245 lines
12 KiB
C
245 lines
12 KiB
C
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/*
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==============================================================================
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This file is part of the JUCE library.
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Copyright (c) 2020 - Raw Material Software Limited
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JUCE is an open source library subject to commercial or open-source
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licensing.
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By using JUCE, you agree to the terms of both the JUCE 6 End-User License
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Agreement and JUCE Privacy Policy (both effective as of the 16th June 2020).
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End User License Agreement: www.juce.com/juce-6-licence
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Privacy Policy: www.juce.com/juce-privacy-policy
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Or: You may also use this code under the terms of the GPL v3 (see
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www.gnu.org/licenses).
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JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
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EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
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DISCLAIMED.
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==============================================================================
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*/
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namespace juce
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{
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//==============================================================================
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/**
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Enables drag-and-drop behaviour for a component and all its sub-components.
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For a component to be able to make or receive drag-and-drop events, one of its parent
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components must derive from this class. It's probably best for the top-level
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component to implement it.
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Then to start a drag operation, any sub-component can just call the startDragging()
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method, and this object will take over, tracking the mouse and sending appropriate
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callbacks to any child components derived from DragAndDropTarget which the mouse
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moves over.
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Note: If all that you need to do is to respond to files being drag-and-dropped from
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the operating system onto your component, you don't need any of these classes: you can do this
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simply by overriding FileDragAndDropTarget::filesDropped().
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@see DragAndDropTarget
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@tags{GUI}
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*/
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class JUCE_API DragAndDropContainer
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{
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public:
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//==============================================================================
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/** Creates a DragAndDropContainer.
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The object that derives from this class must also be a Component.
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*/
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DragAndDropContainer();
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/** Destructor. */
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virtual ~DragAndDropContainer();
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//==============================================================================
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/** Begins a drag-and-drop operation.
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This starts a drag-and-drop operation - call it when the user drags the
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mouse in your drag-source component, and this object will track mouse
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movements until the user lets go of the mouse button, and will send
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appropriate messages to DragAndDropTarget objects that the mouse moves
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over.
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findParentDragContainerFor() is a handy method to call to find the
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drag container to use for a component.
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@param sourceDescription a string or value to use as the description of the thing being dragged -
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this will be passed to the objects that might be dropped-onto so they can
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decide whether they want to handle it
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@param sourceComponent the component that is being dragged
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@param dragImage the image to drag around underneath the mouse. If this is a null image,
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a snapshot of the sourceComponent will be used instead.
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@param allowDraggingToOtherJuceWindows if true, the dragged component will appear as a desktop
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window, and can be dragged to DragAndDropTargets that are the
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children of components other than this one.
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@param imageOffsetFromMouse if an image has been passed-in, this specifies the offset
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at which the image should be drawn from the mouse. If it isn't
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specified, then the image will be centred around the mouse. If
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an image hasn't been passed-in, this will be ignored.
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@param inputSourceCausingDrag the mouse input source which started the drag. When calling
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from within a mouseDown or mouseDrag event, you can pass
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MouseEvent::source to this method. If this param is nullptr then JUCE
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will use the mouse input source which is currently dragging. If there
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are several dragging mouse input sources (which can often occur on mobile)
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then JUCE will use the mouseInputSource which is closest to the sourceComponent.
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*/
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void startDragging (const var& sourceDescription,
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Component* sourceComponent,
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Image dragImage = Image(),
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bool allowDraggingToOtherJuceWindows = false,
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const Point<int>* imageOffsetFromMouse = nullptr,
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const MouseInputSource* inputSourceCausingDrag = nullptr);
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/** Returns true if something is currently being dragged. */
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bool isDragAndDropActive() const;
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/** Returns the number of things currently being dragged. */
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int getNumCurrentDrags() const;
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/** Returns the description of the thing that's currently being dragged.
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If nothing's being dragged, this will return a null var, otherwise it'll return
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the var that was passed into startDragging().
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If you are using drag and drop in a multi-touch environment then you should use the
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getDragDescriptionForIndex() method instead which takes a touch index parameter.
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@see startDragging, getDragDescriptionForIndex
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*/
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var getCurrentDragDescription() const;
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/** Same as the getCurrentDragDescription() method but takes a touch index parameter.
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@see getCurrentDragDescription
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*/
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var getDragDescriptionForIndex (int index) const;
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/** If a drag is in progress, this allows the image being shown to be dynamically updated.
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If you are using drag and drop in a multi-touch environment then you should use the
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setDragImageForIndex() method instead which takes a touch index parameter.
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@see setDragImageForIndex
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*/
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void setCurrentDragImage (const Image& newImage);
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/** Same as the setCurrentDragImage() method but takes a touch index parameter.
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@see setCurrentDragImage
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*/
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void setDragImageForIndex (int index, const Image& newImage);
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/** Utility to find the DragAndDropContainer for a given Component.
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This will search up this component's parent hierarchy looking for the first
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parent component which is a DragAndDropContainer.
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It's useful when a component wants to call startDragging but doesn't know
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the DragAndDropContainer it should to use.
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Obviously this may return nullptr if it doesn't find a suitable component.
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*/
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static DragAndDropContainer* findParentDragContainerFor (Component* childComponent);
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//==============================================================================
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/** This performs an asynchronous drag-and-drop of a set of files to some external
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application.
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You can call this function in response to a mouseDrag callback, and it will
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use a native operating system drag-and-drop operation to move or copy some
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files to another application.
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@param files a list of filenames to drag
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@param canMoveFiles if true, the app that receives the files is allowed to move the files to a new location
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(if this is appropriate). If false, the receiver is expected to make a copy of them.
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@param sourceComponent normally, JUCE will assume that the component under the mouse is the source component
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of the drag, but you can use this parameter to override this.
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@param callback an optional completion callback that will be called when the operation has ended.
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@returns true if the drag operation was successfully started, or false if it failed for some reason
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@see performExternalDragDropOfText
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*/
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static bool performExternalDragDropOfFiles (const StringArray& files, bool canMoveFiles,
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Component* sourceComponent = nullptr,
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std::function<void()> callback = nullptr);
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/** This performs an asynchronous drag-and-drop of a block of text to some external
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application.
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You can call this function in response to a mouseDrag callback, and it will
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use a native operating system drag-and-drop operation to move or copy some
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text to another application.
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@param text the text to copy
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@param sourceComponent Normally, JUCE will assume that the component under the mouse is the source component
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of the drag, but you can use this parameter to override this.
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@param callback an optional completion callback that will be called when the operation has ended.
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@returns true if the drag operation was successfully started, or false if it failed for some reason
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@see performExternalDragDropOfFiles
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*/
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static bool performExternalDragDropOfText (const String& text, Component* sourceComponent = nullptr,
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std::function<void()> callback = nullptr);
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protected:
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/** Override this if you want to be able to perform an external drag of a set of files
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when the user drags outside of this container component.
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This method will be called when a drag operation moves outside the JUCE window,
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and if you want it to then perform a file drag-and-drop, add the filenames you want
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to the array passed in, and return true.
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@param sourceDetails information about the source of the drag operation
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@param files on return, the filenames you want to drag
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@param canMoveFiles on return, true if it's ok for the receiver to move the files; false if
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it must make a copy of them (see the performExternalDragDropOfFiles() method)
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@see performExternalDragDropOfFiles, shouldDropTextWhenDraggedExternally
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*/
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virtual bool shouldDropFilesWhenDraggedExternally (const DragAndDropTarget::SourceDetails& sourceDetails,
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StringArray& files, bool& canMoveFiles);
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/** Override this if you want to be able to perform an external drag of text
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when the user drags outside of this container component.
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This method will be called when a drag operation moves outside the JUCE window,
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and if you want it to then perform a text drag-and-drop, copy the text you want to
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be dragged into the argument provided and return true.
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@param sourceDetails information about the source of the drag operation
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@param text on return, the text you want to drag
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@see shouldDropFilesWhenDraggedExternally
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*/
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virtual bool shouldDropTextWhenDraggedExternally (const DragAndDropTarget::SourceDetails& sourceDetails,
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String& text);
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/** Subclasses can override this to be told when a drag starts. */
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virtual void dragOperationStarted (const DragAndDropTarget::SourceDetails&);
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/** Subclasses can override this to be told when a drag finishes. */
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virtual void dragOperationEnded (const DragAndDropTarget::SourceDetails&);
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private:
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//==============================================================================
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class DragImageComponent;
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OwnedArray<DragImageComponent> dragImageComponents;
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const MouseInputSource* getMouseInputSourceForDrag (Component* sourceComponent, const MouseInputSource* inputSourceCausingDrag);
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bool isAlreadyDragging (Component* sourceComponent) const noexcept;
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JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (DragAndDropContainer)
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};
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} // namespace juce
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