android - 使用自定义相机的 SurfaceView 放大和缩小功能

Question

我已经编写了与自定义相机一起使用的代码，为此我正在使用 SurfaceView，现在我想知道如果我需要实现放大和缩小功能怎么办，我从来没有开发过这种应用程序。

我用来创建自定义相机的代码，如下所示:

MainActivity.java:-

public class MainActivity extends Activity {

    private SurfaceView preview=null;   
    private SurfaceHolder previewHolder=null;   
    public Camera camera ;    
    private boolean inPreview=false;   
    ImageButton btnCapture;


    @SuppressWarnings("deprecation")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);     

            preview=(SurfaceView)findViewById(R.id.surface);     
            previewHolder=preview.getHolder();    
            previewHolder.addCallback(surfaceCallback);    
            previewHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS); 
            previewHolder.setFixedSize(getWindow().getWindowManager()     
                    .getDefaultDisplay().getWidth(), getWindow().getWindowManager() 
                    .getDefaultDisplay().getHeight()); 

      btnCapture = (ImageButton) findViewById(R.id.btnCapture);

      btnCapture.setOnClickListener(new View.OnClickListener() {
          @Override
          public void onClick(View v) {
           Toast.makeText(getApplicationContext(), "Capture Image(s)", Toast.LENGTH_LONG).show();           
          }
      });
    }

    @Override
    public void onResume() {  
        super.onResume();   
        camera=Camera.open(); 
    }  

    @Override   
    public void onPause() {  
        super.onPause();  
        if (inPreview) {  
            camera.stopPreview();   }   
        camera.release();   
        camera=null;   
        inPreview=false;         
    }   


    private Camera.Size getBestPreviewSize(int width, int height,Camera.Parameters parameters){   
        Camera.Size result=null;   
        for (Camera.Size size : parameters.getSupportedPreviewSizes()) 
        {   
            if (size.width<=width && size.height<=height)
            {
                if (result==null) {  
                    result=size;   
                }   else {  
                    int resultArea=result.width*result.height; 
                    int newArea=size.width*size.height;  
                    if (newArea>resultArea) {   
                        result=size;   
                    }  
                }   
            }   
        }   
        return(result);   
    }

    SurfaceHolder.Callback surfaceCallback=new SurfaceHolder.Callback(){

        public void surfaceCreated(SurfaceHolder holder) {     
            try {        
                camera.setPreviewDisplay(previewHolder); 
            }   catch (Throwable t) {   
                Log.e("PreviewDemo-surfaceCallback",
                  "Exception in setPreviewDisplay()", t);
                Toast.makeText(MainActivity.this, t.getMessage(), Toast.LENGTH_LONG).show();       
            }     
        }      

        public void surfaceChanged(SurfaceHolder holder,int format, int width,int height) {
            Camera.Parameters parameters=camera.getParameters();       
            Camera.Size size=getBestPreviewSize(width, height,                                           
                    parameters);       
            if (size!=null) {      
                parameters.setPreviewSize(size.width, size.height);
                camera.setParameters(parameters);       
                camera.startPreview();       
                inPreview=true;       
            }     
        }

        public void surfaceDestroyed(SurfaceHolder holder) {

        }   
    };       
}

activity_main.xml:-

<RelativeLayout 
   xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:background="@drawable/splash_background" >

    <android.view.SurfaceView   
        android:id="@+id/surface"  
        android:layout_width="fill_parent"  
        android:layout_height="fill_parent" />

    <ImageButton
        android:id="@+id/btnCapture"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:background="@drawable/capture"
        android:contentDescription="@string/app_name" />

    </RelativeLayout>

Answer 1

我通过使用多个链接找到了一种方法，它对我有用，最后我将代码添加到我的 surfaceChanged(...) 中，我完整的 surfaceChanged(..) 代码 如下所示:

声明名为 currentZoomLevel 的 int 数据类型的变量 并指定 0 作为初始值值(value)，

  int currentZoomLevel = 0;

代码:-

 public void surfaceChanged(SurfaceHolder holder,int format, int width,int height) {
            params = camera.getParameters();       
            params.setFlashMode(Camera.Parameters.FLASH_MODE_ON);
            Camera.Size size=getBestPreviewSize(width, height,                                           
                    params);       
            if (size!=null) {      
                params.setPreviewSize(size.width, size.height);
                camera.setParameters(params);       
                camera.startPreview();       
                inPreview=true;   
                ZoomControls zoomControls = (ZoomControls) findViewById(R.id.zoomControls);

                if (params.isZoomSupported()) {
                    final int maxZoomLevel = params.getMaxZoom();
                    Log.i("max ZOOM ", "is " + maxZoomLevel);
                    zoomControls.setIsZoomInEnabled(true);
                    zoomControls.setIsZoomOutEnabled(true);

                    zoomControls.setOnZoomInClickListener(new OnClickListener(){
                        public void onClick(View v){
                            if(currentZoomLevel < maxZoomLevel){
                                currentZoomLevel++;
                                //mCamera.startSmoothZoom(currentZoomLevel);
                                params.setZoom(currentZoomLevel);
                                camera.setParameters(params);
                            }
                        }
                    });

                    zoomControls.setOnZoomOutClickListener(new OnClickListener(){
                        public void onClick(View v){
                            if(currentZoomLevel > 0){
                                currentZoomLevel--;
                                params.setZoom(currentZoomLevel);
                                camera.setParameters(params);
                            }
                        }
                    });    
                }
                else
                    zoomControls.setVisibility(View.GONE);
                }     
            }   

XML:-

<ZoomControls
    android:id="@+id/zoomControls"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_centerHorizontal="true" />

我把我的答案贴出来，只是为了更清楚和供观众将来使用..