UIPredicates.java

//----------------------------------------------------------------------------//
//                                                                            //
//                          U I P r e d i c a t e s                           //
//                                                                            //
//----------------------------------------------------------------------------//
// <editor-fold defaultstate="collapsed" desc="hdr">                          //
//  Copyright © Hervé Bitteur and others 2000-2013. All rights reserved.      //
//  This software is released under the GNU General Public License.           //
//  Goto http://kenai.com/projects/audiveris to report bugs or suggestions.   //
//----------------------------------------------------------------------------//
// </editor-fold>
package omr.ui.util;

import omr.WellKnowns;
import static java.awt.event.InputEvent.*;
import java.awt.event.MouseEvent;

import javax.swing.SwingUtilities;

/**
 * Class {@code UIPredicates} gathers convenient methods to check
 * user gesture.
 *
 * @author Hervé Bitteur
 */
public class UIPredicates
{
    //~ Constructors -----------------------------------------------------------

    //--------------//
    // UIPredicates //
    //--------------//
    /**
     * Not meant to be instantiated.
     */
    private UIPredicates ()
    {
    }

    //~ Methods ----------------------------------------------------------------
    //------------------//
    // isAdditionWanted //
    //------------------//
    /**
     * Predicate to check if an additional selection is wanted.
     * Default is the typical selection (left button), while control key is
     * pressed.
     *
     * @param e the mouse context
     * @return the predicate result
     */
    public static boolean isAdditionWanted (MouseEvent e)
    {
        if (WellKnowns.MAC_OS_X) {
            boolean command = e.isMetaDown();
            boolean left = SwingUtilities.isLeftMouseButton(e);

            return left && command && !e.isPopupTrigger();
        } else {
            return (SwingUtilities.isRightMouseButton(e) != SwingUtilities.isLeftMouseButton(
                    e)) && e.isControlDown();
        }
    }

    //-----------------//
    // isContextWanted //
    //-----------------//
    /**
     * Predicate to check if a context selection is wanted.
     * Default is the typical pressing with Right button only.
     *
     * @param e the mouse context
     * @return the predicate result
     */
    public static boolean isContextWanted (MouseEvent e)
    {
        if (WellKnowns.MAC_OS_X) {
            return e.isPopupTrigger();
        } else {
            return SwingUtilities.isRightMouseButton(e)
                   && !SwingUtilities.isLeftMouseButton(e);
        }
    }

    //--------------//
    // isDragWanted //
    //--------------//
    /**
     * Predicate to check whether the zoomed display must be dragged.
     * This method can simply be overridden to adapt to another policy.
     * Default is to have both left and right buttons pressed when moving.
     *
     * @param e the mouse event to check
     * @return true if drag is desired
     */
    public static boolean isDragWanted (MouseEvent e)
    {
        if (WellKnowns.MAC_OS_X) {
            return e.isAltDown();
        } else {
            int onmask = BUTTON1_DOWN_MASK | BUTTON3_DOWN_MASK;
            int offmask = 0;

            return (e.getModifiersEx() & (onmask | offmask)) == onmask;
        }
    }

    //----------------//
    // isRezoomWanted //
    //----------------//
    /**
     * Predicate to check if the display should be rezoomed to fit as
     * close as possible to the rubber definition.
     * Default is to have both Shift and Control keys pressed when the mouse is
     * released.
     *
     * @param e the mouse context
     * @return the predicate result
     */
    public static boolean isRezoomWanted (MouseEvent e)
    {
        if (WellKnowns.MAC_OS_X) {
            return e.isMetaDown() && e.isShiftDown();
        } else {
            return e.isControlDown() && e.isShiftDown();
        }
    }

    //----------------//
    // isRubberWanted //
    //----------------//
    /**
     * Predicate to check if the rubber must be extended while the
     * mouse is being moved.
     * Default is the typical pressing of Shift key while moving the mouse.
     *
     * @param e the mouse context
     * @return the predicate result
     */
    public static boolean isRubberWanted (MouseEvent e)
    {
        int onmask = BUTTON1_DOWN_MASK | SHIFT_DOWN_MASK;
        int offmask = BUTTON2_DOWN_MASK | BUTTON3_DOWN_MASK;

        return (e.getModifiersEx() & (onmask | offmask)) == onmask;
    }
}