您应该如何使用带有 PathShape 的 ShapeDrawable 在自定义视图上绘制一条线？

我试图在自定义中画一条线View。我在这里创建了一个简单的Path仅用一个片段，创建了一个PathShape从那开始，最后将其放入ShapeDrawable目的是利用它来借鉴Canvas inside onDraw()。然而，这是行不通的。请参阅我的示例，此处。

package com.example.test;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.PathShape;
import android.util.Log;
import android.view.View;

public class TestView extends View {

    private Path mPath = null;
    private Paint mPaint = null;
    private PathShape mPathShape = null;
    private ShapeDrawable mShapeDrawable = null;

    public TestView(Context context) {
        super(context);
    }

    private void init() {
        int width = this.getWidth() / 2;
        int height = this.getHeight() / 2;

        Log.d("init", String.format("width: %d; height: %d", width, height));

        this.mPath = new Path();
        this.mPath.moveTo(0, 0);
        this.mPath.lineTo(width, height);

        this.mPaint = new Paint();
        this.mPaint.setColor(Color.RED);

        this.mPathShape = new PathShape(this.mPath, 1, 1);

        this.mShapeDrawable = new ShapeDrawable(this.mPathShape);
        this.mShapeDrawable.getPaint().set(this.mPaint);
        this.mShapeDrawable.setBounds(0, 0, width, height);
    }

    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);

        // Doing this here because in the constructor we don't have the width and height of the view, yet
        this.init();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        Log.d("onDraw", "Drawing");

        // This works, but won't let me do what I'm really trying to do
        canvas.drawLine(0.0f, 0.0f, this.getWidth() / 2.0f, this.getHeight() / 2.0f, this.mPaint);

        // This should work, but does not
        //this.mPathShape.draw(canvas, this.mPaint);

        // This should work, but does not
        //this.mShapeDrawable.draw(canvas);
    }

}

正如你从我的评论中看到的onDraw()方法，既不使用PathShape也不ShapeDrawable画出Path到Canvas实际上有效。当我尝试时什么也没有画出来。有谁知道为什么吗？

我正在测试的设备运行的是 Android 4.1.1。

这有两个问题。

第一个是Paint风格。默认为Paint.Stroke.FILL，但是有了一条线就没有什么可以填充的了。我需要添加这个（谢谢，罗曼·盖伊 http://code.google.com/p/android/issues/detail?id=35229#c1):

this.mPaint.setStyle(Paint.Style.STROKE);

第二个问题是标准的高度和宽度PathShape是不正确的。我读过文档 http://developer.android.com/reference/android/graphics/drawable/shapes/PathShape.html#PathShape%28android.graphics.Path,%20float,%20float%29对此，但没有正确理解。当我解决了第一个问题后，这一点就变得明显了。将其设置为我的自定义视图的高度和宽度（因为我正在整个视图上绘制）解决了这个问题。我还必须改变的界限ShapeDrawable匹配。

this.mPathShape = new PathShape(this.mPath, this.getWidth(), this.getHeight());

and

this.mShapeDrawable.setBounds(0, 0, this.getWidth(), this.getHeight());

希望这对将来的其他人有帮助。