juce_LassoComponent.h

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/*
  ==============================================================================
 
   This file is part of the JUCE library.
   Copyright (c) 2015 - ROLI Ltd.
 
   Permission is granted to use this software under the terms of either:
   a) the GPL v2 (or any later version)
   b) the Affero GPL v3
 
   Details of these licenses can be found 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.juce.com for more information.
 
  ==============================================================================
*/
 
#ifndef JUCE_LASSOCOMPONENT_H_INCLUDED
#define JUCE_LASSOCOMPONENT_H_INCLUDED
 
 
//==============================================================================
template <class SelectableItemType>
class LassoSource
{
public:
    virtual ~LassoSource() {}
 
    virtual void findLassoItemsInArea (Array <SelectableItemType>& itemsFound,
                                       const Rectangle<int>& area) = 0;
 
    virtual SelectedItemSet<SelectableItemType>& getLassoSelection() = 0;
};
 
 
//==============================================================================
template <class SelectableItemType>
class LassoComponent  : public Component
{
public:
    //==============================================================================
    LassoComponent()  : source (nullptr)
    {
    }
 
    //==============================================================================
    void beginLasso (const MouseEvent& e, LassoSource<SelectableItemType>* lassoSource)
    {
        jassert (source == nullptr);  // this suggests that you didn't call endLasso() after the last drag...
        jassert (lassoSource != nullptr); // the source can't be null!
        jassert (getParentComponent() != nullptr);  // you need to add this to a parent component for it to work!
 
        source = lassoSource;
 
        if (lassoSource != nullptr)
            originalSelection = lassoSource->getLassoSelection().getItemArray();
 
        setSize (0, 0);
        dragStartPos = e.getMouseDownPosition();
    }
 
    void dragLasso (const MouseEvent& e)
    {
        if (source != nullptr)
        {
            setBounds (Rectangle<int> (dragStartPos, e.getPosition()));
            setVisible (true);
 
            Array<SelectableItemType> itemsInLasso;
            source->findLassoItemsInArea (itemsInLasso, getBounds());
 
            if (e.mods.isShiftDown())
            {
                itemsInLasso.removeValuesIn (originalSelection); //  to avoid duplicates
                itemsInLasso.addArray (originalSelection);
            }
            else if (e.mods.isCommandDown() || e.mods.isAltDown())
            {
                Array<SelectableItemType> originalMinusNew (originalSelection);
                originalMinusNew.removeValuesIn (itemsInLasso);
 
                itemsInLasso.removeValuesIn (originalSelection);
                itemsInLasso.addArray (originalMinusNew);
            }
 
            source->getLassoSelection() = SelectedItemSet<SelectableItemType> (itemsInLasso);
        }
    }
 
    void endLasso()
    {
        source = nullptr;
        originalSelection.clear();
        setVisible (false);
    }
 
    //==============================================================================
    enum ColourIds
    {
        lassoFillColourId       = 0x1000440, 
        lassoOutlineColourId    = 0x1000441, 
    };
 
    //==============================================================================
    void paint (Graphics& g) override
    {
        getLookAndFeel().drawLasso (g, *this);
 
        // this suggests that you've left a lasso comp lying around after the
        // mouse drag has finished.. Be careful to call endLasso() when you get a
        // mouse-up event.
        jassert (isMouseButtonDownAnywhere());
    }
 
    bool hitTest (int, int) override        { return false; }
 
private:
    //==============================================================================
    Array<SelectableItemType> originalSelection;
    LassoSource<SelectableItemType>* source;
    Point<int> dragStartPos;
 
    JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (LassoComponent)
};
 
 
#endif   // JUCE_LASSOCOMPONENT_H_INCLUDED