internal static extern IntPtr BeginPaint(IntPtr hwnd, ref PI.PAINTSTRUCT ps);
internal static extern bool EndPaint(IntPtr hwnd, ref PI.PAINTSTRUCT ps);
private void WmPaint(ref Message m)
{
IntPtr hdc;
PI.PAINTSTRUCT ps = new PI.PAINTSTRUCT();
// Do we need to BeginPaint or just take the given HDC?
if (m.WParam == IntPtr.Zero)
hdc = PI.BeginPaint(Handle, ref ps);
else
hdc = m.WParam;
// Create bitmap that all drawing occurs onto, then we can blit it later to remove flicker
Rectangle realRect = CommonHelper.RealClientRectangle(Handle);
// No point drawing when one of the dimensions is zero
if ((realRect.Width > 0) && (realRect.Height > 0))
{
IntPtr hBitmap = PI.CreateCompatibleBitmap(hdc, realRect.Width, realRect.Height);
// If we managed to get a compatible bitmap
if (hBitmap != IntPtr.Zero)
{
try
{
// Must use the screen device context for the bitmap when drawing into the
// bitmap otherwise the Opacity and RightToLeftLayout will not work correctly.
PI.SelectObject(_screenDC, hBitmap);
// Easier to draw using a graphics instance than a DC!
using (Graphics g = Graphics.FromHdc(_screenDC))
{
// Ask the view element to layout in given space, needs this before a render call
using (ViewLayoutContext context = new ViewLayoutContext(this, _kryptonListBox.Renderer))
{
context.DisplayRectangle = realRect;
_drawPanel.Layout(context);
}
using (RenderContext context = new RenderContext(this, _kryptonListBox, g, realRect, _kryptonListBox.Renderer))
_drawPanel.Render(context);
// Replace given DC with the screen DC for base window proc drawing
IntPtr beforeDC = m.WParam;
m.WParam = _screenDC;
DefWndProc(ref m);
m.WParam = beforeDC;
if (Items.Count == 0)
using (RenderContext context = new RenderContext(this, _kryptonListBox, g, realRect, _kryptonListBox.Renderer))
_drawPanel.Render(context);
}
// Now blit from the bitmap from the screen to the real dc
PI.BitBlt(hdc, 0, 0, realRect.Width, realRect.Height, _screenDC, 0, 0, PI.SRCCOPY);
// When disabled with no items the above code does not draw the backround!
if (Items.Count == 0)
using (Graphics g = Graphics.FromHdc(hdc))
using (RenderContext context = new RenderContext(this, _kryptonListBox, g, realRect, _kryptonListBox.Renderer))
_drawPanel.Render(context);
}
finally
{
// Delete the temporary bitmap
PI.DeleteObject(hBitmap);
}
}
}
// Do we need to match the original BeginPaint?
if (m.WParam == IntPtr.Zero)
PI.EndPaint(Handle, ref ps);
}