odk/examples/DevelopersGuide/OfficeDev/DesktopEnvironment/NativeView.java

   1 /* -*- Mode: Java; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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  35
  36 // __________ Imports __________
  37
  38 import java.awt.*;
  39
  40 // __________ Implementation __________
  41
  42 /**
  43  * Class to pass the system window handle to the OpenOffice.org toolkit.
  44  * It use special JNI methods to get the system handle of used java window.
  45  *
  46  * Attention!
  47  * Use JNI functions on already visible canvas objects only!
  48  * Otherwise they can make some trouble.
  49  *
  50  */
  51
  52 public class NativeView extends java.awt.Canvas
  53 {
  54
  55
  56     /**
  57      * ctor
  58      * Does nothing really.
  59      * We can use our JNI mechanism for an already visible
  60      * canvas only. So we override the method for showing ("setVisible()")
  61      * and make our initialization there. But we try to show an empty clean
  62      * window till there.
  63      */
  64     public NativeView()
  65     {
  66         maHandle = null;
  67         maSystem = 0;
  68         this.setBackground(Color.white);
  69     }
  70
  71
  72
  73     /**
  74      * Override this method to make necessary initializations here.
  75      * (e.g. get the window handle and necessary system information)
  76      *
  77      * Why here?
  78      * Because the handle seems to be available for already visible windows
  79      * only. So it's the best place to get it. Special helper method
  80      * can be called more than ones - but call native code one times only
  81      * and safe the handle and the system type on our members maHandle/maSystem!
  82      */
  83     @Override
  84     public void setVisible(boolean bState)
  85     {
  86         getHWND();
  87     }
  88
  89
  90
  91     /**
  92      * to guarantee right resize handling inside a swing container
  93      * (e.g. JSplitPane) we must provide some information about our
  94      * preferred/minimum and maximum size.
  95      */
  96     @Override
  97     public Dimension getPreferredSize()
  98     {
  99         return new Dimension(500,300);
 100     }
 101
 102     @Override
 103     public Dimension getMaximumSize()
 104     {
 105         return new Dimension(1024,768);
 106     }
 107
 108     @Override
 109     public Dimension getMinimumSize()
 110     {
 111         return new Dimension(100,100);
 112     }
 113
 114
 115
 116     /**
 117      * Override paint routine to show provide against
 118      * repaint errors if no office view is really plugged
 119      * into this canvas.
 120      * If handle is present - we shouldn't paint anything further.
 121      * May the remote window is already plugged. In such case we
 122      * shouldn't paint it over.
 123      */
 124     @Override
 125     public void paint(Graphics aGraphic)
 126     {
 127         if(maHandle==null)
 128         {
 129             Dimension aSize = getSize();
 130             aGraphic.clearRect(0,0,aSize.width,aSize.height);
 131         }
 132     }
 133
 134
 135
 136     /**
 137      * JNI interface of this class
 138      * These two methods are implemented by using JNI mechanismen.
 139      * The will be used to get the platform dependent window handle
 140      * of a java awt canvas. This handle can be used to create an office
 141      * window as direct child of it. So it's possible to plug Office
 142      * windows in a java UI container.
 143      *
 144      * Note:
 145      * Native code for Windows registers a special function pointer to handle
 146      * window messages... But if it doesn't check for an already-registered
 147      * instance of this handler it will do it twice and produce a stack overflow
 148      * because such method calls itself in a never-ending loop...
 149      * So we try to use the JNI code one time only and save already-obtained
 150      * information inside this class.
 151      */
 152     public  native int  getNativeWindowSystemType();
 153     private native long getNativeWindow(); // private! => use getHWND() with cache mechanism!
 154
 155     public Integer getHWND()
 156     {
 157         if(maHandle==null)
 158         {
 159             maHandle = Integer.valueOf((int)getNativeWindow());
 160             maSystem = getNativeWindowSystemType();
 161         }
 162         return maHandle;
 163     }
 164
 165
 166
 167     /**
 168      * for using of the JNI methods it's necessary to load
 169      * system library which exports it.
 170      */
 171     static
 172     {
 173         System.loadLibrary("nativeview");
 174     }
 175
 176
 177
 178     /**
 179      * @member  maHandle    system window handle
 180      * @member  maSystem    info about currently used platform
 181      */
 182     public Integer maHandle ;
 183     public int     maSystem ;
 184 }
 185
 186 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */