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/*******************************************************************************
 * Copyright (c) 2000, 2018 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *     Lars Vogel  - Bug 497807
 *******************************************************************************/
package org.eclipse.swt.dnd;


import java.lang.reflect.*;

import org.eclipse.swt.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.internal.*;
import org.eclipse.swt.internal.dnd.gtk.*;
import org.eclipse.swt.internal.gtk.*;
import org.eclipse.swt.internal.gtk3.*;
import org.eclipse.swt.internal.gtk4.*;
import org.eclipse.swt.widgets.*;

/**
 *
 * DragSource defines the source object for a drag and drop transfer.
 *
 * 

IMPORTANT: This class is not intended to be subclassed.

* *

A drag source is the object which originates a drag and drop operation. For the specified widget, * it defines the type of data that is available for dragging and the set of operations that can * be performed on that data. The operations can be any bit-wise combination of DND.MOVE, DND.COPY or * DND.LINK. The type of data that can be transferred is specified by subclasses of Transfer such as * TextTransfer or FileTransfer. The type of data transferred can be a predefined system type or it * can be a type defined by the application. For instructions on how to define your own transfer type, * refer to ByteArrayTransfer.

* *

You may have several DragSources in an application but you can only have one DragSource * per Control. Data dragged from this DragSource can be dropped on a site within this application * or it can be dropped on another application such as an external Text editor.

* *

The application supplies the content of the data being transferred by implementing the * DragSourceListener and associating it with the DragSource via DragSource#addDragListener.

* *

When a successful move operation occurs, the application is required to take the appropriate * action to remove the data from its display and remove any associated operating system resources or * internal references. Typically in a move operation, the drop target makes a copy of the data * and the drag source deletes the original. However, sometimes copying the data can take a long * time (such as copying a large file). Therefore, on some platforms, the drop target may actually * move the data in the operating system rather than make a copy. This is usually only done in * file transfers. In this case, the drag source is informed in the DragEnd event that a * DROP_TARGET_MOVE was performed. It is the responsibility of the drag source at this point to clean * up its displayed information. No action needs to be taken on the operating system resources.

* *

The following example shows a Label widget that allows text to be dragged from it.

* *

 *	// Enable a label as a Drag Source
 *	Label label = new Label(shell, SWT.NONE);
 *	// This example will allow text to be dragged
 *	Transfer[] types = new Transfer[] {TextTransfer.getInstance()};
 *	// This example will allow the text to be copied or moved to the drop target
 *	int operations = DND.DROP_MOVE | DND.DROP_COPY;
 *
 *	DragSource source = new DragSource(label, operations);
 *	source.setTransfer(types);
 *	source.addDragListener(new DragSourceListener() {
 *		public void dragStart(DragSourceEvent e) {
 *			// Only start the drag if there is actually text in the
 *			// label - this text will be what is dropped on the target.
 *			if (label.getText().length() == 0) {
 *				event.doit = false;
 *			}
 *		};
 *		public void dragSetData(DragSourceEvent event) {
 *			// A drop has been performed, so provide the data of the
 *			// requested type.
 *			// (Checking the type of the requested data is only
 *			// necessary if the drag source supports more than
 *			// one data type but is shown here as an example).
 *			if (TextTransfer.getInstance().isSupportedType(event.dataType)){
 *				event.data = label.getText();
 *			}
 *		}
 *		public void dragFinished(DragSourceEvent event) {
 *			// A Move operation has been performed so remove the data
 *			// from the source
 *			if (event.detail == DND.DROP_MOVE)
 *				label.setText("");
 *		}
 *	});
 * 
* * *
*
Styles
DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK
*
Events
DND.DragStart, DND.DragSetData, DND.DragEnd
*
* * @see Drag and Drop snippets * @see SWT Example: DNDExample * @see Sample code and further information * @noextend This class is not intended to be subclassed by clients. */ public class DragSource extends Widget { // info for registering as a drag source Control control; Listener controlListener; Transfer[] transferAgents = new Transfer[0]; DragSourceEffect dragEffect; long targetList; //workaround - remember action performed for DragEnd boolean moveData = false; static final String DEFAULT_DRAG_SOURCE_EFFECT = "DEFAULT_DRAG_SOURCE_EFFECT"; //$NON-NLS-1$ /* GTK4 GtkDragSource event controller signal callbacks */ static Callback dragBeginProc, dragPrepareProc, dragEndProc; /* GTK3 GtkWidget drag event signal callbacks */ static Callback DragBegin, DragGetData, DragEnd, DragDataDelete; static { if (GTK.GTK4) { dragBeginProc = new Callback(DragSource.class, "dragBeginProc", void.class, new Type[] { long.class, long.class }); dragPrepareProc = new Callback(DragSource.class, "dragPrepareProc", long.class, new Type[] { long.class, double.class, double.class }); dragEndProc = new Callback(DragSource.class, "dragEndProc", void.class, new Type[] { long.class, long.class, boolean.class }); } else { DragBegin = new Callback(DragSource.class, "DragBegin", 2); //$NON-NLS-1$ DragGetData = new Callback(DragSource.class, "DragGetData", 5); //$NON-NLS-1$ DragEnd = new Callback(DragSource.class, "DragEnd", 2); //$NON-NLS-1$ DragDataDelete = new Callback(DragSource.class, "DragDataDelete", 2); //$NON-NLS-1$ } } /** * Creates a new DragSource to handle dragging from the specified Control. * Creating an instance of a DragSource may cause system resources to be allocated depending on the platform. * It is therefore mandatory that the DragSource instance be disposed when no longer required. * * @param control the Control that the user clicks on to initiate the drag * @param style the bitwise OR'ing of allowed operations; this may be a combination of any of * DND.DROP_NONE, DND.DROP_COPY, DND.DROP_MOVE, DND.DROP_LINK * * @exception SWTException
    *
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the parent
  • *
  • ERROR_INVALID_SUBCLASS - if this class is not an allowed subclass
  • *
* @exception SWTError
    *
  • ERROR_CANNOT_INIT_DRAG - unable to initiate drag source; this will occur if more than one * drag source is created for a control or if the operating system will not allow the creation * of the drag source
  • *
* *

NOTE: ERROR_CANNOT_INIT_DRAG should be an SWTException, since it is a * recoverable error, but can not be changed due to backward compatibility.

* * @see Widget#dispose * @see DragSource#checkSubclass * @see DND#DROP_NONE * @see DND#DROP_COPY * @see DND#DROP_MOVE * @see DND#DROP_LINK */ public DragSource(Control control, int style) { super (control, checkStyle(style)); this.control = control; if (GTK.GTK4) { if (dragBeginProc == null || dragPrepareProc == null || dragEndProc == null) { DND.error(DND.ERROR_CANNOT_INIT_DRAG); } if (control.getData(DND.DRAG_SOURCE_KEY) != null) { DND.error(DND.ERROR_CANNOT_INIT_DRAG); } control.setData(DND.DRAG_SOURCE_KEY, this); long dragSourceController = GTK4.gtk_drag_source_new(); GTK4.gtk_widget_add_controller(control.handle, dragSourceController); OS.g_signal_connect(dragSourceController, OS.drag_begin, dragBeginProc.getAddress(), 0); OS.g_signal_connect(dragSourceController, OS.prepare, dragPrepareProc.getAddress(), 0); OS.g_signal_connect(dragSourceController, OS.drag_end, dragEndProc.getAddress(), 0); // Set permitted actions on the GtkDragSource int actions = opToOsOp(style); GTK4.gtk_drag_source_set_actions(dragSourceController, actions); } else { if (DragGetData == null || DragEnd == null || DragDataDelete == null) { DND.error(DND.ERROR_CANNOT_INIT_DRAG); } if (control.getData(DND.DRAG_SOURCE_KEY) != null) { DND.error(DND.ERROR_CANNOT_INIT_DRAG); } control.setData(DND.DRAG_SOURCE_KEY, this); // There's a native GTK snippet available, find 'Issue0400_WaylandDndEvents.cpp' in this repo. // It may be helpful in understanding / debugging bugs. OS.g_signal_connect(control.handle, OS.drag_begin, DragBegin.getAddress(), 0); OS.g_signal_connect(control.handle, OS.drag_data_get, DragGetData.getAddress(), 0); OS.g_signal_connect(control.handle, OS.drag_end, DragEnd.getAddress(), 0); OS.g_signal_connect(control.handle, OS.drag_data_delete, DragDataDelete.getAddress(), 0); controlListener = event -> { if (event.type == SWT.Dispose) { if (!DragSource.this.isDisposed()) { DragSource.this.dispose(); } } if (event.type == SWT.DragDetect) { if (!DragSource.this.isDisposed()) { DragSource.this.drag(event); } } }; control.addListener (SWT.Dispose, controlListener); control.addListener (SWT.DragDetect, controlListener); Object effect = control.getData(DEFAULT_DRAG_SOURCE_EFFECT); if (effect instanceof DragSourceEffect) { dragEffect = (DragSourceEffect) effect; } else if (control instanceof Tree) { dragEffect = new TreeDragSourceEffect((Tree) control); } else if (control instanceof Table) { dragEffect = new TableDragSourceEffect((Table) control); } else if (control instanceof List) { dragEffect = new ListDragSourceEffect((List) control); } this.addListener(SWT.Dispose, e -> onDispose()); } } static int checkStyle (int style) { if (style == SWT.NONE) return DND.DROP_MOVE; return style; } static void dragBeginProc(long source, long drag) { long widgetHandle = GTK.gtk_event_controller_get_widget(source); DragSource dragSource = FindDragSource(widgetHandle); if (dragSource == null) return; dragSource.dragBeginGtk4(source); } void dragBeginGtk4(long source) { DNDEvent event = new DNDEvent(); event.widget = this; event.doit = true; notifyListeners(DND.DragStart, event); if (!event.doit || transferAgents == null || transferAgents.length == 0) return; // If specified, setup drag icon Image dragIcon = event.image; if (source != 0 && dragIcon != null) { long pixbuf = ImageList.createPixbuf(dragIcon); long texture = GDK.gdk_texture_new_for_pixbuf(pixbuf); OS.g_object_unref(pixbuf); GTK4.gtk_drag_source_set_icon(source, texture, 0, 0); } } static long dragPrepareProc(long source, double x, double y) { long widgetHandle = GTK.gtk_event_controller_get_widget(source); DragSource dragSource = FindDragSource(widgetHandle); if (dragSource == null) return 0; return dragSource.dragPrepare(); } long dragPrepare() { TransferData transferData = new TransferData(); DNDEvent event = new DNDEvent(); event.widget = this; event.dataType = transferData; notifyListeners(DND.DragSetData, event); if (!event.doit) return 0; // TODO: Need to return GdkContentProvider for the data given from event.data // Data from event.data also has to be converted to native through the Transfer class return 0; } static void dragEndProc(long source, long drag, boolean delete_data) { } static long DragBegin(long widget, long context){ DragSource source = FindDragSource(widget); if (source == null) return 0; source.dragBegin(widget, context); return 0; } static long DragDataDelete(long widget, long context){ DragSource source = FindDragSource(widget); if (source == null) return 0; source.dragDataDelete(widget, context); return 0; } static long DragEnd(long widget, long context){ DragSource source = FindDragSource(widget); if (source == null) return 0; source.dragEnd(widget, context); return 0; } static long DragGetData(long widget, long context, long selection_data, long info, long time){ DragSource source = FindDragSource(widget); if (source == null) return 0; source.dragGetData(widget, context, selection_data, (int)info, (int)time); return 0; } static DragSource FindDragSource(long handle) { Display display = Display.findDisplay(Thread.currentThread()); if (display == null || display.isDisposed()) return null; Widget widget = display.findWidget(handle); if (widget == null) return null; return (DragSource)widget.getData(DND.DRAG_SOURCE_KEY); } /** * Adds the listener to the collection of listeners who will * be notified when a drag and drop operation is in progress, by sending * it one of the messages defined in the DragSourceListener * interface. * *
    *
  • dragStart is called when the user has begun the actions required to drag the widget. * This event gives the application the chance to decide if a drag should be started. *
  • dragSetData is called when the data is required from the drag source. *
  • dragFinished is called when the drop has successfully completed (mouse up * over a valid target) or has been terminated (such as hitting the ESC key). Perform cleanup * such as removing data from the source side on a successful move operation. *
* * @param listener the listener which should be notified * * @exception IllegalArgumentException
    *
  • ERROR_NULL_ARGUMENT - if the listener is null
  • *
* @exception SWTException
    *
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • *
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
  • *
* * @see DragSourceListener * @see #getDragListeners * @see #removeDragListener * @see DragSourceEvent */ public void addDragListener(DragSourceListener listener) { if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT); DNDListener typedListener = new DNDListener (listener); typedListener.dndWidget = this; addListener (DND.DragStart, typedListener); addListener (DND.DragSetData, typedListener); addListener (DND.DragEnd, typedListener); } @Override protected void checkSubclass () { String name = getClass().getName (); String validName = DragSource.class.getName(); if (!validName.equals(name)) { DND.error (SWT.ERROR_INVALID_SUBCLASS); } } boolean canBeginDrag() { if (transferAgents == null || transferAgents.length == 0) return false; if (targetList == 0) return false; return true; } void drag(Event dragEvent) { moveData = false; DNDEvent event = new DNDEvent(); event.widget = this; event.x = dragEvent.x; event.y = dragEvent.y; event.time = dragEvent.time; event.doit = true; notifyListeners(DND.DragStart, event); if (!event.doit || !canBeginDrag()) return; int actions = opToOsOp(getStyle()); Image image = event.image; long context; context = GTK3.gtk_drag_begin_with_coordinates(control.handle, targetList, actions, 1, 0, -1, -1); if (context != 0 && image != null) { GTK3.gtk_drag_set_icon_surface(context, image.surface); } } void dragBegin(long widget, long context) { /* * Bug 515035: GTK DnD hijacks the D&D logic we have in SWT. * When we recieve the signal from GTK of DragBegin, we will * notify SWT that a drag has occurred. */ if (this.control instanceof Text) { DNDEvent event = new DNDEvent(); Display display = Display.getCurrent(); Point loc = display.getCursorLocation(); event.widget = this; event.doit = true; event.x = loc.x; event.y = loc.y; notifyListeners(DND.DragStart, event); if (!event.doit || transferAgents == null || transferAgents.length == 0) return; if (targetList == 0) return; Image image = event.image; if (context != 0 && image != null) { GTK3.gtk_drag_set_icon_surface(context, image.surface); } } } void dragEnd(long widget, long context){ /* * Bug in GTK. If a drag is initiated using gtk_drag_begin and the * mouse is released immediately, the mouse and keyboard remain * grabbed. The fix is to release the grab on the mouse and keyboard * whenever the drag is terminated. * * NOTE: We believe that it is never an error to ungrab when * a drag is finished. */ long display; if (GTK.GTK4) { long surface = GTK4.gtk_native_get_surface(GTK4.gtk_widget_get_native (widget)); display = GDK.gdk_surface_get_display(surface); } else { display = GDK.gdk_window_get_display(GTK3.gtk_widget_get_window(widget)); } long pointer = GDK.gdk_get_pointer(display); if (GTK.GTK4) { //TODO: GTK4, ungrab keyboard seat if different from pointer's seat } else { long keyboard = GDK.gdk_device_get_associated_device(pointer); long keyboard_seat = GDK.gdk_device_get_seat(keyboard); GDK.gdk_seat_ungrab(keyboard_seat); } long pointer_seat = GDK.gdk_device_get_seat(pointer); GDK.gdk_seat_ungrab(pointer_seat); int operation = DND.DROP_NONE; if (context != 0) { long dest_window = 0; int action = 0; /* * Feature in GTK: dest_window information is not gathered here in Wayland as the * DragEnd signal does not give the correct destination window. GTK3.14+ with * GTKGestures will handle file operations correctly without the * gdk_drag_context_get_dest_window() call. See Bug 503431. */ action = GDK.gdk_drag_context_get_selected_action(context); if (OS.isX11()) { dest_window = GDK.gdk_drag_context_get_dest_window(context); } if (dest_window != 0 || OS.isWayland()) { // NOTE: if dest_window is 0, drag was aborted if (moveData) { operation = DND.DROP_MOVE; } else { operation = osOpToOp(action); if (operation == DND.DROP_MOVE) operation = DND.DROP_NONE; } } } DNDEvent event = new DNDEvent(); event.widget = this; //event.time = ??? event.doit = operation != 0; event.detail = operation; notifyListeners(DND.DragEnd, event); if (OS.isWayland()) { /* * Feature in GTK: release events are not signaled during the dragEnd phrase of a Drag and Drop * in Wayland. In order to work with the current logic for DnD in multiselection * Widgets (tree, table, list), the selection function needs to be set back to * true on dragEnd as well as release_event(). See bug 503431. */ if (this.control instanceof Table || this.control instanceof Tree || this.control instanceof List) { long selection = GTK.gtk_tree_view_get_selection (widget); GTK.gtk_tree_selection_set_select_function(selection,0,0,0); } } moveData = false; } void dragGetData(long widget, long context, long selection_data, int info, int time){ if (selection_data == 0) return; int length = GTK3.gtk_selection_data_get_length(selection_data); int format = GTK3.gtk_selection_data_get_format(selection_data); long data = GTK3.gtk_selection_data_get_data(selection_data); long target = GTK3.gtk_selection_data_get_target(selection_data); if (target == 0) return; TransferData transferData = new TransferData(); transferData.type = target; transferData.pValue = data; transferData.length = length; transferData.format = format; DNDEvent event = new DNDEvent(); event.widget = this; event.time = time; event.dataType = transferData; notifyListeners(DND.DragSetData, event); if (!event.doit) return; Transfer transfer = null; for (int i = 0; i < transferAgents.length; i++) { Transfer transferAgent = transferAgents[i]; if (transferAgent != null && transferAgent.isSupportedType(transferData)) { transfer = transferAgent; break; } } if (transfer == null) return; transfer.javaToNative(event.data, transferData); if (transferData.result != 1) return; GTK3.gtk_selection_data_set(selection_data, transferData.type, transferData.format, transferData.pValue, transferData.length); OS.g_free(transferData.pValue); return; } void dragDataDelete(long widget, long context){ moveData = true; } /** * Returns the Control which is registered for this DragSource. This is the control that the * user clicks in to initiate dragging. * * @return the Control which is registered for this DragSource */ public Control getControl () { return control; } /** * Returns an array of listeners who will be notified when a drag and drop * operation is in progress, by sending it one of the messages defined in * the DragSourceListener interface. * * @return the listeners who will be notified when a drag and drop * operation is in progress * * @exception SWTException
    *
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • *
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
  • *
* * @see DragSourceListener * @see #addDragListener * @see #removeDragListener * @see DragSourceEvent * * @since 3.4 */ public DragSourceListener[] getDragListeners() { return getTypedListeners(DND.DragStart, DragSourceListener.class).toArray(DragSourceListener[]::new); } /** * Returns the drag effect that is registered for this DragSource. This drag * effect will be used during a drag and drop operation. * * @return the drag effect that is registered for this DragSource * * @since 3.3 */ public DragSourceEffect getDragSourceEffect() { return dragEffect; } /** * Returns the list of data types that can be transferred by this DragSource. * * @return the list of data types that can be transferred by this DragSource */ public Transfer[] getTransfer(){ return transferAgents; } void onDispose() { if (control == null) return; if (targetList != 0) { GTK3.gtk_target_list_unref(targetList); } targetList = 0; if (controlListener != null) { control.removeListener(SWT.Dispose, controlListener); control.removeListener(SWT.DragDetect, controlListener); } controlListener = null; control.setData(DND.DRAG_SOURCE_KEY, null); control = null; transferAgents = null; } int opToOsOp(int operation){ int osOperation = 0; if ((operation & DND.DROP_COPY) == DND.DROP_COPY) osOperation |= GDK.GDK_ACTION_COPY; if ((operation & DND.DROP_MOVE) == DND.DROP_MOVE) osOperation |= GDK.GDK_ACTION_MOVE; if ((operation & DND.DROP_LINK) == DND.DROP_LINK) osOperation |= GDK.GDK_ACTION_LINK; return osOperation; } int osOpToOp(int osOperation){ int operation = DND.DROP_NONE; if ((osOperation & GDK.GDK_ACTION_COPY) == GDK.GDK_ACTION_COPY) operation |= DND.DROP_COPY; if ((osOperation & GDK.GDK_ACTION_MOVE) == GDK.GDK_ACTION_MOVE) operation |= DND.DROP_MOVE; if ((osOperation & GDK.GDK_ACTION_LINK) == GDK.GDK_ACTION_LINK) operation |= DND.DROP_LINK; return operation; } /** * Removes the listener from the collection of listeners who will * be notified when a drag and drop operation is in progress. * * @param listener the listener which should no longer be notified * * @exception IllegalArgumentException
    *
  • ERROR_NULL_ARGUMENT - if the listener is null
  • *
* @exception SWTException
    *
  • ERROR_WIDGET_DISPOSED - if the receiver has been disposed
  • *
  • ERROR_THREAD_INVALID_ACCESS - if not called from the thread that created the receiver
  • *
* * @see DragSourceListener * @see #addDragListener * @see #getDragListeners */ public void removeDragListener(DragSourceListener listener) { if (listener == null) DND.error (SWT.ERROR_NULL_ARGUMENT); removeTypedListener(DND.DragStart, listener); removeTypedListener(DND.DragSetData, listener); removeTypedListener(DND.DragEnd, listener); } /** * Specifies the drag effect for this DragSource. This drag effect will be * used during a drag and drop operation. * * @param effect the drag effect that is registered for this DragSource * * @since 3.3 */ public void setDragSourceEffect(DragSourceEffect effect) { dragEffect = effect; } /** * Specifies the list of data types that can be transferred by this DragSource. * The application must be able to provide data to match each of these types when * a successful drop has occurred. * * @param transferAgents a list of Transfer objects which define the types of data that can be * dragged from this source */ public void setTransfer(Transfer... transferAgents){ if (GTK.GTK4) { this.transferAgents = transferAgents; } else { if (targetList != 0) { GTK3.gtk_target_list_unref(targetList); targetList = 0; } this.transferAgents = transferAgents; if (transferAgents == null || transferAgents.length == 0) return; GtkTargetEntry[] targets = new GtkTargetEntry[0]; for (int i = 0; i < transferAgents.length; i++) { Transfer transfer = transferAgents[i]; if (transfer != null) { int[] typeIds = transfer.getTypeIds(); String[] typeNames = transfer.getTypeNames(); for (int j = 0; j < typeIds.length; j++) { GtkTargetEntry entry = new GtkTargetEntry(); byte[] buffer = Converter.wcsToMbcs(typeNames[j], true); entry.target = OS.g_malloc(buffer.length); C.memmove(entry.target, buffer, buffer.length); entry.info = typeIds[j]; GtkTargetEntry[] newTargets = new GtkTargetEntry[targets.length + 1]; System.arraycopy(targets, 0, newTargets, 0, targets.length); newTargets[targets.length] = entry; targets = newTargets; } } } long pTargets = OS.g_malloc(targets.length * GtkTargetEntry.sizeof); for (int i = 0; i < targets.length; i++) { GTK3.memmove(pTargets + i*GtkTargetEntry.sizeof, targets[i], GtkTargetEntry.sizeof); } targetList = GTK3.gtk_target_list_new(pTargets, targets.length); for (int i = 0; i < targets.length; i++) { OS.g_free(targets[i].target); } } } }




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