TextWithUnit , upper right corner.

TextWithUnit.java

package com.example.zhaosam.textviewtest;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.widget.TextView;

/**
 * Created by zhaosam on 14-10-13.
 */
public class TextWithUnit extends TextView {
    private Paint mPaint;
    private float mCornerSize;
    private Context mContext;

    public TextWithUnit(Context context) {
        super(context);
        init(context);
    }

    public TextWithUnit(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context);
    }

    public TextWithUnit(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context);
    }

    private void init(Context context) {
        mContext = context;
        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setColor(Color.RED);

        mCornerSize = getTextSize() * 0.6f;
        if (mCornerSize > 40) {
            mCornerSize = 40;
        }
        mPaint.setTextSize(mCornerSize);

    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // 不要忘了设置 Padding
        String text = (String) getText();
        Rect bounds = new Rect();
        getPaint().getTextBounds(text, 0, text.length(), bounds);
        canvas.drawText("%", getPaddingLeft() + bounds.right,
                (canvas.getHeight() + bounds.top) / 2 + mPaint.measureText("C"), 
                mPaint);
    }

}