drawbufferedparallelogram.java

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// Fig. 2.11_04: DrawBufferedParallelogram.java
// 利用双缓冲绘制立方体

import java.awt.*; // 引入 java.awt包中所有的类
import javax.swing.*; // 引入 javax.swing包中所有的类

public class DrawBufferedParallelogram extends JApplet
{
    int baseXPts = 10, baseYPts = 200; // 立方体基准点坐标
    int width = 100; // 立方体的宽度
    int height = 120; // 立方体的高度
    int thickness = 30; // 立方体的厚度

    int alpha = 45; // 平行四边形的夹角
    int offsetX = 0; // 偏移量X
    int offsetY = 0; // 偏移量Y
    final int PARALLELOGRAM_POINT_NUMBER = 4; // 平行四边形的端点数目

    // 顶部平行四边形端点的X坐标数组
    int[] pTopX = new int[PARALLELOGRAM_POINT_NUMBER];
    // 顶部平行四边形端点的Y坐标数组
    int[] pTopY = new int[PARALLELOGRAM_POINT_NUMBER];

    // 右侧面平行四边形端点的X坐标数组
    int[] pRightX = new int[PARALLELOGRAM_POINT_NUMBER];
    // 右侧面平行四边形端点的Y坐标数组
    int[] pRightY = new int[PARALLELOGRAM_POINT_NUMBER];

    // 立方体的方向
    //final int UP = 1, RIGHT = 2, DOWN = 3, LEFT = 4;

    // 立方体的绘制风格
    final int OUTLINE = 1, FILL = 2, MIXED = 3;

    Color rFrontFillColor = new Color(178, 0, 0); // 缺省的填充颜色
    Color pTopFillColor = Color.RED; // 缺省的填充颜色
    Color pRightFillColor = new Color(124, 0, 0); // 缺省的填充颜色
    Color outlineColor = Color.LIGHT_GRAY; //缺省的立方体轮廓颜色

	Image offImage; 
    Graphics offGraphics; 

    int appletWidth = 550, appletHeight = 320;

    // 初始化绘图缓冲区
    public void init()
    {
		offImage = createImage(appletWidth, appletHeight);
		offGraphics = offImage.getGraphics();
    }

    // 设置整个立方体的轮廓颜色
    public void setOutlineColor(Color outlineColor)
    {
        this.outlineColor = outlineColor;
    }

    // 设置正面实心矩形的填充颜色
    public void setFrontFillColor(Color rFrontFillColor)
    {
        this.rFrontFillColor = rFrontFillColor;
    }

    // 设置顶部实心平行四边形的填充颜色
    public void setPTopFillColor(Color pTopFillColor)
    {
        this.pTopFillColor = pTopFillColor;
    }

    // 设置右侧面实心平行四边形的填充颜色
    public void setPRightFillColor(Color pRightFillColor)
    {
        this.pRightFillColor = pRightFillColor;
    }


    // 设置基准点的坐标
    public void setBasePoint(int baseXPts, int baseYPts)
    {
        this.baseXPts = baseXPts;
        this.baseYPts = baseYPts;
    }

    // 设置立方体的宽度
    public void setWidth(int width)
    {
        this.width = width;
    }

    // 设置立方体的高度
    public void setHeight(int height)
    {
        this.height = height;
    }

    // 设置立方体的厚度
    public void setThickness(int thickness)
    {
        this.thickness = thickness;
    }

    // 设置平行四边形的夹角alpha
    public void setAngle(int alpha)
    {
        this.alpha = alpha;
    }

    // 计算offsetX和offsetY的值
    public void calculateOffset()
    {
        offsetX = (int)(Math.cos(alpha * Math.PI / 180) * thickness + 0.5);
        offsetY = (int)(Math.sin(alpha * Math.PI / 180) * thickness + 0.5);
    }

    // 设置绘制正面矩形所需的数据
    public void buildRFront()
    {
        pRightX[0] = baseXPts + width;
        pRightY[0] = baseYPts;

        pRightX[1] = pRightX[0];
        pRightY[1] = baseYPts - height;

        pTopX[0] = baseXPts;
        pTopY[0] = pRightY[1];
    }

    // 设置绘制顶部平行四边形所需的数据
    public void buildPTop()
    {
        pTopX[1] = pRightX[1];
        pTopY[1] = pRightY[1];

        pTopX[2] = pTopX[1] + offsetX;
        pTopY[2] = pTopY[1] - offsetY;

        pTopX[3] = pTopX[0] + offsetX;
        pTopY[3] = pTopY[2];
    }

    // 设置绘制右侧面平行四边形所需的数据
    public void buildPRight()
    {
        pRightX[2] = pTopX[2];
        pRightY[2] = pTopY[2];

        pRightX[3] = pRightX[2];
        pRightY[3] = pRightY[2] + height;
    }

    // 绘制立方体
    public void drawParallelogram(int cubeStyle, Graphics g)
    {
        calculateOffset();
        buildRFront();
        buildPTop();
        buildPRight();

        switch (cubeStyle)
        {
            case 1:
                g.setColor(outlineColor);
                g.drawPolygon(pTopX, pTopY, PARALLELOGRAM_POINT_NUMBER);

                g.drawRect(pTopX[0], pTopY[0], width, height);

                g.drawPolygon(pRightX, pRightY, PARALLELOGRAM_POINT_NUMBER);
                break;

            case 2:
                g.setColor(pTopFillColor);
                g.fillPolygon(pTopX, pTopY, PARALLELOGRAM_POINT_NUMBER);

                g.setColor(rFrontFillColor);
                g.fillRect(pTopX[0], pTopY[0], width, height);

                g.setColor(pRightFillColor);
                g.fillPolygon(pRightX, pRightY, PARALLELOGRAM_POINT_NUMBER);

                break;

            case 3:
                g.setColor(pTopFillColor);
                g.fillPolygon(pTopX, pTopY, PARALLELOGRAM_POINT_NUMBER);

                g.setColor(rFrontFillColor);
                g.fillRect(pTopX[0], pTopY[0], width, height);

                g.setColor(pRightFillColor);
                g.fillPolygon(pRightX, pRightY, PARALLELOGRAM_POINT_NUMBER);

                g.setColor(outlineColor);
                g.drawPolygon(pTopX, pTopY, PARALLELOGRAM_POINT_NUMBER);

                g.drawRect(pTopX[0], pTopY[0], width, height);

                g.drawPolygon(pRightX, pRightY, PARALLELOGRAM_POINT_NUMBER);
                break;
        }
    }

    public void paint(Graphics g)
    {
        // 调用父类的 paint 方法
        super.paint(g);
        update(g);
        

    } // paint 方法结束

	 public void update(Graphics g) { 
		
        //offGraphics.setColor(getBackground());
		//offGraphics.fillRect(0,0,aw,ah);
        // 设置字体
        offGraphics.setColor(Color.BLACK);
		offGraphics.setFont(new Font("汉真广标", Font.PLAIN, 35));
        offGraphics.drawString("圆柱体画法", 10, 35);

        // 绘制默认立方体		
        drawParallelogram(FILL, offGraphics);

        // 绘制立方体2
        setBasePoint(150, 300);
        setWidth(80);
        setHeight(220);
        setThickness(40);
        setAngle(60);
        setPTopFillColor(new Color(0, 0, 255));
        setFrontFillColor(new Color(0, 0, 178));
        setPRightFillColor(new Color(0, 0, 124));
        drawParallelogram(FILL, offGraphics);

        // 绘制立方体3
        setBasePoint(280, 300);
        setOutlineColor(Color.ORANGE);
        drawParallelogram(OUTLINE, offGraphics);

        // 绘制立方体4
        setBasePoint(400, 280);
        setWidth(120);
        setHeight(180);
        setThickness(20);
        setAngle(30);
        setPTopFillColor(Color.GREEN);
        setFrontFillColor(Color.MAGENTA);
        setPRightFillColor(Color.PINK);
        setOutlineColor(Color.BLACK);
        drawParallelogram(MIXED, offGraphics);
 
        g.drawImage(offImage, 0, 0, null); 
     } 

} //  DrawBufferedParallelogram 类结束

/**************************************************************************
 * (C) Copyright 2004-2005 by Jingkui Zhong(钟京馗) and Huan Tang(唐桓).  *
 * All Rights Reserved.                                                   *
 *                                                                        *
 * DISCLAIMER: The authors of this code have used their                   *
 * best efforts in preparing the code. These efforts include the          *
 * development, research, and testing of the theories and programs        *
 * to determine their effectiveness. The authors and publisher make       *
 * no warranty of any kind, expressed or implied, with regard to these    *
 * programs or to the documentation contained in these codes. The authors *
 * shall not be liable in any event for incidental or consequential       *
 * damages in connection with, or arising out of, the furnishing,         *
 * performance, or use of these programs.                                 *
 **************************************************************************/