android之相机开发
android之相机开发
在android中应用相机功能,一般有两种:一种是直接调用系统相机,一种自己写的相机。
我将分别演示两种方式的使用:
第一种:是使用Intent跳转到系统相机,action为:android.media.action.STILL_IMAGE_CAMERA
关键代码:
- Intent intent = new Intent(); //调用照相机
- intent.setAction("android.media.action.STILL_IMAGE_CAMERA");
- startActivity(intent);
例子:
- import android.app.Activity;
- import android.content.Intent;
- import android.os.Bundle;
- public class CameraTest_2 extends Activity {
- /** Called when the activity is first created. */
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- setContentView(R.layout.main);
- Intent intent = new Intent(); //调用照相机
- intent.setAction("android.media.action.STILL_IMAGE_CAMERA");
- startActivity(intent);
- }
- }
想要测试的,可以直接新建一个项目,并且把主activity的代码换成上面的,然后运行,我测试了一下,上面这个代码并不
需要权限,毕竟只是调用系统自带的程序。
当然网上还有一些其他相关的调用方法,只要设置对了action,那么系统就会调用系统自带的相机.
第二种:
(1)首先我们要自己创建一个照相界面,必须考虑用什么控件显示照相机中的预览效果,显然android已经帮我们做好了选择,那就是SurfaceView
控制SurfaceView需要一个surfaceHolder,他是系统提供的一个用来设置SurfaceView的一个对象,可以通过surfaceView.getHolder()这个方法来获得.
Camera提供一个setPreviewDisplay(SurfaceHolder)的方法来连接surfaceHolder,并通过他来控制surfaceView.
而我们则使用android的Camera类提供了startPreview()和stopPreview()来开启和关闭预览.
关系如下:
Camera -- -->SurfaceHolder------>SurfaceView.
(2)知道怎么预览了,当然也要知道怎么开启相机.Camera.open()这是个静态方法,如果相机没有别人用着,则会返回一个 相机引用,如果被人用着,则会抛出异常。很奇怪的是,这个方法,不能随便放,如放在构造方法或者onCreate()方法中,都会照成没有预览效果.
(3)
SurfaceHolder.Callback,这是个holder用来显示surfaceView 数据的接口,他分别必须实现3个方法
surfaceCreated()这个方法是surface 被创建后调用的
surfaceChanged()这个方法是当surfaceView发生改变后调用的
surfaceDestroyed()这个是当surfaceView销毁时调用的.
surfaceHolde通过addCallBack()方法将响应的接口绑定到他身上.
surfaceHolder还必须设定一个setType()方法,查看api的时候,发现这个方法已经过时,但是不写,又会报错
(4)
我用以上知识写了一个MySurfaceView类,他继承于SurfaceView,并在里面实现了照相机的预览功能.这个我觉得最简单的照相机预览代码:
MySurfaceView.java:
- import java.io.IOException;
- import android.content.Context;
- import android.graphics.PixelFormat;
- import android.hardware.Camera;
- import android.util.Log;
- import android.view.SurfaceHolder;
- import android.view.SurfaceView;
- public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback{
- SurfaceHolder holder;
- Camera myCamera;
- public MySurfaceView(Context context)
- {
- super(context);
- holder = getHolder();//获得surfaceHolder引用
- holder.addCallback(this);
- holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//设置类型
- }
- @Override
- public void surfaceCreated(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- if(myCamera == null)
- {
- myCamera = Camera.open();//开启相机,不能放在构造函数中,不然不会显示画面.
- try {
- myCamera.setPreviewDisplay(holder);
- } catch (IOException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }
- @Override
- public void surfaceChanged(SurfaceHolder holder, int format, int width,
- int height) {
- myCamera.startPreview();
- }
- @Override
- public void surfaceDestroyed(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- myCamera.stopPreview();//停止预览
- myCamera.release();//释放相机资源
- myCamera = null;
- Log.d("ddd", "4");
- }
- }
主activity代码:
- import android.app.Activity;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- public class CameraTest_3 extends Activity {
- /** Called when the activity is first created. */
- MySurfaceView mySurface;
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- mySurface = new MySurfaceView(this);
- setContentView(mySurface);
- }
- }
而且必须给应用添加权限:
- <uses-permission android:name="android.permission.CAMERA"></uses-permission>
(5)能够预览了,接下来就是拍照了,拍照用到了一个camera.tackPiture()这个方法,这个方法,有三个参数分别是
ShutterCallBack shutter,PictureCallBack raw,PictureCallBack jpeg.
下面是对他们的实现
- private ShutterCallback shutter = new ShutterCallback() {
- @Override
- public void onShutter() {
- // TODO Auto-generated method stub
- Log.d("ddd", "shutter");
- }
- };
- private PictureCallback raw = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- Log.d("ddd", "raw");
- }
- };
- private PictureCallback jpeg = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- Log.d("ddd","jpeg");
- }
- };
当开始拍照时,会依次调用shutter的onShutter()方法,raw的onPictureTaken方法,jpeg的onPictureTaken方法.
三个参数的作用是shutter--拍照瞬间调用,raw--获得没有压缩过的图片数据,jpeg---返回jpeg的图片数据
当你不需要对照片进行处理,可以直接用null代替.
注意,当调用camera.takePiture方法后,camera关闭了预览,这时需要调用startPreview()来重新开启预览。
我用以上知识,加到上面的那个例子,就形成了下面的代码:
MySurfaceView.java:
- package jason.camera;
- import java.io.IOException;
- import android.content.Context;
- import android.graphics.PixelFormat;
- import android.hardware.Camera;
- import android.hardware.Camera.PictureCallback;
- import android.hardware.Camera.ShutterCallback;
- import android.util.Log;
- import android.view.SurfaceHolder;
- import android.view.SurfaceView;
- public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback{
- SurfaceHolder holder;
- Camera myCamera;
- private ShutterCallback shutter = new ShutterCallback() {
- @Override
- public void onShutter() {
- // TODO Auto-generated method stub
- Log.d("ddd", "shutter");
- }
- };
- private PictureCallback raw = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- Log.d("ddd", "raw");
- }
- };
- private PictureCallback jpeg = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- Log.d("ddd","jpeg");
- }
- };
- public MySurfaceView(Context context)
- {
- super(context);
- holder = getHolder();//获得surfaceHolder引用
- holder.addCallback(this);
- holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//设置类型
- }
- public void tackPicture()
- {
- myCamera.takePicture(null,null,null);
- }
- public void voerTack()
- {
- myCamera.startPreview();
- }
- @Override
- public void surfaceChanged(SurfaceHolder holder, int format, int width,
- int height) {
- myCamera.startPreview();
- }
- @Override
- public void surfaceCreated(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- if(myCamera == null)
- {
- myCamera = Camera.open();//开启相机,不能放在构造函数中,不然不会显示画面.
- try {
- myCamera.setPreviewDisplay(holder);
- } catch (IOException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }
- @Override
- public void surfaceDestroyed(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- myCamera.stopPreview();//停止预览
- myCamera.release();//释放相机资源
- myCamera = null;
- }
- }
主activity:
- import android.app.Activity;
- import android.os.Bundle;
- import android.view.View;
- import android.view.View.OnClickListener;
- public class CameraTest_3 extends Activity implements OnClickListener {
- /** Called when the activity is first created. */
- MySurfaceView mySurface;
- boolean isClicked = false;
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- mySurface = new MySurfaceView(this);
- setContentView(mySurface);
- mySurface.setOnClickListener(this);
- }
- @Override
- public void onClick(View v) {
- // TODO Auto-generated method stub
- if(!isClicked)
- {
- mySurface.tackPicture();
- isClicked = true;
- }else
- {
- mySurface.voerTack();
- isClicked = false;
- }
- }
这样就是实现了拍照的功能,那么怎样要图片保存呢?那么这是就需要在那个参数中的jpeg的
方法里面进行处理了,那个方法的data参数,就是相片的数据。
我们通过BitmapFactory.decodeByteArray(data, 0, data.length)来获得图片并通过io处理,将图片保存到想要保存的位置
下面这段代码,是将照片保存到/sdcard/wjh.jpg;并把一些没有用到的代码全部删掉,剩下一些必须的代码
- package java.camera;
- import java.io.BufferedInputStream;
- import java.io.BufferedOutputStream;
- import java.io.File;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import java.io.OutputStream;
- import android.content.Context;
- import android.graphics.Bitmap;
- import android.graphics.BitmapFactory;
- import android.graphics.PixelFormat;
- import android.hardware.Camera;
- import android.hardware.Camera.PictureCallback;
- import android.hardware.Camera.ShutterCallback;
- import android.util.Log;
- import android.view.SurfaceHolder;
- import android.view.SurfaceView;
- public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback{
- SurfaceHolder holder;
- Camera myCamera;
- private PictureCallback jpeg = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- try
- {
- Bitmap bm = BitmapFactory.decodeByteArray(data, 0, data.length);
- File file = new File("/sdcard/wjh.jpg");
- BufferedOutputStream bos
- = new BufferedOutputStream(new FileOutputStream(file));
- bm.compress(Bitmap.CompressFormat.JPEG,100,bos);
- bos.flush();
- bos.close();
- }catch(Exception e)
- {
- e.printStackTrace();
- }
- }
- };
- public MySurfaceView(Context context)
- {
- super(context);
- holder = getHolder();//获得surfaceHolder引用
- holder.addCallback(this);
- holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);//设置类型
- }
- public void tackPicture()
- {
- myCamera.takePicture(null,null,jpeg);
- }
- public void voerTack()
- {
- myCamera.startPreview();
- }
- @Override
- public void surfaceChanged(SurfaceHolder holder, int format, int width,
- int height) {
- myCamera.startPreview();
- }
- @Override
- public void surfaceCreated(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- if(myCamera == null)
- {
- myCamera = Camera.open();//开启相机,不能放在构造函数中,不然不会显示画面.
- try {
- myCamera.setPreviewDisplay(holder);
- } catch (IOException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }
- @Override
- public void surfaceDestroyed(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- myCamera.stopPreview();//停止预览
- myCamera.release();//释放相机资源
- myCamera = null;
- }
- }
注意,这是必须添加在sd卡上写数据的权限
- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
(7)能够拍照了,这下子要考虑如何让图片更好看了,这显然是专业人士的强项,但是我们在程序上,也可以做一些处理,
向上面的那些,因为我直接把surfaceView当做整体布局,就可能出现屏幕被拉开了,不是很好看,所以这时,就可以不要把
surfaceView弄成整体布局,把他弄到一个布局管理器,再设置相关的参数.
这时需要注意的是有些参数不能随便乱设
如以下代码:
- Camera.Parameters parames = myCamera.getParameters();//获得参数对象
- parames.setPictureFormat(PixelFormat.JPEG);//设置图片格式
- parames.setPreviewSize(640,480);//这里面的参数只能是几个特定的参数,否则会报错.(176*144,320*240,352*288,480*360,640*480)
- myCamera.setParameters(parames);
还有自动对焦,当然有些手机没有这个功能,自动对焦是通过autoFocus()这个方法调用一个自动对焦的接口,并在里面进行处理。
注意,这个方法必须在startPreview()和stopPreview()中间。
AutoFocusCallback是自动对焦的接口,实现它必须实现public void onAutoFocus(boolean success, Camera camera)这个方法,
所以我们可以将拍照方法放在这里面,然后对焦后再进行拍摄。。效果会好很多。
注意自动对焦需要添加
- <uses-feature android:name="android.hardware.camera.autofocus" />
下面是主要代码,直接贴出来了
- import java.io.BufferedOutputStream;
- import java.io.File;
- import java.io.FileOutputStream;
- import java.io.IOException;
- import android.app.Activity;
- import android.content.pm.ActivityInfo;
- import android.graphics.Bitmap;
- import android.graphics.BitmapFactory;
- import android.graphics.PixelFormat;
- import android.hardware.Camera;
- import android.hardware.Camera.AutoFocusCallback;
- import android.hardware.Camera.PictureCallback;
- import android.os.Bundle;
- import android.view.SurfaceHolder;
- import android.view.SurfaceView;
- import android.view.View;
- import android.view.Window;
- import android.view.SurfaceHolder.Callback;
- import android.view.View.OnClickListener;
- public class CameraTest_4 extends Activity implements
- Callback, OnClickListener, AutoFocusCallback{
- SurfaceView mySurfaceView;//surfaceView声明
- SurfaceHolder holder;//surfaceHolder声明
- Camera myCamera;//相机声明
- String filePath="/sdcard/wjh.jpg";//照片保存路径
- boolean isClicked = false;//是否点击标识
- //创建jpeg图片回调数据对象
- PictureCallback jpeg = new PictureCallback() {
- @Override
- public void onPictureTaken(byte[] data, Camera camera) {
- // TODO Auto-generated method stub
- try
- {// 获得图片
- Bitmap bm = BitmapFactory.decodeByteArray(data, 0, data.length);
- File file = new File(filePath);
- BufferedOutputStream bos =
- new BufferedOutputStream(new FileOutputStream(file));
- bm.compress(Bitmap.CompressFormat.JPEG, 100, bos);//将图片压缩到流中
- bos.flush();//输出
- bos.close();//关闭
- }catch(Exception e)
- {
- e.printStackTrace();
- }
- }
- };
- /** Called when the activity is first created. */
- @Override
- public void onCreate(Bundle savedInstanceState) {
- super.onCreate(savedInstanceState);
- requestWindowFeature(Window.FEATURE_NO_TITLE);//无标题
- //设置拍摄方向
- this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
- setContentView(R.layout.main);
- //获得控件
- mySurfaceView = (SurfaceView)findViewById(R.id.surfaceView1);
- //获得句柄
- holder = mySurfaceView.getHolder();
- //添加回调
- holder.addCallback(this);
- //设置类型
- holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
- //设置监听
- mySurfaceView.setOnClickListener(this);
- }
- @Override
- public void surfaceChanged(SurfaceHolder holder, int format, int width,
- int height) {
- // TODO Auto-generated method stub
- //设置参数并开始预览
- Camera.Parameters params = myCamera.getParameters();
- params.setPictureFormat(PixelFormat.JPEG);
- params.setPreviewSize(640,480);
- myCamera.setParameters(params);
- myCamera.startPreview();
- }
- @Override
- public void surfaceCreated(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- //开启相机
- if(myCamera == null)
- {
- myCamera = Camera.open();
- try {
- myCamera.setPreviewDisplay(holder);
- } catch (IOException e) {
- // TODO Auto-generated catch block
- e.printStackTrace();
- }
- }
- }
- @Override
- public void surfaceDestroyed(SurfaceHolder holder) {
- // TODO Auto-generated method stub
- //关闭预览并释放资源
- myCamera.stopPreview();
- myCamera.release();
- myCamera = null;
- }
- @Override
- public void onClick(View v) {
- // TODO Auto-generated method stub
- if(!isClicked)
- {
- myCamera.autoFocus(this);//自动对焦
- isClicked = true;
- }else
- {
- myCamera.startPreview();//开启预览
- isClicked = false;
- }
- }
- @Override
- public void onAutoFocus(boolean success, Camera camera) {
- // TODO Auto-generated method stub
- if(success)
- {
- //设置参数,并拍照
- Camera.Parameters params = myCamera.getParameters();
- params.setPictureFormat(PixelFormat.JPEG);
- params.setPreviewSize(640,480);
- myCamera.setParameters(params);
- myCamera.takePicture(null, null, jpeg);
- }
- }
- }
main.xml:
- <linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
- androidrientation="vertical"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- >
- <surfaceview android:id="@+id/surfaceView1"
- android:layout_width="640px"
- android:layout_height="480px"
- android:layout_gravity="center">
AndroidManifest.xml:
- <?xml version="1.0" encoding="utf-8"?>
- <manifest xmlns:android="http://schemas.android.com/apk/res/android"
- package="com.wjh.camera"
- android:versionCode="1"
- android:versionName="1.0">
- <uses-sdk android:minSdkVersion="7" />
- <uses-permission android:name="android.permission.CAMERA"></uses-permission>
- <uses-feature android:name="android.hardware.camera.autofocus" />
- <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
- <application android:icon="@drawable/icon" android:label="@string/app_name">
- <activity android:name=".CameraTest_4"
- android:label="@string/app_name">
- <intent-filter>
- <action android:name="android.intent.action.MAIN" />
- <category android:name="android.intent.category.LAUNCHER" />
- </intent-filter>
- </activity>
- </application>
- </manifest>
PS:其实自己去实现相机的必要性不大,大部分应用都是直接调用系统的相机,毕竟相机是涉及到一些比较专业的成像知识.
posted on 2015-08-28 14:07 qingchen1984 阅读(437) 评论(0) 编辑 收藏 举报