Android 第十天重置版 _Media

 多媒体编程

1、什么是多媒体？
   多种媒体的综合。图片、音乐、视频。

##01_计算机表示图形的方式
    1、bmp 以高质量保存所有类型的图片，用于计算机。
        计算机使用像素点表示图形，每个像素点都是一个颜色，24位深度（24bit）。
        每个像素点的颜色是一个RGB，使用6个十六进制的数值来表示。
        文件头信息占用的数据大小。  体积比较大。
       
    2、jpg 以良好的质量保存图片，用于计算机、电子邮件或网络。
       
      jpg 工业图形的压缩算法，类似rar的算法。人眼识别精度有限，把相邻空间内类似的颜色使用同一个颜色来表示。 体积减小，失真。
    3、png 203.2k 255*340 以高质量保存图片或者绘图，用于计算机或网络。
    
      
    


##02_加载大图片的OOM异常

java.lang.OutOfMemoryError ： 

   堆内存空间：给类实例、数组分配内存空间的。   RGB 
   ARGB 32 

   应用程序在启动时系统为它创建一个进程，系统为每个进程创建dalvik虚拟机（模拟器设置的VM Heap），当图片的大小大于虚拟机的堆内存空间时，就内存溢出（内存泄露）；

  解决办法：缩放图片加载到内存
  步骤：
   1、获得设备屏幕的分辨率；
   2、得到原图的分辨率；
   3、通过比较得到一个合适的比例值；
   4、按照比例值缩放图片
   5、把图片显示在imageview

  

##03_缩放图片并加载到内存中
  解决办法：

    缩放图片加载到内存
    步骤：
       1、获得设备屏幕的分辨率；
       2、得到原图的分辨率；
       3、通过比较得到一个合适的比例值；
       4、按照比例值缩放图片
       5、把图片显示在imageview

 代码：

    package com.itheima.loadbigpic;
    
    import android.app.Activity;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.BitmapFactory.Options;
    import android.os.Bundle;
    import android.os.Environment;
    import android.view.Display;
    import android.view.WindowManager;
    import android.widget.ImageView;
    
    public class MainActivity extends Activity {

    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        iv = (ImageView) findViewById(R.id.iv);
        
    //        1、获得设备屏幕的分辨率；
        //通过服务获得窗口管理器
        WindowManager  wm =  (WindowManager) getSystemService(WINDOW_SERVICE);
        //获得设备分辨率对象
        Display display = wm.getDefaultDisplay();
        
        //api13之前使用这个两个方法，13之后置为过期
        int screenWidth = display.getWidth();
        int screenHeight = display.getHeight();
        
        
    //        2、得到原图的分辨率；
       
        Options opts = new Options();
        opts.inJustDecodeBounds = true;
        //opts为null 可以返回一个图片对象，如果不为null ，就会返回null
        BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/lp.jpg", opts);
        //得到原图的宽和高
         int srcWidth = opts.outWidth;
         int srcHeight = opts.outHeight;
         
         
    //        3、通过比较得到一个合适的比例值；
         //3000/320 = 9 2262/480 =5
         int sx = srcWidth/screenWidth;
         int sy = srcHeight/screenHeight;
         int scale = 0;
         if(sx >= 1 && sx > sy){
             scale = sx;
         }else if(sy >= 1 && sy > sx){
             scale = sy;
         }
         
    //     4、按照比例值缩放图片
           opts.inJustDecodeBounds = false;
           opts.inSampleSize = scale; // 1/scale * 1/scale
           Bitmap bm = BitmapFactory.decodeFile(Environment.getExternalStorageDirectory()+"/lp.jpg", opts);
          
    //    5、把图片显示在imageview
           
           iv.setImageBitmap(bm);
    }
    
    }


##04_在内存中创建原图的副本（重点）
      步骤：
       1、得到原图；
       2、创建一个空白的纸张，参考原图；
       3、创建一个画板，参考空白纸张；
       4、创建一个画笔；
       5、在画板上画画；

  代码：

    package com.itheima.copypic;

    import android.app.Activity;
    import android.graphics.Bitmap;
    import android.graphics.BitmapFactory;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Matrix;
    import android.graphics.Paint;
    import android.os.Bundle;
    import android.widget.ImageView;
    
    public class MainActivity extends Activity {

    private ImageView iv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        iv = (ImageView) findViewById(R.id.iv);
        
        
    //           1、得到原图；
            Bitmap srcPic = BitmapFactory.decodeResource(getResources(), R.drawable.meinv);
            
            //config 包括位深度
    //           2、创建一个空白的纸张，参考原图；
           Bitmap copyPic = Bitmap.createBitmap(srcPic.getWidth(), srcPic.getHeight(), srcPic.getConfig());    
    //           3、创建一个画板，参考空白纸张；
           Canvas canvas = new Canvas(copyPic);
           
    //           4、创建一个画笔；
           Paint paint = new Paint();
           paint.setColor(Color.BLACK);//默认是使用黑色，后面会根据原图的颜色画画
    //           5、在画板上画画；
           canvas.drawBitmap(srcPic, new Matrix(), paint);
           
           iv.setImageBitmap(copyPic);
    }


    }
   

##05_计算机图形处理的API（重点）

    * 旋转
    * 缩放
    * 平移
    * 镜面、倒影
    * 修改颜色
    ColorMatrix cm = new ColorMatrix();
        cm.set(new float[] {
                1, 0, 0, 0, 0,  //red
                0, 1, 0, 0, 0,  //green
                0, 0, 1, 0, 0,  //blue
                0, 0, 0, 1, 0   //透明度
        });
        paint.setColorFilter(new ColorMatrixColorFilter(cm));


##06_微信画画板  

    package com.itheima.painter;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.ImageView;

public class MainActivity extends Activity {

    private ImageView iv;
    private Bitmap srcPic;
    private Bitmap copyPic;
    private Canvas canvas;
    private Paint paint;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        
        iv  = (ImageView) findViewById(R.id.iv);
        
        
        
        srcPic = BitmapFactory.decodeResource(getResources(), R.drawable.bg);
                    
        copyPic = Bitmap.createBitmap(srcPic.getWidth(), srcPic.getHeight(), srcPic.getConfig());
        canvas = new Canvas(copyPic);
                   
        paint = new Paint();
                   paint.setColor(Color.BLACK);//默认是使用黑色，后面会根据原图的颜色画画
    //                   5、在画板上画画；
                   
                   Matrix matrix = new Matrix();
    //                   
                   canvas.drawBitmap(srcPic, matrix, paint);
                   iv.setImageBitmap(copyPic);
                   
                   iv.setOnTouchListener(new OnTouchListener(){
                       int startX ;
                       int startY;
                    @Override
                    public boolean onTouch(View v, MotionEvent event) {
                        int type = event.getAction();
                        
                        
                        switch (type) {
                        case MotionEvent.ACTION_DOWN:
                            
                            //开始坐标点
                             startX = (int) event.getX();
                            
                             startY = (int) event.getY();
                            
                            break;

                        case MotionEvent.ACTION_MOVE :
                            
                            //得到结束点的坐标
                            int newX = (int) event.getX();
                            int newY = (int) event.getY();
                            
                            canvas.drawLine(startX, startY, newX, newY, paint);
                            
                            iv.setImageBitmap(copyPic);
                            
                            //得到新的开始坐标点
                             startX = (int) event.getX();
                            
                             startY = (int) event.getY();
                            break;
                        }
                        
                        //消费掉当前的监听器
                        return true;
                    }
                       
                   });
                   
    }

    

    }


##07_视频播放器videoview（重点）
    

    代码：

    package com.itheima.videoview;
    
    import android.app.Activity;
    import android.os.Bundle;
    import android.widget.VideoView;
    
    public class MainActivity extends Activity {
    
        private VideoView vv;
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            
            vv = (VideoView) findViewById(R.id.vv);
            
            vv.setVideoPath("http://192.168.22.136:8080/11.mp4");
            
            vv.start();
            
            
        }
    
    
    }


##8_视频播放器surfaceview（重点）

surfaceview表面视图

双缓冲区：使用两个线程协调工作;

surfaceview 重量级控件，当画面可见时，双缓冲器被创建，占用较高的cpu和内存资源。
当界面不可见时，双缓冲器占用释放。



##9_音乐播放器API
    package com.itheima.surfaceview;

import android.app.Activity;
import android.media.AudioManager;
import android.media.MediaPlayer;
import android.media.MediaPlayer.OnPreparedListener;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;

public class MainActivity extends Activity {

    private SurfaceView sv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        sv = (SurfaceView) findViewById(R.id.sv);
        
        SurfaceHolder holder = sv.getHolder();
        //推送缓冲数据，api 13之前的版本上必须执行这行代码，13版本之后，播放器可以自动把
        //数据加载到缓冲区
        holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
        
        
        holder.addCallback(new Callback() {
            
            private MediaPlayer mediaPlay;



            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                try {
                    mediaPlay = new MediaPlayer();
                    
                    mediaPlay.setDataSource("http://192.168.22.136:8080/11.mp4");
                    mediaPlay.setAudioStreamType(AudioManager.STREAM_MUSIC);
                    
                    mediaPlay.setDisplay(holder);
                    
                    //使用阻塞式准备方法，等待数据资源准备完成后才开始播放，用于播放本地的音视频文件
//                    mediaPlay.prepare(); 
                    //使用异步式准备方法，使用子线程等待数据资源准备完成后才开始播放，用于播放网络上的音视频文件
                    mediaPlay.prepareAsync();
                    
                    
                    
                    mediaPlay.setOnPreparedListener(new OnPreparedListener() {
                        
                        @Override
                        public void onPrepared(MediaPlayer mp) {
                            
                            mediaPlay.start();
                        }
                    });
                    
                    
                } catch (Exception e) {
                    e.printStackTrace();
                }
                
            }
            
            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                if(mediaPlay != null && mediaPlay.isPlaying()){
                    mediaPlay.stop();
                    
                    mediaPlay.release();
                    
                    mediaPlay = null;
                    
//                    mediaPlay.seekTo(msec);
                    
                }
                
            }
        
            
            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width,
                    int height) {
                // TODO Auto-generated method stub
                
            }
        });
    }

    

}        

##10_vitamio框架的使用

    1 引入vitamio框架  以library、
    
    2 在布局中定义VideoView
       <io.vov.vitamio.widget.VideoView 
        android:id="@+id/vv"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        />



    3 mainactivity代码
       插件vitamio框架检查是否可用
       if (!LibsChecker.checkVitamioLibs(this)) {
            return;
        }
        
        final VideoView vv = (VideoView) findViewById(R.id.vv);
        vv.setVideoPath("http://192.168.1.2:8080/haha.avi");
        vv.setOnPreparedListener(new OnPreparedListener() {
            
            @Override
            public void onPrepared(MediaPlayer mp) {
                vv.start();
                
            }
        });
        //设置video的控制器
        vv.setMediaController(new MediaController(this));


     4 一定要在清单文件初始化InitActivity
        <activity android:name="io.vov.vitamio.activity.InitActivity"></activity>


##11_照相机拍照
    Intent intent = new Intent(MediaStore.ACTION_IMAGE_CAPTURE); 
        
        file = new File(Environment.getExternalStorageDirectory()+"/123.jpg");
        
        intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
        
        startActivityForResult(intent, 0);

##12_录机应用
    Intent intent = new Intent(MediaStore.ACTION_VIDEO_CAPTURE); 
        
        file = new File(Environment.getExternalStorageDirectory()+"/123.3gp");
        
        intent.putExtra(MediaStore.EXTRA_OUTPUT, Uri.fromFile(file));
        
        startActivityForResult(intent, 0);