basicscrollbarui.java

java jdk 1.4的源码

    {
        g.setColor(trackColor);
        g.fillRect(trackBounds.x, trackBounds.y, trackBounds.width, trackBounds.height);	

	if(trackHighlight == DECREASE_HIGHLIGHT)	{
	    paintDecreaseHighlight(g);
	} 
	else if(trackHighlight == INCREASE_HIGHLIGHT)		{
	    paintIncreaseHighlight(g);
	}
    }

	
    protected void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds)  
    {
	if(thumbBounds.isEmpty() || !scrollbar.isEnabled())	{
	    return;
	}

        int w = thumbBounds.width;
        int h = thumbBounds.height;		

	g.translate(thumbBounds.x, thumbBounds.y);

	g.setColor(thumbDarkShadowColor);
	g.drawRect(0, 0, w-1, h-1);    
	g.setColor(thumbColor);
	g.fillRect(0, 0, w-1, h-1);
        
        g.setColor(thumbHighlightColor);
        g.drawLine(1, 1, 1, h-2);
        g.drawLine(2, 1, w-3, 1);
        
        g.setColor(thumbLightShadowColor);
        g.drawLine(2, h-2, w-2, h-2);
        g.drawLine(w-2, 1, w-2, h-3);

	g.translate(-thumbBounds.x, -thumbBounds.y);
    }


    /** 
     * Return the smallest acceptable size for the thumb.  If the scrollbar
     * becomes so small that this size isn't available, the thumb will be
     * hidden.  
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a shared static constant.
     *
     * @return The smallest acceptable size for the thumb.
     * @see #getMaximumThumbSize
     */
    protected Dimension getMinimumThumbSize() { 
	return minimumThumbSize;
    }

    /** 
     * Return the largest acceptable size for the thumb.  To create a fixed 
     * size thumb one make this method and <code>getMinimumThumbSize</code> 
     * return the same value.
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a shared static constant.
     *
     * @return The largest acceptable size for the thumb.
     * @see #getMinimumThumbSize
     */
    protected Dimension getMaximumThumbSize()	{ 
	return maximumThumbSize;
    }


    /*
     * LayoutManager Implementation
     */

    public void addLayoutComponent(String name, Component child) {}
    public void removeLayoutComponent(Component child) {}
    
    public Dimension preferredLayoutSize(Container scrollbarContainer)  {
        return getPreferredSize((JComponent)scrollbarContainer);
    }
    
    public Dimension minimumLayoutSize(Container scrollbarContainer) {
        return getMinimumSize((JComponent)scrollbarContainer);
    }
    

    protected void layoutVScrollbar(JScrollBar sb)  
    {
        Dimension sbSize = sb.getSize();
        Insets sbInsets = sb.getInsets();

	/*
	 * Width and left edge of the buttons and thumb.
	 */
	int itemW = sbSize.width - (sbInsets.left + sbInsets.right);
	int itemX = sbInsets.left;
        
        /* Nominal locations of the buttons, assuming their preferred
	 * size will fit.
	 */
        int decrButtonH = decrButton.getPreferredSize().height;
        int decrButtonY = sbInsets.top;
        
        int incrButtonH = incrButton.getPreferredSize().height;
        int incrButtonY = sbSize.height - (sbInsets.bottom + incrButtonH);
        
        /* The thumb must fit within the height left over after we
	 * subtract the preferredSize of the buttons and the insets.
	 */
        int sbInsetsH = sbInsets.top + sbInsets.bottom;
        int sbButtonsH = decrButtonH + incrButtonH;
        float trackH = sbSize.height - (sbInsetsH + sbButtonsH);
        
        /* Compute the height and origin of the thumb.   The case
	 * where the thumb is at the bottom edge is handled specially 
	 * to avoid numerical problems in computing thumbY.  Enforce
	 * the thumbs min/max dimensions.  If the thumb doesn't
	 * fit in the track (trackH) we'll hide it later.
	 */
	float min = sb.getMinimum();
	float extent = sb.getVisibleAmount();
	float range = sb.getMaximum() - min;
	float value = sb.getValue();

        int thumbH = (range <= 0) 
	    ? getMaximumThumbSize().height : (int)(trackH * (extent / range));
	thumbH = Math.max(thumbH, getMinimumThumbSize().height);
	thumbH = Math.min(thumbH, getMaximumThumbSize().height);
        
	int thumbY = incrButtonY - thumbH;  
	if (sb.getValue() < (sb.getMaximum() - sb.getVisibleAmount())) {
	    float thumbRange = trackH - thumbH;
	    thumbY = (int)(0.5f + (thumbRange * ((value - min) / (range - extent))));
	    thumbY +=  decrButtonY + decrButtonH;
	}

        /* If the buttons don't fit, allocate half of the available 
	 * space to each and move the lower one (incrButton) down.
	 */
        int sbAvailButtonH = (sbSize.height - sbInsetsH);
        if (sbAvailButtonH < sbButtonsH) {
            incrButtonH = decrButtonH = sbAvailButtonH / 2;
            incrButtonY = sbSize.height - (sbInsets.bottom + incrButtonH);
        }
        decrButton.setBounds(itemX, decrButtonY, itemW, decrButtonH);
        incrButton.setBounds(itemX, incrButtonY, itemW, incrButtonH);

	/* Update the trackRect field.
	 */	
	int itrackY = decrButtonY + decrButtonH;
	int itrackH = incrButtonY - itrackY;
	trackRect.setBounds(itemX, itrackY, itemW, itrackH);
	
	/* If the thumb isn't going to fit, zero it's bounds.  Otherwise
	 * make sure it fits between the buttons.  Note that setting the
	 * thumbs bounds will cause a repaint.
	 */
	if(thumbH >= (int)trackH)	{
	    setThumbBounds(0, 0, 0, 0);
	}
	else {
	    if ((thumbY + thumbH) > incrButtonY) {
		thumbY = incrButtonY - thumbH;
	    }
	    if (thumbY  < (decrButtonY + decrButtonH)) {
		thumbY = decrButtonY + decrButtonH + 1;
	    }
	    setThumbBounds(itemX, thumbY, itemW, thumbH);
	}
    }
    

    protected void layoutHScrollbar(JScrollBar sb)  
    {
        Dimension sbSize = sb.getSize();
        Insets sbInsets = sb.getInsets();
        
	/* Height and top edge of the buttons and thumb.
	 */
	int itemH = sbSize.height - (sbInsets.top + sbInsets.bottom);
	int itemY = sbInsets.top;

        boolean ltr = sb.getComponentOrientation().isLeftToRight();

        /* Nominal locations of the buttons, assuming their preferred
	 * size will fit.
	 */
        int leftButtonW = (ltr ? decrButton : incrButton).getPreferredSize().width; 
        int rightButtonW = (ltr ? incrButton : decrButton).getPreferredSize().width;        
        int leftButtonX = sbInsets.left;        
        int rightButtonX = sbSize.width - (sbInsets.right + rightButtonW);

        /* The thumb must fit within the width left over after we
	 * subtract the preferredSize of the buttons and the insets.
	 */
        int sbInsetsW = sbInsets.left + sbInsets.right;
        int sbButtonsW = leftButtonW + rightButtonW;
        float trackW = sbSize.width - (sbInsetsW + sbButtonsW);
        
        /* Compute the width and origin of the thumb.  Enforce
	 * the thumbs min/max dimensions.  The case where the thumb 
	 * is at the right edge is handled specially to avoid numerical 
	 * problems in computing thumbX.  If the thumb doesn't
	 * fit in the track (trackH) we'll hide it later.
	 */
        float min = sb.getMinimum();
        float max = sb.getMaximum();
        float extent = sb.getVisibleAmount();
        float range = max - min;
        float value = sb.getValue();

        int thumbW = (range <= 0) 
	    ? getMaximumThumbSize().width : (int)(trackW * (extent / range));
        thumbW = Math.max(thumbW, getMinimumThumbSize().width);
        thumbW = Math.min(thumbW, getMaximumThumbSize().width);
        
	int thumbX = ltr ? rightButtonX - thumbW : leftButtonX + leftButtonW;
	if (sb.getValue() < (max - sb.getVisibleAmount())) {
	    float thumbRange = trackW - thumbW;
            if( ltr ) {
                thumbX = (int)(0.5f + (thumbRange * ((value - min) / (range - extent))));
            } else {
                thumbX = (int)(0.5f + (thumbRange * ((max - extent - value) / (range - extent))));
            }
	    thumbX +=  leftButtonX + leftButtonW;
	}

        /* If the buttons don't fit, allocate half of the available 
         * space to each and move the right one over.
         */
        int sbAvailButtonW = (sbSize.width - sbInsetsW);
        if (sbAvailButtonW < sbButtonsW) {
            rightButtonW = leftButtonW = sbAvailButtonW / 2;
            rightButtonX = sbSize.width - (sbInsets.right + rightButtonW);
        }
        
        (ltr ? decrButton : incrButton).setBounds(leftButtonX, itemY, leftButtonW, itemH);
        (ltr ? incrButton : decrButton).setBounds(rightButtonX, itemY, rightButtonW, itemH);

	/* Update the trackRect field.
	 */	
	int itrackX = leftButtonX + leftButtonW;
	int itrackW = rightButtonX - itrackX;
	trackRect.setBounds(itrackX, itemY, itrackW, itemH);

	/* Make sure the thumb fits between the buttons.  Note 
	 * that setting the thumbs bounds causes a repaint.
	 */
	if (thumbW >= (int)trackW) {
	    setThumbBounds(0, 0, 0, 0);
	}
	else {
	    if (thumbX + thumbW > rightButtonX) {
		thumbX = rightButtonX - thumbW;
	    }
	    if (thumbX  < leftButtonX + leftButtonW) {
		thumbX = leftButtonX + leftButtonW + 1;
	    }
	    setThumbBounds(thumbX, itemY, thumbW, itemH);
	}
    }

    public void layoutContainer(Container scrollbarContainer) 
    {
	/* If the user is dragging the value, we'll assume that the 
	 * scrollbars layout is OK modulo the thumb which is being 
	 * handled by the dragging code.
	 */
	if (isDragging) {
	    return;
	}

        JScrollBar scrollbar = (JScrollBar)scrollbarContainer;
        switch (scrollbar.getOrientation()) {
        case JScrollBar.VERTICAL:
            layoutVScrollbar(scrollbar);
            break;
            
        case JScrollBar.HORIZONTAL:
            layoutHScrollbar(scrollbar);
            break;
        }
    }


    /**
     * Set the bounds of the thumb and force a repaint that includes
     * the old thumbBounds and the new one.
     *
     * @see #getThumbBounds
     */
    protected void setThumbBounds(int x, int y, int width, int height)
    {
	/* If the thumbs bounds haven't changed, we're done.
	 */
	if ((thumbRect.x == x) && 
	    (thumbRect.y == y) && 
	    (thumbRect.width == width) && 
	    (thumbRect.height == height)) {
	    return;
	}

	/* Update thumbRect, and repaint the union of x,y,w,h and 
	 * the old thumbRect.
	 */
	int minX = Math.min(x, thumbRect.x);
	int minY = Math.min(y, thumbRect.y);
	int maxX = Math.max(x + width, thumbRect.x + thumbRect.width);
	int maxY = Math.max(y + height, thumbRect.y + thumbRect.height);

	thumbRect.setBounds(x, y, width, height);
	scrollbar.repaint(minX, minY, maxX - minX, maxY - minY);
    }


    /**
     * Return the current size/location of the thumb.
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a reference to the actual rectangle, not a copy.
     *
     * @return The current size/location of the thumb.
     * @see #setThumbBounds
     */
    protected Rectangle getThumbBounds() {
	return thumbRect;
    }


    /**
     * Returns the current bounds of the track, i.e. the space in between
     * the increment and decrement buttons, less the insets.  The value
     * returned by this method is updated each time the scrollbar is
     * laid out (validated).
     * <p>
     * <b>Warning </b>: the value returned by this method should not be
     * be modified, it's a reference to the actual rectangle, not a copy.
     *
     * @return the current bounds of the scrollbar track
     * @see #layoutContainer
     */
    protected Rectangle getTrackBounds() {
	return trackRect;
    }

    /*
     * Method for scrolling by a block increment.
     * Added for mouse wheel scrolling support, RFE 4202656.
     */
    static void scrollByBlock(JScrollBar scrollbar, int direction) {
        // This method is called from BasicScrollPaneUI to implement wheel
        // scrolling, and also from scrollByBlock().
	    int oldValue = scrollbar.getValue();
	    int blockIncrement = scrollbar.getBlockIncrement(direction);
	    int delta = blockIncrement * ((direction > 0) ? +1 : -1);

	    scrollbar.setValue(oldValue + delta);			
    }

    protected void scrollByBlock(int direction)
    {
        scrollByBlock(scrollbar, direction);
	    trackHighlight = direction > 0 ? INCREASE_HIGHLIGHT : DECREASE_HIGHLIGHT;
	    Rectangle dirtyRect = getTrackBounds();
	    scrollbar.repaint(dirtyRect.x, dirtyRect.y, dirtyRect.width, dirtyRect.height);
    }
    
    /*
     * Method for scrolling by a unit increment.
     * Added for mouse wheel scrolling support, RFE 4202656.
     */
    static void scrollByUnits(JScrollBar scrollbar, int direction,
                                   int units) {
        // This method is called from BasicScrollPaneUI to implement wheel
        // scrolling, as well as from scrollByUnit().
        int delta = units;

        if (direction > 0) {
            delta *= scrollbar.getUnitIncrement(direction);
        }
        else {
            delta *= -scrollbar.getUnitIncrement(direction);
        }

        int oldValue = scrollbar.getValue();
        int newValue = oldValue + delta;

        // Check for overflow.
        if (delta > 0 && newValue < oldValue) {
            newValue = scrollbar.getMaximum();
        }
        else if (delta < 0 && newValue > oldValue) {
            newValue = scrollbar.getMinimum();
        }
        scrollbar.setValue(newValue);
    }

    protected void scrollByUnit(int direction)	{
        scrollByUnits(scrollbar, direction, 1);
    }

    /**
     * Indicates whether the user can absolutely position the offset with
     * a mouse click (usually the middle mouse button).
     * <p>The return value is determined from the UIManager property
     * ScrollBar.allowsAbsolutePositioning.
     */
    private boolean getSupportsAbsolutePositioning() {
	return supportsAbsolutePositioning;
    }

    /**
     * A listener to listen for model changes.
     *
     */
    protected class ModelListener implements ChangeListener {
        public void stateChanged(ChangeEvent e) {
	    layoutContainer(scrollbar);
        }
    }


    /**
     * Track mouse drags.
     */
    protected class TrackListener
        extends MouseAdapter implements MouseMotionListener
    {
	protected transient int offset;
	protected transient int currentMouseX, currentMouseY;
 	private transient int direction = +1;