org.eclipse.linuxtools.lttng.ui/src/org/eclipse/linuxtools/internal/lttng/ui/views/latency/listeners/ZoomListener.java

   1 /*******************************************************************************
   2  * Copyright (c) 2011 Ericsson
   3  *
   4  * All rights reserved. This program and the accompanying materials are
   5  * made available under the terms of the Eclipse Public License v1.0 which
   6  * accompanies this distribution, and is available at
   7  * http://www.eclipse.org/legal/epl-v10.html
   8  *
   9  * Contributors:
  10  *   Philippe Sawicki (INF4990.A2010@gmail.com)   - Initial API and implementation
  11  *   Mathieu Denis    (mathieu.denis55@gmail.com) - Refactored code
  12  *******************************************************************************/
  13 package org.eclipse.linuxtools.internal.lttng.ui.views.latency.listeners;
  14
  15 import org.eclipse.linuxtools.internal.lttng.ui.views.latency.AbstractViewer;
  16 import org.eclipse.swt.SWT;
  17 import org.eclipse.swt.widgets.Canvas;
  18 import org.eclipse.swt.widgets.Event;
  19 import org.eclipse.swt.widgets.Listener;
  20
  21 /**
  22  * <b><u>ZoomListener</u></b>
  23  * <p>
  24  *
  25  * Canvas zoom listener.
  26  *
  27  * @author Philippe Sawicki
  28  */
  29 public class ZoomListener implements Listener {
  30
  31     // ------------------------------------------------------------------------
  32     // Attributes
  33     // ------------------------------------------------------------------------
  34
  35     /**
  36      * A reference to the observed view.
  37      */
  38     protected AbstractViewer fView;
  39     /**
  40      * Default zoom factor.
  41      */
  42     protected int fZoomFactor;
  43     /**
  44      * Zoom increment.
  45      */
  46     protected int fZoomIncrement = 30;
  47
  48     // ------------------------------------------------------------------------
  49     // Constructors
  50     // ------------------------------------------------------------------------
  51
  52     /**
  53      * Constructor.
  54      * @param view
  55      *            A reference to the observed view.
  56      * @param defaultZoomFactor
  57      *            Default zoom factor.
  58      */
  59     public ZoomListener(AbstractViewer view, int defaultZoomFactor) {
  60         fView = view;
  61         fZoomFactor = defaultZoomFactor;
  62     }
  63
  64     /**
  65      * Constructor.
  66      * @param view
  67      *            A reference to the observed view.
  68      */
  69     public ZoomListener(AbstractViewer view) {
  70         this(view, 1);
  71     }
  72
  73     // ------------------------------------------------------------------------
  74     // Accessors
  75     // ------------------------------------------------------------------------
  76
  77     /**
  78      * Returns the zoom factor.
  79      * @return The zoom factor.
  80      */
  81     public int getZoomFactor() {
  82         if (fZoomFactor < 1)
  83             return 1;
  84         else
  85             return fZoomFactor;
  86     }
  87
  88     /**
  89      * Returns the zoom increment.
  90      * @return The zoom increment.
  91      */
  92     public int getZoomIncrement() {
  93         return fZoomIncrement;
  94     }
  95
  96     // ------------------------------------------------------------------------
  97     // Operations
  98     // ------------------------------------------------------------------------
  99
 100     /*
 101      * (non-Javadoc)
 102      * @see org.eclipse.swt.widgets.Listener#handleEvent(org.eclipse.swt.widgets.Event)
 103      */
 104     @Override
 105     public void handleEvent(Event event) {
 106         switch (event.type) {
 107             case SWT.MouseWheel:
 108                 boolean scrollDown = (event.count == 0 ? false : (event.count > 0 ? false : true));
 109                 int zoomStep = fZoomIncrement;
 110                 if (scrollDown)
 111                     zoomStep = -fZoomIncrement;
 112                 fZoomFactor = Math.max(0, fZoomFactor + zoomStep);
 113
 114                 Canvas canvas = (Canvas) event.widget;
 115                 if (fView != null) {
 116                     // clear the background to allow redraw of values of the vertical axis.
 117                     fView.clearBackground();
 118                     fView.redrawTitle();
 119                     fView.askForRedraw();
 120                 }
 121                 canvas.redraw();
 122                 break;
 123         }
 124     }
 125
 126     /**
 127      * Sets the zoom increment.
 128      * @param zoomIncrement
 129      *            The new zoom increment.
 130      */
 131     public void setZoomIncrement(int zoomIncrement) {
 132         fZoomIncrement = zoomIncrement;
 133     }
 134 }