Android学习笔记之Bitmap位图虽触摸点移动

 

package xiaosi.bitmap;

import android.app.Activity;
import android.os.Bundle;

public class mianActivity extends Activity
{

private surfaceView bitmapView = null;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
bitmapView = new surfaceView(this);
setContentView(bitmapView);
}
}

surfaceView surfaceView .java

package xiaosi.bitmap;

import java.io.InputStream;

import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.BitmapDrawable;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;


public class surfaceView extends SurfaceView{
// 控制surface的接口，提供了控制surface的大小、格式、像素
private SurfaceHolder surfaceHolder;
private Canvas canvas = null;
// x y用户才触摸屏幕的坐标
private float x=0,y=0;
private Bitmap bitmap = null;

public surfaceView(Context context) {
super(context);
// 获取SurfaceHolder接口
surfaceHolder = this.getHolder();
// 设置屏幕保持开启状态
this.setKeepScreenOn(true);
// 获取资源文件res
Resources res=getResources();
// 获取位图资源文件的输入流
InputStream inputStream=res.openRawResource(R.drawable.h);
// 创建可绘制的位图对象
BitmapDrawable bitmapDrawable=new BitmapDrawable(inputStream);
// 通过可绘制位图对象得到位图引用
bitmap=bitmapDrawable.getBitmap();
/*
 * // 获取资源文件的引用res  
        Resources res = getResources();  
        // 获取图形资源文件  
        Bitmap bmp = BitmapFactory.decodeResource(res, R.drawable.h);  
 */
}

//绘制位图
private void onDraw() {
try {
// 锁定Canvas画布
canvas = surfaceHolder.lockCanvas();
// 设置canvas画布背景为黑色
canvas.drawColor(Color.GREEN);
// 在画布上绘制位图
//让位图的中心正好在触摸点位置上
        canvas.drawBitmap(bitmap, x-bitmap.getWidth()/2, y-bitmap.getHeight()/2, null);  
} catch (Exception ex) {
} finally { 
if (canvas != null)
// 解锁画布，并显示绘制图片
surfaceHolder.unlockCanvasAndPost(canvas); 
}
}
//触摸事件
 public boolean onTouchEvent(MotionEvent event){
 x = event.getX();
 y = event.getY();
 onDraw();
return true; 
 }

}