视Android版本而异

Question

I try to draw some Pie Chart graph but got different result:
This is on Android 4.3(correct variant)

On Android 4.1 get next(incorrect variant):

My code below:

@Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
//        int saveFlag = Canvas.MATRIX_SAVE_FLAG | Canvas.CLIP_SAVE_FLAG | Canvas.HAS_ALPHA_LAYER_SAVE_FLAG
//                | Canvas.FULL_COLOR_LAYER_SAVE_FLAG | Canvas.CLIP_TO_LAYER_SAVE_FLAG;

//        int sc = canvas.saveLayer(0, 0, getWidth(), getHeight(), null, saveFlag);
//        canvas.translate(0, 0);
        float temp = 0;
        float values[] = {700, 500, 300, 444, 222};
        values = calculateData(values);
        float[] value_degree;
        value_degree = new float[values.length];
        for (int i = 0; i < values.length; i++) {
            value_degree[i] = values[i];
        }
        int height = getHeight();
        int width = getWidth();
        Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStrokeWidth(20f);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setColor(getResources().getColor(R.color.circle_background));
        int radius = (int) ((height / 2) + (Math.pow((double) width, 2) / (8 * height))) / 2;
        float left = width / 2 - radius;
        float top = height / 2 - radius;
        float right = width / 2 + radius;
        float bottom = height / 2 + radius;
        RectF rectF = new RectF(left, top, right, bottom);
        canvas.drawOval(rectF, mPaint);
        rectF.set(left + 11f, top + 11f, right - 11f, bottom - 11f);
        mPaint.setColor(Color.GRAY);
        mPaint.setStyle(Paint.Style.FILL);
        Random r;
        for (int i = 0; i < value_degree.length; i++) {
            if (i == 0) {
                r = new Random();
                int color = Color.argb(100, r.nextInt(256), r.nextInt(256),
                        r.nextInt(256));
                mPaint.setColor(color);
                canvas.drawArc(rectF, 270, value_degree[i], true, mPaint);
            } else {
                if (i == 1) {
                    temp += value_degree[i - 1] + 270 - 360;
                } else {
                    temp += value_degree[i - 1];
                }
                r = new Random();
                int color = Color.argb(255, r.nextInt(256), r.nextInt(256),
                        r.nextInt(256));
                mPaint.setColor(color);
                canvas.drawArc(rectF, temp, value_degree[i], true, mPaint);
            }
        }
        mPaint.setColor(getResources().getColor(R.color.circle_background_small));
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(20f);
        canvas.drawCircle(rectF.centerX(), rectF.centerY(), radius / 1.8f, mPaint);
//        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        mPaint.setColor(getResources().getColor(android.R.color.transparent));
        mPaint.setAlpha(1);
        mPaint.setStyle(Paint.Style.FILL);
        canvas.drawCircle(rectF.centerX(), rectF.centerY(), radius / 1.9f, mPaint);
}

What I doing wrong?
Regards
PS On center should be transparent circle with background of activity, for this I use PorterDuffXfermode and restoring layers. But now it's comment on.

Answer 1

When drawing on the canvas, the sizes specified are in pixels rather than density independent pixels (dp or dip). In order to scale the values you should specify the size you want and multiply it by the screen's density.

mPaint.setStrokeWidth(20f * getResources().getDisplayMetrics().density);

(Although you might want to cache the density somewhere first).

This will scale the stroke width depending upon the screen's density, and thus the widths should all match.