JUCE/modules/juce_gui_basics/mouse/juce_ComponentDragger.cpp

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

   This file is part of the JUCE library - "Jules' Utility Class Extensions"
   Copyright 2004-11 by Raw Material Software Ltd.

  ------------------------------------------------------------------------------

   JUCE can be redistributed and/or modified under the terms of the GNU General
   Public License (Version 2), as published by the Free Software Foundation.
   A copy of the license is included in the JUCE distribution, or can be found
   online at www.gnu.org/licenses.

   JUCE is distributed in the hope that it will be useful, but WITHOUT ANY
   WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
   A PARTICULAR PURPOSE.  See the GNU General Public License for more details.

  ------------------------------------------------------------------------------

   To release a closed-source product which uses JUCE, commercial licenses are
   available: visit www.rawmaterialsoftware.com/juce for more information.

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

ComponentDragger::ComponentDragger() {}
ComponentDragger::~ComponentDragger() {}

//==============================================================================
void ComponentDragger::startDraggingComponent (Component* const componentToDrag, const MouseEvent& e)
{
    jassert (componentToDrag != nullptr);
    jassert (e.mods.isAnyMouseButtonDown()); // The event has to be a drag event!

    if (componentToDrag != nullptr)
        mouseDownWithinTarget = e.getEventRelativeTo (componentToDrag).getMouseDownPosition();
}

void ComponentDragger::dragComponent (Component* const componentToDrag, const MouseEvent& e,
                                      ComponentBoundsConstrainer* const constrainer)
{
    jassert (componentToDrag != nullptr);
    jassert (e.mods.isAnyMouseButtonDown()); // The event has to be a drag event!

    if (componentToDrag != nullptr)
    {
        Rectangle<int> bounds (componentToDrag->getBounds());

        // If the component is a window, multiple mouse events can get queued while it's in the same position,
        // so their coordinates become wrong after the first one moves the window, so in that case, we'll use
        // the current mouse position instead of the one that the event contains...
        if (componentToDrag->isOnDesktop())
            bounds += componentToDrag->getMouseXYRelative() - mouseDownWithinTarget;
        else
            bounds += e.getEventRelativeTo (componentToDrag).getPosition() - mouseDownWithinTarget;

        if (constrainer != nullptr)
            constrainer->setBoundsForComponent (componentToDrag, bounds, false, false, false, false);
        else
            componentToDrag->setBounds (bounds);
    }
}