Android的绘制文本对象FontMetrics的介绍及绘制文本
一。Android绘制文本对象FontMetrics介绍

FontMetrics对象
它以四个基本坐标为基准，分别为：

?FontMetrics.top
?FontMetrics.ascent
?FontMetrics.descent
?FontMetrics.bottom




实例JAVA代码如下：
Paint textPaint = new Paint( Paint.ANTI_ALIAS_FLAG);
textPaint.setTextSize( 35);
textPaint.setColor( Color.WHITE);

// FontMetrics对象
FontMetrics fontMetrics = textPaint.getFontMetrics();
String text = "abcdefghijklmnopqrstu";

// 计算每一个坐标
float baseX = 0;
float baseY = 100;
float topY = baseY + fontMetrics.top;
float ascentY = baseY + fontMetrics.ascent;
float descentY = baseY + fontMetrics.descent;
float bottomY = baseY + fontMetrics.bottom;

// 绘制文本
canvas.drawText( text, baseX, baseY, textPaint);

// BaseLine描画
Paint baseLinePaint = new Paint( Paint.ANTI_ALIAS_FLAG);
baseLinePaint.setColor( Color.RED);
canvas.drawLine(0, baseY, getWidth(), baseY, baseLinePaint);

// Base描画
canvas.drawCircle( baseX, baseY, 5, baseLinePaint);

// TopLine描画
Paint topLinePaint = new Paint( Paint.ANTI_ALIAS_FLAG);
topLinePaint.setColor( Color.LTGRAY);
canvas.drawLine(0, topY, getWidth(), topY, topLinePaint);

// AscentLine描画
Paint ascentLinePaint = new Paint( Paint.ANTI_ALIAS_FLAG);
ascentLinePaint.setColor( Color.GREEN);
canvas.drawLine(0, ascentY, getWidth(), ascentY, ascentLinePaint);

// DescentLine描画
Paint descentLinePaint = new Paint( Paint.ANTI_ALIAS_FLAG);
descentLinePaint.setColor( Color.YELLOW);
canvas.drawLine(0, descentY, getWidth(), descentY, descentLinePaint);

// ButtomLine描画
Paint bottomLinePaint = new Paint( Paint.ANTI_ALIAS_FLAG);
bottomLinePaint.setColor( Color.MAGENTA);
canvas.drawLine(0, bottomY, getWidth(), bottomY, bottomLinePaint);

二。文本。

1.TextUtil

 

3. DrawText  Activity.

package com.wistron.test.DrawText;import android.app.Activity;import android.os.Bundle;import android.view.KeyEvent;public class DrawText extends Activity {    /** Called when the activity is first created. */ private MyView mv; @Override public void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  mv = new MyView(this);  setContentView(mv); } @Override public boolean onKeyDown(int keyCode, KeyEvent event) {  mv.onKeyDown(keyCode, event);  return super.onKeyDown(keyCode, event); }}