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Android 创建自己的Camera App

2024-08-12 15:09:03   214人阅读

在sdk中找到/sdk/docs/guide/topics/media/camera.html#custom-camera，里面有详细的api参考

在清单文件中添加相应的权限：

        <uses-permission android:name="android.permission.CAMERA" />    <uses-feature android:name="android.hardware.camera" />    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />    <uses-permission android:name="android.permission.RECORD_AUDIO" />

按照官方文档，分为下面几步：

  • Detect and Access Camera - Create code to check for the existence of cameras and request access.
  • Create a Preview Class - Create a camera preview class that extends SurfaceView and implements theSurfaceHolder interface. This class previews the live images from the camera.
  • Build a Preview Layout - Once you have the camera preview class, create a view layout that incorporates the preview and the user interface controls you want.
  • Setup Listeners for Capture - Connect listeners for your interface controls to start image or video capture in response to user actions, such as pressing a button.
  • Capture and Save Files - Setup the code for capturing pictures or videos and saving the output.
  • Release the Camera - After using the camera, your application must properly release it for use by other applications.

接下来分别实现：

1、检查设备是否有照相机

    /** 检查设备是否存在照相机 */    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;        }    }

2、得到一个照相机

 /** 一种安全的方式获取Cameer对象的实例. */    public static Camera getCameraInstance(){        Camera c = null;        try {            c = Camera.open(); // attempt to get a Camera instance        }        catch (Exception e){            // Camera is not available (in use or does not exist)        }        return c; // returns null if camera is unavailable    }

3、新建一个名为CameraPreview的类

package com.wuyudong.mycamera;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 {    private static final String TAG = "CameraPreview";    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.        mHolder = getHolder();        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 {            mCamera.setPreviewDisplay(holder);            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());        }    }}

4、设置一个预览功能的layout，将原来布局文件中的内容替换成下面的代码

<?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>

5、在清单文件中加入 android:screenOrientation="landscape" 调整相机为横向拍摄

6、在MainActivity中添加

public class MainActivity extends Activity {    private Camera mCamera;    private CameraPreview mPreview;    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        // Create an instance of Camera        mCamera = getCameraInstance();        // Create our Preview view and set it as the content of our activity.        mPreview = new CameraPreview(this, mCamera);        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);        preview.addView(mPreview);    }}

7、实现拍摄按钮的功能

（1）添加拍照回调方法

    private PictureCallback mPicture = new PictureCallback() {        @Override        public void onPictureTaken(byte[] data, Camera camera) {            File pictureFile = new File("/sdcard/" + System.currentTimeMillis()+".jpg");            try {                FileOutputStream fos = new FileOutputStream(pictureFile);                fos.write(data);                fos.close();            } catch (IOException e) {                Log.d("TAG", "Error accessing file: " + e.getMessage());            }        }    };

给拍照按钮添加注册事件：

        // Add a listener to the Capture button        Button captureButton = (Button) findViewById(R.id.button_capture);        captureButton.setOnClickListener(            new View.OnClickListener() {                @Override                public void onClick(View v) {                    // get an image from the camera                    mCamera.takePicture(null, null, mPicture);                }            }        );

完整的代码如下：

package com.wuyudong.mycamera;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.sql.Date;import android.os.Bundle;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.util.Log;import android.view.Menu;import android.view.View;import android.widget.Button;import android.widget.FrameLayout;public class MainActivity extends Activity {    private Camera mCamera;    private CameraPreview mPreview;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        // 创建一个 Camera 的实例        mCamera = getCameraInstance();        // 创建一个预览界面        mPreview = new CameraPreview(this, mCamera);        FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);        preview.addView(mPreview);                // Add a listener to the Capture button        Button captureButton = (Button) findViewById(R.id.button_capture);        captureButton.setOnClickListener(            new View.OnClickListener() {                @Override                public void onClick(View v) {                    mCamera.autoFocus(new AutoFocusCallback() {  // 对焦                                                @Override                        public void onAutoFocus(boolean success, Camera camera) {                            // get an image from the camera                            mCamera.takePicture(null, null, mPicture);                                                    }                    });                                    }            }        );    }    /** 检查设备是否存在照相机 */    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;        }    }    /** 一种安全的方式获取Cameer对象的实例. */    public static Camera getCameraInstance() {        Camera c = null;        try {            c = Camera.open(); // attempt to get a Camera instance        } 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() {        @Override        public void onPictureTaken(byte[] data, Camera camera) {            File pictureFile = new File("/sdcard/" + System.currentTimeMillis()+".jpg");            try {                FileOutputStream fos = new FileOutputStream(pictureFile);                fos.write(data);                fos.close();            } catch (IOException e) {                Log.d("TAG", "Error accessing file: " + e.getMessage());            }        }    };        protected void onDestory() {        if(mCamera != null) {    //释放资源            mCamera.release();            mCamera = null;        }    }}

 

Android 创建自己的Camera App


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