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

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   3  *  $RCSfile: NativeView.java,v $
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   5  *  $Revision: 1.4 $
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   7  *  last change: $Author: rt $ $Date: 2005-01-31 16:39:23 $
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  40
  41 // __________ Imports __________
  42
  43 import java.awt.*;
  44 import java.lang.*;
  45 import java.awt.event.*;
  46
  47 // __________ Implementation __________
  48
  49 /**
  50  * Class to pass the system window handle to the OpenOffice.org toolkit.
  51  * It use special JNI methods to get the system handle of used java window.
  52  *
  53  * Attention!
  54  * Use JNI functions on already visible canvas objects only!
  55  * Otherwise they can make some trouble.
  56  *
  57  * @author  Andreas Schl&uuml;ns
  58  * @created 22.02.2002 08:47
  59  */
  60
  61 public class NativeView extends java.awt.Canvas
  62 {
  63     // ____________________
  64
  65     /**
  66      * ctor
  67      * Does nothing realy.
  68      * We can use our JNI mechanism for an already visible
  69      * canvas only. So we overload the method for showing ("setVisible()")
  70      * and make our intialization there. BUt we try to show an empty clean
  71      * window till there.
  72      */
  73     public NativeView()
  74     {
  75         maHandle = null;
  76         maSystem = 0;
  77         this.setBackground(Color.white);
  78     }
  79
  80     // ____________________
  81
  82     /**
  83      * Overload this method to make neccessary initializations here.
  84      * (e.g. get the window handle and neccessary system informations)
  85      *
  86      * Why here?
  87      * Because the handle seams to be available for already visible windows
  88      * only. So it's the best place to get it. Special helper method
  89      * can be called more then ones - but call native code one times only
  90      * and safe the handle and the system type on our members maHandle/maSystem!
  91      */
  92     public void setVisible(boolean bState)
  93     {
  94         getHWND();
  95     }
  96
  97     // ____________________
  98
  99     /**
 100      * to guarantee right resize handling inside a swing container
 101      * (e.g. JSplitPane) we must provide some informations about our
 102      * prefered/minimum and maximum size.
 103      */
 104     public Dimension getPreferredSize()
 105     {
 106         return new Dimension(500,300);
 107     }
 108
 109     public Dimension getMaximumSize()
 110     {
 111         return new Dimension(1024,768);
 112     }
 113
 114     public Dimension getMinimumSize()
 115     {
 116         return new Dimension(100,100);
 117     }
 118
 119     // ____________________
 120
 121     /**
 122      * overload paint routine to show provide against
 123      * repaint errors if no office view is realy plugged
 124      * into this canvas.
 125      * If handle is present - we shouldn't paint anything further.
 126      * May the remote window is already plugged. In such case we
 127      * shouldn't paint it over.
 128      */
 129     public void paint(Graphics aGraphic)
 130     {
 131         if(maHandle==null)
 132         {
 133             Dimension aSize = getSize();
 134             aGraphic.clearRect(0,0,aSize.width,aSize.height);
 135         }
 136     }
 137
 138     // ____________________
 139
 140     /**
 141      * JNI interface of this class
 142      * These two methods are implemented by using JNI mechanismen.
 143      * The will be used to get the platform dependent window handle
 144      * of a java awt canvas. This handle can be used to create an office
 145      * window as direct child of it. So it's possible to plug Office
 146      * windows in a java UI container.
 147      *
 148      * Note:
 149      * Native code for windows register special function pointer to handle
 150      * window messages ... But if it doesn't check for an already registered
 151      * instance of this handler it will do it twice and produce a stack overflow
 152      * because such method call herself in a never ending loop ...
 153      * So we try to use the JNI code one times only and safe already getted
 154      * informations inside this class.
 155      */
 156     public  native int  getNativeWindowSystemType();
 157     private native long getNativeWindow(); // private! => use getHWND() with cache mechanism!
 158
 159     public Integer getHWND()
 160     {
 161         if(maHandle==null)
 162         {
 163             maHandle = new Integer((int)getNativeWindow());
 164             maSystem = getNativeWindowSystemType();
 165         }
 166         return maHandle;
 167     }
 168
 169     // ____________________
 170
 171     /**
 172      * for using of the JNI methods it's neccessary to load
 173      * system library which exports it.
 174      */
 175     static
 176     {
 177         System.loadLibrary("nativeview");
 178     }
 179
 180     // ____________________
 181
 182     /**
 183      * @member  maHandle    system window handle
 184      * @member  maSystem    info about currently used platform
 185      */
 186     public Integer maHandle ;
 187     public int     maSystem ;
 188 }