tabpanel.java

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package rcm.awt;

import java.awt.*;
import java.awt.event.*;

public class TabPanel extends Panel {
  static final int MAX_TABS = 25;
  static final int selUpper=2;
  static final int lineWidth=2;
  static final int horRound=2;  
  static final int verRound=2;
  static final int internalMargin = 4;
  static final int xTabOffset = 2;
  static final int XTitle=4;
  static final int YTitle=2;
    
  Font plainFont;     // computed by recalculate ()
  Font boldFont;       // computed by recalculate ()
  FontMetrics fmBoldFont;    // computed by recalculate ()
  
  final Color light=new Color(223,223,223);
  final Color shadow=new Color(127,127,127);
    
  CardLayout tabLayout=new CardLayout();
  Panel tabPanel=new Panel();
  
  boolean mustRecalculate = true;
  
  int Z;   // computed by recalculate ()
  
  int W;
  int H;
    
  Component cards[] = new Component[MAX_TABS];
  String arrName[]=new String[MAX_TABS];
  int arrEnd[]=new int[MAX_TABS];   // computed by recalculate ()
  int arrBeg[]=new int[MAX_TABS];   // computed by recalculate ()
  
  int nbTab=0;
  int selected=-1;

  // Extra feature: zero or more buttons flush-right on tab line
    final static int BUTTON_GUTTER = 2; // pixels between buttons

  public TabPanel() {
    setLayout(null);
    tabPanel.setLayout(tabLayout);
    add(tabPanel);
    addMouseListener (new MouseHandler ());
  }

  void recalculate () {
    plainFont = getFont ();
    if (plainFont == null)
        plainFont = new Font ("Helvetica", Font.PLAIN, 12);
    boldFont = new Font (plainFont.getFamily(), Font.BOLD, plainFont.getSize());
    fmBoldFont = getFontMetrics (boldFont);
    
    Z = fmBoldFont.getHeight()+2*lineWidth+2*YTitle+1;

    for (int i=0; i<nbTab; ++i) {
        arrBeg[i]=(i==0) ? xTabOffset : arrEnd[i-1];
        arrEnd[i]=arrBeg[i]+2*XTitle+fmBoldFont.stringWidth(arrName[i])+2*lineWidth;
        
    }

    if (selected >= 0) {
        arrBeg[selected] -= lineWidth;
        arrEnd[selected] += lineWidth;
    }
    
    mustRecalculate = false;
  }
  
  public void layout () {
    if (mustRecalculate)
        recalculate ();
    Dimension external = getSize ();
    W = external.width;
    H = external.height;
    
    int x = lineWidth+internalMargin;
    int y = Z+1+internalMargin;
    int w = W-2*(lineWidth+internalMargin);
    int h = H-Z-2*(lineWidth+internalMargin);
    
    tabPanel.setBounds (x, y, w, h);
    tabPanel.validate ();

    Component[] c = getComponents ();
    int bx = external.width;
    for (int i=c.length-1; i>=0; --i) 
        if (c[i] != tabPanel && c[i].isVisible()) {
            Dimension d = c[i].getPreferredSize();
            bx -= d.width;
            c[i].setBounds (bx, 0, d.width, d.height);
            bx -= BUTTON_GUTTER;
        }
  }
  
    public Dimension getPreferredSize () {
        Dimension d = super.getPreferredSize ();
        return new Dimension (d.width + 2*(lineWidth+internalMargin), 
                              d.height + Z + 2*(lineWidth+internalMargin));
    }

    public Dimension getMinimumSize () {
        Dimension d = super.getMinimumSize ();
        return new Dimension (d.width + 2*(lineWidth+internalMargin), 
                              d.height + Z + 2*(lineWidth+internalMargin));
    }

  public void addTabPanel(String name, boolean enabled, Component c) {
    if (c.getParent() == tabPanel   // panel already added
        || nbTab>=arrBeg.length     // too many tabs
        || c==this)                 // can't add self
        return;

    cards[nbTab] = c;
    arrName[nbTab]=name;
    tabPanel.add(String.valueOf (nbTab), c);
    nbTab++;

    if (selected < 0)
        select (0);

    mustRecalculate = true;
    repaint ();
  }
  
  public String[] getPanelLabels () {
    return arrName;
  }

  public void removeAllTabPanels () {
    for (int i=nbTab-1; i>=0; --i)
        removeTabPanel (i);
  }
  
  public void removeTabPanel(Component c) {
    //finding the tab
    for(int i=0;i<cards.length;i++) {
      if(cards[i]==c) {
        removeTabPanel (i);
        break;
      }
    }
  }
        
  public void removeTabPanel(int i) {
    if (i<0 || i >= nbTab)
        return;
    tabPanel.remove(cards[i]);
    for(int j=i;j<nbTab-1;j++) {
      arrName[j]=arrName[j+1];
      cards[j]=cards[j+1];
    }
    nbTab--;
    if (selected == i)
        select (Math.min (selected+1, nbTab-1));
    mustRecalculate = true;
    repaint ();
  }
  
  public int countTabs () {
    return nbTab;
  }

  public void renameTab(String oldName, String newName) {
    for(int i=0;i<nbTab;i++) {
      if(arrName[i].equals(oldName)) {
        arrName[i]=new String(newName);          
        mustRecalculate = true;
        repaint ();
        break;
      }
    }
  }

  public void select (int num) {
    if(num<0||num>nbTab||num==selected)
        return;
    selected=num;
    tabLayout.show(tabPanel,Integer.toString(selected));
    mustRecalculate = true;
    repaint ();
  }

  public Component getSelectedComponent () {
      if (selected < 0 || selected >= nbTab)
          return null;
      else
          return cards[selected];
  }

  public synchronized void update (Graphics g) {
    // avoid clearing background
    paint (g); // FIX: what happens if a component leaves garbage behind?
  }
  
  public synchronized void paint (Graphics g){    
    if (mustRecalculate || getFont() != plainFont)
        recalculate ();
    
    Dimension d = getSize ();
    g.setColor(getBackground());
    g.fillRect(0,0,W,Z+1);
         
    for (int curr=0;curr<nbTab;curr++) {
      int upper=(curr==selected) ? 0 : selUpper;
      g.setFont((curr==selected) ? boldFont : plainFont);
      
      g.setColor(shadow);
      for (int i=lineWidth;curr!=(selected-1) && i>0;i--) {
        if(i==1) g.setColor(Color.black);
        g.drawLine(arrEnd[curr]-i,upper+verRound,arrEnd[curr]-i,Z-lineWidth);
        if(i==1) g.drawLine(arrEnd[curr]-lineWidth,upper+1,arrEnd[curr]-lineWidth,upper+1);
      }

      g.setColor(Color.black);
      g.drawString(arrName[curr],
                   arrBeg[curr]+(curr==selected ? 2*lineWidth : lineWidth)+XTitle,
                   upper+YTitle+lineWidth+fmBoldFont.getAscent());
      
      g.setColor(Color.white);
      for (int i=0;i<lineWidth;i++) {
        if(i==1) g.setColor(light);
        g.drawLine(arrBeg[curr]+horRound,upper+i,arrEnd[curr]-lineWidth-horRound+1,upper+i);      
        if(curr!=(selected+1)) {
          g.drawLine(arrBeg[curr]+i,upper+verRound,arrBeg[curr]+i,Z);
          if(i==0)g.drawLine(arrBeg[curr]+1,upper+1,arrBeg[curr]+1,upper+1);
        }
      }
    }
    
    g.setColor(Color.white);
    for (int i=0;i<lineWidth;i++) {
      if(i==1) g.setColor(light);
      g.drawLine(i,Z,i,H-1);
      if (selected >= 0) {
          if(selected!=0) g.drawLine(0,Z-lineWidth+i+1,arrBeg[selected],Z-lineWidth+i+1);
          g.drawLine(arrEnd[selected],Z-lineWidth+i+1,W-1,Z-lineWidth+i+1);
      }
      else {
          g.drawLine(0,Z-lineWidth+i+1,W-1,Z-lineWidth+i+1);
      }
    }
    
    g.setColor(shadow);
    for (int i=lineWidth;i>0;i--) {
      if(i==1) g.setColor(Color.black);
      g.drawLine(0,H-i,W,H-i);
      g.drawLine(W-i,Z,W-i,H-1);
    }
    
  }

    void clickTab (int x, int y) {
      for (int i=0;i<nbTab;i++)
        if (x>arrBeg[i] && x<arrEnd[i])
            select (i);
    }
    
    class MouseHandler extends MouseAdapter {
        public void mousePressed (MouseEvent event) {
            if(event.getY () < Z)
                clickTab (event.getX (), event.getY ());
        }
    }

}