protected override void OnPaint(PaintEventArgs pe)
{
//these settings aren't even needed for good perf, but they are helpful
pe.Graphics.InterpolationMode = InterpolationMode.Low;
pe.Graphics.CompositingQuality = CompositingQuality.HighSpeed;
pe.Graphics.SmoothingMode = SmoothingMode.HighSpeed;
if (image != null)
{
//draw empty area, if it exists, in an optimized way.
if (AutoScrollPosition.X == 0)
{
int emptyRightAreaWidth = Width - image.Bitmap.Width;
if (emptyRightAreaWidth > 0)
{
Rectangle fillRect = new Rectangle(image.Bitmap.Width, 0, emptyRightAreaWidth, Height);
fillRect.Intersect(pe.ClipRectangle);
pe.Graphics.FillRectangle(SystemBrushes.Control, fillRect);
}
}
if (AutoScrollPosition.Y == 0)
{
int emptyRightAreaHeight = Height - image.Bitmap.Height;
if (emptyRightAreaHeight > 0)
{
Rectangle fillRect = new Rectangle(0, image.Bitmap.Height, Width, emptyRightAreaHeight);
fillRect.Intersect(pe.ClipRectangle);
pe.Graphics.FillRectangle(SystemBrushes.Control, fillRect);
}
}
//calculate the visible area of the bitmap
Rectangle bitmapRect = new Rectangle(AutoScrollPosition.X, AutoScrollPosition.Y, image.Bitmap.Width, image.Bitmap.Height);
Rectangle visibleClientRect = bitmapRect;
visibleClientRect.Intersect(pe.ClipRectangle);
if (visibleClientRect.Width == 0 || visibleClientRect.Height == 0)
{
return;
}
Rectangle visibleBitmapRect = visibleClientRect;
visibleBitmapRect.Offset(-AutoScrollPosition.X, -AutoScrollPosition.Y);
//draw bitmap
if (newMethod)
{
using (EditableBitmap section = image.CreateView(visibleBitmapRect))
pe.Graphics.DrawImageUnscaled(section.Bitmap, visibleClientRect.Location);
}
else //normal method
{
pe.Graphics.DrawImage(image.Bitmap, visibleClientRect, visibleBitmapRect, GraphicsUnit.Pixel);
}
}
else //if no bitmap just fill with background color
{
pe.Graphics.FillRectangle(SystemBrushes.Control, pe.ClipRectangle);
}
}
protected void Dispose(bool disposing)
{
if (disposed)
{
return;
}
bitmap.Dispose();
byteArray.ReleaseReference();
disposed = true;
//Set managed object refs to null if explicitly disposing, so that they can be cleaned up by the GC.
if (disposing)
{
owner = null;
bitmap = null;
}
}
/// <summary>
/// Creates an <see cref="EditableBitmap"/> as a view on a section of an existing <see cref="EditableBitmap"/>.
/// </summary>
/// <param name="source"></param>
/// <param name="viewArea"></param>
protected EditableBitmap(EditableBitmap source, Rectangle viewArea)
{
owner = source;
pixelFormatSize = source.pixelFormatSize;
byteArray = source.byteArray;
byteArray.AddReference();
stride = source.stride;
try
{
startOffset = source.startOffset + (stride * viewArea.Y) + (viewArea.X * pixelFormatSize);
bitmap = new Bitmap(viewArea.Width, viewArea.Height, stride, source.Bitmap.PixelFormat,
(IntPtr)(((int)byteArray.bitPtr) + startOffset));
}
finally
{
if (bitmap == null)
{
byteArray.ReleaseReference();
}
}
}