Android中实现自定义的拍照应用

Posted 2020-08-03 陈驰字新宇

可以参考：http://www.android-doc.com/guide/topics/media/camera.html

一、添加相应的权限

 <uses-permission android:name="android.permission.CAMERA" />
    <uses-feature android:name="android.hardware.camera" /><!-- 拍照的功能 -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />





 <activity
            android:name=".MainActivity"
            android:label="@string/app_name" 
            android:screenOrientation="landscape"><!-- 写死横屏 -->
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
 </activity>

 

二、布局文件的配置

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >
  <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:text="Capture"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    />
</LinearLayout>

 

三、系统关键代码和注释

创建预览类CameraPreview：

import java.io.IOException;

import android.content.Context;
import android.hardware.Camera;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

/** A basic Camera preview class */
public class CameraPreview extends SurfaceView implements SurfaceHolder.Callback {
    public static final String TAG = "camera";
    private SurfaceHolder mHolder;
    private Camera mCamera;

    public CameraPreview(Context context, Camera camera) {
        super(context);
        mCamera = camera;

        // Install a SurfaceHolder.Callback so we get notified when the
        // underlying surface is created and destroyed.
        //获取surfaceview的控制器
        mHolder = getHolder();
        //创建侦听
        mHolder.addCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
    }

    public void surfaceCreated(SurfaceHolder holder) {
        // The Surface has been created, now tell the camera where to draw the preview.
        try {
            //设置摄像头预览界面在holder对应的那个surfaceview
            mCamera.setPreviewDisplay(holder);
            //开始预览
            mCamera.startPreview();
        } catch (IOException e) {
            Log.d(TAG, "Error setting camera preview: " + e.getMessage());
        }
    }

    public void surfaceDestroyed(SurfaceHolder holder) {
        // empty. Take care of releasing the Camera preview in your activity.
    }

    public void surfaceChanged(SurfaceHolder holder, int format, int w, int h) {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (mHolder.getSurface() == null){
          // preview surface does not exist
          return;
        }

        // stop preview before making changes
        try {
            mCamera.stopPreview();
        } catch (Exception e){
          // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here

        // start preview with new settings
        try {
            mCamera.setPreviewDisplay(mHolder);
            mCamera.startPreview();

        } catch (Exception e){
            Log.d(TAG, "Error starting camera preview: " + e.getMessage());
        }
    }
}

 

主类MainActivity：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import android.app.Activity;
import android.content.Context;
import android.content.pm.PackageManager;
import android.hardware.Camera;
import android.hardware.Camera.AutoFocusCallback;
import android.hardware.Camera.PictureCallback;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;

public class MainActivity extends Activity {

    private Camera mCamera;
    private CameraPreview mPreview;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        if(checkCameraHardware(this)){
            // Create an instance of Camera
            //创建摄像头实例
            mCamera = getCameraInstance();
        } else {
            return;
        }

        // Create our Preview view and set it as the content of our activity.
        //创建预览类的对象
        mPreview = new CameraPreview(this, mCamera);
        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
        //把预览类设置为帧布局的子节点
        preview.addView(mPreview);
        
        
        //给按钮设置监听
        Button captureButton = (Button) findViewById(R.id.button_capture);
        captureButton.setOnClickListener(
            new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    //设置聚焦
                    mCamera.autoFocus(new AutoFocusCallback() {
                        
                        @Override
                        public void onAutoFocus(boolean success, Camera camera) {
                             //进行拍照
                            mCamera.takePicture(null, null, mPicture);
                        }
                    });
                   
                }
            }
        );
    }

    
    /** 检测手机是否有摄像头 */
    private boolean checkCameraHardware(Context context) {
        if (context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)){
            // this device has a camera
            return true;
        } else {
            // no camera on this device
            return false;
        }
    }
    
    /** 一个获取摄像头对象的安全实例 */
    public static Camera getCameraInstance(){
        Camera c = null;
        try {
            c = Camera.open(); //获取第一个后置摄像头的实例
        }
        catch (Exception e){
            // Camera is not available (in use or does not exist)
        }
        return c; // returns null if camera is unavailable
    }
    
    private PictureCallback mPicture = new PictureCallback() {

        //拍照时会调用此方法
        //data：照片的字节数组
        @Override
        public void onPictureTaken(byte[] data, Camera camera) {

            try {
                File pictureFile = new File("sdcard/mr.jpg");
                FileOutputStream fos = new FileOutputStream(pictureFile);
                fos.write(data);
                fos.close();
            } catch (FileNotFoundException e) {
                Log.d(CameraPreview.TAG, "File not found: " + e.getMessage());
            } catch (IOException e) {
                Log.d(CameraPreview.TAG, "Error accessing file: " + e.getMessage());
            } finally {
                //拍照完成后重新进入预览
                camera.startPreview();
            }
        }
    };

}

显示效果：