如何在缩放时正确缩放和Android路径

我试图执行缩放以放大具有路径的自定义视图。路径应该相应地缩放。如何在缩放时正确缩放和Android路径

以下代码正常工作，直到放大水平达到一个临界点，其中应用崩溃，并显示：

A/libc的：致命信号11（SIGSEGV），码2，在TID 25828故障地址0xb88799c0（ RenderThread）

而且，粉碎之前它显示：

W/OpenGLRenderer：路径过大而被渲染到纹理

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; 
    } 
}

而不是缩放路径我试图缩放画布。这工作得很好，但路径线在放大时会变形，这不是理想的行为。

来源

2016-01-12 Andres Y.

该问题与硬件加速有关。

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

来源

2016-01-13 00:28:19

如何在缩放时正确缩放和Android路径

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