Question

我有一条封闭的路径，我想用一种颜色（白色）填充它并在其周围放置另一种颜色（红色）的边缘。我认为自定义视图类可以让我实现这个目的：

public class StrokeFill extends View{
private Path shapePath;
private Paint strokePaint;
private Paint fillPaint;


public StrokeFill(Context context, Path path) {
    super(context);
    shapePath = path;
    fillPaint.setColor(android.graphics.Color.WHITE);
    fillPaint.setStyle(Paint.Style.FILL);
    fillPaint.setStrokeWidth(0);
    strokePaint.setColor(android.graphics.Color.RED);
    strokePaint.setStyle(Paint.Style.STROKE);
    strokePaint.setStrokeWidth(3);
    // TODO Auto-generated constructor stub
}

protected void onDraw(Canvas canvas) {
    // TODO Auto-generated method stub
    //canvas.drawColor(Color.BLACK);
    super.onDraw(canvas);
    canvas.drawPath(shapePath, fillPaint);
    canvas.drawPath(shapePath, strokePaint);
}
}

在我的主Activity中，我刚刚做了这个（没有XML布局文件）：

setContentView(new StrokeFill(this, testpath));

testpath是我在Activity中定义的路径。这是有效的，因为我在使用它定义PathShape时能够绘制它。但在这种情况下，Eclipse给出了错误java.lang.NullPointerException。我尝试在XML布局中定义自定义视图，但这也不起作用。到目前为止，使用android中的形状一直非常令人沮丧，所以如果有人可以提供帮助就会很棒！

Answer 1

初始化问题看看这个

public class StrokeFill extends View{
    private Path shapePath;
    private Paint strokePaint;
    private Paint fillPaint;

    public StrokeFill(Context context, Path path) {
       super(context);
       shapePath = new Path();        
       shapePath = path;
       fillPaint = new Paint();
       fillPaint.setColor(android.graphics.Color.WHITE);
       fillPaint.setStyle(Paint.Style.FILL);
       fillPaint.setStrokeWidth(0);
       strokePaint = new Paint();
       strokePaint.setColor(android.graphics.Color.RED);
       strokePaint.setStyle(Paint.Style.STROKE);
       strokePaint.setStrokeWidth(3);
       // TODO Auto-generated constructor stub
    }

   protected void onDraw(Canvas canvas) {
      // TODO Auto-generated method stub
      //canvas.drawColor(Color.BLACK);
      super.onDraw(canvas);
      canvas.drawPath(shapePath, fillPaint);
      canvas.drawPath(shapePath, strokePaint);
  }
}

Answer 2

strokePaint永远不会在您的代码中初始化...是您的nullPointer吗？

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Android自定义视图中的DrawPath

2 个答案: