0

所以我遇到了图像将放大的错误，但不是放大到我的两个手指的中点，而是放大到原始图片的角落。这会创建一个非常不自然的用户界面。

@Override
protected void onDraw(Canvas canvas) {

    canvas.save();
    canvas.translate(mPosX, mPosY);
    canvas.scale(mScaleFactor, mScaleFactor);
    super.onDraw(canvas);
    canvas.restore();
}

使用我的 onTouchEvent，myScale.onTouch 会将程序发送到 scaleListener 以获取缩放信息

@Override
public boolean onTouchEvent(MotionEvent event) {
    super.onTouchEvent(event);
    midPoint(mid,event);
    myScale.onTouchEvent(event);
    switch (event.getAction() & MotionEvent.ACTION_MASK){
            case MotionEvent.ACTION_DOWN: {
                final float x = event.getX();
                final float y = event.getY();
                mode=DRAG;
                // Remember where we started
                mLastTouchX = x;
                mLastTouchY = y;
                mActivePointerId = event.getPointerId(0);
                break;
            }
        case MotionEvent.ACTION_POINTER_DOWN: {
           final float gx = myScale.getFocusX();
            final float gy = myScale.getFocusY();
            mLastGestureX=gx;
            mLastGestureY=gy;
            mode=ZOOM;
            break;
        }


            case MotionEvent.ACTION_MOVE: {
                final int pointerIndex = event.findPointerIndex(mActivePointerId);
                final float x = event.getX(pointerIndex);
                final float y = event.getY(pointerIndex);

                // Calculate the distance moved

            if(!myScale.isInProgress()){
                    // Move the object

                    final float dx = x - mLastTouchX;
                    final float dy = y - mLastTouchY;
                    mPosX += dx;
                    mPosY += dy;

                    // Remember this touch position for the next move event


                    // Invalidate to request a redraw
                    invalidate();

            }
                mLastTouchX = x;
                mLastTouchY = y;

                break;

            }

I have deleted action up and action pointer up because they have nothing to do with this problems





        }

    invalidate();
    return true;
}






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




private void midPoint(PointF point, MotionEvent event) {
    float x = event.getX(0) + event.getX(1);
    float y = event.getY(0) + event.getY(1);
    point.set(x / 2, y / 2);
}

private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
    @Override
    public boolean onScale(ScaleGestureDetector detector) {

        mScaleFactor *= detector.getScaleFactor();

        // Don't let the object get too small or too large.
        mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 10.0f));
        float currentdist=detector.getCurrentSpan();
        float last=detector.getPreviousSpan();
        float ratio = currentdist/last;

        mScaleFactor = Math.max(0.1f, Math.min(mScaleFactor, 5.0f));

        Matrix temp = new Matrix();
        temp.postScale(ratio, ratio, mid.x,mid.y);
        temp.preConcat(matrix);

        matrix=temp;

        invalidate();
        return true;
    }
}
4

1 回答 1

0

使用 scale (float sx, float sy, float px, float py) 而不是 scale (float sx, float sy)

http://developer.android.com/reference/android/graphics/Canvas.html#scale%28float,%20float,%20float,%20float%29

于 2013-06-19T12:59:00.340 回答