• Android Camera开发:使用TextureView和SurfaceTexture预览Camera 基础拍照demo


    Google自Android4.0出了TextureView,为什么推出呢?就是为了弥补Surfaceview的不足,另外一方面也是为了平衡GlSurfaceView,当然这是本人揣度的。关于TextureView、Surfaceview、SurfaceTexture、GLSurfaceView的关系,待咱家推出GLSurfaceview预览Camera后再专门分析。本文主要介绍使用TextureView预览Camera。

    其实关于如何用TextureView预览Camera,官网已经给出了demo,参见这里。另外,链接1 链接2也给出了完整的预览Camera的demo,但都是一堆东西染在一块。本文就利用前文 搭建的一个轻量级的Camera框架来快速替换掉Surfaceview。因为用Surfaceview预览的话传一个SurfaceHolder进去,用Textureview预览的话需要传进去一个SurfaceTexture。其他的Camera流程不变。

    一、新建CameraTextureView类继承TextureView,并实现TextureView.SurfaceTextureListener接口。实现这个接口就像实现SurfaceHolder.Callback,最主要的目的是在SurfaceTexture准备好后能够知道,也即onSurfaceTextureAvailable这个函数。

    CameraTextureView.java

     
    1.  1 package org.yanzi.camera.preview;  
       2   
       3 import org.yanzi.camera.CameraInterface;  
       4   
       5 import android.content.Context;  
       6 import android.graphics.PixelFormat;  
       7 import android.graphics.SurfaceTexture;  
       8 import android.util.AttributeSet;  
       9 import android.util.Log;  
      10 import android.view.SurfaceHolder;  
      11 import android.view.SurfaceView;  
      12 import android.view.TextureView;  
      13   
      14 public class CameraTextureView extends TextureView implements TextureView.SurfaceTextureListener {  
      15     private static final String TAG = "yanzi";  
      16     Context mContext;  
      17     SurfaceTexture mSurface;  
      18     public CameraTextureView(Context context, AttributeSet attrs) {  
      19         super(context, attrs);  
      20         // TODO Auto-generated constructor stub  
      21         mContext = context;  
      22         this.setSurfaceTextureListener(this);  
      23     }  
      24     @Override  
      25     public void onSurfaceTextureAvailable(SurfaceTexture surface, int width,  
      26             int height) {  
      27         // TODO Auto-generated method stub  
      28         Log.i(TAG, "onSurfaceTextureAvailable...");  
      29         mSurface = surface;  
      30 //      CameraInterface.getInstance().doStartPreview(surface, 1.33f);  
      31     }  
      32     @Override  
      33     public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {  
      34         // TODO Auto-generated method stub  
      35         Log.i(TAG, "onSurfaceTextureDestroyed...");  
      36         CameraInterface.getInstance().doStopCamera();  
      37         return true;  
      38     }  
      39     @Override  
      40     public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width,  
      41             int height) {  
      42         // TODO Auto-generated method stub  
      43         Log.i(TAG, "onSurfaceTextureSizeChanged...");  
      44     }  
      45     @Override  
      46     public void onSurfaceTextureUpdated(SurfaceTexture surface) {  
      47         // TODO Auto-generated method stub  
      48         Log.i(TAG, "onSurfaceTextureUpdated...");  
      49           
      50     }  
      51       
      52     /* 让Activity能得到TextureView的SurfaceTexture 
      53      * @see android.view.TextureView#getSurfaceTexture() 
      54      */  
      55     public SurfaceTexture _getSurfaceTexture(){  
      56         return mSurface;  
      57     }  
      58 }  

    二、在布局文件里把它加上就行了,因为他的父类就是View,当成一般的View就行

    1.  1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"  
       2     xmlns:tools="http://schemas.android.com/tools"  
       3     android:layout_width="match_parent"  
       4     android:layout_height="match_parent"  
       5     tools:context=".CameraActivity" >  
       6     <FrameLayout  
       7         android:layout_width="wrap_content"  
       8         android:layout_height="wrap_content" >  
       9         <org.yanzi.camera.preview.CameraTextureView  
      10             android:id="@+id/camera_textureview"  
      11             android:layout_width="0dip"  
      12             android:layout_height="0dip" />  
      13     </FrameLayout>  
      14     <ImageButton  
      15         android:id="@+id/btn_shutter"  
      16         android:layout_width="wrap_content"  
      17         android:layout_height="wrap_content"  
      18         android:background="@drawable/btn_shutter_background"  
      19         android:layout_alignParentBottom="true"  
      20         android:layout_centerHorizontal="true"   
      21         android:layout_marginBottom="10dip"/>  
      22 </RelativeLayout>  


    三、在CameraInterface里,我封装了两个函数:

     1  /**使用Surfaceview开启预览 
     2 
     3      * @param holder 
     4      * @param previewRate 
     5      */  
     6     public void doStartPreview(SurfaceHolder holder, float previewRate){  
     7         Log.i(TAG, "doStartPreview...");  
     8         if(isPreviewing){  
     9             mCamera.stopPreview();  
    10             return;  
    11         }  
    12         if(mCamera != null){  
    13             try {  
    14                 mCamera.setPreviewDisplay(holder);  
    15             } catch (IOException e) {  
    16                 // TODO Auto-generated catch block  
    17                 e.printStackTrace();  
    18             }  
    19             initCamera(previewRate);  
    20         }  
    21   
    22   
    23     }  
    24     /**使用TextureView预览Camera 
    25      * @param surface 
    26      * @param previewRate 
    27      */  
    28     public void doStartPreview(SurfaceTexture surface, float previewRate){  
    29         Log.i(TAG, "doStartPreview...");  
    30         if(isPreviewing){  
    31             mCamera.stopPreview();  
    32             return;  
    33         }  
    34         if(mCamera != null){  
    35             try {  
    36                 mCamera.setPreviewTexture(surface);  
    37             } catch (IOException e) {  
    38                 // TODO Auto-generated catch block  
    39                 e.printStackTrace();  
    40             }  
    41             initCamera(previewRate);  
    42         }  
    43           
    44     }
     

    分别对应Surfaceview和TextureView预览。可以看到就是传进来的参数不一样,initCamera()的东西都一样。

     1  private void initCamera(float previewRate){  
     2 
     3 if(mCamera != null){  
     4             mParams = mCamera.getParameters();  
     5             mParams.setPictureFormat(PixelFormat.JPEG);//设置拍照后存储的图片格式  
     6 //          CamParaUtil.getInstance().printSupportPictureSize(mParams);  
     7 //          CamParaUtil.getInstance().printSupportPreviewSize(mParams);  
     8 //设置PreviewSize和PictureSize  
     9             Size pictureSize = CamParaUtil.getInstance().getPropPictureSize(  
    10                     mParams.getSupportedPictureSizes(),previewRate, 800);  
    11             mParams.setPictureSize(pictureSize.width, pictureSize.height);  
    12             Size previewSize = CamParaUtil.getInstance().getPropPreviewSize(  
    13                     mParams.getSupportedPreviewSizes(), previewRate, 800);  
    14             mParams.setPreviewSize(previewSize.width, previewSize.height);  
    15             mCamera.setDisplayOrientation(90);  
    16 //          CamParaUtil.getInstance().printSupportFocusMode(mParams);  
    17             List<String> focusModes = mParams.getSupportedFocusModes();  
    18 if(focusModes.contains("continuous-video")){  
    19                 mParams.setFocusMode(Camera.Parameters.FOCUS_MODE_CONTINUOUS_VIDEO);  
    20             }  
    21             mCamera.setParameters(mParams);   
    22             mCamera.startPreview();//开启预览  
    23             isPreviewing = true;  
    24             mPreviwRate = previewRate;  
    25             mParams = mCamera.getParameters(); //重新get一次  
    26             Log.i(TAG, "最终设置:PreviewSize--With = " + mParams.getPreviewSize().width  
    27                     + "Height = " + mParams.getPreviewSize().height);  
    28             Log.i(TAG, "最终设置:PictureSize--With = " + mParams.getPictureSize().width  
    29                     + "Height = " + mParams.getPictureSize().height);  
    30         }  
    31     }

    四、在Activity里,依旧开一个线程去open Camera

    1 Thread openThread = new Thread(){  
    2 
    3             @Override  
    4             public void run() {  
    5                 // TODO Auto-generated method stub  
    6                 CameraInterface.getInstance().doOpenCamera(CameraActivity.this);  
    7             }  
    8         };  
    9         openThread.start();


    在Camera Open完的回调里开预览:

    @Override  
        public void cameraHasOpened() {  
            // TODO Auto-generated method stub  
            SurfaceTexture surface = textureView._getSurfaceTexture();  
            CameraInterface.getInstance().doStartPreview(surface, previewRate);  
        }
     


    之后就能正常运行了,可以看到与前文Surfaceview预览Camera 改动非常之小。

     

    几个注意事项:

    1、TextureView是Android 4.0之后加入的,低版本么这个类。TextureView必须工作在开启硬件加速的环境中,也即配置文件里Activity的设置项里:android:hardwareAccelerated="true" 默认的这个属性就是true,因此不用再写了。但如果写成false,可以看到onSurfaceTextureAvailable()这个回调就进不来了,TextureView没有了SurfaceTexture还玩个屁啊。

    2、本文demo打开camera并预览的正常log是:

     1    Line 417: 06-22 12:37:43.682 I/yanzi   ( 4917): Camera open....  
     2     Line 489: 06-22 12:37:43.758 I/yanzi   ( 4917): onSurfaceTextureAvailable...  
     3     Line 533: 06-22 12:37:43.819 I/yanzi   ( 4917): Camera open over....  
     4     Line 535: 06-22 12:37:43.819 I/yanzi   ( 4917): doStartPreview...  
     5     Line 537: 06-22 12:37:43.825 I/yanzi   ( 4917): PictureSize : w = 1280h = 720  
     6     Line 539: 06-22 12:37:43.825 I/yanzi   ( 4917): PreviewSize:w = 800h = 448  
     7     Line 555: 06-22 12:37:43.874 I/yanzi   ( 4917): 最终设置:PreviewSize--With = 800Height = 448  
     8     Line 557: 06-22 12:37:43.874 I/yanzi   ( 4917): 最终设置:PictureSize--With = 1280Height = 720  
     9     Line 577: 06-22 12:37:44.106 I/yanzi   ( 4917): onSurfaceTextureUpdated...  
    10     Line 579: 06-22 12:37:44.138 I/yanzi   ( 4917): onSurfaceTextureUpdated...  
    11     Line 583: 06-22 12:37:44.169 I/yanzi   ( 4917): onSurfaceTextureUpdated...  
    12     Line 585: 06-22 12:37:44.220 I/yanzi   ( 4917): onSurfaceTextureUpdated...  
    13     Line 587: 06-22 12:37:44.253 I/yanzi   ( 4917): onSurfaceTextureUpdated...
     


    测试手机为中兴Geek,这个手机Camera还是很牛逼的,比手里的华为G700强,就是偶尔会连不上Camera Service,汗。从log可以看到,onSurfaceTextureAvailable这个回调需要一定时间。Camera.open()这句话用了130多ms。但有两点跟Surfaceview不同。第一,TextureView创建过程中没有进到onSurfaceTextureSizeChanged()这个函数里。而SurfaceView在创建过程中,从无到有的时候会进到大小发生变化回调里。第二,onSurfaceTextureUpdated()这个函数每上来一帧数据,这块就进来一次。这是跟Surfaceview相比,最伟大的一个地方。通过这个接口,可以将上来的SurfaceTexture送给OpenGL再去处理。这个回调是实时的,而非用Camera的PreviewCallback这种2次回调的方式。从时间看,基本上每32ms左右上来一帧数据,即每秒30帧,跟本手机的Camera的性能吻合。

    3、Camera再执行startPreview时必须保证TextureView的SurfaceTexture上来了,如果因为一些性能原因onSurfaceTextureAvailable()这个回调上不来就开预览,就开不了的。如果发生这种情况,就在onSurfaceTextureAvailable()回调里执行open和startPreview操作,保证万无一失。

    4、TextureView本身就有getSurfaceTexture()这个函数,我又封装了个:

     
    /* 让Activity能得到TextureView的SurfaceTexture 
         * @see android.view.TextureView#getSurfaceTexture() 
         */  
        public SurfaceTexture _getSurfaceTexture(){  
            return mSurface;  
        }

    这里的mSurface就是onSurfaceTextureAvailable()回调里传上来的SurfaceTexture。测试证明,开预览时直接调

    textureView.getSurfaceTexture(),把它传给Camera: mCamera.setPreviewTexture(surface);也是能正常预览的。但是推荐使用前者,原因见官方上的这段话:

    A TextureView's SurfaceTexture can be obtained either by invoking getSurfaceTexture() or by using a TextureView.SurfaceTextureListener. It is important to know that a SurfaceTexture is available only after the TextureView is attached to a window (and onAttachedToWindow() has been invoked.) It is therefore highly recommended you use a listener to be notified when the SurfaceTexture becomes available.

    两种方式获得SurfaceTexture,推荐使用监听。因为只有在TextureView执行完onAttachedToWindow时,它的tSurfaceTexture才上来。

    5、SurfaceTexture和TextureView的关系:

    Using a TextureView is simple: all you need to do is get its SurfaceTexture. The SurfaceTexture can then be used to render content

    如果说TextureView是一幅画的话,那SurfaceTexture就是画布,真正渲染的载体是SurfaceTexture。

    6、TextureView可以像一般View执行各种变化,其中有个textureView.setAlpha(1.0f);默认不写这句话,它的alpha也是1.0f,即不透明。如果设成透明0.0f,可以看到啥都看不到了,这一点跟Surfaceview刚好相反。Surfaceview的SurfaceHolder一般要设一下Transparent即透明。但TextureView因为是个view,任何一个png的照片透明度设成0肯定啥都看不到。

    7、如果认为预览个Camera这就是TextureView和SurfaceTexture的使命的话,就大错特错了,真正用意是和OpenGL无缝连接。

    --------------------本文系原创,转载请注明作者yanzi1225627

    版本号:PlayCamera_V2.0.0[2014-6-22].zip

    CSDN下载链接:http://download.csdn.net/detail/yanzi1225627/7540903

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  • 原文地址:https://www.cnblogs.com/Sharley/p/5964436.html
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