("srcBitmapHandle");
}
Point[] points = new Point[] { dstRect.Location };
dstMatrix.TransformPoints(points);
dstRect.Location = points[0];
IntPtr hdc = IntPtr.Zero;
IntPtr hbitmap = IntPtr.Zero;
IntPtr chdc = IntPtr.Zero;
IntPtr old = IntPtr.Zero;
try
{
hdc = dst.GetHdc();
chdc = SafeNativeMethods.CreateCompatibleDC(hdc);
old = SafeNativeMethods.SelectObject(chdc, srcBitmapHandle);
SafeNativeMethods.BitBlt(hdc, dstRect.Left, dstRect.Top, dstRect.Width,
dstRect.Height, chdc, srcOffsetX, srcOffsetY, NativeConstants.SRCCOPY);
}
finally
{
if (old != IntPtr.Zero)
{
SafeNativeMethods.SelectObject(chdc, old);
old = IntPtr.Zero;
}
if (chdc != IntPtr.Zero)
{
SafeNativeMethods.DeleteDC(chdc);
chdc = IntPtr.Zero;
}
if (hdc != IntPtr.Zero)
{
dst.ReleaseHdc(hdc);
hdc = IntPtr.Zero;
}
}
GC.KeepAlive(dst);
}
public NullGraphics()
{
this.hdc = SafeNativeMethods.CreateCompatibleDC(IntPtr.Zero);
if (this.hdc == IntPtr.Zero)
{
NativeMethods.ThrowOnWin32Error("CreateCompatibleDC returned NULL");
}
this.graphics = Graphics.FromHdc(this.hdc);
}
