Android中利用画图类和线程画出闪烁的心形

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
本文讲解主要涉及的知识点:
1.线程控制 
2.画图类 
3.心形函数
大家先看图片:
<ignore_js_op>
Android中利用画图类和线程画出闪烁的心形
因为前一段时间在写画图类,刚好有一个线程控制画图闪烁的,我就想说我能不能做一个心形闪烁的,出来的效果就如图,先贴再讲解代码:
里面设置两个类,一个是我们的activity类,这个类用来显示示图,然后建一个继承SurfaceView的类,我们在这里面画图。先贴两个累的代码:
主类名:GameMainActivity,画图类类名:Love.
public class MainActivity extends Activity {

	@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// setContentView(new FxCanvasView(this, null));
setContentView(new Love(this));
} @Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
} }

  

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Typeface;
import android.view.SurfaceHolder;
import android.view.SurfaceView; /**
* @author CZ
*
*/
public class Love extends SurfaceView implements SurfaceHolder.Callback,
Runnable { boolean mbloop = false;
SurfaceHolder mSurfaceHolder = null;
private Canvas canvas;
int miCount = 0;
int y = 50; /**
* @param context
*/
public Love(Context context) {
super(context);
mSurfaceHolder = this.getHolder();
mSurfaceHolder.addCallback(this);
this.setFocusable(true);
this.setKeepScreenOn(true);
mbloop = true;
} /*
* (non-Javadoc)
*
* @see
* android.view.SurfaceHolder.Callback#surfaceChanged(android.view.SurfaceHolder
* , int, int, int)
*/
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub } /*
* (non-Javadoc)
*
* @see
* android.view.SurfaceHolder.Callback#surfaceCreated(android.view.SurfaceHolder
* )
*/
@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
new Thread(this).start();
} /*
* (non-Javadoc)
*
* @seeandroid.view.SurfaceHolder.Callback#surfaceDestroyed(android.view.
* SurfaceHolder)
*/
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
mbloop = false;
} /*
* (non-Javadoc)
*
* @see java.lang.Runnable#run()
*/
@Override
public void run() {
// TODO Auto-generated method stub
while (mbloop) {
try {
Thread.sleep(200);
} catch (Exception e) {
// TODO: handle exception
}
synchronized (mSurfaceHolder) {
Draw();
}
}
} /**
*
* Year:2011 Date:2011-7-27 Time:下午06:52:04 Author:CZ TODO
*/
private void Draw() {
// TODO Auto-generated method stub
canvas = mSurfaceHolder.lockCanvas();
try {
if (mSurfaceHolder == null || canvas == null) {
return;
}
if (miCount < 100) {
miCount++;
} else {
miCount = 0;
}
Paint paint = new Paint();
paint.setAntiAlias(true);
paint.setColor(Color.BLACK);
canvas.drawRect(0, 0, 320, 480, paint);
switch (miCount % 6) {
case 0:
paint.setColor(Color.BLUE);
break;
case 1:
paint.setColor(Color.GREEN);
break;
case 2:
paint.setColor(Color.RED);
break;
case 3:
paint.setColor(Color.YELLOW);
break;
case 4:
paint.setColor(Color.argb(255, 255, 181, 216));
break;
case 5:
paint.setColor(Color.argb(255, 0, 255, 255));
break;
default:
paint.setColor(Color.WHITE);
break;
}
int i, j;
double x, y, r; for (i = 0; i <= 90; i++) {
for (j = 0; j<= 90; j++) {
r = Math.PI / 45 * i * (1 - Math.sin(Math.PI / 45 * j))
* 20;
x = r * Math.cos(Math.PI / 45 * j)
* Math.sin(Math.PI / 45 * i) + 320 / 2;
y = -r * Math.sin(Math.PI / 45 * j) + 400 / 4;
canvas.drawPoint((float) x, (float) y, paint);
}
} paint.setTextSize(32);
paint.setTypeface(Typeface.create(Typeface.SERIF, Typeface.ITALIC)); RectF rect = new RectF(60, 400, 260, 405);
canvas.drawRoundRect(rect, (float) 1.0, (float) 1.0, paint);
canvas.drawText("Loving You", 75, 400, paint);
mSurfaceHolder.unlockCanvasAndPost(canvas);
} catch (Exception e) {
} }
}
关于这个程序要讲解的几点:
1. 画图的时候你可以继承View,也可以继承SurfaceView,这两者的区别在于:surfaceView是在一个新起的单独线程中可以重新绘制画面而View必须在UI的主线程中更新画面。SurfaceView可以控制表面的格式,比如大小,显示在屏幕中的位置,最关键是的提供了SurfaceHolder类,使用getHolder方法获取,还有涉及的surfaceCreated(SurfaceHolder holder),surfaceDestroyed(SurfaceHolder holder),surfaceChanged(SurfaceHolder holder, int format, int width, int height)方法,而在SurfaceHolder.Callback 接口回调中可以通过重写来改变这些方法
2.程序其实很简单, 既然生命了Runnable接口,就有相对应的Run方法,在surfaceCreate()的时候开启线程,线程每隔200ms就刷新一次,这样我们看到的效果就是闪烁的,每200毫秒 画一次图,根据经过的间隔时间来设置画笔的颜色,然后通过循环描点,画出心形,然后设置字体大小,画字和字下面的横线。
3.关于心形函数,是从一个例子中看来得,关于x和y的得到,
x = r * Math.cos(Math.PI / 45 * j)  * Math.sin(Math.PI / 45 * i) + 320 / 2;  y = -r * Math.sin(Math.PI / 45 * j) + 400 / 4;
320是屏幕的宽度,本来竖屏我设置的是480,可是下面得写字,就设置为400的了,关于画更好看的心形还有一个函数,大家可以看下:
Android中利用画图类和线程画出闪烁的心形
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