Zxing的简单使用及优化

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随着二维码使用的流行，现在基本上什么APP都会用到二维码功能，所以不管怎样，在项目中集成二维码功能都是非常有必要的。

ZXing

ZXing是由谷歌开发的一款条码，二维码扫描工具
官方github地址： https://github.com/zxing/zxing

这个工程非常庞大包含很多项目，这里主要说一下关于android方面的。

说明

首先需要说明，因为工作的关系，APP的开发一般使用Eclipse，当然偶尔也会用AS。所以这里的开发环境是基于Eclipse的。由于官方android部分，包含了剪切板，扫描历史，分享，扫描二维码等等功能。如果只使用扫码功能，就需要剔除其他的功能。

这里奉上一个自用的库，里面已经包含了最新的zxing.jar包，并且进行了一些界面修改，因为我电脑的操作系统系繁体中文的，所以要在简体操作系统上使用记得要将编码格式改为GBK
链接在此，点击我下载
效果图：
效果图

简单的使用

clone项目，并导入Eclipse后
项目目录
选中项目，快捷键Alt+Enter，打开项目属性窗口，将项目设置为库
属性配置
再新建一个安卓项目，重复操作打开项目属性窗口，点击Add按钮将库项目添加到新项目中去。
在新项目中添加按键监听事件

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Button scanBarCodeButton = (Button) this.findViewById(R.id.btn_scan_barcode);
scanBarCodeButton.setOnClickListener(new OnClickListener() {
	
    @Override
    public void onClick(View v) {
      //打开扫描界面扫描条形码或二维码
      Intent openCameraIntent = new Intent(BarCodeTestActivity.this,CaptureActivity.class);
      startActivityForResult(openCameraIntent, 0);
    }
});

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    //处理扫描结果（在界面上显示）
    if (resultCode == RESULT_OK) {
	    Bundle bundle = data.getExtras();
	    String scanResult = bundle.getString("result");
	    resultTextView.setText(scanResult);
    }
}

到这里就可以使用二维码扫描功能了，不要忘记在AndroidManifest.xml添加权限和对应Activity。

常用功能优化

横屏竖屏修改

1.修改CameraConfigurationManager类中的setDesiredCameraParameters方法

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void setDesiredCameraParameters(Camera camera) {
	Camera.Parameters parameters = camera.getParameters();
	Log.d(TAG, "Setting preview size: " + cameraResolution);
	parameters.setPreviewSize(cameraResolution.x, cameraResolution.y);
	setFlash(parameters);
	setZoom(parameters);

	//**90度豎屏  0為橫屏
	camera.setDisplayOrientation(90);    
	camera.setParameters(parameters);
}

2.修改CameraManager类中的getFramingRectInPreview方法

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public Rect getFramingRectInPreview() {
	if (framingRectInPreview == null) {
	  Rect rect = new Rect(getFramingRect());						
	  Point cameraResolution = configManager.getCameraResolution();
	  Point screenResolution = configManager.getScreenResolution();
	  //**橫屏
	  //rect.left = rect.left * cameraResolution.x / screenResolution.x;
	  //rect.right = rect.right * cameraResolution.x / screenResolution.x;
	  //rect.top = rect.top * cameraResolution.y / screenResolution.y;
	  //rect.bottom = rect.bottom * cameraResolution.y / screenResolution.y;
	  
	  //**豎屏
	  rect.left = rect.left * cameraResolution.y / screenResolution.x;
	  rect.right = rect.right * cameraResolution.y / screenResolution.x;
	  rect.top = rect.top * cameraResolution.x / screenResolution.y;
	  rect.bottom = rect.bottom * cameraResolution.x / screenResolution.y;
	  framingRectInPreview = rect;
	}
	return framingRectInPreview;
}

3.修改DecodeHandler类中的decode方法

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private void decode(byte[] data, int width, int height) {
	long start = System.currentTimeMillis();
	Result rawResult = null;

	//*************************竖屏解码段*****************************
	byte[] rotatedData = new byte[data.length];
	for (int y = 0; y < height; y++) {
		for (int x = 0; x < width; x++)
			rotatedData[x * height + height - y - 1] = data[x + y * width];
	}
	int tmp = width; // Here we are swapping, that's the difference to #11
	width = height;
	height = tmp;
	
	PlanarYUVLuminanceSource source = CameraManager.get().buildLuminanceSource(rotatedData, width, height);
	//**************************************************************
	
	//*****橫屏解碼段*****
	//PlanarYUVLuminanceSource source = CameraManager.get().buildLuminanceSource(data, width, height);
	
	......
}

竖屏拉伸问题

改为竖屏显示时，常常伴有画面拉伸的现象，解决该问题可以修改CameraConfigurationManager类中的initFromCameraParameters方法

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void initFromCameraParameters(Camera camera) {
    Camera.Parameters parameters = camera.getParameters();
    previewFormat = parameters.getPreviewFormat();
    previewFormatString = parameters.get("preview-format");
    Log.d(TAG, "Default preview format: " + previewFormat + '/' + previewFormatString);
    WindowManager manager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = manager.getDefaultDisplay();
    screenResolution = new Point(display.getWidth(), display.getHeight());
    Log.d(TAG, "Screen resolution: " + screenResolution);
    
    //---------------------竖屏拉伸解决函数-----------------
    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, screenResolutionForCamera);
    //-----------------------------------------------------     
    Log.d(TAG, "Camera resolution: " + screenResolution);
}

扫描框美化

绘制白色边框及绿色边角

1.扫描框是自定义组件，要改变样式需要修改ViewfinderView类的onDraw方法，首先添加白色边框方法和边角方法

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private void drawFrame(Canvas canvas, Rect frame){
	//**繪製白色邊框
	paint.setColor(Color.WHITE);
	canvas.drawRect(frame.left, frame.top, frame.right + 1, frame.top + 2, paint);
	canvas.drawRect(frame.left, frame.top + 2, frame.left + 2, frame.bottom - 1, paint);
	canvas.drawRect(frame.right - 1, frame.top, frame.right + 1, frame.bottom - 1, paint);
	canvas.drawRect(frame.left, frame.bottom - 1, frame.right + 1, frame.bottom + 1, paint);
}
private void drawFrameCorner(Canvas canvas, Rect frame){
	//**繪製4個綠色邊角
	paint.setColor(Color.GREEN);
	// 左上角
	canvas.drawRect(frame.left, frame.top, frame.left + 20,frame.top + 10, paint);
	canvas.drawRect(frame.left, frame.top, frame.left + 10,frame.top + 20, paint);
	// 右上角
	canvas.drawRect(frame.right - 20, frame.top, frame.right,frame.top + 10, paint);
	canvas.drawRect(frame.right - 10, frame.top, frame.right,frame.top + 20, paint);
	// 左下角
	canvas.drawRect(frame.left, frame.bottom - 10, frame.left + 20,frame.bottom, paint);
	canvas.drawRect(frame.left, frame.bottom - 20, frame.left + 10,frame.bottom, paint);
	// 右下角
	canvas.drawRect(frame.right - 20, frame.bottom - 10, frame.right,frame.bottom, paint);
	canvas.drawRect(frame.right - 10, frame.bottom - 20, frame.right,frame.bottom, paint);
}

扫描线循环滚动

2.扫描线循环滚动关键代码段

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int move = frame.top + slideTop;      //**掃描線循環滾動
if ((slideTop  += SPEEN_DISTANCE) < frame.bottom - frame.top) {
  canvas.drawRect(frame.left + 2, move-1, frame.right - 1, move+2, paint);
  invalidate();
}else{
  slideTop  = 0;  
}

3.修改ViewfinderView类的onDraw方法改变扫描框样式，只贴出关键部分

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@Override
public void onDraw(Canvas canvas) {
	......
	
	if (resultBitmap != null) {
	  // Draw the opaque result bitmap over the scanning rectangle
	  //paint.setAlpha(OPAQUE);
	  paint.setAlpha(OPAQUE);
	  canvas.drawBitmap(resultBitmap, frame.left, frame.top, paint);
	}else{
	  //******************************扫描框修改*****************************
	  // Draw a two pixel solid black border inside the framing rect
	  drawFrame(canvas, frame);		  //**繪製白色邊框
	  drawFrameCorner(canvas, frame);		//**繪製4個綠色邊角

	  // Draw a red "laser scanner" line through the middle to show decoding is active
	  paint.setColor(laserColor);
	  paint.setAlpha(SCANNER_ALPHA[scannerAlpha]);
	  scannerAlpha = (scannerAlpha + 1) % SCANNER_ALPHA.length;
	  int middle = frame.height() / 2 + frame.top;
	  int move = frame.top + slideTop;      //**掃描線循環滾動
	  if ((slideTop  += SPEEN_DISTANCE) < frame.bottom - frame.top) {
		  canvas.drawRect(frame.left + 2, move-1, frame.right - 1, move+2, paint);
		  invalidate();
	  }else{
		  slideTop  = 0;  
	  }
	  //***************************************************************
	  .....
	}
}

实现重复扫描功能

有些应用可能会需要用到连续扫描的功能，例如当做扫描枪使用之类什么的。修改CaptureActivity的handleDecode方法

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public void handleDecode(Result result, Bitmap barcode) {
	inactivityTimer.onActivity();
	playBeepSoundAndVibrate();
	String resultString = result.getText();
	//FIXME
	if (resultString.equals("")) {
		Toast.makeText(CaptureActivity.this, "Scan failed!", Toast.LENGTH_SHORT).show();
	}else {
		Intent resultIntent = new Intent();
		Bundle bundle = new Bundle();
		bundle.putString("result", resultString);
		resultIntent.putExtras(bundle);
		this.setResult(RESULT_OK, resultIntent);
	}
	hder.postDelayed(rePreview, 2500); 		// **解碼回調函數	
}

/*
 * 掃描界面回調
 */
private static Handler hder = new Handler();
Runnable rePreview = new Runnable() {
	@Override
	public void run() {
		if(LoginActivity.connectSwitch){ connect(); }
		CameraManager.get().startPreview();
		handler.restartPreviewAndDecode();
	}
};

关于回调方法，第二个参数是回调时间，部分机型不能设置太短，会造成程序崩溃
我对小米，索尼，华为，夏普等手机进行测试，2500毫秒是临界点，个人猜测是手机摄像头硬件的限制

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hder.postDelayed(rePreview, 2500);