Android 使用zxing扫描二维码横屏转竖屏

原文地址：http://blog.csdn.net/qq171297273/article/details/51305446

Zxing 竖屏切换 Android

在google上下载的ZxingDemo 为横屏状态

我简单的在Androidmanifest.xml把Activity换成竖屏Android:screenOrientation="portrait"

屏幕虽然正了但是屏幕上显示的拍摄画面还是横着的

查了一些网上的资料结合自己手工调试

在这里总结分享一下

步骤:

1) 在AndroidManifest.xml中把标签 CaptureActivity 的screenOrientation修改为

[java] view plain copy

android:screenOrientation="portrait"

2) 在CameraManager.Java类中的getFramingRectInPreview()替换掉原先的 left right top bottom

[java] view plain copy

//竖屏
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;

3) 在CameraConfigurationManager.java中void setDesiredCameraParameters(Camera camera)方法

在setParameters之前增加

[java] view plain copy

camera.setDisplayOrientation(90);

4) 在DecodeHandler.java中的 decode(byte[] data, int width, int height)方法在

PlanarYUVLuminanceSource source = CameraManager.get().buildLuminanceSource(data, width, height);

之前添加:

[java] view plain copy

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;
data = rotatedData;

5) 将CameraConfigurationManager的 initFromCameraParameters(Camera camera)方法整个替换如下

该方法防止竖屏后屏幕拉伸

[java] view plain copy

/**
* Reads, one time, values from the camera that are needed by the app.
*/
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);
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);
}

还有一种方法我没有用不知道是否真的管用。

原文地址：http://blog.csdn.net/u011511368/article/details/51394732

在使用zxing扫码时，如果做了横竖屏的兼容处理。一般会发现当扫码距离较近时，有些手机上无法识别二维码的问题。
这个主要是由于设定的PreviewSize不对导致的。
主要修改的方法是CameraConfigurationManager.getCameraResolution。
他主要对cameraResolution进行初始化，而这个值有影响了，我们在解码时(DecodeHandler.decode())的解码区域相关。
CameraConfigurationManager.getCameraResolution调用findBestPreviewSizeValue获得PreviewSize。系统本身提供了一套，但是这里我推荐使用以下方式来查找合适的PreviewSize。
1、PreviewSize的height应该大于当前的扫码区域(CameraManager.get().getFramingRect())。
2、PreviewSize的宽高比应该和当前屏幕的宽高比一致，否则会有拉伸的问题。
3、如果按照以上方式未找到合适的，则调用系统之前的方法进行补漏。

进而得到的方法如下:

    private static Point findBestPreviewSizeValue(Camera.Parameters parameters,                                                  Point screenResolution) {        Point point = null;        Rect frame = CameraManager.get().getFramingRect();        int frameSize = frame.right - frame.left;        int discountMax = Integer.MAX_VALUE;        int width = 0;        int height = 0;        List supportedPreviewSizes = parameters.getSupportedPreviewSizes();        for (Size size : supportedPreviewSizes) {            int discount = size.height - frameSize;            if (discount > 0 && size.height * screenResolution.x == screenResolution.y * size.width) {                if (discount < discountMax) {                    discountMax = discount;                    width = size.width;                    height = size.height;                }            }        }        if (width * height != 0) {            point = new Point(width, height);        }        if (point == null) {            String previewSizeValueString = parameters.get("preview-size-values");            // saw this on Xperia            if (previewSizeValueString == null) {                previewSizeValueString = parameters.get("preview-size-value");            }            if (previewSizeValueString != null) {                Log.d(TAG, "preview-size-values parameter: " + previewSizeValueString);                return findBestPreviewSizeValue(previewSizeValueString, screenResolution);            } else {                return null;            }        } else {            return point;        }    }ss

然后在CameraConfigurationManager.getCameraResolution中调用新的方法，如下：

        private static Point getCameraResolution(Camera.Parameters parameters, Point screenResolution) {         Point cameraResolution = null;         cameraResolution = findBestPreviewSizeValue(parameters, screenResolution);         if (cameraResolution == null) {            // Ensure that the camera resolution is a multiple of 8, as the            // screen may not be.            cameraResolution = new Point((screenResolution.x >> 3) << 3,                (screenResolution.y >> 3) << 3);        }         return cameraResolution;    }

另外在CameraManager中修改最大Frame的size也可以提高识别率
更改如下参数：
CameraManager.MAX_FRAME_WIDTH
CameraManager.MAX_FRAME_HEIGHT

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