graphiccanvas.java

在eclipse环境下

import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Graphics;

/**
 * 用于绘制图形的画布
 */
class GraphicCanvas extends Canvas {
    final static int LINE = 0;
    final static int RECTANGL_NO_FILL = 1;
    final static int RECTANGL_FILL = 2;
    final static int ARC_NO_FILL = 3;
    final static int ARC_FILL = 4;
    final static int ROUNDRECTANGLE_NO_FILL = 5;
    final static int ROUNDRECTANGLE_FILL = 6;
    final static int TRIANGLE_FILL = 7;
    
    //指针的起始位置
    private int startX, startY;
    //指针的新位置
    private int newX, newY;
    
    //显示是否为拖动模式
    private boolean isDragMode;
    
    //当前绘图模式
    private int mode;
    
    /**
     * 在这个方法中绘制屏幕
     */
    protected void paint(Graphics g) {
        //清除屏幕 - 背景黑色
        g.setColor(0x000000);
        g.fillRect(0, 0, this.getWidth(), this.getHeight());
        //设置绘图颜色为白色
        g.setColor(0xFFFFFF);
        
        if (isDragMode) {
            //用虚线绘制
            g.setStrokeStyle(Graphics.DOTTED);
        } else {
            //用实线绘制
            g.setStrokeStyle(Graphics.SOLID);
        }
        switch(mode) {
            case LINE:
                g.drawLine(startX, startY, newX, newY);
                break;
            case RECTANGL_NO_FILL:
                g.drawRect(startX, startY, newX-startX, newY-startY);
                break;
            case RECTANGL_FILL:
                g.fillRect(startX, startY, newX-startX, newY-startY);
                break;
            case ARC_NO_FILL:
                g.drawArc(startX, startY, 
                        newX-startX, newY-startY, 0, 180);
                break;
            case ARC_FILL:
                g.fillArc(startX, startY, 
                        newX-startX, newY-startY, 0, 180);
                break;
             case ROUNDRECTANGLE_NO_FILL:
                g.drawRoundRect(startX, startY, 
                        newX-startX, newY-startY, 10, 10);
                break;
            case ROUNDRECTANGLE_FILL:
                g.fillRoundRect(startX, startY, 
                        newX-startX, newY-startY, 10, 10);
                break;
            case TRIANGLE_FILL:
                g.fillTriangle(startX, startY, 
                        newX, newY, newX, newY+50);
                break;         
            default:
                break;                    
        }                   
    }
    
    /**
     * 指针按下时触发
     */
    protected void pointerPressed(int x, int y) {
        startX = x;
        startY = y;
        isDragMode = true;
    }
    
    /**
     * 指针拖动时触发
     */
    protected void pointerDragged(int x, int y) {
        newX = x;
        newY = y;
        repaint();
    }
    
    /**
     * 指针释放时触发
     */
    protected void pointerReleased(int x, int y) {
        isDragMode = false;
        newX = x;
        newY = y;
        repaint();
    }

    void draw(int mode) {
        this.mode = mode;
        repaint();
    }
}