缩放时如何正确缩放和Android路径

Question

我试图在带有路径的自定义视图上执行缩放操作。路径应该相应地缩放。

以下代码运行良好，直到放大级别达到应用程序崩溃并显示的临界点：

A/libc:致命信号11（SIGSEGV），代码2，tid 25828（RenderThread）中的故障地址0xb88799c0

此外，在压碎之前，它显示：

W/OpenGLRenderer:路径太大，无法渲染到纹理中

public class TestView extends View implements ScaleGestureDetector.OnScaleGestureListener {
    private String DEBUG_TAG = "TestView";
    private ScaleGestureDetector mScaleDetector;
    private Path mPath;
    private Paint mPaint;
    private float mScaleFactor = 1.f;
    private float mScaleMax = 2f;
    private float mScaleMin = 0.5f;
    private Matrix mMatrix;
    private boolean mScaling = false;
    private PointF mScaleFocus = new PointF();
    public TestView(Context context) {
        super(context);
        setupDrawing();
    }
    public TestView(Context context, AttributeSet attrs) {
        super(context, attrs);
        setupDrawing();
    }
    public TestView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        setupDrawing();
    }
    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public TestView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        setupDrawing();
    }
    private void setupDrawing(){
        mPath = new Path();
        mPaint = new Paint();
        mPaint.setColor(0xFF660000);
        mPaint.setAntiAlias(true);
        mPaint.setStrokeWidth(10);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeJoin(Paint.Join.ROUND);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mMatrix = new Matrix();
        mScaleDetector = new ScaleGestureDetector(getContext(), this);
        mPath = new Path();
        int width = 100;
        int start = 20;
        mPath.moveTo(start,start);
        mPath.lineTo(start + width, start);
        mPath.lineTo(start + width, start + width);
        mPath.lineTo(start,start+width);
        mPath.close();
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.save();
        mPath.transform(mMatrix);
        canvas.drawPath(mPath, mPaint);
        canvas.restore();
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        mScaleDetector.onTouchEvent(event);
        if(mScaling) return true;
        if (event.getPointerCount() > 1){
            return true;
        }
        invalidate();
        return true;
    }
    @Override
    public boolean onScale(ScaleGestureDetector detector) {
        mScaleFactor = detector.getScaleFactor();
        mScaleFactor = Math.max(mScaleMin, Math.min(mScaleFactor, mScaleMax));
        mScaleFocus.set(detector.getFocusX(), detector.getFocusY());
        Log.d(DEBUG_TAG, "onScale: " + mScaleFactor);
        mMatrix.setScale(mScaleFactor, mScaleFactor, mScaleFocus.x, mScaleFocus.y);
        invalidate();
        return true;
    }
    @Override
    public boolean onScaleBegin(ScaleGestureDetector detector) {
        Log.d(DEBUG_TAG, "onScaleBegin: " + mScaleFactor);
        mScaling = true;
        return true;
    }
    @Override
    public void onScaleEnd(ScaleGestureDetector detector) {
        Log.d(DEBUG_TAG, "onScaleEnd: " + mScaleFactor);
        mScaling = false;
    }
}

我没有缩放路径，而是尝试缩放画布。这很好，但放大时路径线会失真，这不是理想的行为。

Answer 1

该问题与硬件加速有关。

在活动中设置android:hardwareAccelerated="false"解决了问题。