如何绘制不同半径的弧来绘制饼图？

Question

如何在canvas中为这些弧设置不同的半径？

PieView.java

public class PieView extends View {
    private ArrayList<Float> divisionPoints = new ArrayList<>();
    private float viewWidth;
    private float viewHeight;
    private float radius;
    private Paint paint = new Paint();
    private RectF rectF = new RectF();
    private float startAngle = 90;
    private RadialGradient radialGradientCyan, radialGradientBlue, radialGradientDarkBlue, radialGradientGreen;
    private ArrayList<RadialGradient> radialGradients = new ArrayList<>();

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

    public PieView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }

    public PieView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @Override
    protected void onLayout(boolean changed, int l, int t, int r, int b) {
        super.onLayout(changed, l, t, r, b);
        viewWidth = r - l;
        viewHeight = b - t;
    }
    public void setUp(final ArrayList<Float> points) {
        this.postDelayed(new Runnable() {
            @Override
            public void run() {
                divisionPoints.addAll(points);
                if (viewHeight > viewWidth) {
                    radius = viewWidth / 2;
                } else {
                    radius = viewHeight / 2;
                }
                setRectValues();
                //edit the stop points to edit the gradients
                float[] stopPoints = {.6f, .8f};

                int[] blue = {Color.parseColor("#FF2D82AE"), Color.parseColor("#FF2D82AE")};
                int[] darkBlue = {Color.parseColor("#FF2A79A4"), Color.parseColor("#FF2A79A4")};
                int[] cyan = {Color.parseColor("#FF50C0CA"), Color.parseColor("#FF50C0CA")};
                int[] green = {Color.parseColor("#FF9BDC90"), Color.parseColor("#FF9BDC90")};


                radialGradientCyan = new RadialGradient(viewWidth / 2, viewHeight / 2, radius, cyan, stopPoints, Shader.TileMode.CLAMP);
                radialGradientBlue = new RadialGradient(viewWidth / 2, viewHeight / 2, radius, blue, stopPoints, Shader.TileMode.CLAMP);
                radialGradientDarkBlue = new RadialGradient(viewWidth / 2, viewHeight / 2, radius, darkBlue, stopPoints, Shader.TileMode.CLAMP);
                radialGradientGreen = new RadialGradient(viewWidth / 2, viewHeight / 2, radius, green, stopPoints, Shader.TileMode.CLAMP);
                radialGradients.add(radialGradientCyan);
                radialGradients.add(radialGradientBlue);
                radialGradients.add(radialGradientDarkBlue);
                radialGradients.add(radialGradientGreen);
                postInvalidate();
            }
        }, 0);
    }
    private void setRectValues() {
        rectF.left = viewWidth / 2 - radius;
        rectF.top = viewHeight / 2 - radius;
        rectF.right = viewWidth / 2 + radius;
        rectF.bottom = viewHeight / 2 + radius;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (divisionPoints != null) {

            for (int i = 0; i < divisionPoints.size(); i++) {
                float distance = (float) (divisionPoints.get(i) * 3.6);
                paint.reset();
                paint.setAntiAlias(true);
                paint.setShader(radialGradients.get(i));
                canvas.drawArc(rectF, startAngle, distance, true,paint);
                startAngle += distance;
            }
        }
        paint.reset();
    }
}

像这样输出我的观点。

如何根据PieActivity中给出的饼图数据设置半径的小偏移而不使用任何库。

drawArc() - 方法没有要绘制的radius参数。

我发现只有两个

drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)

drawArc(float left, float top, float right, float bottom, float startAngle, float sweepAngle, boolean useCenter, Paint paint)