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

#include <juce_DragAndDropContainer.h>

Inheritance diagram for DragAndDropContainer:

Collaboration diagram for DragAndDropContainer:

Public Member Functions
	DragAndDropContainer ()
	Creates a DragAndDropContainer. More...

virtual	~DragAndDropContainer ()
	Destructor. More...

var	getCurrentDragDescription () const
	Returns the description of the thing that's currently being dragged. More...

bool	isDragAndDropActive () const
	Returns true if something is currently being dragged. More...

void	setCurrentDragImage (const Image &newImage)
	If a drag is in progress, this allows the image being shown to be dynamically updated. More...

void	startDragging (const var &sourceDescription, Component sourceComponent, Image dragImage=Image(), bool allowDraggingToOtherJuceWindows=false, const Point< int > imageOffsetFromMouse=nullptr)
	Begins a drag-and-drop operation. More...

Static Public Member Functions
static DragAndDropContainer *	findParentDragContainerFor (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 void	dragOperationEnded (const DragAndDropTarget::SourceDetails &)
	Subclasses can override this to be told when a drag finishes. More...

virtual void	dragOperationStarted (const DragAndDropTarget::SourceDetails &)
	Subclasses can override this to be told when a drag starts. More...

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...

Private Attributes
ScopedPointer< DragImageComponent >	dragImageComponent

Friends
struct	ContainerDeletePolicy< DragImageComponent >

class	DragImageComponent

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

◆ dragOperationEnded()

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

protectedvirtual

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

◆ dragOperationStarted()

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

protectedvirtual

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

◆ 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.

◆ 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().

See also: startDragging

◆ isDragAndDropActive()

bool DragAndDropContainer::isDragAndDropActive ( ) const

Returns true if something is currently being dragged.

◆ 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

files	a list of filenames to drag
canMoveFiles	if 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.
sourceComponent	Normally, 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

text	the text to copy
sourceComponent	Normally, 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

◆ setCurrentDragImage()

void DragAndDropContainer::setCurrentDragImage ( const Image & newImage )

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

◆ 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

sourceDetails	information about the source of the drag operation
files	on return, the filenames you want to drag
canMoveFiles	on 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

sourceDetails	information about the source of the drag operation
text	on return, the text you want to drag

See also: shouldDropFilesWhenDraggedExternally

◆ startDragging()

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

sourceDescription	a 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
sourceComponent	the component that is being dragged
dragImage	the image to drag around underneath the mouse. If this is a null image, a snapshot of the sourceComponent will be used instead.
allowDraggingToOtherJuceWindows	if 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.
imageOffsetFromMouse	if 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.

Friends And Related Function Documentation

◆ ContainerDeletePolicy< DragImageComponent >

friend struct ContainerDeletePolicy< DragImageComponent >

friend

◆ DragImageComponent

friend class DragImageComponent

friend

Member Data Documentation

◆ dragImageComponent

ScopedPointer<DragImageComponent> DragAndDropContainer::dragImageComponent

private

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

juce_DragAndDropContainer.h

Public Member Functions

Static Public Member Functions

Protected Member Functions

Private Attributes

Friends

Detailed Description

Constructor & Destructor Documentation

◆ DragAndDropContainer()

◆ ~DragAndDropContainer()

Member Function Documentation

◆ dragOperationEnded()

◆ dragOperationStarted()

◆ findParentDragContainerFor()

◆ getCurrentDragDescription()

◆ isDragAndDropActive()

◆ performExternalDragDropOfFiles()

◆ performExternalDragDropOfText()

◆ setCurrentDragImage()

◆ shouldDropFilesWhenDraggedExternally()

◆ shouldDropTextWhenDraggedExternally()

◆ startDragging()

Friends And Related Function Documentation

◆ ContainerDeletePolicy< DragImageComponent >

◆ DragImageComponent

Member Data Documentation

◆ dragImageComponent