JUCE/modules/juce_gui_basics/mouse/juce_ComponentDragger.h

/*
  ==============================================================================

   This file is part of the JUCE 6 technical preview.
   Copyright (c) 2020 - Raw Material Software Limited

   You may use this code under the terms of the GPL v3
   (see www.gnu.org/licenses).

   For this technical preview, this file is not subject to commercial licensing.

   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
   DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

//==============================================================================
/**
    An object to take care of the logic for dragging components around with the mouse.

    Very easy to use - in your mouseDown() callback, call startDraggingComponent(),
    then in your mouseDrag() callback, call dragComponent().

    When starting a drag, you can give it a ComponentBoundsConstrainer to use
    to limit the component's position and keep it on-screen.

    e.g. @code
    class MyDraggableComp
    {
        ComponentDragger myDragger;

        void mouseDown (const MouseEvent& e)
        {
            myDragger.startDraggingComponent (this, e);
        }

        void mouseDrag (const MouseEvent& e)
        {
            myDragger.dragComponent (this, e, nullptr);
        }
    };
    @endcode

    @tags{GUI}
*/
class JUCE_API  ComponentDragger
{
public:
    //==============================================================================
    /** Creates a ComponentDragger. */
    ComponentDragger();

    /** Destructor. */
    virtual ~ComponentDragger();

    //==============================================================================
    /** Call this from your component's mouseDown() method, to prepare for dragging.

        @param componentToDrag      the component that you want to drag
        @param e                    the mouse event that is triggering the drag
        @see dragComponent
    */
    void startDraggingComponent (Component* componentToDrag,
                                 const MouseEvent& e);

    /** Call this from your mouseDrag() callback to move the component.

        This will move the component, using the given constrainer object to check
        the new position.

        @param componentToDrag      the component that you want to drag
        @param e                    the current mouse-drag event
        @param constrainer          an optional constrainer object that should be used
                                    to apply limits to the component's position. Pass
                                    null if you don't want to constrain the movement.
        @see startDraggingComponent
    */
    void dragComponent (Component* componentToDrag,
                        const MouseEvent& e,
                        ComponentBoundsConstrainer* constrainer);

private:
    //==============================================================================
    Point<int> mouseDownWithinTarget;

    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (ComponentDragger)
};

} // namespace juce