DropTarget.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / FX-1434 / FX-1434 / 1.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / DropTarget.cs / 1 / DropTarget.cs
                        

                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

 
namespace System.Windows.Forms 
{
        using System; 
        using System.Diagnostics;
        using System.Security.Permissions;
        using System.Security;
        using System.ComponentModel; 

        using IComDataObject = System.Runtime.InteropServices.ComTypes.IDataObject; 
 
        /// 
        ///  
        internal class DropTarget : UnsafeNativeMethods.IOleDropTarget {
            private IDataObject lastDataObject = null;
            private DragDropEffects lastEffect = DragDropEffects.None;
            private IDropTarget owner; 

            public DropTarget(IDropTarget owner) { 
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "DropTarget created"); 
                this.owner = owner;
            } 

#if DEBUG
            ~DropTarget() {
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "DropTarget destroyed"); 
            }
#endif 
 
            private DragEventArgs CreateDragEventArgs(object pDataObj, int grfKeyState, NativeMethods.POINTL pt, int pdwEffect) {
 
                IDataObject data = null;

                if (pDataObj == null) {
                    data = lastDataObject; 
                }
                else { 
                    if (pDataObj is IDataObject) { 
                        data = (IDataObject)pDataObj;
                    } 
                    else if (pDataObj is IComDataObject) {
                        data = new DataObject(pDataObj);
                    }
                    else { 
                        return null; // Unknown data object interface; we can't work with this so return null
                    } 
                } 

                DragEventArgs drgevent = new DragEventArgs(data, grfKeyState, pt.x, pt.y, (DragDropEffects)pdwEffect, lastEffect); 
                lastDataObject = data;
                return drgevent;
            }
 
            int UnsafeNativeMethods.IOleDropTarget.OleDragEnter(object pDataObj, int grfKeyState,
                                                          long pt, 
                                                          ref int pdwEffect) { 
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "OleDragEnter recieved");
                NativeMethods.POINTL ptl = new NativeMethods.POINTL(); 
                ptl.x = GetX(pt);
                ptl.y = GetY(pt);
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "\t" + (ptl.x) + "," + (ptl.y));
                Debug.Assert(pDataObj != null, "OleDragEnter didn't give us a valid data object."); 
                DragEventArgs drgevent = CreateDragEventArgs(pDataObj, grfKeyState, ptl, pdwEffect);
 
                if (drgevent != null) { 
                    owner.OnDragEnter(drgevent);
                    pdwEffect = (int)drgevent.Effect; 
                    lastEffect = drgevent.Effect;
                }
                else {
                    pdwEffect = (int)DragDropEffects.None; 
                }
                return NativeMethods.S_OK; 
            } 
            int UnsafeNativeMethods.IOleDropTarget.OleDragOver(int grfKeyState, long pt, ref int pdwEffect) {
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "OleDragOver recieved"); 
                NativeMethods.POINTL ptl = new NativeMethods.POINTL();
                ptl.x = GetX(pt);
                ptl.y = GetY(pt);
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "\t" + (ptl.x) + "," + (ptl.y)); 
                DragEventArgs drgevent = CreateDragEventArgs(null, grfKeyState, ptl, pdwEffect);
                owner.OnDragOver(drgevent); 
                pdwEffect = (int)drgevent.Effect; 
                lastEffect = drgevent.Effect;
                return NativeMethods.S_OK; 
            }
            int UnsafeNativeMethods.IOleDropTarget.OleDragLeave() {
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "OleDragLeave recieved");
                owner.OnDragLeave(EventArgs.Empty); 
                return NativeMethods.S_OK;
            } 
            int UnsafeNativeMethods.IOleDropTarget.OleDrop(object pDataObj, int grfKeyState, long pt, ref int pdwEffect) { 
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "OleDrop recieved");
                NativeMethods.POINTL ptl = new NativeMethods.POINTL(); 
                ptl.x = GetX(pt);
                ptl.y = GetY(pt);
                Debug.WriteLineIf(CompModSwitches.DragDrop.TraceInfo, "\t" + (ptl.x) + "," + (ptl.y));
                DragEventArgs drgevent = CreateDragEventArgs(pDataObj, grfKeyState, ptl, pdwEffect); 

                if (drgevent != null) { 
                    owner.OnDragDrop(drgevent); 
                    pdwEffect = (int)drgevent.Effect;
                } 
                else {
                    pdwEffect = (int)DragDropEffects.None;
                }
 
                lastEffect = DragDropEffects.None;
                lastDataObject = null; 
                return NativeMethods.S_OK; 
            }
 
            private int GetX(long pt) {
                return(int)(pt & 0xFFFFFFFF);

            } 

            private int GetY(long pt) { 
                return(int)((pt >> 32) & 0xFFFFFFFF); 
            }
        } 


}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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