/// <summary>
/// Sets a drop description flag.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <param name="flag">The drop description flag to set.</param>
/// <param name="enabled">True to set the flag, False to unset it.</param>
private static void SetDropDescriptionFlag(IComDataObject dataObject, DropDescriptionFlags flag, bool enabled)
{
var current = GetDropDescriptionFlag(dataObject);
var next = enabled ? (current | flag) : (current | flag) ^ flag;
if (current != next)
{
dataObject.SetData("DropDescriptionFlags", (int)next);
}
}
/// <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>
/// Sets a drop description flag.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <param name="flag">The drop description flag to set.</param>
/// <param name="enabled">True to set the flag, False to unset it.</param>
private static void SetDropDescriptionFlag(IComDataObject dataObject, DropDescriptionFlags flag, bool enabled)
{
var current = GetDropDescriptionFlag(dataObject);
var next = enabled ? (current | flag) : (current | flag) ^ flag;
if (current != next)
{
dataObject.SetData("DropDescriptionFlags", (int)next);
}
}
/// <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);
}
/// <summary>
/// Sets a drop description.
/// </summary>
public static void SetDropDescription(IComDataObject data, DropImageType dragDropEffects, string format, string insert)
{
if (format != null && format.Length > 259)
{
throw new ArgumentException("Format string exceeds the maximum allowed length of 259.", "format");
}
if (insert != null && insert.Length > 259)
{
throw new ArgumentException("Insert string exceeds the maximum allowed length of 259.", "insert");
}
// Fill the structure
DropDescription dd;
dd.type = dragDropEffects;
dd.szMessage = format;
dd.szInsert = insert;
data.SetData("DropDescription", dd);
}
/// <summary>
/// Check if the description is valid.
/// </summary>
public static bool IsDropDescriptionValid(IComDataObject dataObject)
{
return(GetDropImageType(dataObject) != DropImageType.Invalid);
}
/// <summary>
/// Gets the image type from a drop description.
/// </summary>
public static DropImageType GetDropImageType(IComDataObject dataObject)
{
var data = GetDropDescription(dataObject);
return((data is DropDescription) ? ((DropDescription)data).type : DropImageType.Invalid);
}
/// <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>
/// Checks if the IsDefault drop description flag is set for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <returns>True if the IsDefault flag is set, otherwise False.</returns>
public static bool IsDropDescriptionDefault(IComDataObject dataObject)
{
var current = GetDropDescriptionFlag(dataObject);
return((current & DropDescriptionFlags.IsDefault) == DropDescriptionFlags.IsDefault);
}
/// <summary>
/// Check if the description is valid.
/// </summary>
public static bool IsDropDescriptionValid(IComDataObject dataObject)
{
return GetDropImageType(dataObject) != DropImageType.Invalid;
}
/// <summary>
/// Checks if the InvalidateRequired drop description flag is set for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <returns>True if the InvalidateRequired flag is set, otherwise False.</returns>
public static bool InvalidateRequired(IComDataObject dataObject)
{
var current = GetDropDescriptionFlag(dataObject);
return (current & DropDescriptionFlags.InvalidateRequired) == DropDescriptionFlags.InvalidateRequired;
}
/// <summary>
/// Sets the IsDefault drop description flag for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <param name="isDefault">True to set the flag, False to unset it.</param>
public static void SetDropDescriptionIsDefault(IComDataObject dataObject, bool isDefault)
{
SetDropDescriptionFlag(dataObject, DropDescriptionFlags.IsDefault, isDefault);
}
/// <summary>
/// Checks if the IsDefault drop description flag is set for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <returns>True if the IsDefault flag is set, otherwise False.</returns>
public static bool IsDropDescriptionDefault(IComDataObject dataObject)
{
var current = GetDropDescriptionFlag(dataObject);
return (current & DropDescriptionFlags.IsDefault) == DropDescriptionFlags.IsDefault;
}
// 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>
/// 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>
/// Sets the IsDefault drop description flag for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associdated DataObject.</param>
/// <param name="isDefault">True to set the flag, False to unset it.</param>
public static void SetDropDescriptionIsDefault(IComDataObject dataObject, bool isDefault)
{
SetDropDescriptionFlag(dataObject, DropDescriptionFlags.IsDefault, isDefault);
}
/// <summary>
/// Sets the InvalidatedRequired drop description flag for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <param name="required">True to set the flag, False to unset it.</param>
public static void SetInvalidateRequired(IComDataObject dataObject, bool required)
{
SetDropDescriptionFlag(dataObject, DropDescriptionFlags.InvalidateRequired, required);
}
/// <summary>
/// Gets the image type from a drop description.
/// </summary>
public static DropImageType GetDropImageType(IComDataObject dataObject)
{
var data = GetDropDescription(dataObject);
return (data is DropDescription) ? ((DropDescription)data).type : DropImageType.Invalid;
}
/// <summary>
/// Checks if the InvalidateRequired drop description flag is set for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associated DataObject.</param>
/// <returns>True if the InvalidateRequired flag is set, otherwise False.</returns>
public static bool InvalidateRequired(IComDataObject dataObject)
{
var current = GetDropDescriptionFlag(dataObject);
return((current & DropDescriptionFlags.InvalidateRequired) == DropDescriptionFlags.InvalidateRequired);
}
public static extern int OleGetClipboard(ref IComDataObject data);
/// <summary>
/// Sets the InvalidatedRequired drop description flag for the associated DataObject.
/// </summary>
/// <param name="dataObject">The associdated DataObject.</param>
/// <param name="required">True to set the flag, False to unset it.</param>
public static void SetInvalidateRequired(IComDataObject dataObject, bool required)
{
SetDropDescriptionFlag(dataObject, DropDescriptionFlags.InvalidateRequired, required);
}
public static extern int OleIsCurrentClipboard(IComDataObject pDataObj);
/// <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>
/// Sets a drop description.
/// </summary>
public static void SetDropDescription(IComDataObject data, DropImageType dragDropEffects, string format, string insert)
{
if (format != null && format.Length > 259)
throw new ArgumentException("Format string exceeds the maximum allowed length of 259.", "format");
if (insert != null && insert.Length > 259)
throw new ArgumentException("Insert string exceeds the maximum allowed length of 259.", "insert");
// Fill the structure
DropDescription dd;
dd.type = dragDropEffects;
dd.szMessage = format;
dd.szInsert = insert;
data.SetData("DropDescription", dd);
}
public static extern int OleSetClipboard(IComDataObject pDataObj);
/// <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;
}
