Enables drag-and-drop behaviour for a component and all its sub-components. More...

Inheritance diagram for DragAndDropContainer:

Public Member Functions

 DragAndDropContainer ()
 Creates a DragAndDropContainer. More...
 
virtual ~DragAndDropContainer ()
 Destructor. More...
 
void startDragging (const var &sourceDescription, Component *sourceComponent, Image dragImage=Image(), bool allowDraggingToOtherJuceWindows=false, const Point< int > *imageOffsetFromMouse=nullptr, const MouseInputSource *inputSourceCausingDrag=nullptr)
 Begins a drag-and-drop operation. More...
 
bool isDragAndDropActive () const
 Returns true if something is currently being dragged. More...
 
int getNumCurrentDrags () const
 Returns the number of things currently being dragged. More...
 
var getCurrentDragDescription () const
 Returns the description of the thing that's currently being dragged. More...
 
var getDragDescriptionForIndex (int index) const
 Same as the getCurrentDragDescription() method but takes a touch index parameter. More...
 
void setCurrentDragImage (const Image &newImage)
 If a drag is in progress, this allows the image being shown to be dynamically updated. More...
 
void setDragImageForIndex (int index, const Image &newImage)
 Same as the setCurrentDragImage() method but takes a touch index parameter. More...
 

Static Public Member Functions

static DragAndDropContainerfindParentDragContainerFor (Component *childComponent)
 Utility to find the DragAndDropContainer for a given Component. More...
 
static bool performExternalDragDropOfFiles (const StringArray &files, bool canMoveFiles, Component *sourceComponent=nullptr)
 This performs a synchronous drag-and-drop of a set of files to some external application. More...
 
static bool performExternalDragDropOfText (const String &text, Component *sourceComponent=nullptr)
 This performs a synchronous drag-and-drop of a block of text to some external application. More...
 

Protected Member Functions

virtual bool shouldDropFilesWhenDraggedExternally (const DragAndDropTarget::SourceDetails &sourceDetails, StringArray &files, bool &canMoveFiles)
 Override this if you want to be able to perform an external drag of a set of files when the user drags outside of this container component. More...
 
virtual bool shouldDropTextWhenDraggedExternally (const DragAndDropTarget::SourceDetails &sourceDetails, String &text)
 Override this if you want to be able to perform an external drag of text when the user drags outside of this container component. More...
 
virtual void dragOperationStarted (const DragAndDropTarget::SourceDetails &)
 Subclasses can override this to be told when a drag starts. More...
 
virtual void dragOperationEnded (const DragAndDropTarget::SourceDetails &)
 Subclasses can override this to be told when a drag finishes. More...
 

Detailed Description

Enables drag-and-drop behaviour for a component and all its sub-components.

For a component to be able to make or receive drag-and-drop events, one of its parent components must derive from this class. It's probably best for the top-level component to implement it.

Then to start a drag operation, any sub-component can just call the startDragging() method, and this object will take over, tracking the mouse and sending appropriate callbacks to any child components derived from DragAndDropTarget which the mouse moves over.

Note: If all that you need to do is to respond to files being drag-and-dropped from the operating system onto your component, you don't need any of these classes: you can do this simply by overriding FileDragAndDropTarget::filesDropped().

See also
DragAndDropTarget

Constructor & Destructor Documentation

◆ DragAndDropContainer()

DragAndDropContainer::DragAndDropContainer ( )

Creates a DragAndDropContainer.

The object that derives from this class must also be a Component.

◆ ~DragAndDropContainer()

virtual DragAndDropContainer::~DragAndDropContainer ( )
virtual

Destructor.

Member Function Documentation

◆ startDragging()

void DragAndDropContainer::startDragging ( const var sourceDescription,
Component sourceComponent,
Image  dragImage = Image(),
bool  allowDraggingToOtherJuceWindows = false,
const Point< int > *  imageOffsetFromMouse = nullptr,
const MouseInputSource inputSourceCausingDrag = nullptr 
)

Begins a drag-and-drop operation.

This starts a drag-and-drop operation - call it when the user drags the mouse in your drag-source component, and this object will track mouse movements until the user lets go of the mouse button, and will send appropriate messages to DragAndDropTarget objects that the mouse moves over.

findParentDragContainerFor() is a handy method to call to find the drag container to use for a component.

Parameters
sourceDescriptiona string or value to use as the description of the thing being dragged - this will be passed to the objects that might be dropped-onto so they can decide whether they want to handle it
sourceComponentthe component that is being dragged
dragImagethe image to drag around underneath the mouse. If this is a null image, a snapshot of the sourceComponent will be used instead.
allowDraggingToOtherJuceWindowsif true, the dragged component will appear as a desktop window, and can be dragged to DragAndDropTargets that are the children of components other than this one.
imageOffsetFromMouseif an image has been passed-in, this specifies the offset at which the image should be drawn from the mouse. If it isn't specified, then the image will be centred around the mouse. If an image hasn't been passed-in, this will be ignored.
inputSourceCausingDragthe mouse input source which started the drag. When calling from within a mouseDown or mouseDrag event, you can pass MouseEvent::source to this method. If this param is nullptr then JUCE will use the mouse input source which is currently dragging. If there are several dragging mouse input sources (which can often occur on mobile) then JUCE will use the mouseInputSource which is closest to the sourceComponent.

◆ isDragAndDropActive()

bool DragAndDropContainer::isDragAndDropActive ( ) const

Returns true if something is currently being dragged.

◆ getNumCurrentDrags()

int DragAndDropContainer::getNumCurrentDrags ( ) const

Returns the number of things currently being dragged.

◆ getCurrentDragDescription()

var DragAndDropContainer::getCurrentDragDescription ( ) const

Returns the description of the thing that's currently being dragged.

If nothing's being dragged, this will return a null var, otherwise it'll return the var that was passed into startDragging().

If you are using drag and drop in a multi-touch environment then you should use the getDragDescriptionForIndex() method instead which takes a touch index parameter.

See also
startDragging, getDragDescriptionForIndex

◆ getDragDescriptionForIndex()

var DragAndDropContainer::getDragDescriptionForIndex ( int  index) const

Same as the getCurrentDragDescription() method but takes a touch index parameter.

See also
getCurrentDragDescription

◆ setCurrentDragImage()

void DragAndDropContainer::setCurrentDragImage ( const Image newImage)

If a drag is in progress, this allows the image being shown to be dynamically updated.

If you are using drag and drop in a multi-touch environment then you should use the setDragImageForIndex() method instead which takes a touch index parameter.

See also
setDragImageForIndex

◆ setDragImageForIndex()

void DragAndDropContainer::setDragImageForIndex ( int  index,
const Image newImage 
)

Same as the setCurrentDragImage() method but takes a touch index parameter.

See also
setCurrentDragImage

◆ findParentDragContainerFor()

static DragAndDropContainer* DragAndDropContainer::findParentDragContainerFor ( Component childComponent)
static

Utility to find the DragAndDropContainer for a given Component.

This will search up this component's parent hierarchy looking for the first parent component which is a DragAndDropContainer.

It's useful when a component wants to call startDragging but doesn't know the DragAndDropContainer it should to use.

Obviously this may return nullptr if it doesn't find a suitable component.

◆ performExternalDragDropOfFiles()

static bool DragAndDropContainer::performExternalDragDropOfFiles ( const StringArray files,
bool  canMoveFiles,
Component sourceComponent = nullptr 
)
static

This performs a synchronous drag-and-drop of a set of files to some external application.

You can call this function in response to a mouseDrag callback, and it will block, running its own internal message loop and tracking the mouse, while it uses a native operating system drag-and-drop operation to move or copy some files to another application.

Parameters
filesa list of filenames to drag
canMoveFilesif true, the app that receives the files is allowed to move the files to a new location (if this is appropriate). If false, the receiver is expected to make a copy of them.
sourceComponentNormally, JUCE will assume that the component under the mouse is the source component of the drag, but you can use this parameter to override this.
Returns
true if the files were successfully dropped somewhere, or false if it was interrupted
See also
performExternalDragDropOfText

◆ performExternalDragDropOfText()

static bool DragAndDropContainer::performExternalDragDropOfText ( const String text,
Component sourceComponent = nullptr 
)
static

This performs a synchronous drag-and-drop of a block of text to some external application.

You can call this function in response to a mouseDrag callback, and it will block, running its own internal message loop and tracking the mouse, while it uses a native operating system drag-and-drop operation to move or copy some text to another application.

Parameters
textthe text to copy
sourceComponentNormally, JUCE will assume that the component under the mouse is the source component of the drag, but you can use this parameter to override this.
Returns
true if the text was successfully dropped somewhere, or false if it was interrupted
See also
performExternalDragDropOfFiles

◆ shouldDropFilesWhenDraggedExternally()

virtual bool DragAndDropContainer::shouldDropFilesWhenDraggedExternally ( const DragAndDropTarget::SourceDetails sourceDetails,
StringArray files,
bool &  canMoveFiles 
)
protectedvirtual

Override this if you want to be able to perform an external drag of a set of files when the user drags outside of this container component.

This method will be called when a drag operation moves outside the JUCE window, and if you want it to then perform a file drag-and-drop, add the filenames you want to the array passed in, and return true.

Parameters
sourceDetailsinformation about the source of the drag operation
fileson return, the filenames you want to drag
canMoveFileson return, true if it's ok for the receiver to move the files; false if it must make a copy of them (see the performExternalDragDropOfFiles() method)
See also
performExternalDragDropOfFiles, shouldDropTextWhenDraggedExternally

◆ shouldDropTextWhenDraggedExternally()

virtual bool DragAndDropContainer::shouldDropTextWhenDraggedExternally ( const DragAndDropTarget::SourceDetails sourceDetails,
String text 
)
protectedvirtual

Override this if you want to be able to perform an external drag of text when the user drags outside of this container component.

This method will be called when a drag operation moves outside the JUCE window, and if you want it to then perform a text drag-and-drop, copy the text you want to be dragged into the argument provided and return true.

Parameters
sourceDetailsinformation about the source of the drag operation
texton return, the text you want to drag
See also
shouldDropFilesWhenDraggedExternally

◆ dragOperationStarted()

virtual void DragAndDropContainer::dragOperationStarted ( const DragAndDropTarget::SourceDetails )
protectedvirtual

Subclasses can override this to be told when a drag starts.

◆ dragOperationEnded()

virtual void DragAndDropContainer::dragOperationEnded ( const DragAndDropTarget::SourceDetails )
protectedvirtual

Subclasses can override this to be told when a drag finishes.


The documentation for this class was generated from the following file: