/// <summary>
/// Gets a drop description flag.
/// </summary>
private static DropDescriptionFlags GetDropDescriptionFlag(IComDataObject dataObject)
{
int flag;
if (dataObject.TryGetData("DropDescriptionFlags", out flag))
{
return((DropDescriptionFlags)flag);
}
return(DropDescriptionFlags.None);
}
/// <summary>
/// Gets a drop description.
/// </summary>
public static object GetDropDescription(IComDataObject dataObject)
{
DropDescription desc;
if (dataObject.TryGetData("DropDescription", out desc))
{
return(desc);
}
return(null);
}
// The drag image manager sets this flag to indicate if the current
// drop target supports drag images.
private static bool IsShowingLayered(IComDataObject dataObject)
{
int value;
if (dataObject.TryGetData("IsShowingLayered", out value))
{
return(value != 0);
}
return(false);
}
/// <summary>
/// Gets a drop description.
/// </summary>
public static object GetDropDescription(IComDataObject dataObject)
{
// CFSTR_DROPDESCRIPTION
DropDescription desc;
if (dataObject.TryGetData("DropDescription", out desc))
{
return(desc);
}
return(null);
}
/// <summary>
/// Default feedback handler.
/// </summary>
public static void DefaultGiveFeedback(IComDataObject data, GiveFeedbackEventArgs e)
{
// For drop targets that don't set the drop description, we'll
// set a default one. Drop targets that do set drop descriptions
// should set an invalid drop description during DragLeave.
var setDefaultDropDesc = false;
var isDefaultDropDesc = IsDropDescriptionDefault(data);
var currentType = DropImageType.Invalid;
if (!IsDropDescriptionValid(data) || isDefaultDropDesc)
{
currentType = GetDropImageType(data);
setDefaultDropDesc = true;
}
if (IsShowingLayered(data))
{
// The default drag source implementation uses drop descriptions,
// so we won't use default cursors.
e.UseDefaultCursors = false;
Cursor.Current = Cursors.Default;
}
else
{
e.UseDefaultCursors = true;
}
// We need to invalidate the drag image to refresh the drop description.
// This is tricky to implement correctly, but we try to mimic the Windows
// Explorer behavior. We internally use a flag to tell us to invalidate
// the drag image, so if that is set, we'll invalidate. Otherwise, we
// always invalidate if the drop description was set by the drop target,
// *or* if the current drop image is not None. So if we set a default
// drop description to anything but None, we'll always invalidate.
if (InvalidateRequired(data) || !isDefaultDropDesc || currentType != DropImageType.None)
{
IntPtr hwnd;
if (data.TryGetData("DragWindow", out hwnd))
{
const uint WM_INVALIDATEDRAGIMAGE = 0x403;
PostMessage(hwnd, WM_INVALIDATEDRAGIMAGE, IntPtr.Zero, IntPtr.Zero);
}
// The invalidate required flag only lasts for one invalidation
SetInvalidateRequired(data, false);
}
// If the drop description is currently invalid, or if it is a default
// drop description already, we should check about re-setting it.
if (setDefaultDropDesc && (DropImageType)e.Effect != currentType)
{
if (e.Effect != DragDropEffects.None)
{
SetDropDescription(data, (DropImageType)e.Effect, e.Effect.ToString(), null);
}
else
{
SetDropDescription(data, (DropImageType)e.Effect, e.Effect.ToString(), null);
}
SetDropDescriptionIsDefault(data, true);
// We can't invalidate now, because the drag image manager won't
// pick it up... so we set this flag to invalidate on the next
// GiveFeedback event.
SetInvalidateRequired(data, true);
}
}
/// <summary>
/// Gets a drop description flag.
/// </summary>
private static DropDescriptionFlags GetDropDescriptionFlag(IComDataObject dataObject)
{
int flag;
if (dataObject.TryGetData("DropDescriptionFlags", out flag))
{
return (DropDescriptionFlags)flag;
}
return DropDescriptionFlags.None;
}
// The drag image manager sets this flag to indicate if the current
// drop target supports drag images.
private static bool IsShowingLayered(IComDataObject dataObject)
{
int value;
if (dataObject.TryGetData("IsShowingLayered", out value))
{
return (value != 0);
}
return false;
}
/// <summary>
/// Default feedback handler.
/// </summary>
public static void DefaultGiveFeedback(IComDataObject data, GiveFeedbackEventArgs e)
{
// For drop targets that don't set the drop description, we'll
// set a default one. Drop targets that do set drop descriptions
// should set an invalid drop description during DragLeave.
var setDefaultDropDesc = false;
var isDefaultDropDesc = IsDropDescriptionDefault(data);
var currentType = DropImageType.Invalid;
if (!IsDropDescriptionValid(data) || isDefaultDropDesc)
{
currentType = GetDropImageType(data);
setDefaultDropDesc = true;
}
if (IsShowingLayered(data))
{
// The default drag source implementation uses drop descriptions,
// so we won't use default cursors.
e.UseDefaultCursors = false;
Cursor.Current = Cursors.Default;
}
else
{
e.UseDefaultCursors = true;
}
// We need to invalidate the drag image to refresh the drop description.
// This is tricky to implement correctly, but we try to mimic the Windows
// Explorer behavior. We internally use a flag to tell us to invalidate
// the drag image, so if that is set, we'll invalidate. Otherwise, we
// always invalidate if the drop description was set by the drop target,
// *or* if the current drop image is not None. So if we set a default
// drop description to anything but None, we'll always invalidate.
if (InvalidateRequired(data) || !isDefaultDropDesc || currentType != DropImageType.None)
{
IntPtr hwnd;
if (data.TryGetData("DragWindow", out hwnd))
{
const uint WM_INVALIDATEDRAGIMAGE = 0x403;
User32.PostMessage(hwnd, WM_INVALIDATEDRAGIMAGE, IntPtr.Zero, IntPtr.Zero);
}
// The invalidate required flag only lasts for one invalidation
SetInvalidateRequired(data, false);
}
// If the drop description is currently invalid, or if it is a default
// drop description already, we should check about re-setting it.
if (setDefaultDropDesc && (DropImageType)e.Effect != currentType)
{
if (e.Effect != DragDropEffects.None)
{
SetDropDescription(data, (DropImageType)e.Effect, e.Effect.ToString(), null);
}
else
{
SetDropDescription(data, (DropImageType)e.Effect, e.Effect.ToString(), null);
}
SetDropDescriptionIsDefault(data, true);
// We can't invalidate now, because the drag image manager won't
// pick it up... so we set this flag to invalidate on the next
// GiveFeedback event.
SetInvalidateRequired(data, true);
}
}
/// <summary>
/// Gets a drop description.
/// </summary>
public static object GetDropDescription(IComDataObject dataObject)
{
DropDescription desc;
if (dataObject.TryGetData("DropDescription", out desc))
{
return desc;
}
return null;
}
/// <summary>
/// Gets a drop description.
/// </summary>
public static object GetDropDescription(IComDataObject dataObject)
{
// CFSTR_DROPDESCRIPTION
DropDescription desc;
if (dataObject.TryGetData("DropDescription", out desc))
{
return desc;
}
return null;
}