s13.htm

提供给JAVA编程者图形界面卷

              JLabel view1 = new JLabel(<br>
              new ImageIcon(&quot;gjMedium.gif&quot;));<br>
              JLabel view2 = new JLabel(<br>
              new ImageIcon(&quot;anjinAndMariko.gif&quot;));</p>
            <p> JScrollPane sp1 = new JScrollPane(view1);<br>
              JScrollPane sp2 = new JScrollPane(view2);</p>
            <p> setContentPane(contentPane);<br>
              sp1.setPreferredSize(new Dimension(250,250));<br>
              sp2.setPreferredSize(new Dimension(250,250));</p>
            <p> contentPane.add(sp1);<br>
              contentPane.add(sp2);<br>
              }<br>
              }<br>
              class CustomContentPane extends JPanel { <br>
              private ImageIcon rain = new ImageIcon(&quot;rain.gif&quot;);</p>
            <p> public CustomContentPane() {<br>
              setLayout(new FlowLayout());<br>
              } <br>
              public void paintComponent(Graphics g) {<br>
              int rainw = rain.getIconWidth();<br>
              int rainh = rain.getIconHeight();</p>
            <p> Dimension size = getSize();</p>
            <p> for(int row=0; row &lt; size.height; row += rainh)<br>
              for(int col=0; col &lt; size.width; col += rainw)<br>
              rain.paintIcon(this,g,col,row);<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 13.2.6 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 13.3 Scrollable接口</p>
            <p>&nbsp;</p>
            <p align="center"><b>例13-10 跟踪视口宽度</b></p>
            <hr noshade size="1">
            import java.io.*;<br>
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import javax.swing.*;<br>
            import javax.swing.text.*;
            <p>public class Test extends JApplet {<br>
              private JTextArea textArea = new JTextArea();</p>
            <p> public void init() {<br>
              Container contentPane = getContentPane();</p>
            <p> readFile();</p>
            <p> contentPane.add(new ControlPanel(), BorderLayout.NORTH);<br>
              contentPane.add(new JScrollPane(textArea), <br>
              BorderLayout.CENTER);<br>
              }<br>
              private void readFile() {<br>
              DefaultEditorKit kit = new DefaultEditorKit();</p>
            <p> try {<br>
              kit.read(new FileReader(&quot;Test.java&quot;),<br>
              textArea.getDocument(), 0);<br>
              }<br>
              catch(Exception ex) { ex.printStackTrace(); }<br>
              }<br>
              class ControlPanel extends JPanel { <br>
              public ControlPanel() {<br>
              final JCheckBox cb = new JCheckBox(&quot;wrap&quot;);</p>
            <p> add(cb);</p>
            <p> cb.addItemListener(new ItemListener() {<br>
              public void itemStateChanged(ItemEvent e) {<br>
              if(cb.isSelected())<br>
              textArea.setLineWrap(true);<br>
              else<br>
              textArea.setLineWrap(false);<br>
              }<br>
              });<br>
              }<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 13.4 JScrollBar</p>
            <p>&nbsp;</p>
            <p>&nbsp;</p>
            <p> 13.4.1 使用Swing的JScrollBar类进行手动滚动</p>
            <p>&nbsp;</p>
            <p> 13.4.2 块增量和单元增量</p>
            <p>&nbsp;</p>
            <p> 13.4.3 JScrollBar属性</p>
            <p>&nbsp;</p>
            <p align="center"><b>例13-11 为JScrollBar的实例指定单增量和块增量</b></p>
            <hr noshade size="1">
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import javax.swing.*;<br>
            import javax.swing.event.*;
            <p>public class Test extends JApplet {<br>
              private JScrollBar vsb = new JScrollBar(JScrollBar.VERTICAL);<br>
              private SSPanel panel = new SSPanel();</p>
            <p> public Test() {<br>
              Container contentPane = getContentPane();</p>
            <p> contentPane.add(panel, BorderLayout.CENTER);<br>
              contentPane.add(vsb, BorderLayout.EAST);</p>
            <p> vsb.addAdjustmentListener(new AdjustmentListener() {<br>
              public void adjustmentValueChanged(<br>
              AdjustmentEvent e) {<br>
              JScrollBar sb = (JScrollBar)e.getSource();<br>
              showScrollBarValues();<br>
              panel.setTopIndexByPixelValue(e.getValue());<br>
              panel.repaint();<br>
              }<br>
              });<br>
              }<br>
              public void paint(Graphics g) {<br>
              Dimension pref = panel.getPreferredSize();<br>
              Dimension size = panel.getSize();<br>
              int extent = size.height, max = pref.height;<br>
              int value = Math.max(0, <br>
              Math.min(vsb.getValue(), max - extent));</p>
            <p> vsb.setVisible(extent &lt; max);<br>
              vsb.setUnitIncrement(panel.getUnitHeight());<br>
              vsb.setBlockIncrement(extent - vsb.getUnitIncrement());<br>
              vsb.setValues(value, extent, 0, max);</p>
            <p> showScrollBarValues();<br>
              super.paint(g);<br>
              }<br>
              private void showScrollBarValues() {<br>
              showStatus(&quot;min: &quot; + vsb.getMinimum() +<br>
              &quot;, max: &quot; + vsb.getMaximum() +<br>
              &quot;, visible amount: &quot; + <br>
              vsb.getVisibleAmount() +<br>
              &quot;, value: &quot; + vsb.getValue());<br>
              }<br>
              }<br>
              class SSPanel extends JPanel { <br>
              private int topIndex = 0;<br>
              private int fh;</p>
            <p> private String[] data = {<br>
              &quot;Brown, Ted: 000-00-0001&quot;, &quot;Brown, Ted: 000-00-0002&quot;,<br>
              &quot;Brown, Ted: 000-00-0003&quot;, &quot;Brown, Ted: 000-00-0004&quot;,<br>
              &quot;Brown, Ted: 000-00-0005&quot;, &quot;Brown, Ted: 000-00-0006&quot;,<br>
              &quot;Brown, Ted: 000-00-0007&quot;, &quot;Brown, Ted: 000-00-0008&quot;,<br>
              &quot;Brown, Ted: 000-00-0009&quot;, &quot;Brown, Ted: 000-00-00010&quot;,<br>
              &quot;Brown, Ted: 000-00-00011&quot;, &quot;Brown, Ted: 000-00-00012&quot;,<br>
              &quot;Brown, Ted: 000-00-00013&quot;, &quot;Brown, Ted: 000-00-00014&quot;,<br>
              &quot;Brown, Ted: 000-00-00015&quot;, &quot;Brown, Ted: 000-00-00016&quot;,<br>
              &quot;Brown, Ted: 000-00-00017&quot;, &quot;Brown, Ted: 000-00-00018&quot;,<br>
              &quot;Brown, Ted: 000-00-00019&quot;, &quot;Brown, Ted: 000-00-00020&quot;,<br>
              &quot;Brown, Ted: 000-00-00021&quot;, &quot;Brown, Ted: 000-00-00022&quot;,<br>
              &quot;Brown, Ted: 000-00-00023&quot;, &quot;Brown, Ted: 000-00-00024&quot;,<br>
              &quot;Brown, Ted: 000-00-00025&quot;, &quot;Brown, Ted: 000-00-00026&quot;,<br>
              &quot;Brown, Ted: 000-00-00027&quot;, &quot;Brown, Ted: 000-00-00028&quot;,<br>
              &quot;Brown, Ted: 000-00-00029&quot;, &quot;Brown, Ted: 000-00-00030&quot;,<br>
              };<br>
              public void paintComponent(Graphics g) {<br>
              Color color = g.getColor();<br>
              super.paintComponent(g);<br>
              g.setColor(color);</p>
            <p> Dimension size = getSize();<br>
              Insets insets = getInsets();<br>
              int y = insets.top;</p>
            <p> for(int i = topIndex; i &lt; data.length; ++i, y += fh) {<br>
              g.drawString(data[i], 0, y);</p>
            <p> if(y + fh &gt; size.height - insets.bottom)<br>
              break;<br>
              }<br>
              }<br>
              public void setTopIndexByPixelValue(int pixelValue) {<br>
              topIndex = pixelValue / fh;<br>
              }<br>
              public int getUnitHeight() {<br>
              return fh;<br>
              }<br>
              public Dimension getPreferredSize() {<br>
              Dimension dim = new Dimension();<br>
              Graphics g = getGraphics();</p>
            <p> try {<br>
              FontMetrics fm = g.getFontMetrics();<br>
              fh = fm.getHeight();</p>
            <p> dim.width = fm.stringWidth(data[data.length-1]);<br>
              dim.height = fm.getHeight() * (data.length + 1);<br>
              }<br>
              finally {<br>
              g.dispose();<br>
              }<br>
              return dim;<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 13.4.4 JScrollBar事件</p>
            <p>&nbsp;</p>
            <p align="center"><b>例13-12 使用JScrollBar的valueIsAdjusting属性</b></p>
            <hr noshade size="1">
            import java.awt.*;<br>
            import java.awt.event.*;<br>
            import javax.swing.*;
            <p>public class Test extends JApplet {<br>
              public Test() {<br>
              Container contentPane = getContentPane();<br>
              JScrollBar sb = new JScrollBar();</p>
            <p> contentPane.add(sb, BorderLayout.EAST);</p>
            <p> sb.addAdjustmentListener(new AdjustmentListener() {<br>
              public void adjustmentValueChanged(<br>
              AdjustmentEvent e) {<br>
              JScrollBar jsb = (JScrollBar)e.getAdjustable();</p>
            <p> if(jsb.getValueIsAdjusting())<br>
              showStatus(&quot;adjusting ...&quot;);<br>
              else<br>
              showStatus(Integer.toString(e.getValue()));<br>
              }<br>
              });<br>
              }<br>
              }</p>
            <hr size="1" noshade>
            <p> 13.4.5 JScrollBar类总结</p>
            <p>&nbsp;</p>
            <p> 13.4.6 AWT兼容</p>
            <p>&nbsp;</p>
            <p> 13.5 本章回顾</p>
            <p>&nbsp;</p>
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