满填充透明背景二维码生成

前几天项目上线的时候发现一个问题：通过Hutool工具包生成的二维码在内容较少时无法填满(Margin 已设置为 0)给定大小的图片。因此导致前端在显示二维码时样式异常。


从图片中我们可以看到，相同大小的图片，留白内容是不一样的。其中上半部分的图片是一个短字符串，下半部分的图片是一个长的字符串。因此基于Hutool包进行了裁边和缩放。代码如下：

Maven配置

<dependency><groupId>com.google.zxing</groupId><artifactId>core</artifactId><version>3.3.3</version>
</dependency>
<dependency><groupId>com.google.zxing</groupId><artifactId>javase</artifactId><version>3.3.3</version>
</dependency>

QrCodeConfig.java

import com.google.zxing.EncodeHintType;
import com.google.zxing.client.j2se.MatrixToImageConfig;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import lombok.Getter;
import lombok.Setter;
import lombok.ToString;import java.awt.*;
import java.util.HashMap;
import java.util.Map;/*** 二维吗配置信息*/
@Getter
@Setter
@ToString
public class QrCodeConfig {/*** 塞入二维码的信息*/private String msg;/*** 生成二维码的宽*/private Integer w;/*** 生成二维码的高*/private Integer h;/*** 生成二维码的颜色*/private MatrixToImageConfig matrixToImageConfig;private Map<EncodeHintType, Object> hints;@ToStringpublic static class QrCodeConfigBuilder {/*** The message to put into QrCode*/private String msg;/*** qrcode image width*/private Integer w;/*** qrcode image height*/private Integer h;/*** qrcode message's code, default UTF-8*/private String code;/*** 0 - 4*/private Integer padding;/*** error level, default H*/private ErrorCorrectionLevel errorCorrection;public String getMsg() {return msg;}public QrCodeConfigBuilder setMsg(String msg) {this.msg = msg;return this;}public Integer getW() {return w == null ? (h == null ? 200 : h) : w;}public QrCodeConfigBuilder setW(Integer w) {if (w != null && w < 0) {throw new IllegalArgumentException("???????????0");}this.w = w;return this;}public Integer getH() {if (w != null && w < 0) {throw new IllegalArgumentException("???????????0");}return h == null ? (w == null ? 200 : w) : h;}public QrCodeConfigBuilder setH(Integer h) {this.h = h;return this;}public String getCode() {return code == null ? "UTF-8" : code;}public QrCodeConfigBuilder setCode(String code) {this.code = code;return this;}public Integer getPadding() {if (padding == null) {return 1;}if (padding < 0) {return 0;}if (padding > 4) {return 4;}return padding;}public QrCodeConfigBuilder setPadding(Integer padding) {this.padding = padding;return this;}public ErrorCorrectionLevel getErrorCorrection() {return errorCorrection == null ? ErrorCorrectionLevel.H : errorCorrection;}public QrCodeConfigBuilder setErrorCorrection(ErrorCorrectionLevel errorCorrection) {this.errorCorrection = errorCorrection;return this;}private void validate() {if (msg == null || msg.length() == 0) {throw new IllegalArgumentException("????????????!");}}private QrCodeConfig create() {this.validate();QrCodeConfig qrCodeConfig = new QrCodeConfig();qrCodeConfig.setMsg(getMsg());qrCodeConfig.setH(getH());qrCodeConfig.setW(getW());Map<EncodeHintType, Object> hints = new HashMap<>(3);hints.put(EncodeHintType.ERROR_CORRECTION, this.getErrorCorrection());hints.put(EncodeHintType.CHARACTER_SET, this.getCode());hints.put(EncodeHintType.MARGIN, this.getPadding());qrCodeConfig.setHints(hints);qrCodeConfig.setMatrixToImageConfig(new MatrixToImageConfig(new Color(0, 0, 0, 255).getRGB(),new Color(0, 0, 0, 0).getRGB()));return qrCodeConfig;}/*** create qrcodeConfig** @return 返回构造的 QrCodeConfig 对象*/public QrCodeConfig build() {return create();}}
}

MatrixToImageUtil.java

import com.google.zxing.common.BitMatrix;
import java.awt.*;
import java.awt.image.BufferedImage;public class MatrixToImageUtil {public static BufferedImage toBufferedImage(QrCodeConfig qrCodeConfig, BitMatrix bitMatrix) {int qrCodeWidth = bitMatrix.getWidth();int qrCodeHeight = bitMatrix.getHeight();BufferedImage qrCode = new BufferedImage(qrCodeWidth, qrCodeHeight, BufferedImage.TYPE_INT_ARGB);int onColor = qrCodeConfig.getMatrixToImageConfig().getPixelOnColor();int offColor = qrCodeConfig.getMatrixToImageConfig().getPixelOffColor();for (int x = 0; x < qrCodeWidth; x++) {for (int y = 0; y < qrCodeHeight; y++) {boolean pixelOn = bitMatrix.get(x, y);int pixelColor = pixelOn ? onColor : offColor;// 设置透明度int alpha = pixelOn ? 255 : 0;Color color = new Color(pixelColor, true);Color colorWithAlpha = new Color(color.getRed(), color.getGreen(), color.getBlue(), alpha);qrCode.setRGB(x, y, colorWithAlpha.getRGB());}}// 缩放二维码图片int realQrCodeWidth = qrCodeConfig.getW();int realQrCodeHeight = qrCodeConfig.getH();if (qrCodeWidth != realQrCodeWidth || qrCodeHeight != realQrCodeHeight) {BufferedImage tmp = new BufferedImage(realQrCodeWidth, realQrCodeHeight, BufferedImage.TYPE_INT_ARGB);tmp.getGraphics().drawImage(qrCode.getScaledInstance(realQrCodeWidth, realQrCodeHeight, Image.SCALE_SMOOTH),0, 0, null);qrCode = tmp;}return qrCode;}
}

QrCodeGenWrapper.java

import cn.hutool.core.img.ImgUtil;
import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;
import com.google.zxing.qrcode.encoder.ByteMatrix;
import com.google.zxing.qrcode.encoder.Encoder;
import com.google.zxing.qrcode.encoder.QRCode;
import lombok.extern.slf4j.Slf4j;
import org.apache.commons.lang3.StringUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Map;/*** 对 zxing 的 QRCodeWriter 进行扩展, 解决白边过多的问题，原参考 <a href="https://my.oschina.net/u/566591/blog/872770">...</a>*/
@Slf4j
public class QrCodeGenWrapper {private static final Logger logger = LoggerFactory.getLogger(QrCodeGenWrapper.class);private static final int QUIET_ZONE_SIZE = 4;/*** 构造 二维吗配置信息* @return QrCodeConfig*/public static QrCodeConfig.QrCodeConfigBuilder createQrCodeConfig() {return new QrCodeConfig.QrCodeConfigBuilder();}/*** 生成base64格式二维吗* @param content 二维吗内容* @param width 宽度 默认 300* @param height 高度 默认 300* @param imageType 图片类型默认 png* @return 返回base64格式二维码信息*/public static String generateAsBase64(String content, Integer width, Integer height, String imageType){QrCodeConfig qrConfig = QrCodeGenWrapper.createQrCodeConfig().setMsg(content).setH(width == null? 300 : width).setW(height == null? 300 : height).setPadding(0).setErrorCorrection(ErrorCorrectionLevel.L).build();try {return ImgUtil.toBase64DataUri(asBufferedImage(qrConfig), StringUtils.isBlank(imageType)? "png" : imageType);} catch (Exception e) {log.error("QrCodeGenWrapper.generateAsBase64 error", e);throw new RuntimeException("QrCodeGenWrapper.generateAsBase64 生成二维码异常");}}public static BufferedImage asBufferedImage(QrCodeConfig qrCodeConfig) throws WriterException, IOException {BitMatrix bitMatrix = encode(qrCodeConfig);return MatrixToImageUtil.toBufferedImage(qrCodeConfig, bitMatrix);}/*** 对 zxing 的 QRCodeWriter 进行扩展, 解决白边过多的问题* <p/>* 源码参考 {@link com.google.zxing.qrcode.QRCodeWriter#encode(String, BarcodeFormat, int, int, Map)}*/private static BitMatrix encode(QrCodeConfig qrCodeConfig) throws WriterException {ErrorCorrectionLevel errorCorrectionLevel = ErrorCorrectionLevel.L;int quietZone = 1;if (qrCodeConfig.getHints() != null) {if (qrCodeConfig.getHints().containsKey(EncodeHintType.ERROR_CORRECTION)) {errorCorrectionLevel = ErrorCorrectionLevel.valueOf(qrCodeConfig.getHints().get(EncodeHintType.ERROR_CORRECTION).toString());}if (qrCodeConfig.getHints().containsKey(EncodeHintType.MARGIN)) {quietZone = Integer.parseInt(qrCodeConfig.getHints().get(EncodeHintType.MARGIN).toString());}if (quietZone > QUIET_ZONE_SIZE) {quietZone = QUIET_ZONE_SIZE;} else if (quietZone < 0) {quietZone = 0;}}QRCode code = Encoder.encode(qrCodeConfig.getMsg(), errorCorrectionLevel, qrCodeConfig.getHints());return renderResult(code, qrCodeConfig.getW(), qrCodeConfig.getH(), quietZone);}/*** 对 zxing 的 QRCodeWriter 进行扩展, 解决白边过多的问题* <p/>* 源码参考** @param code {@link QRCode}* @param width 高* @param height 宽* @param quietZone 取值 [0, 4]* @return {@link BitMatrix}*/private static BitMatrix renderResult(QRCode code, int width, int height, int quietZone) {ByteMatrix input = code.getMatrix();if (input == null) {throw new IllegalStateException();}// xxx 二维码宽高相等, 即 qrWidth == qrHeightint inputWidth = input.getWidth();int inputHeight = input.getHeight();int qrWidth = inputWidth + (quietZone * 2);int qrHeight = inputHeight + (quietZone * 2);// 白边过多时, 缩放int minSize = Math.min(width, height);int scale = calculateScale(qrWidth, minSize);if (scale > 0) {if (logger.isDebugEnabled()) {logger.debug("qrCode scale enable! scale: {}, qrSize:{}, expectSize:{}x{}", scale, qrWidth, width, height);}int padding, tmpValue;// 计算边框留白padding = (minSize - qrWidth * scale) / QUIET_ZONE_SIZE * quietZone;tmpValue = qrWidth * scale + padding;if (width == height) {width = tmpValue;height = tmpValue;} else if (width > height) {width = width * tmpValue / height;height = tmpValue;} else {height = height * tmpValue / width;width = tmpValue;}}int outputWidth = Math.max(width, qrWidth);int outputHeight = Math.max(height, qrHeight);int multiple = Math.min(outputWidth / qrWidth, outputHeight / qrHeight);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 barcodefor (int inputX = 0, outputX = leftPadding; inputX < inputWidth; inputX++, outputX += multiple) {if (input.get(inputX, inputY) == 1) {output.setRegion(outputX, outputY, multiple, multiple);}}}return output;}/*** 如果留白超过15% , 则需要缩放* (15% 可以根据实际需要进行修改)** @param qrCodeSize 二维码大小* @param expectSize 期望输出大小* @return 返回缩放比例, <= 0 则表示不缩放, 否则指定缩放参数*/private static int calculateScale(int qrCodeSize, int expectSize) {if (qrCodeSize >= expectSize) {return 0;}int scale = expectSize / qrCodeSize;int abs = expectSize - scale * qrCodeSize;// 在这里配置超过多少留白，则进行缩放（这里已经把  0.15 改成 0 了）if (abs < 0) {return 0;}return scale;}
}

最终效果：

---------------------------------- 只能活一次的人生当然要比谁都炽热，浑浑噩噩谁也可以。 ---------------------------------