/// <summary>Registers a thumbnail to be drawn on a window.</summary>
/// <remarks>The thumbnail will not be drawn until you update the thumbnail's properties calling Update().</remarks>
/// <param name="destination">The handle (HWND) of the window on which the thumbnail will be drawn.</param>
/// <param name="source">The handle (HWND) of the window that has to be drawn.</param>
/// <returns>A Thumbnail instance, needed to unregister and to update properties.</returns>
public static Thumbnail Register(IntPtr destination, IntPtr source) {
if (!OsSupport.IsVistaOrBetter)
throw new DwmCompositionException(Resources.ExceptionMessages.DWMOsNotSupported);
if (!OsSupport.IsCompositionEnabled)
throw new DwmCompositionException(Resources.ExceptionMessages.DWMNotEnabled);
if (destination == source)
throw new DwmCompositionException(Resources.ExceptionMessages.DWMWindowMatch);
Thumbnail ret = new Thumbnail();
if (NativeMethods.DwmRegisterThumbnail(destination, source, out ret) == 0) {
return ret;
}
else {
throw new DwmCompositionException(String.Format(Resources.ExceptionMessages.NativeCallFailure, "DwmRegisterThumbnail"));
}
}
public static extern int DwmQueryThumbnailSourceSize(Thumbnail hThumbnail, out DwmSize pSize);
public static extern int DwmUpdateThumbnailProperties(Thumbnail hThumbnailId, ref DwmThumbnailProperties ptnProperties);
public static extern int DwmRegisterThumbnail(IntPtr hwndDestination, IntPtr hwndSource, out Thumbnail phThumbnailId);
private void RecomputeParentForm()
{
//Get the owning form
Form nextParent = this.TopLevelControl as Form;
if (nextParent == null) {
//No owning form found (!)
_topLevelForm = null;
if (_thumbnail != null) {
_thumbnail.Dispose();
_thumbnail = null;
}
return;
}
if (_thumbnail != null && _topLevelForm != nextParent) {
//Parent changed from last time
_thumbnail.Dispose();
_thumbnail = null;
}
_topLevelForm = nextParent;
}
void originForm_FormClosed(object sender, FormClosedEventArgs e)
{
if (_thumbnail != null) {
_thumbnail.Dispose();
_thumbnail = null;
}
}
public void SetThumbnail(IntPtr originHandle)
{
RecomputeParentForm();
if (_topLevelForm != null) {
_thumbnail = DwmManager.Register(_topLevelForm, originHandle);
UpdateThumbnail(Visible);
}
else
throw new Exception("Control must have an owner.");
}
public static void Unregister(Thumbnail handle) {
if (handle != null) {
handle.Close();
}
}
public static extern int DwmUpdateThumbnailProperties(Thumbnail hThumbnailId, ref DwmThumbnailProperties ptnProperties);
public static extern int DwmRegisterThumbnail(IntPtr hwndDestination, IntPtr hwndSource, out Thumbnail phThumbnailId);
public static extern int DwmQueryThumbnailSourceSize(Thumbnail hThumbnail, out DwmSize pSize);
