第二十五讲：Android动画入门（二）
本讲内容： Android中的绘画动画 SurfaceView
SurfaceView是View的一个子类，它提供了一种比普通View组件绘制速度更快的绘图方式，在游戏、视频等要求高帧速和高流畅度的场合，使用SurfaceView成了一种很好的选择。本讲让我们通过一个能发送莫尔斯码的灯塔实例来讲解SurfaceView的使用，请留意代码中的注释。
一、实例：窈窈莫尔斯灯塔
1、创建项目 Lesson25_Morse , 启动Activity名字叫 MainActivity.java
2、创建一个莫尔斯码的工具类 Morse.java
package basic.android.lesson37;
import java.util.HashMap;
import java.util.Map;
public class Morse {
public static Map standardMorseCharactersMap = new HashMap ();
static {
standardMorseCharactersMap.put("a", ".-");
standardMorseCharactersMap.put("b", "-...");
standardMorseCharactersMap.put("c", "-.-.");
standardMorseCharactersMap.put("d", "-..");
standardMorseCharactersMap.put("e", ".");
standardMorseCharactersMap.put("f", "..-.");
standardMorseCharactersMap.put("g", "--.");
standardMorseCharactersMap.put("h", "....");
standardMorseCharactersMap.put("i", "..");
standardMorseCharactersMap.put("j", ".---");
standardMorseCharactersMap.put("k", "-.-");
standardMorseCharactersMap.put("l", ".-..");
standardMorseCharactersMap.put("m", "--");
standardMorseCharactersMap.put("n", "-.");
standardMorseCharactersMap.put("o", "---");
standardMorseCharactersMap.put("p", ".--.");
standardMorseCharactersMap.put("q", "--.-");
standardMorseCharactersMap.put("r", ".-.");
standardMorseCharactersMap.put("s", "...");
standardMorseCharactersMap.put("t", "-");
standardMorseCharactersMap.put("u", "..-");
standardMorseCharactersMap.put("v", "...-");
standardMorseCharactersMap.put("w", ".--");
standardMorseCharactersMap.put("x", "-..-");
standardMorseCharactersMap.put("y", "-.--");
standardMorseCharactersMap.put("z", "--..");
standardMorseCharactersMap.put("0", "-----");
standardMorseCharactersMap.put("1", ".----");
standardMorseCharactersMap.put("2", "..---");
standardMorseCharactersMap.put("3", "...--");
standardMorseCharactersMap.put("4", "....-");
standardMorseCharactersMap.put("5", ".....");
standardMorseCharactersMap.put("6", "-....");
standardMorseCharactersMap.put("7", "--...");
standardMorseCharactersMap.put("8", "---..");
standardMorseCharactersMap.put("9", "----.");
standardMorseCharactersMap.put(".", ".-.-.-");
standardMorseCharactersMap.put("-", "-....-");
standardMorseCharactersMap.put(",", "--..--");
standardMorseCharactersMap.put("?", "..--..");
standardMorseCharactersMap.put("/", "-..-.");
standardMorseCharactersMap.put(";", "-.-.-.");
standardMorseCharactersMap.put("(", "-.--.");
standardMorseCharactersMap.put(")", "-.--.-");
standardMorseCharactersMap.put("@", ".--.-.");
standardMorseCharactersMap.put("*", "...-.-");
standardMorseCharactersMap.put("+", ".-.-.");
standardMorseCharactersMap.put("%", ".-...");
standardMorseCharactersMap.put("\\", "---...");
standardMorseCharactersMap.put("\"", ".-..-.");
standardMorseCharactersMap.put("'", ".----.");
standardMorseCharactersMap.put("!", "=---.");
standardMorseCharactersMap.put("$", "...-..-");
standardMorseCharactersMap.put(" ", "/");
}
public static String morseEncoder(String input) {
String output = "";
for (char c : input.toCharArray()) {
output += standardMorseCharactersMap.get(String.valueOf(c)) + " ";
}
return output;
}
public static void main(String[] args) {
String input = "yao mu yang";
String output = Morse.morseEncoder(input);
System.out.println(output);
}
}
3、布局文件 main.xml 的内容如下：
<?xml version="1.0" encoding="utf-8"?>
4、MainActivity.java的内容如下：
package basic.android.lesson37;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
private LinearLayout layout;
//莫尔斯码数组变量
char[] chars;
//莫尔斯码数组计数变量
int count = 0;
//开关标志
boolean flag = false;
//循环标志
boolean loop = false;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// 定义UI组件
final Button b1 = (Button) findViewById(R.id.Button01);
final Button b2 = (Button) findViewById(R.id.Button02);
final EditText et1 = (EditText) findViewById(R.id.EditText01);
final EditText et2 = (EditText) findViewById(R.id.EditText02);
layout = (LinearLayout) findViewById(R.id.LinearLayout01);
// 单击转换按钮，转换莫尔斯码
b1.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
String text = Morse.morseEncoder(et1.getText().toString());
et2.setText(text);
}
});
// 单击发送信号按钮，把莫尔斯码用灯信号的方式发送出去
b2.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
//当morse码文本框中有内容的时候就发送灯信号
if (et2.getText() != null && et2.getText().toString().length() > 0) {
//把莫尔斯码拆解成一个一个字符
chars = et2.getText().toString().toCharArray();
//计数
count = chars.length;
//创建SurfaceView
LightView light = new LightView(MainActivity.this);
//把SurfaceView动态加入Activity
layout.addView(light);
}
}
});
}
// 信号灯
class LightView extends SurfaceView {
//声明 surfaceHolder 对象
SurfaceHolder holder;
// 构造方法
public LightView(Context context) {
super(context);
// 从 SurfaceView 中获取 SurfaceHolder对象
holder = this.getHolder();
// addCallback 对象
holder.addCallback(new SurfaceHolder.Callback() { //创建SurfaceHolder.Callback匿名内部类
//在SurfaceHolder.Callback内部类的内部创建它所需要的线程内部类
class LightThread implements Runnable {
@Override
public void run() {
while (loop) {
if (count > 0) {
Log.i("yao", "" + count);
String s = String.valueOf(chars[chars.length - count]);
// 锁定canvas,开始绘图
Canvas canvas = holder.lockCanvas(null);
Paint paint = new Paint();
paint.setAntiAlias(true);
//清屏幕
paint.setColor(Color.BLACK);
canvas.drawRect(0, 0, 480, 480, paint);
//标志位是真的时候关一下灯
if(flag){
sleep(2);
paint.setColor(Color.BLACK);
}else{ //为假的时候就亮灯
// di 亮2个时间点
if (s.equalsIgnoreCase(".")) {
sleep(2);
paint.setColor(Color.YELLOW);
} else if(s.equalsIgnoreCase("-")) {
// dah 亮4个时间点
sleep(4);
paint.setColor(Color.YELLOW);
}else if(s.equalsIgnoreCase(" ")){
// 空格 亮2个时间点
sleep(2);
paint.setColor(Color.BLACK);
}else if(s.equalsIgnoreCase("/")){
// 单词之间的空白亮2个时间点
sleep(2);
paint.setColor(Color.BLACK);
}else{
// 出问题的时候亮红灯
sleep(2);
paint.setColor(Color.RED);
}
count--;
}
//绘制灯光
canvas.drawCircle(250.0f, 200.0f, 100, paint);
//标准位开关
flag = !flag;
// 释放canvas,绘图完毕
holder.unlockCanvasAndPost(canvas);
}
}
}
//休眠
public void sleep(int time){
try {
Thread.sleep(time*80);
} catch (Exception e) {
//no nothing
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
// do nothing
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
//在SurfaceView被创建的时候执行
new Thread(new LightThread()).start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
loop = false;
}
});
loop = true;
}
}
}
5、编译并运行程序，查看结果：
好了，本讲就到这里，下次再见。祝福我们家宝宝小yaoyao。
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