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<a href="http://www.bruceeckel.com/javabook.html">Bruce Eckel's Thinking in Java</a>
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<a href="tij_c.html">Contents</a> | <a href="tij0148.html">Prev</a> | <a href="tij0150.html">Next</a>
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<H2 ALIGN=LEFT>
Java
1.1 UI APIs
</H2>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Java
1.1<A NAME="Index2108"></A>
has also added some important new functionality, including focus traversal,
desktop color access, printing &#8220;inside the sandbox,&#8221; and the
beginnings of clipboard support.
</FONT><P></DIV><DIV ALIGN=LEFT><A NAME="Index2109"></A><A NAME="Index2110"></A><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Focus
traversal is quite easy, since it&#8217;s transparently present in the AWT
library components and you don&#8217;t have to do anything to make it work. If
you make your own components and want them to handle focus traversal, you
override <A NAME="Index2111"></A><A NAME="Index2112"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>isFocusTraversable(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to return 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>true</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.
If you want to capture the keyboard focus on a mouse click, you catch the mouse
down event and call <A NAME="Index2113"></A><A NAME="Index2114"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>requestFocus(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">.</FONT><a name="_Toc408018714"></a><P></DIV>
<A NAME="Heading448"></A><H3 ALIGN=LEFT>
Desktop
colors
</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
<A NAME="Index2115"></A><A NAME="Index2116"></A><A NAME="Index2117"></A>desktop
colors provide a way for you to know what the various color choices are on the
current user&#8217;s desktop. This way, you can use those colors in your
program if you desire. The colors are automatically initialized and placed in 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>static</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
members of class 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>SystemColor</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
so all you need to do is read the member you&#8217;re interested in. The names
are intentionally self-explanatory: 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>desktop</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>activeCaption</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>activeCaptionText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>activeCaptionBorder</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>inactiveCaption</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>inactiveCaptionText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>inactiveCaptionBorder</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>window</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>windowBorder</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>windowText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>menu</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>menuText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>text</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>textText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>textHighlight</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>textHighlightText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>textInactiveText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>control</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>controlText</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>controlHighlight</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>controlLtHighlight</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>controlShadow</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>controlDkShadow</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>scrollbar</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">,
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>info
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">(for
help), and 
</FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>infoText
</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">(for
help text).
</FONT><a name="_Toc408018715"></a><P></DIV>
<A NAME="Heading449"></A><H3 ALIGN=LEFT>
Printing</H3>
<DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">Unfortunately,
there isn&#8217;t much that&#8217;s automatic with printing. Instead you must
go through a number of mechanical, non-OO steps in order to print. Printing a
component graphically can be slightly more automatic: by default, the <A NAME="Index2118"></A><A NAME="Index2119"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>print(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
method calls <A NAME="Index2120"></A><A NAME="Index2121"></A></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black"><B>paint(&#160;)</B></FONT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">
to do its work. There are times when this is satisfactory, but if you want to
do anything more specialized you must know that you&#8217;re printing so you
can in particular find out the page dimensions.
</FONT><P></DIV><DIV ALIGN=LEFT><FONT FACE="Carmina Md BT" SIZE=3 COLOR="Black">The
following example demonstrates the printing of both text and graphics, and the
different approaches you can use for printing graphics. In addition, it tests
the printing support:
</FONT><P></DIV>

<font color="#990000"><PRE><font color="#009900">//: PrintDemo.java</font>
<font color="#009900">// Printing with Java 1.1</font>
<font color="#0000ff">import</font> java.awt.*;
<font color="#0000ff">import</font> java.awt.event.*;

<font color="#0000ff">public</font> <font color="#0000ff">class</font> PrintDemo <font color="#0000ff">extends</font> Frame {
  Button 
    printText = <font color="#0000ff">new</font> Button("Print Text"),
    printGraphics = <font color="#0000ff">new</font> Button("Print Graphics");
  TextField ringNum = <font color="#0000ff">new</font> TextField(3);
  Choice faces = <font color="#0000ff">new</font> Choice();
  Graphics g = <font color="#0000ff">null</font>;
  Plot plot = <font color="#0000ff">new</font> Plot3(); <font color="#009900">// Try different plots</font>
  Toolkit tk = Toolkit.getDefaultToolkit();
  <font color="#0000ff">public</font> PrintDemo() {
    ringNum.setText("3");
    ringNum.addTextListener(<font color="#0000ff">new</font> RingL());
    Panel p = <font color="#0000ff">new</font> Panel();
    p.setLayout(<font color="#0000ff">new</font> FlowLayout());
    printText.addActionListener(<font color="#0000ff">new</font> TBL());
    p.add(printText);
    p.add(<font color="#0000ff">new</font> Label("Font:"));
    p.add(faces);
    printGraphics.addActionListener(<font color="#0000ff">new</font> GBL());
    p.add(printGraphics);
    p.add(<font color="#0000ff">new</font> Label("Rings:"));
    p.add(ringNum);
    setLayout(<font color="#0000ff">new</font> BorderLayout());
    add(p, BorderLayout.NORTH);
    add(plot, BorderLayout.CENTER);
    String[] fontList = tk.getFontList();
    <font color="#0000ff">for</font>(<font color="#0000ff">int</font> i = 0; i &lt; fontList.length; i++)
      faces.add(fontList[i]);
    faces.select("Serif");
  }
  <font color="#0000ff">class</font> PrintData {
    <font color="#0000ff">public</font> PrintJob pj;
    <font color="#0000ff">public</font> <font color="#0000ff">int</font> pageWidth, pageHeight;
    PrintData(String jobName) {
      pj = getToolkit().getPrintJob(
        PrintDemo.<font color="#0000ff">this</font>, jobName, <font color="#0000ff">null</font>);
      <font color="#0000ff">if</font>(pj != <font color="#0000ff">null</font>) {
        pageWidth = pj.getPageDimension().width;
        pageHeight= pj.getPageDimension().height;
        g = pj.getGraphics();
      }
    }
    <font color="#0000ff">void</font> end() { pj.end(); }
  }
  <font color="#0000ff">class</font> ChangeFont {
    <font color="#0000ff">private</font> <font color="#0000ff">int</font> stringHeight;
    ChangeFont(String face, <font color="#0000ff">int</font> style,<font color="#0000ff">int</font> point){
      <font color="#0000ff">if</font>(g != <font color="#0000ff">null</font>) {
        g.setFont(<font color="#0000ff">new</font> Font(face, style, point));
        stringHeight = 
          g.getFontMetrics().getHeight();
      }
    }
    <font color="#0000ff">int</font> stringWidth(String s) {
      <font color="#0000ff">return</font> g.getFontMetrics().stringWidth(s);
    }
    <font color="#0000ff">int</font> stringHeight() { <font color="#0000ff">return</font> stringHeight; }
  }
  <font color="#0000ff">class</font> TBL <font color="#0000ff">implements</font> ActionListener {
    <font color="#0000ff">public</font> <font color="#0000ff">void</font> actionPerformed(ActionEvent e) {
      PrintData pd = 
        <font color="#0000ff">new</font> PrintData("Print Text Test");
      <font color="#009900">// Null means print job canceled:</font>
      <font color="#0000ff">if</font>(pd == <font color="#0000ff">null</font>) <font color="#0000ff">return</font>;
      String s = "PrintDemo";
      ChangeFont cf = <font color="#0000ff">new</font> ChangeFont(
        faces.getSelectedItem(), Font.ITALIC,72);
      g.drawString(s, 
        (pd.pageWidth - cf.stringWidth(s)) / 2,
        (pd.pageHeight - cf.stringHeight()) / 3);

      s = "A smaller point size";
      cf = <font color="#0000ff">new</font> ChangeFont(
        faces.getSelectedItem(), Font.BOLD, 48);
      g.drawString(s, 
        (pd.pageWidth - cf.stringWidth(s)) / 2,
        (<font color="#0000ff">int</font>)((pd.pageHeight - 
           cf.stringHeight())/1.5));
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