Android中生成彩色位置探測點的二維碼

前段時間項目有需要要顯示彩色探測點的二維碼，網上搜了下，有基於java,c等的源碼。網上的java源碼直接照搬有些問題，自己改了改。不說廢話，先上結果圖。

原理其實很簡單，利用zxing的寫二維碼功能生成二維碼圖片時，對相應像素點進行著色即可。關鍵是如何准確獲取到二維碼探測點在matrix裡的位置。
　　

二維碼一共有40個尺寸。官方叫版本Version。Version 1是21 x 21的矩陣，Version 2是 25 x 25的矩陣，Version 3是29的尺寸，每增加一個version，就會增加4的尺寸，公式是：(V-1)*4 + 21（V是版本號） 最高Version 40，(40-1)*4+21 = 177，所以最高是177 x 177 的正方形。……而三個角的探測點的長度相對來講是固定的。

上面這段話是對二維碼的尺寸規格的說明。另外，探測點在任何尺寸的二維碼中，單邊長度都是8個模塊（包含外圍的一條白邊）。根據這些，我們就可以計算出探測點在像素矩陣中的具體位置了。

利用zxing生成二維碼，是先生成Matrix，再由BarcodeEncoder轉成Bitmap。看BarcodeEncoder中代碼：

    public Bitmap createBitmap(BitMatrix matrix) {
        int width = matrix.getWidth();
        int height = matrix.getHeight();
        int[] pixels = new int[width * height];
        for (int y = 0; y < height; y++) {
            int offset = y * width;
            for (int x = 0; x < width; x++) {
                pixels[offset + x] = matrix.get(x, y) ? BLACK : WHITE;
            }
        }

        Bitmap bitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        bitmap.setPixels(pixels, 0, width, 0, 0, width, height);
        return bitmap;
    }

其中重要的一句

pixels[offset + x] = matrix.get(x, y) ? BLACK : WHITE;

根據矩陣中的0，1做顏色轉換，由此我們可以自己來設定自己所需要的顏色。現在我們的任務就是確定探測點的准確位置。

確定生成的二維碼探測點位置

　　
要想確定生成的二維碼探測點位置，首先要確定生成的二維碼的尺寸。看zxing中的QRCodeWriter類，其中

public BitMatrix encode(String contents,
                      BarcodeFormat format,
                      int width,
                      int height,
                      Map hints) throws WriterException {

if (contents.isEmpty()) {
  throw new IllegalArgumentException("Found empty contents");
}

if (format != BarcodeFormat.QR_CODE) {
  throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);
}

if (width < 0 || height < 0) {
  throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' +
      height);
}
ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
int quietZone = QUIET_ZONE_SIZE;
if (hints != null) {
  ErrorCorrectionLevel requestedECLevel = (ErrorCorrectionLevel) hints.get(EncodeHintType.ERROR_CORRECTION);
  if (requestedECLevel != null) {
    errorCorrectionLevel = requestedECLevel;
  }
  Integer quietZoneInt = (Integer) hints.get(EncodeHintType.MARGIN);
  if (quietZoneInt != null) {
    quietZone = quietZoneInt;
  }
}

QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);
return renderResult(code, width, height, quietZone);
}

主要是調用Encoder中的encode生成一個QRCode，再由renderResult方法生成一個BitMatrix。而生成的QRCode中包含了我們所需要的Version信息。所以我們可以自己改寫一個QRCodeWriter類，拿到QRCode。直接將QRCodeWriter復制出來，重寫幾個方法即可。如我寫的ColorQRCodeWriter：

public class ColorQRCodeWriter {
private static final int QUIET_ZONE_SIZE = 4;

public Map encode(String contents, BarcodeFormat format, int width, int height)
        throws WriterException {
    return encode(contents, format, width, height, null);
}

public Map encode(String contents,
                                 BarcodeFormat format,
                                 int width,
                                 int height,
                                 Map hints) throws WriterException {

    if (contents.isEmpty()) {
        throw new IllegalArgumentException("Found empty contents");
    }

    if (format != BarcodeFormat.QR_CODE) {
        throw new IllegalArgumentException("Can only encode QR_CODE, but got " + format);
    }

    if (width < 0 || height < 0) {
        throw new IllegalArgumentException("Requested dimensions are too small: " + width + 'x' +
                height);
    }

    ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;
    int quietZone = QUIET_ZONE_SIZE;
    if (hints != null) {
        ErrorCorrectionLevel requestedECLevel = (ErrorCorrectionLevel) hints.get(EncodeHintType.ERROR_CORRECTION);
        if (requestedECLevel != null) {
            errorCorrectionLevel = requestedECLevel;
        }
        Integer quietZoneInt = (Integer) hints.get(EncodeHintType.MARGIN);
        if (quietZoneInt != null) {
            quietZone = quietZoneInt;
        }
    }

    QRCode code = Encoder.encode(contents, errorCorrectionLevel, hints);
    return renderResult(code, width, height, quietZone);
}

// Note that the input matrix uses 0 == white, 1 == black, while the output matrix uses
// 0 == black, 255 == white (i.e. an 8 bit greyscale bitmap).
private static Map renderResult(QRCode code, int width, int height, int quietZone) {
    ByteMatrix input = code.getMatrix();
    if (input == null) {
        throw new IllegalStateException();
    }
    int inputWidth = input.getWidth();
    int inputHeight = input.getHeight();
    int qrWidth = inputWidth + (quietZone * 2);
    int qrHeight = inputHeight + (quietZone * 2);
    int outputWidth = Math.max(width, qrWidth);
    int outputHeight = Math.max(height, qrHeight);

    int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);
    // Padding includes both the quiet zone and the extra white pixels to accommodate the requested
    // dimensions. For example, if input is 25x25 the QR will be 33x33 including the quiet zone.
    // If the requested size is 200x160, the multiple will be 4, for a QR of 132x132. These will
    // handle all the padding from 100x100 (the actual QR) up to 200x160.
    int leftPadding = (outputWidth - (inputWidth * multiple)) / 2;
    int topPadding = (outputHeight - (inputHeight * multiple)) / 2;

    BitMatrix output = new BitMatrix(outputWidth, outputHeight);

    for (int inputY = 0, outputY = topPadding; inputY < inputHeight; inputY++, outputY += multiple) {
        // Write the contents of this row of the barcode
        for (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {
            if (input.get(inputX, inputY) == 1) {
                output.setRegion(outputX, outputY, multiple, multiple);
            }
        }
    }
    Map map=new HashMap<>();
    map.put("BitMatrix",output);
    map.put("Version",code.getVersion());
    return map;
}

public Bitmap encodeBitmap(String content, int width, int height,boolean all){
    return encodeBitmap(content,width,height,null,null,null,all);
}

/**
 * 生成基點顏色不同的圖片
 * @param content  需要生成的二維碼的內容
 * @param width     二維碼寬
 * @param height    二維碼高
 * @param topLeftColor    左基點顏色
 * @param topRightColor    右頂基點顏色
 * @param bottomLeftColor    左底基點顏色
 * @return
 */
public Bitmap encodeBitmap(String content, int width, int height,
                           Integer topLeftColor, Integer topRightColor, Integer bottomLeftColor,boolean all){
    try {
        int startModel=2;
        int endModel=5;
        if(all){
            startModel=0;
            endModel=7;
        }
        Map hints = new HashMap();
        hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");
        hints.put(EncodeHintType.MARGIN, 1);
        Map map= encode(content,BarcodeFormat.QR_CODE,width,height,hints);
        BitMatrix matrix= (BitMatrix) map.get("BitMatrix");
        Version version= (Version) map.get("Version");
        int[] tl=matrix.getTopLeftOnBit();
        int totalModelNum=(version.getVersionNumber()-1)*4+5+16;    //獲取單邊模塊數
        int resultWidth=width-2*(tl[0]);
        int modelWidth=resultWidth/totalModelNum;   //得到每個模塊長度
        //得到三個基准點的起始與終點
        int topEndX=tl[0]+modelWidth*endModel;
        int topStartX=tl[0]+modelWidth*startModel;
        int topStartY=tl[0]+modelWidth*startModel;
        int topEndY=tl[0]+modelWidth*endModel;
        int rightStartX=(totalModelNum-endModel)*modelWidth+tl[0];
        int rightEndX=width-modelWidth*startModel-tl[0];
        int leftStartY=height-modelWidth*endModel-tl[1];
        int leftEndY=height-modelWidth*startModel-tl[1];
        int[] pixels=new int[width*height];
        for(int y=0;y=topStartX&&x=topStartY&&y=rightStartX&&y>=topStartY&&y=topStartX&&x=leftStartY&&y
其中的addLogo方法直接從網上找的。
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