FontView.java

package com.mcxtzhang.cstviewdemo.widget;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.text.Layout;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;

public class FontView extends View {
    private static final String TEXT = "This is used by widgets to control text layout. You should not need to use this class directly unless you are implementing your own widget or custom display object, or would be tempted to call Canvas.drawText() directly.";
    private Paint mPaint, linePaint;// 文本的画笔和中心线的画笔  ;// 画笔
    private Paint.FontMetrics mFontMetrics;// 文本测量对象

    private StaticLayout mStaticLayout;// 文本布局
    private TextPaint mTextPaint;// 文本的画笔

    public FontView(Context context) {
        this(context, null);
    }

    public FontView(Context context, AttributeSet attrs) {
        super(context, attrs);

        // 初始化画笔  
        initPaint();
    }

    /**
     * 初始化画笔
     */
    private void initPaint() {
        // 实例化画笔  
        mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        mPaint.setTextSize(50);
        mPaint.setColor(Color.BLACK);

        linePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        linePaint.setStyle(Paint.Style.STROKE);
        linePaint.setStrokeWidth(1);
        linePaint.setColor(Color.RED);


        mFontMetrics = mPaint.getFontMetrics();

        Log.d("Aige", "ascent：" + mFontMetrics.ascent);
        Log.d("Aige", "top：" + mFontMetrics.top);
        Log.d("Aige", "leading：" + mFontMetrics.leading);
        Log.d("Aige", "descent：" + mFontMetrics.descent);
        Log.d("Aige", "bottom：" + mFontMetrics.bottom);

        mTextPaint = new TextPaint();
        // 实例化画笔
        mTextPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG);
        mTextPaint.setTextSize(50);
        mTextPaint.setColor(Color.BLACK);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
/*        int midX = (int) (canvas.getWidth() / 2 - mPaint.measureText(TEXT) / 2);
        int midY = (int) (canvas.getHeight() / 2 - (mFontMetrics.top / 2 + mFontMetrics.bottom / 2));


        canvas.drawText(TEXT, midX, midY, mPaint);

        // 为了便于理解我们在画布中心处绘制一条中线
        canvas.drawLine(0, canvas.getHeight() / 2, canvas.getWidth(), canvas.getHeight() / 2, linePaint);*/

        mTextPaint.setUnderlineText(true);
        mStaticLayout = new StaticLayout(TEXT, mTextPaint, canvas.getWidth(), Layout.Alignment.ALIGN_NORMAL, 1.0f, 0.0f, false);
        mStaticLayout.draw(canvas);
        //canvas.restore();


        // 画一个矩形
        canvas.drawRect(10, 10, 200, 200, mPaint);

    }
}