Android 放大镜效果实现.pdf

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1、Android 放大镜效果实现放大镜就是直接调用相机，使用放大缩小的功能实现，调用相机有两种方式，一种是直接调用系统的；另一种是自定义相机，需要自定义一个预览界面，下面简单介绍自定义相机方式：参考:http:/ 里添加使用相机的权限/使用相机属性/相机自动对焦12345671234567然后再判断是否有相机存在：/*Check if this device has a camera*/private boolean checkCameraHardware(Context context)if(context.getPackageManager().hasSystemFeature(Packag

2、eManager.FEATURE_CAMERA)/this device has a camerareturn true;else/no camera on this devicereturn false;12345678910123456789102.打开相机，官网实现的安全方式打开相机/*A safe way to get an instance of the Camera object.*/public static Camera getCameraInstance()Camera c=null;try c=Camera.open();/attempt to get a Camerain

3、stancecatch(Exception e)/Camera is not available(in use or does notexist)return c;/returns null if camera is unavailable123456789101112345678910113、创建预览窗口，这是最主要的部分SurfaceView：该类是一个视图组件，实现了照片的预览功能。SurfaceHolder：一个抽象接口，是 SurfaceView 的支持类，一般通过 SurfaceView 的 getHolder()方法获得。允许你控制界面的尺寸和格式、编辑界面的像素，以及监控界面尺

4、寸的改变。SurfaceHolder.Callback：SurfaceHolder 的一个内部接口，可以实现该接口获取界面改变的信息。该接口中有三个方法，surfaceCreated()方法在界面创建时被调用，一般在该方法中打开 照相机并设置预览。surfaceChanged()方法在界面尺寸改变时 被调用，一般在该方法中设置相机的参数（大小、格式等）。surfaceDestroyed()方法在界面被销毁时调用，在该方法中清除相机实例，释放资源。Camera：相机类，实现拍照功能。Camera.PictureCallback：Camera 的一个内部接口，处理照片准备好后的回调。接着我们定义预

5、览窗口的自定义 View/*A basic Camera preview class*/public class MyPreview extends SurfaceViewimplements SurfaceHolder.Callback private SurfaceHolder mHolder;private Camera mCamera;public MyPreview(Context context,Cameracamera)super(context);mCamera=camera;/Install a SurfaceHolder.Callback so we getnotified

6、 when the/underlying surface is created anddestroyed.mHolder=getHolder();mHolder.addCallback(this);/deprecated setting,but required on Androidversions prior to 3.0mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);public void surfaceCreated(SurfaceHolder holder)/The Surface has been created,no

7、w tell thecamera where to draw the preview./获取相机属性Camera.Parameters parameters=mCamera.getParameters();/自动对焦parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);/由于相机默认是横屏的，创建时旋转一下调正位置if(this.getResources().getConfiguration().orientation!=Configuration.ORIENTATION_LANDSCAPE)parameters.set(orie

8、ntation,portrait);mCamera.setDisplayOrientation(90);parameters.setRotation(90);elseparameters.set(orientation,landscape);mCamera.setDisplayOrientation(0);parameters.setRotation(0);mCamera.setParameters(parameters);try mCamera.setPreviewDisplay(holder);mCamera.startPreview();catch(IOException e)e.pri

9、ntStackTrace();public void surfaceDestroyed(SurfaceHolderholder)/empty.Take care of releasing the Camerapreview in your activity.public void surfaceChanged(SurfaceHolderholder,int format,int w,int h)/If your preview can change or rotate,takecare of those events here./Make sure to stop the preview be

10、foreresizing or reformatting it.if(mHolder.getSurface()=null)/preview surface does not existreturn;/stop preview before making changestry mCamera.stopPreview();catch(Exception e)/ignore:tried to stop a non-existentpreview/make any resize,rotate or reformattingchanges here/start preview with new sett

11、ingstry mCamera.setPreviewDisplay(mHolder);mCamera.startPreview();catch(Exception e)e.printStackTrace();Overridepublic boolean onTouchEvent(MotionEvent event)/return super.onTouchEvent(event);/按下时自动对焦if(event.getAction()=MotionEvent.ACTION_DOWN)mCamera.autoFocus(null);return true;1234567891011121314

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13、4854、添加 seekbar 调节预览区域的缩放。由于在 Nexus5 上获取到的 maxZoom 是 99，如果你的设备取不到这么大，那么需要将 progress 的刻度乘一个比例，以免报错。/*maxZoom=parameters.getMaxZoom();最大缩放*ratio=100/maxZoom；获取比例*/seekBar.setOnSeekBarChangeListener(newSeekBar.OnSeekBarChangeListener()Camera c=mCamera;Overridepublic void onProgressChanged(SeekBarseekBa

14、r,int progress,boolean fromUser)if(progress/ratio 0)ratio=100/maxZoom;/parameters.setZoom(99);/mCamera.setParameters(parameters);/*maxZoom=parameters.getMaxZoom();最大缩放*ratio=100/maxZoom；获取比例*/seekBar.setOnSeekBarChangeListener(newSeekBar.OnSeekBarChangeListener()Camera c=mCamera;Overridepublic void

15、onProgressChanged(SeekBarseekBar,int progress,boolean fromUser)if(progress/ratio maxZoom)parameters.setZoom(progress/ratio);c.setParameters(parameters);c.autoFocus(null);Overridepublic void onStartTrackingTouch(SeekBarseekBar)Overridepublic void onStopTrackingTouch(SeekBarseekBar);Overrideprotected

16、void onPause()super.onPause();if(mCamera!=null)mCamera.release();Overrideprotected void onResume()super.onResume();mCamera=safeCameraOpen();/cameraprivate Camera safeCameraOpen()Camera c=null;try c=Camera.open();catch(Exception e)Log.e(getString(R.string.app_name),failedto open Camera);e.printStackT

17、race();return c;/自定义相机展览区public class MyPreview extends SurfaceViewimplements SurfaceHolder.Callback private SurfaceHolder mHolder;private Camera mCamera;public MyPreview(Context context,Cameracamera)super(context);mCamera=camera;/Install a SurfaceHolder.Callback so we getnotified when the/underlyin

18、g surface is created anddestroyed.mHolder=getHolder();mHolder.addCallback(this);/deprecated setting,but required on Androidversions prior to 3.0mHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);public void surfaceCreated(SurfaceHolder holder)/The Surface has been created,now tell thecamera wh

19、ere to draw the preview./获取相机属性Camera.Parameters parameters=mCamera.getParameters();/自动对焦parameters.setFocusMode(Camera.Parameters.FOCUS_MODE_AUTO);/由于相机默认是横屏的，创建时旋转一下调正位置if(this.getResources().getConfiguration().orientation!=Configuration.ORIENTATION_LANDSCAPE)parameters.set(orientation,portrait);m

20、Camera.setDisplayOrientation(90);parameters.setRotation(90);elseparameters.set(orientation,landscape);mCamera.setDisplayOrientation(0);parameters.setRotation(0);mCamera.setParameters(parameters);try mCamera.setPreviewDisplay(holder);mCamera.startPreview();catch(IOException e)e.printStackTrace();publ

21、ic void surfaceDestroyed(SurfaceHolderholder)/empty.Take care of releasing the Camerapreview in your activity.public void surfaceChanged(SurfaceHolderholder,int format,int w,int h)/If your preview can change or rotate,takecare of those events here./Make sure to stop the preview beforeresizing or ref

22、ormatting it.if(mHolder.getSurface()=null)/preview surface does not existreturn;/stop preview before making changestry mCamera.stopPreview();catch(Exception e)/ignore:tried to stop a non-existentpreview/make any resize,rotate or reformattingchanges here/start preview with new settingstry mCamera.set

23、PreviewDisplay(mHolder);mCamera.startPreview();catch(Exception e)e.printStackTrace();Overridepublic boolean onTouchEvent(MotionEvent event)/return super.onTouchEvent(event);/按下时自动对焦if(event.getAction()=MotionEvent.ACTION_DOWN)mCamera.autoFocus(null);return true;/*Check if this device has a camera*/p

24、rivate boolean checkCameraHardware(Contextcontext)if(context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA)/this device has a camerareturn true;else/no camera on this devicereturn false;123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051

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