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分类: Android平台

2018-05-07 14:44:39

https://blog.csdn.net/fukaimei/article/details/78144951

现在Android智能手机的像素都会提供照相的功能,大部分的手机的摄像头的像素都在1000万以上的像素,有的甚至会更高。它们大多都会支持光学变焦、曝光以及快门等等。

下面的程序Demo实例示范了使用Camera v2来进行拍照,当用户按下拍照键时,该应用会自动对焦,当对焦成功时拍下照片。

  • layout/activity_main.xml界面布局代码如下:
 <manifest xmlns:android="" package="com.fukaimei.camerav2test">  <uses-permission android:name="android.permission.CAMERA" /> <application  android:allowBackup="true" android:icon="@mipmap/ic_launcher" android:label="@string/app_name" android:roundIcon="@mipmap/ic_launcher_round" android:supportsRtl="true" android:theme="@style/AppTheme"> <activity android:name=".MainActivity"> <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> intent-filter> activity> application> manifest>
	
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上面的程序的界面提供了一个自定义TextureView来显示预览取景,十分简单。该自定义TextureView类的代码如下:

  • AutoFitTextureView.java逻辑代码如下:
package com.fukaimei.camerav2test; import android.content.Context; import android.util.AttributeSet; import android.view.TextureView; /**
 * Created by FuKaimei on 2017/9/29.
 */ public class AutoFitTextureView extends TextureView { private int mRatioWidth = 0; private int mRatioHeight = 0; public AutoFitTextureView(Context context, AttributeSet attrs) { super(context, attrs);
    } public void setAspectRatio(int width, int height) {
        mRatioWidth = width;
        mRatioHeight = height;
        requestLayout();
    } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int width = MeasureSpec.getSize(widthMeasureSpec); int height = MeasureSpec.getSize(heightMeasureSpec); if (0 == mRatioWidth || 0 == mRatioHeight) {
            setMeasuredDimension(width, height);
        } else { if (width < height * mRatioWidth / mRatioHeight) {
                setMeasuredDimension(width, width * mRatioHeight / mRatioWidth);
            } else {
                setMeasuredDimension(height * mRatioWidth / mRatioHeight, height);
            }
        }
    }
}
	
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接来了的MainActivity.java程序将会使用CameraManager来打开CameraDevice,并通过 CameraDevice创建CameraCaptureSession,然后即可通过CameraCaptureSession进行预览或拍照了。

  • MainActivity.java逻辑代码如下:
package com.fukaimei.camerav2test; import android.Manifest; import android.app.Activity; import android.content.Context; import android.content.pm.PackageManager; import android.content.res.Configuration; import android.graphics.ImageFormat; import android.graphics.SurfaceTexture; import android.hardware.camera2.CameraAccessException; import android.hardware.camera2.CameraCaptureSession; import android.hardware.camera2.CameraCharacteristics; import android.hardware.camera2.CameraDevice; import android.hardware.camera2.CameraManager; import android.hardware.camera2.CameraMetadata; import android.hardware.camera2.CaptureRequest; import android.hardware.camera2.TotalCaptureResult; import android.hardware.camera2.params.StreamConfigurationMap; import android.media.Image; import android.media.ImageReader; import android.os.Build; import android.os.Bundle; import android.support.annotation.RequiresApi; import android.support.v4.app.ActivityCompat; import android.util.Log; import android.util.Size; import android.util.SparseIntArray; import android.view.Surface; import android.view.TextureView; import android.view.View; import android.widget.Toast; import java.io.File; import java.io.FileOutputStream; import java.nio.ByteBuffer; import java.util.ArrayList; import java.util.Arrays; import java.util.Collections; import java.util.Comparator; import java.util.List; @RequiresApi(api = Build.VERSION_CODES.LOLLIPOP) public class MainActivity extends Activity implements View.OnClickListener { private static final SparseIntArray ORIENTATIONS = new SparseIntArray(); private static final String TAG = "MainActivity"; static {
        ORIENTATIONS.append(Surface.ROTATION_0, 90);
        ORIENTATIONS.append(Surface.ROTATION_90, 0);
        ORIENTATIONS.append(Surface.ROTATION_180, 270);
        ORIENTATIONS.append(Surface.ROTATION_270, 180);
    } private AutoFitTextureView textureView; // 摄像头ID(通常0代表后置摄像头,1代表前置摄像头) private String mCameraId = "0"; // 定义代表摄像头的成员变量 private CameraDevice cameraDevice; // 预览尺寸 private Size previewSize; private CaptureRequest.Builder previewRequestBuilder; // 定义用于预览照片的捕获请求 private CaptureRequest previewRequest; // 定义CameraCaptureSession成员变量 private CameraCaptureSession captureSession; private ImageReader imageReader; private final TextureView.SurfaceTextureListener mSurfaceTextureListener
            = new TextureView.SurfaceTextureListener() { @Override public void onSurfaceTextureAvailable(SurfaceTexture texture
                , int width, int height) { // 当TextureView可用时,打开摄像头 openCamera(width, height);
        } @Override public void onSurfaceTextureSizeChanged(SurfaceTexture texture
                , int width, int height) {
        } @Override public boolean onSurfaceTextureDestroyed(SurfaceTexture texture) { return true;
        } @Override public void onSurfaceTextureUpdated(SurfaceTexture texture) {
        }
    }; private final CameraDevice.StateCallback stateCallback = new CameraDevice.StateCallback() { //  摄像头被打开时激发该方法 @Override public void onOpened(CameraDevice cameraDevice) {
            MainActivity.this.cameraDevice = cameraDevice; // 开始预览 createCameraPreviewSession(); // ② } // 摄像头断开连接时激发该方法 @Override public void onDisconnected(CameraDevice cameraDevice) {
            cameraDevice.close();
            MainActivity.this.cameraDevice = null;
        } // 打开摄像头出现错误时激发该方法 @Override public void onError(CameraDevice cameraDevice, int error) {
            cameraDevice.close();
            MainActivity.this.cameraDevice = null;
            MainActivity.this.finish();
        }
    }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textureView = (AutoFitTextureView) findViewById(R.id.texture); // 为该组件设置监听器 textureView.setSurfaceTextureListener(mSurfaceTextureListener);
        findViewById(R.id.capture).setOnClickListener(this);
    } @Override public void onClick(View view) {
        captureStillPicture();
    } private void captureStillPicture() { try { if (cameraDevice == null) { return;
            } // 创建作为拍照的CaptureRequest.Builder final CaptureRequest.Builder captureRequestBuilder =
                    cameraDevice.createCaptureRequest(CameraDevice.TEMPLATE_STILL_CAPTURE); // 将imageReader的surface作为CaptureRequest.Builder的目标 captureRequestBuilder.addTarget(imageReader.getSurface()); // 设置自动对焦模式 captureRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                    CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); // 设置自动曝光模式 captureRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
                    CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); // 获取设备方向 int rotation = getWindowManager().getDefaultDisplay().getRotation(); // 根据设备方向计算设置照片的方向 captureRequestBuilder.set(CaptureRequest.JPEG_ORIENTATION
                    , ORIENTATIONS.get(rotation)); // 停止连续取景 captureSession.stopRepeating(); // 捕获静态图像 captureSession.capture(captureRequestBuilder.build()
                    , new CameraCaptureSession.CaptureCallback() // ⑤ { // 拍照完成时激发该方法 @Override public void onCaptureCompleted(CameraCaptureSession session
                                , CaptureRequest request, TotalCaptureResult result) { try { // 重设自动对焦模式 previewRequestBuilder.set(CaptureRequest.CONTROL_AF_TRIGGER,
                                        CameraMetadata.CONTROL_AF_TRIGGER_CANCEL); // 设置自动曝光模式 previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
                                        CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); // 打开连续取景模式 captureSession.setRepeatingRequest(previewRequest, null, null);
                            } catch (CameraAccessException e) {
                                e.printStackTrace();
                            }
                        }
                    }, null);
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    } // 打开摄像头 private void openCamera(int width, int height) {
        setUpCameraOutputs(width, height);
        CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try { // 打开摄像头 if (ActivityCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) { // TODO: Consider calling //    ActivityCompat#requestPermissions // here to request the missing permissions, and then overriding //   public void onRequestPermissionsResult(int requestCode, String[] permissions, //                                          int[] grantResults) // to handle the case where the user grants the permission. See the documentation // for ActivityCompat#requestPermissions for more details. return;
            }
            manager.openCamera(mCameraId, stateCallback, null); // ① } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    } private void createCameraPreviewSession() { try {
            SurfaceTexture texture = textureView.getSurfaceTexture();
            texture.setDefaultBufferSize(previewSize.getWidth(), previewSize.getHeight());
            Surface surface = new Surface(texture); // 创建作为预览的CaptureRequest.Builder previewRequestBuilder = cameraDevice
                    .createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW); // 将textureView的surface作为CaptureRequest.Builder的目标 previewRequestBuilder.addTarget(new Surface(texture)); // 创建CameraCaptureSession,该对象负责管理处理预览请求和拍照请求 cameraDevice.createCaptureSession(Arrays.asList(surface
                    , imageReader.getSurface()), new CameraCaptureSession.StateCallback() // ③ { @Override public void onConfigured(CameraCaptureSession cameraCaptureSession) { // 如果摄像头为null,直接结束方法 if (null == cameraDevice) { return;
                            } // 当摄像头已经准备好时,开始显示预览 captureSession = cameraCaptureSession; try { // 设置自动对焦模式 previewRequestBuilder.set(CaptureRequest.CONTROL_AF_MODE,
                                        CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE); // 设置自动曝光模式 previewRequestBuilder.set(CaptureRequest.CONTROL_AE_MODE,
                                        CaptureRequest.CONTROL_AE_MODE_ON_AUTO_FLASH); // 开始显示相机预览 previewRequest = previewRequestBuilder.build(); // 设置预览时连续捕获图像数据 captureSession.setRepeatingRequest(previewRequest, null, null); // ④ } catch (CameraAccessException e) {
                                e.printStackTrace();
                            }
                        } @Override public void onConfigureFailed(CameraCaptureSession cameraCaptureSession) {
                            Toast.makeText(MainActivity.this, "配置失败!" , Toast.LENGTH_SHORT).show();
                        }
                    }, null );
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    } private void setUpCameraOutputs(int width, int height) {
        CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE); try { // 获取指定摄像头的特性 CameraCharacteristics characteristics
                    = manager.getCameraCharacteristics(mCameraId); // 获取摄像头支持的配置属性 StreamConfigurationMap map = characteristics.get(
                    CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP); // 获取摄像头支持的最大尺寸 Size largest = Collections.max(
                    Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)), new CompareSizesByArea()); // 创建一个ImageReader对象,用于获取摄像头的图像数据 imageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
                    ImageFormat.JPEG, 2);
            imageReader.setOnImageAvailableListener( new ImageReader.OnImageAvailableListener() { // 当照片数据可用时激发该方法 @Override public void onImageAvailable(ImageReader reader) { // 获取捕获的照片数据 Image image = reader.acquireNextImage();
                            ByteBuffer buffer = image.getPlanes()[0].getBuffer(); byte[] bytes = new byte[buffer.remaining()]; // 使用IO流将照片写入指定文件 File file = new File(getExternalFilesDir(null), "pic.jpg");
                            buffer.get(bytes); try (
                                    FileOutputStream output = new FileOutputStream(file)) {
                                output.write(bytes);
                                Toast.makeText(MainActivity.this, "保存: " + file, Toast.LENGTH_LONG).show();
                            } catch (Exception e) {
                                e.printStackTrace();
                            } finally {
                                image.close();
                            }
                        }
                    }, null); // 获取最佳的预览尺寸 previewSize = chooseOptimalSize(map.getOutputSizes(
                    SurfaceTexture.class), width, height, largest); // 根据选中的预览尺寸来调整预览组件(TextureView的)的长宽比 int orientation = getResources().getConfiguration().orientation; if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                textureView.setAspectRatio(
                        previewSize.getWidth(), previewSize.getHeight());
            } else {
                textureView.setAspectRatio(
                        previewSize.getHeight(), previewSize.getWidth());
            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        } catch (NullPointerException e) {
            Log.d(TAG, "出现错误");
        }
    } private static Size chooseOptimalSize(Size[] choices
            , int width, int height, Size aspectRatio) { // 收集摄像头支持的打过预览Surface的分辨率 List bigEnough = new ArrayList<>(); int w = aspectRatio.getWidth(); int h = aspectRatio.getHeight(); for (Size option : choices) { if (option.getHeight() == option.getWidth() * h / w &&
                    option.getWidth() >= width && option.getHeight() >= height) {
                bigEnough.add(option);
            }
        } // 如果找到多个预览尺寸,获取其中面积最小的。 if (bigEnough.size() > 0) { return Collections.min(bigEnough, new CompareSizesByArea());
        } else {
            System.out.println("找不到合适的预览尺寸!!!"); return choices[0];
        }
    } // 为Size定义一个比较器Comparator static class CompareSizesByArea implements Comparator { @Override public int compare(Size lhs, Size rhs) { // 强转为long保证不会发生溢出 return Long.signum((long) lhs.getWidth() * lhs.getHeight() -
                    (long) rhs.getWidth() * rhs.getHeight());
        }
    }
}
	
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上面的程序中序号①的代码是用于打开系统摄像头,openCamera()方法的第一个参数代表请求打开的摄像头ID,此处传入的摄像头ID为 “0”,这代表打开设备后置摄像头;如果需要打开设备指定摄像头(比如前置摄像头),可以在调用openCamera()方法时传入相应的摄像头ID。

  • 注意:由于该程序需要使用手机的摄像头,因此还需要在清单文件AndroidManifest.xml文件中授权相应的权限:
 <uses-permission android:name="android.permission.CAMERA" />
	
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  • Demo程序运行效果界面截图如下:
    这里写图片描述

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