path: root/javax/swing/plaf/basic/BasicButtonUI.java

/* BasicButtonUI.java --
   Copyright (C) 2002, 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

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permission to link this library with independent modules to produce an
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package javax.swing.plaf.basic;

import java.awt.Dimension;
import java.awt.Font;
import java.awt.FontMetrics;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.Rectangle;
import java.beans.PropertyChangeListener;

import javax.swing.AbstractButton;
import javax.swing.ButtonModel;
import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.LookAndFeel;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.plaf.ButtonUI;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.UIResource;
import javax.swing.text.View;

/**
 * A UI delegate for the {@link JButton} component.
 */
public class BasicButtonUI extends ButtonUI
{
  /**
   * Cached rectangle for layouting the label. Used in paint() and
   * BasicGraphicsUtils.getPreferredButtonSize().
   */
  static Rectangle viewR = new Rectangle();

  /**
   * Cached rectangle for layouting the label. Used in paint() and
   * BasicGraphicsUtils.getPreferredButtonSize().
   */
  static Rectangle iconR = new Rectangle();

  /**
   * Cached rectangle for layouting the label. Used in paint() and
   * BasicGraphicsUtils.getPreferredButtonSize().
   */
  static Rectangle textR = new Rectangle();

  /**
   * The shared button UI.
   */
  private static BasicButtonUI sharedUI;

  /**
   * The shared BasicButtonListener.
   */
  private static BasicButtonListener sharedListener;

  /**
   * A constant used to pad out elements in the button's layout and
   * preferred size calculations.
   */
  protected int defaultTextIconGap = 4;

  /**
   * A constant added to the defaultTextIconGap to adjust the text
   * within this particular button.
   */
  protected int defaultTextShiftOffset;

  private int textShiftOffset;

  /**
   * Factory method to create an instance of BasicButtonUI for a given
   * {@link JComponent}, which should be an {@link AbstractButton}.
   *
   * @param c The component.
   *
   * @return A new UI capable of drawing the component
   */
  public static ComponentUI createUI(final JComponent c) 
  {
    if (sharedUI == null)
      sharedUI = new BasicButtonUI();
    return sharedUI;
  }

  /**
   * Returns the default gap between the button's text and icon (in pixels).
   * 
   * @param b  the button (ignored).
   * 
   * @return The gap.
   */
  public int getDefaultTextIconGap(AbstractButton b)
  {
    return defaultTextIconGap;
  }

  /**
   * Sets the text shift offset to zero.
   * 
   * @see #setTextShiftOffset()
   */
  protected void clearTextShiftOffset()
  {
    textShiftOffset = 0;
  }
  
  /**
   * Returns the text shift offset.
   * 
   * @return The text shift offset.
   * 
   * @see #clearTextShiftOffset()
   * @see #setTextShiftOffset()
   */
  protected int getTextShiftOffset()
  {
    return textShiftOffset;
  }

  /**
   * Sets the text shift offset to the value in {@link #defaultTextShiftOffset}.
   * 
   * @see #clearTextShiftOffset()
   */
  protected void setTextShiftOffset()
  {
    textShiftOffset = defaultTextShiftOffset;
  }

  /**
   * Returns the prefix for the UI defaults property for this UI class.
   * This is 'Button' for this class.
   *
   * @return the prefix for the UI defaults property
   */
  protected String getPropertyPrefix()
  {
    return "Button.";
  }

  /**
   * Installs the default settings.
   * 
   * @param b  the button (<code>null</code> not permitted).
   */
  protected void installDefaults(AbstractButton b)
  {
    String prefix = getPropertyPrefix();
    // Install colors and font.
    LookAndFeel.installColorsAndFont(b, prefix + "background",
                                     prefix + "foreground", prefix + "font");
    // Install border.
    LookAndFeel.installBorder(b, prefix + "border");

    // Install margin property.
    if (b.getMargin() == null || b.getMargin() instanceof UIResource)
      b.setMargin(UIManager.getInsets(prefix + "margin"));

    // Install rollover property.
    Object rollover = UIManager.get(prefix + "rollover");
    if (rollover != null)
      LookAndFeel.installProperty(b, "rolloverEnabled", rollover);

    // Fetch default textShiftOffset.
    defaultTextShiftOffset = UIManager.getInt(prefix + "textShiftOffset");

    // Make button opaque if needed.
    if (b.isContentAreaFilled())
      LookAndFeel.installProperty(b, "opaque", Boolean.TRUE);
    else
      LookAndFeel.installProperty(b, "opaque", Boolean.FALSE);
  }

  /**
   * Removes the defaults added by {@link #installDefaults(AbstractButton)}.
   * 
   * @param b  the button (<code>null</code> not permitted).
   */
  protected void uninstallDefaults(AbstractButton b)
  {
    // The other properties aren't uninstallable.
    LookAndFeel.uninstallBorder(b);
  }

  /**
   * Creates and returns a new instance of {@link BasicButtonListener}.  This
   * method provides a hook to make it easy for subclasses to install a 
   * different listener.
   * 
   * @param b  the button.
   * 
   * @return A new listener.
   */
  protected BasicButtonListener createButtonListener(AbstractButton b)
  {
    // Note: The RI always returns a new instance here. However,
    // the BasicButtonListener class is perfectly suitable to be shared
    // between multiple buttons, so we return a shared instance here
    // for efficiency.
    if (sharedListener == null)
      sharedListener = new BasicButtonListener(b);
    return sharedListener;
  }

  /**
   * Installs listeners for the button.
   * 
   * @param b  the button (<code>null</code> not permitted).
   */
  protected void installListeners(AbstractButton b)
  {
    BasicButtonListener listener = createButtonListener(b);
    if (listener != null)
      {
        b.addChangeListener(listener);
        b.addPropertyChangeListener(listener);
        b.addFocusListener(listener);    
        b.addMouseListener(listener);
        b.addMouseMotionListener(listener);
      }
  }

  /**
   * Uninstalls listeners for the button.
   * 
   * @param b  the button (<code>null</code> not permitted).
   */
  protected void uninstallListeners(AbstractButton b)
  {
    BasicButtonListener listener = getButtonListener(b);
    if (listener != null)
      {
        b.removeChangeListener(listener);
        b.removePropertyChangeListener(listener);
        b.removeFocusListener(listener);    
        b.removeMouseListener(listener);
        b.removeMouseMotionListener(listener);
      }
  }

  protected void installKeyboardActions(AbstractButton b)
  {
    BasicButtonListener listener = getButtonListener(b);
    if (listener != null)
      listener.installKeyboardActions(b);
  }

  protected void uninstallKeyboardActions(AbstractButton b)
  {
    BasicButtonListener listener = getButtonListener(b);
    if (listener != null)
      listener.uninstallKeyboardActions(b);
  }

  /**
   * Install the BasicButtonUI as the UI for a particular component.
   * This means registering all the UI's listeners with the component,
   * and setting any properties of the button which are particular to 
   * this look and feel.
   *
   * @param c The component to install the UI into
   */
  public void installUI(final JComponent c) 
  {
    super.installUI(c);
    if (c instanceof AbstractButton)
      {
        AbstractButton b = (AbstractButton) c;
        installDefaults(b);
        // It is important to install the listeners before installing
        // the keyboard actions, because the keyboard actions
        // are actually installed on the listener instance.
        installListeners(b);
        installKeyboardActions(b);
        BasicHTML.updateRenderer(b, b.getText());
      }
  }

  /**
   * Uninstalls the UI from the component.
   *
   * @param c the component from which to uninstall the UI
   */
  public void uninstallUI(JComponent c)
  {
    if (c instanceof AbstractButton)
      {
        AbstractButton b = (AbstractButton) c;
        uninstallKeyboardActions(b);
        uninstallListeners(b);
        uninstallDefaults(b);
        BasicHTML.updateRenderer(b, "");
      }
  }

  /**
   * Calculates the minimum size for the specified component.
   *
   * @param c the component for which to compute the minimum size
   *
   * @return the minimum size for the specified component
   */
  public Dimension getMinimumSize(JComponent c)
  {
    Dimension size = getPreferredSize(c);
    // When the HTML view has a minimum width different from the preferred
    // width, then substract this here accordingly. The height is not
    // affected by that.
    View html = (View) c.getClientProperty(BasicHTML.propertyKey);
    if (html != null)
      {
        size.width -= html.getPreferredSpan(View.X_AXIS)
                      - html.getPreferredSpan(View.X_AXIS);
      }
    return size;
  }

  /**
   * Calculates the maximum size for the specified component.
   *
   * @param c the component for which to compute the maximum size
   *
   * @return the maximum size for the specified component
   */
  public Dimension getMaximumSize(JComponent c)
  {
    Dimension size = getPreferredSize(c);
    // When the HTML view has a maximum width different from the preferred
    // width, then add this here accordingly. The height is not
    // affected by that.
    View html = (View) c.getClientProperty(BasicHTML.propertyKey);
    if (html != null)
      {
        size.width += html.getMaximumSpan(View.X_AXIS)
                      - html.getPreferredSpan(View.X_AXIS);
      }
    return size;
  }

  /**
   * Calculate the preferred size of this component, by delegating to
   * {@link BasicGraphicsUtils#getPreferredButtonSize}.
   *
   * @param c The component to measure
   *
   * @return The preferred dimensions of the component
   */
  public Dimension getPreferredSize(JComponent c) 
  {
    AbstractButton b = (AbstractButton) c;
    Dimension d = BasicGraphicsUtils.getPreferredButtonSize(b,
                                                           b.getIconTextGap());
    return d;
  }

  static Icon currentIcon(AbstractButton b)
  {
    Icon i = b.getIcon();
    ButtonModel model = b.getModel();

    if (model.isPressed() && b.getPressedIcon() != null && b.isEnabled())
      i = b.getPressedIcon();

    else if (model.isRollover())
      {
        if (b.isSelected() && b.getRolloverSelectedIcon() != null)
          i = b.getRolloverSelectedIcon();
        else if (b.getRolloverIcon() != null)
          i = b.getRolloverIcon();
      }    

    else if (b.isSelected() && b.isEnabled())
      {
        if (b.isEnabled() && b.getSelectedIcon() != null)
          i = b.getSelectedIcon();
        else if (b.getDisabledSelectedIcon() != null)
          i = b.getDisabledSelectedIcon();
      }

    else if (! b.isEnabled() && b.getDisabledIcon() != null)
      i = b.getDisabledIcon();

    return i;
  }

  /**
   * Paint the component, which is an {@link AbstractButton}, according to 
   * its current state.
   *
   * @param g The graphics context to paint with
   * @param c The component to paint the state of
   */
  public void paint(Graphics g, JComponent c)
  {
    AbstractButton b = (AbstractButton) c;

    Insets i = c.getInsets();
    viewR.x = i.left;
    viewR.y = i.top;
    viewR.width = c.getWidth() - i.left - i.right;
    viewR.height = c.getHeight() - i.top - i.bottom;
    textR.x = 0;
    textR.y = 0;
    textR.width = 0;
    textR.height = 0;
    iconR.x = 0;
    iconR.y = 0;
    iconR.width = 0;
    iconR.height = 0;

    Font f = c.getFont();
    g.setFont(f);
    Icon icon = b.getIcon();
    String text = b.getText();
    text = SwingUtilities.layoutCompoundLabel(c, g.getFontMetrics(f), 
                                              text, icon,
                                              b.getVerticalAlignment(), 
                                              b.getHorizontalAlignment(),
                                              b.getVerticalTextPosition(), 
                                              b.getHorizontalTextPosition(),
                                              viewR, iconR, textR, 
                                              text == null ? 0
                                                         : b.getIconTextGap());

    ButtonModel model = b.getModel();
    if (model.isArmed() && model.isPressed())
      paintButtonPressed(g, b);

    if (icon != null)
      paintIcon(g, c, iconR);
    if (text != null)
      {
        View html = (View) b.getClientProperty(BasicHTML.propertyKey);
        if (html != null)
          html.paint(g, textR);
        else
          paintText(g, b, textR, text);
      }
    if (b.isFocusOwner() && b.isFocusPainted())
      paintFocus(g, b, viewR, textR, iconR);
  }

  /**
   * Paint any focus decoration this {@link JComponent} might have.  The
   * component, which in this case will be an {@link AbstractButton},
   * should only have focus decoration painted if it has the focus, and its
   * "focusPainted" property is <code>true</code>.
   *
   * @param g Graphics context to paint with
   * @param b Button to paint the focus of
   * @param vr Visible rectangle, the area in which to paint
   * @param tr Text rectangle, contained in visible rectangle
   * @param ir Icon rectangle, contained in visible rectangle
   *
   * @see AbstractButton#isFocusPainted()
   * @see JComponent#hasFocus()
   */
  protected void paintFocus(Graphics g, AbstractButton b, Rectangle vr,
                            Rectangle tr, Rectangle ir)
  {
    // In the BasicLookAndFeel no focus border is drawn. This can be
    // overridden in subclasses to implement such behaviour.
  }

  /**
   * Paint the icon for this component. Depending on the state of the
   * component and the availability of the button's various icon
   * properties, this might mean painting one of several different icons.
   *
   * @param g Graphics context to paint with
   * @param c Component to paint the icon of
   * @param iconRect Rectangle in which the icon should be painted
   */
  protected void paintIcon(Graphics g, JComponent c, Rectangle iconRect)
  {
    AbstractButton b = (AbstractButton) c;
    Icon i = currentIcon(b);

    if (i != null)
      {
        ButtonModel m = b.getModel();
        if (m.isPressed() && m.isArmed())
          {
            int offs = getTextShiftOffset();
            i.paintIcon(c, g, iconRect.x + offs, iconRect.y + offs);
          }
        else
          i.paintIcon(c, g, iconRect.x, iconRect.y);
      }
  }

  /**
   * Paints the background area of an {@link AbstractButton} in the pressed
   * state.  This means filling the supplied area with a darker than normal 
   * background.
   *
   * @param g The graphics context to paint with
   * @param b The button to paint the state of
   */
  protected void paintButtonPressed(Graphics g, AbstractButton b)
  {
    if (b.isContentAreaFilled() && b.isOpaque())
      {
        Rectangle area = new Rectangle();
        SwingUtilities.calculateInnerArea(b, area);
        g.setColor(UIManager.getColor(getPropertyPrefix() + "shadow"));
        g.fillRect(area.x, area.y, area.width, area.height);
      }
  }
    
  /**
   * Paints the "text" property of an {@link AbstractButton}.
   *
   * @param g The graphics context to paint with
   * @param c The component to paint the state of
   * @param textRect The area in which to paint the text
   * @param text The text to paint
   */
  protected void paintText(Graphics g, JComponent c, Rectangle textRect,
                           String text) 
  {	
    paintText(g, (AbstractButton) c, textRect, text);
  }

  /**
   * Paints the "text" property of an {@link AbstractButton}.
   *
   * @param g The graphics context to paint with
   * @param b The button to paint the state of
   * @param textRect The area in which to paint the text
   * @param text The text to paint
   *
   * @since 1.4
   */
  protected void paintText(Graphics g, AbstractButton b, Rectangle textRect,
			   String text)
  {
    Font f = b.getFont();
    g.setFont(f);
    FontMetrics fm = g.getFontMetrics(f);

    if (b.isEnabled())
      {
        g.setColor(b.getForeground());
        // FIXME: Underline mnemonic.
        BasicGraphicsUtils.drawString(b, g, text, -1, textRect.x,
                                      textRect.y + fm.getAscent());
      }
    else
      {
        String prefix = getPropertyPrefix();
        g.setColor(UIManager.getColor(prefix + "disabledText"));
        // FIXME: Underline mnemonic.
        BasicGraphicsUtils.drawString(b, g, text, -1, textRect.x,
                                      textRect.y + fm.getAscent());
      }
  } 

  /**
   * A helper method that finds the BasicButtonListener for the specified
   * button. This is there because this UI class is stateless and
   * shared for all buttons, and thus can't store the listener
   * as instance field. (We store our shared instance in sharedListener,
   * however, subclasses may override createButtonListener() and we would
   * be lost in this case).
   *
   * @param b the button
   *
   * @return the UI event listener
   */
  private BasicButtonListener getButtonListener(AbstractButton b)
  {
    // The listener gets installed as PropertyChangeListener,
    // so look for it in the list of property change listeners.
    PropertyChangeListener[] listeners = b.getPropertyChangeListeners();
    BasicButtonListener l = null;
    for (int i = 0; listeners != null && l == null && i < listeners.length;
           i++)
      {
        if (listeners[i] instanceof BasicButtonListener)
          l = (BasicButtonListener) listeners[i];
      }
    return l;
  }
}