（一）Zxing二維碼掃描框大小調整

控制掃描框大小程式碼是在CameraManager類中

google在CameraManager類中設定掃描框大小主要在getFramingRect()中：

  private static final int MIN_FRAME_WIDTH = 240;
  private static final int MIN_FRAME_HEIGHT = 240;
  private static final int MAX_FRAME_WIDTH = 480;
  private static final int MAX_FRAME_HEIGHT = 360;
  
public Rect getFramingRect() {
    Point screenResolution = configManager.getScreenResolution();
    if (framingRect == null) {
      if (camera == null) {
        return null;
      }
    int width = screenResolution.x * 3 / 4;
      if (width < MIN_FRAME_WIDTH) {
        width = MIN_FRAME_WIDTH;
      } else if (width > MAX_FRAME_WIDTH) {
        width = MAX_FRAME_WIDTH;
      }
      int height = screenResolution.y * 3 / 4;
      if (height < MIN_FRAME_HEIGHT) {
        height = MIN_FRAME_HEIGHT;
      } else if (height > MAX_FRAME_HEIGHT) {
        height = MAX_FRAME_HEIGHT;
      }
     int leftOffset = (screenResolution.x - width) / 2;
     int topOffset = (screenResolution.y - height) / 2;

      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.d(TAG, "Calculated framing rect: " + framingRect);
    }
    return framingRect;
  }
 

 public Rect getFramingRect() {
    Point screenResolution = configManager.getScreenResolution();
    if (framingRect == null) {
      if (camera == null) {
        return null;
      }
     DisplayMetrics metrics = context.getResources().getDisplayMetrics();
     int width = (int)(metrics.widthPixels * 0.6);
     int height = (int)(width * 0.9); 
     int leftOffset = (screenResolution.x - width) / 2;
     int topOffset = (screenResolution.y - height) / 2;
      framingRect = new Rect(leftOffset, topOffset, leftOffset + width, topOffset + height);
      Log.d(TAG, "Calculated framing rect: " + framingRect);
    }
    return framingRect;
  }
 

以上方式可以實現掃描框擴大，但是部分機型會出現，掃描後閃退現象，原因是在 MipcaActivityCapture的handleDecode中向bundle中新增的bitmap過大，程式碼是bundle.putParcelable("bitmap", barcode);  handleDecode是用來處理掃描結果的，例如向呼叫MipcaActivityCapture的Activity回傳掃描結果和掃描得到的bitmap。但bitmap不能過大超出記憶體限制就會奔潰。

解決的辦法：如果不需要顯示掃描得到的圖片，我們可以不將bitmap匯入bundle,直接將bundle.putParcelable("bitmap", barcode)註釋掉。

                     如果一定要獲得bitmap,則需要在匯入前將bitmap壓縮

（二）Zxing是google提供的二維碼掃描工程

掃描框預設是橫屏的轉換成豎屏後圖片會出現拉伸現象

解決的辦法:

Zxing  修改 CameraConfigurationManager.Java檔案的

void initFromCameraParameters(Camera camera)方法，在 Log.d(TAG, "Screen resolution: " + screenResolution);這句之後增加

Point screenResolutionForCamera = new Point();  
        screenResolutionForCamera.x = screenResolution.x;  
        screenResolutionForCamera.y = screenResolution.y;  
        // preview size is always something like 480*320, other 320*480  
        if (screenResolution.x < screenResolution.y) {  
        screenResolutionForCamera.x = screenResolution.y;  
        screenResolutionForCamera.y = screenResolution.x;  
        }  

cameraResolution = getCameraResolution(parameters, screenResolution); 

cameraResolution = getCameraResolution(parameters, screenResolutionForCamera);