利用zxing识别图片二维码

图片处理

import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;

public class ImageUtils {	
	/**
	 * drawableToBitmap with white background
	 * @param drawable
	 * @return
	 */
	public static Bitmap drawableToBitmap(Drawable drawable) {
        // 取 drawable 的长宽
        int w = drawable.getIntrinsicWidth();
        int h = drawable.getIntrinsicHeight();
        
        // 取 drawable 的颜色格式
        Bitmap.Config config = Bitmap.Config.ARGB_8888;
        // 建立对应 bitmap
        Bitmap bitmap = Bitmap.createBitmap(w, h, config);
        // 建立对应 bitmap 的画布
        Canvas canvas = new Canvas(bitmap);
        // 白色底色   应对透明图
        Paint paint = new Paint();
        paint.setColor(Color.WHITE);
        canvas.drawRect(0, 0, w, h, paint);
        drawable.setBounds(0, 0, w, h);
        // 把 drawable 内容画到画布中
        drawable.draw(canvas);
        return bitmap;
    }
	
	/**
	 * YUV420sp
	 * 
	 * @param inputWidth
	 * @param inputHeight
	 * @param scaled
	 * @return
	 */
	public static byte[] getYUV420sp(int inputWidth, int inputHeight,
			Bitmap scaled) {
		int[] argb = new int[inputWidth * inputHeight];

		scaled.getPixels(argb, 0, inputWidth, 0, 0, inputWidth, inputHeight);

		byte[] yuv = new byte[inputWidth * inputHeight * 3 / 2];
		
		encodeYUV420SP(yuv, argb, inputWidth, inputHeight);

		scaled.recycle();

		return yuv;
	}

	/**
	 * RGB转YUV420sp
	 * 
	 * @param yuv420sp
	 *            inputWidth * inputHeight * 3 / 2
	 * @param argb
	 *            inputWidth * inputHeight
	 * @param width
	 * @param height
	 */
	private static void encodeYUV420SP(byte[] yuv420sp, int[] argb, int width,
			int height) {
		// 帧图片的像素大小
		final int frameSize = width * height;
		// ---YUV数据---
		int Y, U, V;
		// Y的index从0开始
		int yIndex = 0;
		// UV的index从frameSize开始
		int uvIndex = frameSize;

		// ---颜色数据---
//		int a, R, G, B;
		int R, G, B;
		//
		int argbIndex = 0;
		//

		// ---循环所有像素点，RGB转YUV---
		for (int j = 0; j < height; j++) {
			for (int i = 0; i < width; i++) {

				// a is not used obviously
//				a = (argb[argbIndex] & 0xff000000) >> 24;
				R = (argb[argbIndex] & 0xff0000) >> 16;
				G = (argb[argbIndex] & 0xff00) >> 8;
				B = (argb[argbIndex] & 0xff);
				//
				argbIndex++;

				// well known RGB to YUV algorithm
				Y = ((66 * R + 129 * G + 25 * B + 128) >> 8) + 16;
				U = ((-38 * R - 74 * G + 112 * B + 128) >> 8) + 128;
				V = ((112 * R - 94 * G - 18 * B + 128) >> 8) + 128;

				//
				Y = Math.max(0, Math.min(Y, 255));
				U = Math.max(0, Math.min(U, 255));
				V = Math.max(0, Math.min(V, 255));

				// NV21 has a plane of Y and interleaved planes of VU each
				// sampled by a factor of 2
				// meaning for every 4 Y pixels there are 1 V and 1 U. Note the
				// sampling is every other
				// pixel AND every other scanline.
				// ---Y---
				yuv420sp[yIndex++] = (byte) Y;
				// ---UV---
				if ((j % 2 == 0) && (i % 2 == 0)) {
					//
					yuv420sp[uvIndex++] = (byte) V;
					//
					yuv420sp[uvIndex++] = (byte) U;
				}
			}
		}
	}
}

二维码读取，bitmap-->yuv数据--->解析

import java.util.Hashtable;

import android.graphics.Bitmap;
import android.graphics.drawable.Drawable;

import com.google.zxing.BarcodeFormat;
import com.google.zxing.BinaryBitmap;
import com.google.zxing.DecodeHintType;
import com.google.zxing.PlanarYUVLuminanceSource;
import com.google.zxing.Result;
import com.google.zxing.common.HybridBinarizer;
import com.google.zxing.qrcode.QRCodeReader;

public class QRCodeUtils {

	public static String getStringFromQRCode(Drawable drawable) {
		String httpString = null;
        
		Bitmap bmp = ImageUtils.drawableToBitmap(drawable);
		byte[] data = ImageUtils.getYUV420sp(bmp.getWidth(), bmp.getHeight(), bmp);
		// 处理
        try {
            Hashtable<DecodeHintType, Object> hints = new Hashtable<DecodeHintType, Object>();
//            hints.put(DecodeHintType.CHARACTER_SET, "utf-8");
            hints.put(DecodeHintType.TRY_HARDER, Boolean.TRUE);
            hints.put(DecodeHintType.POSSIBLE_FORMATS, BarcodeFormat.QR_CODE);
            PlanarYUVLuminanceSource source = new PlanarYUVLuminanceSource(data, 
            		bmp.getWidth(), 
            		bmp.getHeight(),
    				0, 0,
    				bmp.getWidth(), 
    				bmp.getHeight(),
    				false);
            BinaryBitmap bitmap1 = new BinaryBitmap(new HybridBinarizer(source)); 
            QRCodeReader reader2= new QRCodeReader();
            Result result = reader2.decode(bitmap1, hints);

            httpString = result.getText();
        } catch (Exception e) {
            e.printStackTrace();
        } 
        
        bmp.recycle();
        bmp = null;
        
        return httpString;
	}
}

调用示例

String http = QRCodeUtils.getStringFromQRCode(drawable);

注意：

1. png图片的透明部分要处理好
2. 将图片转换成yuv可以提高识别率