/*
 * Drawer.java
 *
 * Created on June 8, 2007, 11:52 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */
package dyno.swing.beans;

import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Rectangle;

import javax.swing.JComponent;


/**
 * 該類是個輔助類，目的是實現動畫狀態時透明圖像及組件的移動效果
 * 像是一個抽屜，放應用程序的組件
 *
 * @author William Chen
 */
class Drawer extends JComponent {
    //目前抽屜抽開比例，同時是透明度值
    private double ratio = 1.0;

    //目前是否處于動畫狀態
    private boolean animating;

    //應用程序的組件
    private JComponent content;

    //保存有應用程序組件的虛屏圖像
    private Image offImage;

    /** Creates a new instance of Drawer */
    Drawer(double r, JComponent comp) {
        this.ratio = r;
        this.content = comp;
        add(comp);
        setLayout(null);
    }
    
    int getContentHeight() {
        return content.getHeight();
    }

    int getContentWidth() {
        return content.getWidth();
    }
    void setContentWidth(int w){
        Rectangle bounds=content.getBounds();
        bounds.width=w;
        content.setBounds(bounds);
    }
    void setRatio(double ratio) {
        this.ratio = ratio;
        repaint();
    }

    double getRatio() {
        return this.ratio;
    }

    //覆蓋父類的paintChildren
    protected void paintChildren(Graphics g) {
        if (animating) {
            //動畫狀態畫出當前透明的應用程序組件以及抽拉狀態
            Graphics2D g2d = (Graphics2D) g;
            g2d.setComposite(AlphaComposite.getInstance(
                    AlphaComposite.SRC_OVER, (float) ratio));
            g2d.drawImage(getOffImage(), 0, getHeight() - content.getHeight(),
                this);
        } else {
            //普通狀態簡單使用容器缺省的渲染
            super.paintChildren(g);
        }
    }

    void clearOffImage() {
        offImage = null;
    }

    void setAnimating(boolean animating) {
        this.animating = animating;
    }

    //創建應用程序組件的虛屏圖像
    private Image getOffImage() {
        if (offImage == null) {
            int contentWidth = content.getWidth();
            int contentHeight = content.getHeight();

            if (offImage == null) {
                offImage = createImage(contentWidth, contentHeight);

                Graphics g = offImage.getGraphics();
                //使用Renderer機制
                content.paint(g);
            }
        }

        return offImage;
    }
}