/// <summary>
/// Raises the <see cref="E:System.Windows.Forms.Control.Paint" /> event.
/// </summary>
/// <param name="e">A <see cref="T:System.Windows.Forms.PaintEventArgs" /> that contains the event data.</param>
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
if (BufferedPaintSupported)
{
bool stateChanged = !Object.Equals(currentState, newState);
using (var hdc = new SafeGDIHandle(e.Graphics))
{
if (!hdc.IsInvalid)
{
// see if this paint was generated by a soft-fade animation
if (!NativeMethods.BufferedPaintRenderAnimation(this.Handle, hdc))
{
NativeMethods.BufferedPaintAnimationParams animParams = new NativeMethods.BufferedPaintAnimationParams(NativeMethods.BufferedPaintAnimationStyle.Linear);
// get appropriate animation time depending on state transition (or 0 if unchanged)
if (stateChanged)
{
foreach (var item in transitions)
{
if (item.currentState == currentState && item.newState == newState)
{
animParams.Duration = item.duration;
break;
}
}
}
Rectangle rc = this.ClientRectangle;
IntPtr hdcFrom, hdcTo;
IntPtr hbpAnimation = NativeMethods.BeginBufferedAnimation(this.Handle, hdc, ref rc, NativeMethods.BufferedPaintBufferFormat.CompatibleBitmap, IntPtr.Zero, ref animParams, out hdcFrom, out hdcTo);
if (hbpAnimation != IntPtr.Zero)
{
if (hdcFrom != IntPtr.Zero)
{
using (Graphics gfxFrom = Graphics.FromHdc(hdcFrom))
PaintControl(new PaintEventArgs(gfxFrom, e.ClipRectangle));
}
currentState = newState;
if (hdcTo != IntPtr.Zero)
{
using (Graphics gfxTo = Graphics.FromHdc(hdcTo))
PaintControl(new PaintEventArgs(gfxTo, e.ClipRectangle));
}
NativeMethods.EndBufferedAnimation(hbpAnimation, true);
}
else
{
hdc.Dispose();
currentState = newState;
PaintControl(e);
}
}
}
}
}
else
{
// buffered painting not supported, just paint using the current state
currentState = newState;
PaintControl(e);
}
}