近期。在改动Android4.4的原生相机Camera2，非常习惯的去寻找SurfaceView。结果任凭我使用grep还是ack。都无法搜索到SurfaceView，最后还是通过代码CameraActivity-->CameraModule-->PhotoUI-->R.layout.photo_module找到。原来是使用了TextureView。不是非常了解此控件，百度之。在官方API文档中找到此控件：
http://android.toolib.net/reference/android/view/TextureView.html
官方文档大概的意思是：
TextureView能够用来显示内容流。这样一个内容流比如能够视频或者OpenGL的场景。
内容流能够来自本应用程序以及其它进程。
Textureview必须在硬件加速开启的窗体中。
与SurfaceView相比，TextureView不会创建一个单独的窗体。这使得它能够像一般的View一样运行一些变换操作，比方移动、动画等等，比如,你能够通过调用myView.setAlpha(0.5f)将TextureView设置成半透明。
使用TextureView非常easy：你须要使用的就是SurfaceTexture，SurfaceTexture能够用于呈现内容。
以下是我写一个小样例来演示怎样渲染相机预览到TextureView，在官方文档样例的基础上略微修改了一下：
main.xml:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="horizontal" > <FrameLayout
android:id="@+id/camera_preview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1" /> <Button
android:id="@+id/button_capture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:text="Capture" /> </LinearLayout>
CameraPreview.java:
import java.io.IOException; import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.view.TextureView; @SuppressLint("NewApi")
public class CameraPreview extends TextureView implements
TextureView.SurfaceTextureListener {
private Camera mCamera;
private TextureView mTextureView;
public CameraPreview(Context context , Camera camera) {
super(context);
mCamera = camera;
// TODO Auto-generated constructor stub
} public void onSurfaceTextureAvailable(SurfaceTexture surface, int width,
int height) {
// mCamera = Camera.open();
try {
mCamera.setPreviewTexture(surface);
mCamera.startPreview();
} catch (IOException ioe) {
// Something bad happened
}
} public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width,
int height) {
// Ignored, Camera does all the work for us
} public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
mCamera.stopPreview();
mCamera.release();
return true;
} public void onSurfaceTextureUpdated(SurfaceTexture surface) {
// Invoked every time there's a new Camera preview frame
} }
CameraTest.java:
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date; import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Intent;
import android.hardware.Camera;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.Toast; import com.example.mycamera.R.id; @SuppressLint("NewApi")
public class CameraTest extends Activity {
public static final int MEDIA_TYPE_IMAGE = 1;
public static final int MEDIA_TYPE_VIDEO = 2;
private static final int CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE = 100;
private static final int CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE = 200;
private Camera mCamera;
private CameraPreview mPreview;
private static final String TAG = "ERROR";
private PictureCallback mPicture = new PictureCallback() {
@Override
public void onPictureTaken(byte[] data, Camera camera) {
File pictureFile = getOutputMediaFile(MEDIA_TYPE_IMAGE);
if (pictureFile == null) {
Log.d(TAG,
"Error creating media file, check storage permissions: "
+ "e.getMessage()");
return;
}
try {
FileOutputStream fos = new FileOutputStream(pictureFile);
fos.write(data);
fos.close();
} catch (FileNotFoundException e) {
Log.d(TAG, "File not found: " + e.getMessage());
} catch (IOException e) {
Log.d(TAG, "Error accessing file: " + e.getMessage());
}
}
}; @Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
// 创建Camera实例
mCamera = getCameraInstance();
// 创建Preview view并将其设为activity中的内容
mPreview = new CameraPreview(this, mCamera);
mPreview.setSurfaceTextureListener(mPreview);
//设置浑浊
mPreview.setAlpha(0.5f);
FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
// preview.setAlpha(0.0f);
preview.addView(mPreview);
// 在Capture按钮中增加listener
Button captureButton = (Button) findViewById(id.button_capture);
captureButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// 从摄像头获取图片
mCamera.takePicture(null, null, mPicture);
}
});
} /** 安全获取Camera对象实例的方法 */ public static Camera getCameraInstance() {
Camera c = null;
try {
c = Camera.open(); // 试图获取Camera实例
}
catch (Exception e) {
// 摄像头不可用（正被占用或不存在）
}
return c; // 不可用则返回null
} /** 为保存图片或视频创建File */
private static File getOutputMediaFile(int type) {
// 安全起见，在使用前应该
// 用Environment.getExternalStorageState()检查SD卡是否已装入
File mediaStorageDir = new File(
Environment
.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
"MyCameraApp");
// 假设期望图片在应用程序卸载后还存在、且能被其他应用程序共享，
// 则此保存位置最合适
// 假设不存在的话，则创建存储文件夹
if (!mediaStorageDir.exists()) {
if (!mediaStorageDir.mkdirs()) {
Log.d("MyCameraApp", "failed to create directory");
return null;
}
Log.d("MyCameraApp", "failed to create directory");
}
// 创建媒体文件名称
String timeStamp = new SimpleDateFormat("yyyyMMdd_HHmmss")
.format(new Date());
File mediaFile;
if (type == MEDIA_TYPE_IMAGE) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "IMG_" + timeStamp + ".jpg");
} else if (type == MEDIA_TYPE_VIDEO) {
mediaFile = new File(mediaStorageDir.getPath() + File.separator
+ "VID_" + timeStamp + ".mp4");
} else {
return null;
}
return mediaFile;
} @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
if (requestCode == CAPTURE_IMAGE_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
// 捕获的图像保存到Intent指定的fileUri
Toast.makeText(this, "Image saved to:\n" + data.getData(),
Toast.LENGTH_LONG).show();
} else if (resultCode == RESULT_CANCELED) {
// 用户取消了图像捕获
} else {
// 图像捕获失败，提示用户
}
} if (requestCode == CAPTURE_VIDEO_ACTIVITY_REQUEST_CODE) {
if (resultCode == RESULT_OK) {
// 捕获的视频保存到Intent指定的fileUri
Toast.makeText(this, "Video saved to:\n" + data.getData(),
Toast.LENGTH_LONG).show();
} else if (resultCode == RESULT_CANCELED) {
// 用户取消了视频捕获
} else {
// 视频捕获失败。提示用户
}
}
} @Override
protected void onPause() {
super.onPause();
releaseCamera(); // 在暂停事件中马上释放摄像头
} private void releaseCamera() {
if (mCamera != null) {
mCamera.release(); // 为其他应用释放摄像头
mCamera = null;
}
} }