我正在尝试使 View 跟随我的手指并使用以下代码在多点触控中进行一些旋转和缩放

@Override
public boolean onTouch(View view, MotionEvent motionEvent) {

    final int action = motionEvent.getActionMasked();
    int newPosX,newPosY;
    switch (action) {
        case MotionEvent.ACTION_DOWN: {
            final int pointerIndex = motionEvent.getActionIndex();
            final float x = motionEvent.getX( pointerIndex);
            final float y = motionEvent.getY( pointerIndex);

            RelativeLayout.LayoutParams parms = (RelativeLayout.LayoutParams) view.getLayoutParams();

            // Remember where we started (for dragging)
            mLastTouchX = (int) x;
            mLastTouchY = (int) y;
            // Save the ID of this pointer (for dragging)
            mActivePointerId = motionEvent.getPointerId( 0);
            break;
        }

        case MotionEvent.ACTION_MOVE: {
            if(motionEvent.getPointerCount()==2){
                float newDist = spacing(motionEvent);
                float scale = newDist / oldDist * view.getScaleX();
                view.setScaleY(scale);
                view.setScaleX(scale);

                float newAngle = rotation(motionEvent);
                float a = newAngle - oldAngle;
                view.animate().rotationBy(a).setDuration(0).setInterpolator(new LinearInterpolator()).start();
            }
            // Find the index of the active pointer and fetch its position
            final int pointerIndex =
                    motionEvent.findPointerIndex( mActivePointerId);

            final float x = motionEvent.getX( pointerIndex);
            final float y = motionEvent.getY( pointerIndex);

            // Calculate the distance moved
            final float dx = x - mLastTouchX;
            final float dy = y - mLastTouchY;
            RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();

            layoutParams.leftMargin += dx;
            layoutParams.topMargin += dy;

            view.setLayoutParams(layoutParams);

            break;
        }
        case MotionEvent.ACTION_POINTER_DOWN:{
            oldDist = spacing(motionEvent);
            oldAngle = rotation(motionEvent);
            break;
        }

        case MotionEvent.ACTION_UP: {
            mActivePointerId = INVALID_POINTER_ID;
            break;
        }

        case MotionEvent.ACTION_CANCEL: {
            mActivePointerId = INVALID_POINTER_ID;
            break;
        }

        case MotionEvent.ACTION_POINTER_UP: {

            final int pointerIndex = motionEvent.getActionIndex();
            final int pointerId = motionEvent.getPointerId( pointerIndex);

            if (pointerId == mActivePointerId) {
                // This was our active pointer going up. Choose a new
                // active pointer and adjust accordingly.
                final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
                mLastTouchX = (int) motionEvent.getX( newPointerIndex);
                mLastTouchY = (int) motionEvent.getY( newPointerIndex);
                mActivePointerId = motionEvent.getPointerId( newPointerIndex);
            }
            break;
        }
    }
    return true;

}
    private float spacing(MotionEvent event) {
    float x = event.getX(0) - event.getX(1);
    float y = event.getY(0) - event.getY(1);
    return (float) Math.sqrt(x * x + y * y);
}

private float rotation(MotionEvent event) {
    double delta_x = (event.getX(0) - event.getX(1));
    double delta_y = (event.getY(0) - event.getY(1));
    double radians = Math.atan2(delta_y, delta_x);
    return (float) Math.toDegrees(radians);
}

一切正常直到 View 旋转。当它旋转超过 90 度并且我们尝试拖动它时，它会围绕触摸点跳跃。我认为这与

layoutParams.leftMargin += dx;
layoutParams.topMargin += dy;

setLayoutParams(layoutParams);

过去两天我一直在努力使这项工作成功，但没有成功。

注意:我想要实现的是使 View 拖动旋转并用 2 个手指缩放(也用单指拖动) 我遵循了谷歌文档中的拖动代码，以使其在切换手指时不会跳跃。 我用这个来旋转 view.animate().rotationBy(a).setDuration(0).setInterpolator(new LinearInterpolator()).start();

因为当我使用 view.setRotate() 时， View 在振动。

编辑 1: 我删除了

layoutParams.leftMargin += dx;
layoutParams.topMargin += dy;

并将其替换为:

//To get the moved distance of the finger(X and Y)

float diffX = motionEvent.getX(pointerIndex) - mLastTouchX;
                    float diffY = motionEvent.getY(pointerIndex) - mLastTouchY;

//to get the distance from touch point and the top or left of the view
                    final float dx = motionEvent.getRawX() - (motionEvent.getRawX()-motionEvent.getX());
                    final float dy = motionEvent.getRawY() - (motionEvent.getRawY()-motionEvent.getY());
                    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) view.getLayoutParams();

//Settings appropriate value for the margin top and margin left.

                    layoutParams.leftMargin = (int) ((( motionEvent.getRawX() )-dx )+ diffX );
                    layoutParams.topMargin = (int) ((( motionEvent.getRawY() )-dy )+ diffY );

现在即使旋转 View 也不会四处移动。但是当我切换 Activity 手指时，它会从实际位置跳来跳去。

在 ACTION_POINTER_UP 上，我这样做是为了改变 Activity 手指的移动

case MotionEvent.ACTION_POINTER_UP: {

                final int pointerIndex = motionEvent.getActionIndex();
                final int pointerId = motionEvent.getPointerId( pointerIndex);

                if (pointerId == mActivePointerId) {
                    // This was our active pointer going up. Choose a new
                    // active pointer and adjust accordingly.
                    final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
                    Log.d(TAG,"New pointer index :"+newPointerIndex);
                    mLastTouchX = (int) motionEvent.getX( newPointerIndex);
                    mLastTouchY = (int) motionEvent.getY( newPointerIndex);
                    mActivePointerId = motionEvent.getPointerId( newPointerIndex);
                }
                break;
            }

最佳答案

通常我会建议不要在运行时过多地操纵 View 的位置和大小，它会不必要地更新布局会降低性能，难以控制并且很少看起来不错。

相反，如果您不想深入研究 OpenGl，那么我的建议是自定义 View ，创建一个 extend View 的类稍后将其添加到布局 XML 中，<com.packagename.MyCustomView ... /> . 此 View 将具有整个屏幕的大小。 你@Override onDraw(Canvas canvas)方法，它会给你 View 的 Canvas ，你可以使用 Canvas 在 View 中绘制图形。

写invalidate();到底是你onDraw()告诉 View 尝试在可用时再次调用 onDraw()，一旦用户停止触摸您的 View ，您应该停止调用它，因此向它添加一些 boolean 值。

现在触摸，您可以像以前一样注册触摸事件，但在您的自定义 View 中，并使用 canvas.getWidth() 中的 x、y 和 View 大小。和 canvas.getHeight()确定要做什么。

如果在到达 onDraw() 之前需要 View 的大小，请覆盖 onMeasure() .

夏天

这可能看起来不那么容易，但确实如此，而且它速度快且退出效率高，图形会很流畅，如果您想要最好的结果并且不害怕大量代码，那么您可以使用 OpenGl 进行绘图，但是对于您尝试做的事情，我不会建议您这样做。

希望我理解了问题并帮助了你 - 祝你好运!

关于java - 通过调整布局参数拖动旋转 View ，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/47233746/