/// <summary>
/// Defines a target control for the drag and drop operation.
/// </summary>
/// <typeparam name="TControl">The type of the control to drop on</typeparam>
/// <param name="target">The target control to drop on</param>
/// <param name="dragDrop">A function to handle the drop on the target control</param>
/// <returns></returns>
public DragOperation <T> To <TControl>(TControl target, Action <TControl, T> dragDrop) where TControl : Control
{
var handler = DragHandler <T> .CreateDefault();
handler.DragDrop = (value, _) =>
{
_previewFormController?.Stop(target, wasCancelled: false);
dragDrop?.Invoke(target, value);
};
return(To(target, handler));
}
/// <summary>
/// Starts the drag and drop operation
/// </summary>
/// <param name="effect">The desired drag and drop effect like Copy, Move or Link</param>
private void Start(DragDropEffects effect)
{
StopTrackingForDeferredStartOnMouseMove();
var canProceed = _conditionEvaluator.Invoke();
if (!canProceed)
{
return;
}
_previewFormController = new PreviewFormController();
var preview = _previewEvaluator?.Invoke();
var hookId = IntPtr.Zero;
var resultEffect = DragDropEffects.None;
try
{
hookId = NativeMethods.HookMouseMove(() => _previewFormController.Move());
_previewFormController.Start(SourceControl, _effects, preview, _cursorOffset);
var data = Data == null ? (object)new NullPlaceholder() : Data;
resultEffect = SourceControl.DoDragDrop(data, effect);
}
finally
{
NativeMethods.RemoveHook(hookId);
// always send "canceled" here -> if the drag and drop operation was successful
// this call is too late and will not do anything
_previewFormController.Stop(null, wasCancelled: true);
CleanUp();
}
}
/// <summary>
/// Starts the drag and drop operation
/// </summary>
/// <param name="effect">The desired drag and drop effect like Copy, Move or Link</param>
private void Start(DragDropEffects effect)
{
StopTrackingForDeferredStartOnMouseMove();
var canProceed = _conditionEvaluator.Invoke();
if (!canProceed)
{
return;
}
OnSafeguardedBeforeStart();
_previewFormController = new PreviewFormController();
var preview = _previewEvaluator?.Invoke();
var hookId = IntPtr.Zero;
var resultEffect = DragDropEffects.None;
try
{
if (_allowMouseHooks)
{
hookId = NativeMethods.HookMouseMove(() => _previewFormController.Move());
}
else
{
SourceControl.GiveFeedback += SourceControl_GiveFeedback;
}
var offset = _offsetEvaluator?.Invoke(CalculatePreviewSize()) ?? Point.Empty;
_previewFormController.Start(SourceControl, _effects, preview, offset);
var data = Data == null ? (object)new NullPlaceholder() : Data;
OnSafeguardedAfterStart();
resultEffect = SourceControl.DoDragDrop(data, effect);
}
finally
{
if (_allowMouseHooks)
{
NativeMethods.RemoveHook(hookId);
}
else
{
SourceControl.GiveFeedback -= SourceControl_GiveFeedback;
}
// always send "canceled" here -> if the drag and drop operation was successful
// this call is too late and will not do anything
_previewFormController.Stop(null, wasCancelled: true);
InvokeCancelIfNotDroppedAction();
CleanUp();
}
}
