Java2实用教程(第二版)程序代码——第十四章 Component类的常用方法
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//例子1
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import java.applet.*;import java.awt.*;
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import java.awt.event.*;
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import javax.swing.JTextArea;
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public class Example14_1 extends Applet implements ItemListener
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{ List list ;
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JTextArea text;
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public void init()
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{ list=new List(6,false);
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text=new JTextArea(6,15);text.setForeground(Color.blue);
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GraphicsEnvironment ge=GraphicsEnvironment.getLocalGraphicsEnvironment();
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String fontName[]=ge.getAvailableFontFamilyNames();
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for(int i=0;i<fontName.length;i++)
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{ list.add(fontName[i]);
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}
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add(list);
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Panel p=new Panel();
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p.setBackground(Color.pink);
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p.add(text);
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add(p);
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list.addItemListener(this);
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}
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public void itemStateChanged(ItemEvent e)
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{ String name=list.getSelectedItem();
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Font f=new Font(name,Font.BOLD,16);
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text.setFont(f);
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text.setText("\nWelcome 欢迎您");
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}
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}
30![](/Images/OutliningIndicators/None.gif)
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//例子2
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import java.awt.*;import java.awt.event.*;
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public class Example14_2 extends java.applet.Applet implements ActionListener
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{ Button button;
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Label label;
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public void init()
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{ button=new Button("横向走动"); button.setBackground(Color.red);
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button.addActionListener(this);
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label=new Label("我可以被碰掉",Label.CENTER);
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label.setBackground(Color.yellow);
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add(button); add(label);
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}
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public void actionPerformed(ActionEvent e)
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{ Rectangle rect=button.getBounds();
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if(rect.intersects(label.getBounds()))
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{ label.setVisible(false);
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}
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if(label.isVisible())
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{ button.setLocation(rect.x+3,rect.y);
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}
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else
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{ button.setLocation(rect.x,rect.y+3);
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button.setLabel("纵向走动");
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}
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}
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}
57![](/Images/OutliningIndicators/None.gif)
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//例子3
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import java.awt.*;import java.awt.event.*;
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class MyCanvas extends Canvas
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{ int n=-1;
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MyCanvas()
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{ setSize(150,120);setBackground(Color.pink);
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}
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public void paint(Graphics g)
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{ g.setColor(Color.red);
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g.drawString("部分清除时我将消失",10,12);
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g.drawString("我们正在学习repaint方法",10,80);
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}
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public void setN(int n)
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{ this.n=n;
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}
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public void update(Graphics g)
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{ int width=0, height=0;
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width=getSize().width;height=getSize().height;
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if(n==0)
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{ g.clearRect(0,0,width,height);
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//paint(g); //如果取消该注释,update的功能就与父类相同。
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}
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else if(n==1)
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{ g.clearRect(2,2,width,40);
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}
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}
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}
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public class Example14_3 extends java.applet.Applet implements ActionListener
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{ Button b1,b2;MyCanvas canvas;
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public void init()
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{ canvas=new MyCanvas();
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b1=new Button("全部清除"); b1.addActionListener(this);
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b2=new Button("部分清除"); b2.addActionListener(this);
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add(b1); add(b2); add(canvas);
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}
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public void actionPerformed(ActionEvent e)
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{ if(e.getSource()==b1)
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{ canvas.setN(0);canvas.repaint();
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}
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if(e.getSource()==b2)
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{ canvas.setN(1);canvas.repaint();
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}
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}
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}
102![](/Images/OutliningIndicators/None.gif)
![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedBlockEnd.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedBlockEnd.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedBlockEnd.gif)
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![](/Images/OutliningIndicators/None.gif)
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![](/Images/OutliningIndicators/ExpandedBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/InBlock.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
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![](/Images/OutliningIndicators/None.gif)