android怎么实现多点触摸应用

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JhkMultiTouchActivity.java

package com.android.forlinx; import android.app.Activity;import android.os.Bundle;import android.view.Window;import android.view.WindowManager; public class JhkMultiTouchActivity extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);     //   setContentView(R.layout.main);              //隐藏标题栏                 requestWindowFeature(Window.FEATURE_NO_TITLE);                //设置成全屏                  getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,                        WindowManager.LayoutParams.FLAG_FULLSCREEN);                //设置为上面的MTView                setContentView(new MTView(this));     }}

MTView.java

package com.android.forlinx;  import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.Typeface;import android.view.MotionEvent;import android.view.SurfaceHolder;import android.view.SurfaceView; public class MTView extends SurfaceView implements SurfaceHolder.Callback {     private static final int MAX_TOUCHPOINTS = 10;    private static final String START_TEXT = "请随便触摸屏幕进行测试";    private Paint textPaint = new Paint();    private Paint touchPaints[] = new Paint[MAX_TOUCHPOINTS];    private int colors[] = new int[MAX_TOUCHPOINTS];     private int width, height;    private float scale = 1.0f;     public MTView(Context context) {        super(context);        SurfaceHolder holder = getHolder();        holder.addCallback(this);        setFocusable(true); // 确保我们的View能获得输入焦点        setFocusableInTouchMode(true); // 确保能接收到触屏事件        init();    }     private void init() {        // 初始化10个不同颜色的画笔        textPaint.setColor(Color.GREEN);        textPaint.setTypeface(null);        textPaint.setAlpha(200);        colors[0] = Color.BLUE;        colors[1] = Color.RED;        colors[2] = Color.GREEN;        colors[3] = Color.YELLOW;        colors[4] = Color.CYAN;        colors[5] = Color.MAGENTA;        colors[6] = Color.DKGRAY;        colors[7] = Color.WHITE;        colors[8] = Color.LTGRAY;        colors[9] = Color.GRAY;        for (int i = 0; i < MAX_TOUCHPOINTS; i++) {            touchPaints[i] = new Paint();            touchPaints[i].setColor(colors[i]);            touchPaints[i].setAlpha(50);        }    }     /*     * 处理触屏事件     */    @Override    public boolean onTouchEvent(MotionEvent event) {        // 获得屏幕触点数量        int pointerCount = event.getPointerCount();        if (pointerCount > MAX_TOUCHPOINTS) {            pointerCount = MAX_TOUCHPOINTS;        }                // 锁定Canvas,开始进行相应的界面处理        Canvas c = getHolder().lockCanvas();        if (c != null) {            c.drawColor(Color.BLACK);            if (event.getAction() == MotionEvent.ACTION_UP) {                // 当手离开屏幕时，清屏            } else {                // 先在屏幕上画一个十字，然后画一个圆                for (int i = 0; i < pointerCount; i++) {                    // 获取一个触点的坐标，然后开始绘制                    int id = event.getPointerId(i);                    int x = (int) event.getX(i);                    int y = (int) event.getY(i);                    drawCrosshairsAndText(x, y, touchPaints[id], i, id, c);                }                for (int i = 0; i < pointerCount; i++) {                    int id = event.getPointerId(i);                    int x = (int) event.getX(i);                    int y = (int) event.getY(i);                    drawCircle(x, y, touchPaints[id], c);                }            }            // 画完后，unlock            getHolder().unlockCanvasAndPost(c);        }        return true;    }     /**     * 画十字及坐标信息     *     * @param x     * @param y     * @param paint     * @param ptr     * @param id     * @param c     */    private void drawCrosshairsAndText(int x, int y, Paint paint, int ptr,            int id, Canvas c) {        c.drawLine(0, y, width, y, paint);        c.drawLine(x, 0, x, height, paint);        int textY = (int) ((15 + 20 * ptr) * scale);        c.drawText("x" + ptr + "=" + x, 10 * scale, textY, textPaint);        c.drawText("y" + ptr + "=" + y, 70 * scale, textY, textPaint);        c.drawText("id" + ptr + "=" + id, width - 55 * scale, textY, textPaint);    }     /**     * 画圆     *     * @param x     * @param y     * @param paint     * @param c     */    private void drawCircle(int x, int y, Paint paint, Canvas c) {        c.drawCircle(x, y, 40 * scale, paint);    }     /*     * 进入程序时背景画成黑色，然后把"START_TEXT"写到屏幕     */    public void surfaceChanged(SurfaceHolder holder, int format, int width,            int height) {        this.width = width;        this.height = height;        if (width > height) {            this.scale = width / 480f;        } else {            this.scale = height / 480f;        }        textPaint.setTextSize(14 * scale);        Canvas c = getHolder().lockCanvas();        if (c != null) {            // 背景黑色            c.drawColor(Color.BLACK);            float tWidth = textPaint.measureText(START_TEXT);            c.drawText(START_TEXT, width / 2 - tWidth / 2, height / 2,                    textPaint);            getHolder().unlockCanvasAndPost(c);        }    }     public void surfaceCreated(SurfaceHolder holder) {    }     public void surfaceDestroyed(SurfaceHolder holder) {    } }

效果图

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