多点触控 之 两个手指

/**
* 绘制出第二个手指第位置
*/
public class MultiTouchTest extends CustomView {
String TAG = “Gcs”;

// 用于判断第2个手指是否存在boolean haveSecondPoint = false;// 记录第2个手指第位置PointF point = new PointF(0, 0);public MultiTouchTest(Context context) {    this(context, null);}public MultiTouchTest(Context context, AttributeSet attrs) {    super(context, attrs);    mDeafultPaint.setAntiAlias(true);    mDeafultPaint.setTextAlign(Paint.Align.CENTER);    mDeafultPaint.setTextSize(30);}@Overridepublic boolean onTouchEvent(MotionEvent event) {    int index = event.getActionIndex();    switch (event.getActionMasked()) {        case MotionEvent.ACTION_POINTER_DOWN:            // 判断是否是第2个手指按下            if (event.getPointerId(index) == 1){                haveSecondPoint = true;                point.set(event.getY(), event.getX());            }            break;        case MotionEvent.ACTION_POINTER_UP:            // 判断抬起的手指是否是第2个            if (event.getPointerId(index) == 1){                haveSecondPoint = false;                point.set(0, 0);            }            break;        case MotionEvent.ACTION_MOVE:            if (haveSecondPoint) {                // 通过 pointerId 来获取 pointerIndex                int pointerIndex = event.findPointerIndex(1);                // 通过 pointerIndex 来取出对应的坐标                point.set(event.getX(pointerIndex), event.getY(pointerIndex));            }            break;    }    invalidate();   // 刷新    return true;}@Overrideprotected void onDraw(Canvas canvas) {    canvas.save();    canvas.translate(mViewWidth/2, mViewHeight/2);    canvas.drawText("追踪第2个按下手指的位置", 0, 0, mDeafultPaint);    canvas.restore();    // 如果屏幕上有第2个手指则绘制出来其位置    if (haveSecondPoint) {        canvas.drawCircle(point.x, point.y, 50, mDeafultPaint);    }}

}