使用画布在Arc内绘制文本

Question

我正在一个Android应用程序中绘制一个圆圈并将它们平均分开并将文本绑定在圆圈中的分割部分内（如pichart）。我画了一个圆圈并将它们平分，但我想将文本绑定在分割部分内。请查看我的代码并提供解决方案。提前谢谢。

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    float values[] = { 130, 130, 130, 130, 130 };

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        LinearLayout linear = (LinearLayout) findViewById(R.id.linearlay);
        values = calculateData(values);
        linear.addView(new MyGraphview(this, values));
    }

    private float[] calculateData(float[] data) {

        float total = 0;
        for (int i = 0; i < data.length; i++) {
            total += data[i];
        }
        for (int i = 0; i < data.length; i++) {
            data[i] = 360 * (data[i] / total);
        }
        return data;

    }

    public class MyGraphview extends View {

        private Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);     
        private float[] value_degree;
        private int[] COLORS = { Color.YELLOW, Color.GREEN, Color.WHITE,
                Color.CYAN, Color.RED };
        RectF rectf = new RectF(10, 10, 300, 300);
        Rect rect = new Rect(10, 10, 300, 300);
        int temp = 0;
        String rotatedtext;
        Path path;

        public MyGraphview(Context context, float[] values) {
            super(context);
            path = new Path();
            value_degree = new float[values.length];
            for (int i = 0; i < values.length; i++) {
                value_degree[i] = values[i];
            }

            paint.setTextSize(16);
            rotatedtext = "Rotated  :)";
        }

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

            for (int i = 0; i < value_degree.length; i++) {
                if (i == 0) {

                    paint.setColor(COLORS[i]);
                    canvas.drawArc(rectf, 0, value_degree[i], true, paint);

                } else {

                    temp += (int) value_degree[i - 1];
                    paint.setColor(COLORS[i]);
                    canvas.drawArc(rectf, temp, value_degree[i], true, paint); //

                }
            }

        }

    }
}

Answer 1

试试这个：

private String[] STRINGS = { "Yellow", "GREEN", "WHITE", "CYAN", "RED" }; // Array of strings, just for the sample

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

        temp = 0;

        int centerX = (rect.left + rect.right) / 2;
        int centerY = (rect.top + rect.bottom) / 2;
        int radius = (rect.right - rect.left) / 2;

        radius *= 0.5; // 1 will put the text in the border, 0 will put the text in the center. Play with this to set the distance of your text.

        for (int i = 0; i < data.length; i++) 
        {
            if (i > 0) 
                temp += (int) data[i - 1]; // rewrote your code here a bit, to avoid duplicate code.

            paint.setColor(COLORS[i]);
            canvas.drawArc(rectf, temp, data[i], true, paint);

            paint.setColor(Color.BLACK); // set this to the text color.
            float medianAngle = (temp + (data[i] / 2f)) * (float)Math.PI / 180f; // this angle will place the text in the center of the arc.
            canvas.drawText(STRINGS[i], (float)(centerX + (radius * Math.cos(medianAngle))), (float)(centerY + (radius * Math.sin(medianAngle))), paint);
        }
    }

此外，为了获得更好的结果，请确保在绘制任何文本之前在绘画中设置Align.CENTER属性：

paint.setTextSize(16);
paint.setTextAlign(Align.CENTER);

希望这会有所帮助：）