前段时间写了关于一篇关于调用系统相机的博客，如果需要调用系统相机和截图可以看一看这篇博客：Android学习之调用系统相机拍照、截图并保存最近发现不同手机，调用系统相机效果不太好,，所以学习Android 的相机原理，自定义了一个Android相机。看了这篇博客，相信大家都会写一个自己的相机。

我对比了一下小猿搜题、学霸君、作业帮、阿凡题这四款app的拍照功能，个人感觉小猿搜题的体验要好一些，因为从主界面进入拍照界面，连个界面没有一个旋转的过渡，而学霸君就有一个过渡，有一丝丝的影响体验。也就是说学霸君的拍照界面是横屏的，在activity的onCreate方法里面调用了setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE)来设置全屏，而切换界面的时候又从竖屏切换为横屏，就会有个过渡的效果，影响了体验。

项目地址：/Terrybthvi/MyCamera

这个项目仿照小猿搜题app，首先我们将相机布局最低层是显示摄像头获取到的图像，上层是网格线，聚焦图标等。

效果图如下所示：

1、绘制网格参考线

绘制网格参考线就是绘制拍照时屏幕中的竖线和直线，代码如下所示：

2、自定义相机代码

这里我们要创建一个SurfaceView，将摄像头获取到的图像放到SurfsaceView中显示。主要方法如下：

1、继承SurfaceView，定义变量，初始化类。

2、实现三个方法对sufarceView监听。

surfaceCreated();surfaceChanged();surfaceDestroyed();

3、获取相机实例

4、设置相机监听

5、增加自动聚焦 和点击屏幕聚焦

6、拍照以及设置图片格式

3、为相机添加聚焦功能

4、Activity调用相机

actiity中注册了SensorEventListener，也就是使用传感器监听用户手机的移动，如果有一定距离的移动，则自动聚焦，这样体验好一点。

<span style="font-family:SimHei;font-size:18px;">package com.example.terry.mycamera;import android.animation.AnimatorSet;import android.animation.ObjectAnimator;import android.annotation.TargetApi;import android.app.Activity;import android.content.ContentResolver;import android.content.ContentValues;import android.content.Context;import android.content.Intent;import android.content.res.Configuration;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.hardware.Sensor;import android.hardware.SensorEvent;import android.hardware.SensorEventListener;import android.hardware.SensorManager;import .Uri;import android.os.Build;import android.os.Bundle;import android.os.Environment;import android.provider.MediaStore;import android.text.format.DateFormat;import android.util.Log;import android.view.View;import android.view.Window;import android.view.WindowManager;import android.view.animation.LinearInterpolator;import android.widget.LinearLayout;import android.widget.RelativeLayout;import android.widget.TextView;import com.example.terry.mycamera.Crop.CropImageView;import com.example.terry.mycamera.Crop.CropperImage;import com.example.terry.mycamera.camare.CameraPreview;import com.example.terry.mycamera.camare.FocusView;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.io.OutputStream;/*** @Class: TakePhotoActivity* @Description: 拍照界面* @author: leiqi(/u013132758)* @Date: /3/15*/public class TakePhotoActivity extends Activity implements CameraPreview.OnCameraStatusListener,SensorEventListener {private static final String TAG = "TakePhoteActivity";public static final Uri IMAGE_URI = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;public static final String PATH = Environment.getExternalStorageDirectory().toString() + "/AndroidMedia/";CameraPreview mCameraPreview;CropImageView mCropImageView;RelativeLayout mTakePhotoLayout;LinearLayout mCropperLayout;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);// 设置横屏// setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);// 设置全屏requestWindowFeature(Window.FEATURE_NO_TITLE);getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);setContentView(R.layout.activity_take_photo);// Initialize components of the appmCropImageView = (CropImageView) findViewById(R.id.CropImageView);mCameraPreview = (CameraPreview) findViewById(R.id.cameraPreview);FocusView focusView = (FocusView) findViewById(R.id.view_focus);mTakePhotoLayout = (RelativeLayout) findViewById(R.id.take_photo_layout);mCropperLayout = (LinearLayout) findViewById(R.id.cropper_layout);mCameraPreview.setFocusView(focusView);mCameraPreview.setOnCameraStatusListener(this);mCropImageView.setGuidelines(2);mSensorManager = (SensorManager) getSystemService(Context.SENSOR_SERVICE);mAccel = mSensorManager.getDefaultSensor(Sensor.TYPE_ACCELEROMETER);}boolean isRotated = false;@TargetApi(Build.VERSION_CODES.HONEYCOMB)@Overrideprotected void onResume() {super.onResume();if(!isRotated) {TextView hint_tv = (TextView) findViewById(R.id.hint);ObjectAnimator animator = ObjectAnimator.ofFloat(hint_tv, "rotation", 0f, 90f);animator.setStartDelay(800);animator.setDuration(1000);animator.setInterpolator(new LinearInterpolator());animator.start();View view = findViewById(R.id.crop_hint);AnimatorSet animSet = new AnimatorSet();ObjectAnimator animator1 = ObjectAnimator.ofFloat(view, "rotation", 0f, 90f);ObjectAnimator moveIn = ObjectAnimator.ofFloat(view, "translationX", 0f, -50f);animSet.play(animator1).before(moveIn);animSet.setDuration(10);animSet.start();isRotated = true;}mSensorManager.registerListener(this, mAccel, SensorManager.SENSOR_DELAY_UI);}@Overrideprotected void onPause() {super.onPause();mSensorManager.unregisterListener(this);}@Overridepublic void onConfigurationChanged(Configuration newConfig) {Log.e(TAG, "onConfigurationChanged");super.onConfigurationChanged(newConfig);}public void takePhoto(View view) {if(mCameraPreview != null) {mCameraPreview.takePicture();}}public void openlight(View view){if (mCameraPreview != null){mCameraPreview.openLight();view.setVisibility(View.GONE);View v = findViewById(R.id.nolight);v.setVisibility(View.VISIBLE);}}public void offlight(View v){if (mCameraPreview != null){mCameraPreview.offLight();v.setVisibility(View.GONE);View view = findViewById(R.id.light);view.setVisibility(View.VISIBLE);}}public void close(View view) {finish();}/*** 关闭截图界面* @param view*/public void closeCropper(View view) {showTakePhotoLayout();}/*** 开始截图，并保存图片* @param view*/public void startCropper(View view) {//获取截图并旋转90度CropperImage cropperImage = mCropImageView.getCroppedImage();Log.e(TAG, cropperImage.getX() + "," + cropperImage.getY());Log.e(TAG, cropperImage.getWidth() + "," + cropperImage.getHeight());Bitmap bitmap = Utils.rotate(cropperImage.getBitmap(), -90);// Bitmap bitmap = mCropImageView.getCroppedImage();// 系统时间long dateTaken = System.currentTimeMillis();// 图像名称String filename = DateFormat.format("yyyy-MM-dd kk.mm.ss", dateTaken).toString() + ".jpg";Uri uri = insertImage(getContentResolver(), filename, dateTaken, PATH,filename, bitmap, null);cropperImage.getBitmap().recycle();cropperImage.setBitmap(null);Intent intent = new Intent(this, PreviewActivity.class);intent.setData(uri);intent.putExtra("path", PATH + filename);intent.putExtra("width", bitmap.getWidth());intent.putExtra("height", bitmap.getHeight());intent.putExtra("cropperImage", cropperImage);startActivity(intent);bitmap.recycle();finish();super.overridePendingTransition(R.anim.fade_in,R.anim.fade_out);// doAnimation(cropperImage);}/*** 拍照成功后回调* 存储图片并显示截图界面* @param data*/@Overridepublic void onCameraStopped(byte[] data) {Log.i("TAG", "==onCameraStopped==");// 创建图像Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length);// 系统时间long dateTaken = System.currentTimeMillis();// 图像名称String filename = DateFormat.format("yyyy-MM-dd kk.mm.ss", dateTaken).toString() + ".jpg";// 存储图像（PATH目录）Uri source = insertImage(getContentResolver(), filename, dateTaken, PATH,filename, bitmap, data);//准备截图try {mCropImageView.setImageBitmap(MediaStore.Images.Media.getBitmap(this.getContentResolver(), source));// mCropImageView.rotateImage(90);} catch (IOException e) {Log.e(TAG, e.getMessage());}showCropperLayout();}/*** 存储图像并将信息添加入媒体数据库*/private Uri insertImage(ContentResolver cr, String name, long dateTaken,String directory, String filename, Bitmap source, byte[] jpegData) {OutputStream outputStream = null;String filePath = directory + filename;try {File dir = new File(directory);if (!dir.exists()) {dir.mkdirs();}File file = new File(directory, filename);if (file.createNewFile()) {outputStream = new FileOutputStream(file);if (source != null) {press(pressFormat.JPEG, 100, outputStream);} else {outputStream.write(jpegData);}}} catch (FileNotFoundException e) {Log.e(TAG, e.getMessage());return null;} catch (IOException e) {Log.e(TAG, e.getMessage());return null;} finally {if (outputStream != null) {try {outputStream.close();} catch (Throwable t) {}}}ContentValues values = new ContentValues(7);values.put(MediaStore.Images.Media.TITLE, name);values.put(MediaStore.Images.Media.DISPLAY_NAME, filename);values.put(MediaStore.Images.Media.DATE_TAKEN, dateTaken);values.put(MediaStore.Images.Media.MIME_TYPE, "image/jpeg");values.put(MediaStore.Images.Media.DATA, filePath);return cr.insert(IMAGE_URI, values);}private void showTakePhotoLayout() {mTakePhotoLayout.setVisibility(View.VISIBLE);mCropperLayout.setVisibility(View.GONE);}private void showCropperLayout() {mTakePhotoLayout.setVisibility(View.GONE);mCropperLayout.setVisibility(View.VISIBLE);mCameraPreview.start(); //继续启动摄像头}private float mLastX = 0;private float mLastY = 0;private float mLastZ = 0;private boolean mInitialized = false;private SensorManager mSensorManager;private Sensor mAccel;@Overridepublic void onSensorChanged(SensorEvent event) {float x = event.values[0];float y = event.values[1];float z = event.values[2];if (!mInitialized){mLastX = x;mLastY = y;mLastZ = z;mInitialized = true;}float deltaX = Math.abs(mLastX - x);float deltaY = Math.abs(mLastY - y);float deltaZ = Math.abs(mLastZ - z);if(deltaX > 0.8 || deltaY > 0.8 || deltaZ > 0.8){mCameraPreview.setFocus();}mLastX = x;mLastY = y;mLastZ = z;}@Overridepublic void onAccuracyChanged(Sensor sensor, int accuracy) {}}</span>

5、添加计算焦点及测光区域、拍照后图片旋转以及检测摄像头是否可用

<span style="font-family:SimHei;font-size:18px;">package com.example.terry.mycamera;import android.content.Context;/*** Created by leiqi on 15/9/29.*/import android.content.pm.PackageManager;import android.graphics.Bitmap;import android.graphics.Matrix;import android.graphics.Rect;import android.os.Environment;import android.util.DisplayMetrics;import java.io.File;/*** @Class:* @Description:* @author: leiqi(/u013132758)* @Date: /3/15*/public class Utils {public static DisplayMetrics getScreenWH(Context context) {DisplayMetrics dMetrics = new DisplayMetrics();dMetrics = context.getResources().getDisplayMetrics();return dMetrics;}/*** 计算焦点及测光区域** @param focusWidth* @param focusHeight* @param areaMultiple* @param x* @param y* @param previewleft* @param previewRight* @param previewTop* @param previewBottom* @return Rect(left,top,right,bottom) : left、top、right、bottom是以显示区域中心为原点的坐标*/public static Rect calculateTapArea(int focusWidth, int focusHeight,float areaMultiple, float x, float y, int previewleft,int previewRight, int previewTop, int previewBottom) {int areaWidth = (int) (focusWidth * areaMultiple);int areaHeight = (int) (focusHeight * areaMultiple);int centerX = (previewleft + previewRight) / 2;int centerY = (previewTop + previewBottom) / 2;double unitx = ((double) previewRight - (double) previewleft) / 2000;double unity = ((double) previewBottom - (double) previewTop) / 2000;int left = clamp((int) (((x - areaWidth / 2) - centerX) / unitx),-1000, 1000);int top = clamp((int) (((y - areaHeight / 2) - centerY) / unity),-1000, 1000);int right = clamp((int) (left + areaWidth / unitx), -1000, 1000);int bottom = clamp((int) (top + areaHeight / unity), -1000, 1000);return new Rect(left, top, right, bottom);}public static int clamp(int x, int min, int max) {if (x > max)return max;if (x < min)return min;return x;}/*** 检测摄像头设备是否可用* Check if this device has a camera* @param context* @return*/public static boolean checkCameraHardware(Context context) {if (context != null && context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)) {// this device has a camerareturn true;} else {// no camera on this devicereturn false;}}/*** @param context* @return app_cache_path/dirName*/public static String getDBDir(Context context) {String path = null;if (Environment.MEDIA_MOUNTED.equals(Environment.getExternalStorageState())) {path = Environment.getExternalStorageDirectory().getAbsolutePath() +File.separator + "bbk" + File.separator + "cloudteacher" + File.separator + "db";File externalCacheDir = context.getExternalCacheDir();if (externalCacheDir != null) {path = externalCacheDir.getPath();}}if (path == null) {File cacheDir = context.getCacheDir();if (cacheDir != null && cacheDir.exists()) {path = cacheDir.getPath();}}return path;}/*** bitmap旋转* @param b* @param degrees* @return*/public static Bitmap rotate(Bitmap b, int degrees) {if (degrees != 0 && b != null) {Matrix m = new Matrix();m.setRotate(degrees, (float) b.getWidth() / 2, (float) b.getHeight() / 2);try {Bitmap b2 = Bitmap.createBitmap(b, 0, 0, b.getWidth(), b.getHeight(), m, true);if (b != b2) {b.recycle(); //Android开发再次提示Bitmap操作完应该显示的释放b = b2;}} catch (OutOfMemoryError ex) {// Android123建议大家如何出现了内存不足异常，最好return 原始的bitmap对象。.}}return b;}public static final int getHeightInPx(Context context) {final int height = context.getResources().getDisplayMetrics().heightPixels;return height;}public static final int getWidthInPx(Context context) {final int width = context.getResources().getDisplayMetrics().widthPixels;return width;}}</span>

源码下载地址：/Terrybthvi/MyCamera