Question

我曾搜索过Multitouch＆amp; amp;我有很多与

相关的例子

pich放大＆amp;缩小＆amp;

获得多个触摸坐标，但

我想使用多点触控在视图上绘制一个圆圈..我试过这个但是当我绘制它时坐标会改变圆圈没有在我触摸屏幕的确切位置绘制..

这是CODE ....

public class TestMultiTouchActivity extends Activity {
public class MultiTouchView extends View {

    // In this test, handle maximum of 2 pointer
    final int MAX_POINT_CNT = 2;

    private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    float[] x = new float[MAX_POINT_CNT];
    float[] y = new float[MAX_POINT_CNT];
    boolean[] isTouch = new boolean[MAX_POINT_CNT];

    public MultiTouchView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    @Override
    protected void onDraw(Canvas canvas) {
        // TODO Auto-generated method stub
        if (isTouch[0]) {
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(1);
            paint.setColor(Color.RED);
            // canvas.drawCircle(x[0], y[0], 50f, paint);
        }
        if (isTouch[1]) {
            paint.setStyle(Paint.Style.STROKE);
            paint.setStrokeWidth(1);
            paint.setColor(Color.BLUE);
            // canvas.drawCircle(x[1], y[1], 50f, paint);
        }
        float x1 = (Math.abs((x[0] - x[1]))) / 2;
        float y1 = (Math.abs((y[0] - y[1]))) / 2;

        float r = Math.abs(x1 - x[0]);
        canvas.drawCircle(x1, y1, r, paint);

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // TODO Auto-generated method stub
        setMeasuredDimension(MeasureSpec.getSize(widthMeasureSpec),
                MeasureSpec.getSize(heightMeasureSpec));
    }

    @Override
    public boolean onTouchEvent(MotionEvent motionEvent) {
        // TODO Auto-generated method stub

        int pointerIndex = ((motionEvent.getAction() & MotionEvent.ACTION_POINTER_ID_MASK) >> MotionEvent.ACTION_POINTER_ID_SHIFT);
        int pointerId = motionEvent.getPointerId(pointerIndex);
        int action = (motionEvent.getAction() & MotionEvent.ACTION_MASK);
        int pointCnt = motionEvent.getPointerCount();

        if (pointCnt <= MAX_POINT_CNT) {
            if (pointerIndex <= MAX_POINT_CNT - 1) {

                for (int i = 0; i < pointCnt; i++) {
                    int id = motionEvent.getPointerId(i);
                    x[id] = (int) motionEvent.getX(i);
                    y[id] = (int) motionEvent.getY(i);
                }

                switch (action) {
                case MotionEvent.ACTION_DOWN:
                    isTouch[pointerId] = true;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    isTouch[pointerId] = true;
                    break;
                case MotionEvent.ACTION_MOVE:
                    isTouch[pointerId] = true;
                    break;
                case MotionEvent.ACTION_UP:
                    isTouch[pointerId] = false;
                    break;
                case MotionEvent.ACTION_POINTER_UP:
                    isTouch[pointerId] = false;
                    break;
                case MotionEvent.ACTION_CANCEL:
                    isTouch[pointerId] = false;
                    break;
                default:
                    isTouch[pointerId] = false;
                }
            }
        }

        invalidate();
        return true;
    }
}

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new MultiTouchView(this));
}

Answer 1

尝试使用此方法计算圆的大小/位置：

// Calculate average x and y.
float x1 = (x[0] + x[1]) / 2.0f;
float y1 = (y[0] + y[1]) / 2.0f;

// Calculate the distance between the points
float r = Math.sqrt(Math.pow(x[1] - x[0], 2.0f) + Math.pow(y[1] - y[0], 2.0f) / 2.0f;

canvas.drawCircle(x1, y1, r, paint);

如何使用Multitouch绘制圆圈

1 个答案: