Create QrCodeRenderer.java

Added a QRCodeRenderer to make rendering QRCodes reusable out of the box.  This creates a much more usable experience without needing to read and understand lower level details about graphics, QRCode, etc.

java/src/main/java/io/nayuki/qrcodegen/QrCodeRenderer.java

@@ -0,0 +1,208 @@
+package com.fuseanalytics.archiver.util;
+
+import io.nayuki.qrcodegen.QrCode;
+
+import javax.imageio.ImageIO;
+import java.awt.*;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.io.OutputStream;
+
+/**
+ * Use this class to generate images of your {@link io.nayuki.qrcodegen.QrCode} instances.
+ * It uses sensible defaults to make the resulting QRCode look presentable without much
+ * tweaking.  This class can be used by multiple threads provided after construction and 
+ * configuration.  So any render* method will not cause threading issues, but calling the
+ * configuration methods {@link #colors(Color, Color)}, {@link #border(int)}, {@link #scale}
+ * will cause unpredictable errors.  As long as you use the configuration methods on one
+ * thread before sharing the instance and only use render* methods from multiple threads
+ * this class is thread safe.
+ * <p> 
+ * Here is a simple example of generating a {@see java.awt.BufferedImage}:
+ * </p>
+ *
+ * <pre>{@code
+ *  QrCode qr = QrCode.encodeText( "Hello World!", QrCode.Ecc.MEDIUM );
+ *  BufferedImage img = new QrCodeRenderer().renderImage(qrCode);
+ * }</pre>
+ *
+ * <p>
+ * Here is an example, for rendering a PNG to a file:
+ * </p>
+ * <pre>{@code
+ *  QrCode qr = QrCode.encodeText( "Hello World!", QrCode.Ecc.MEDIUM );
+ *  File target = new QrCodeRenderer().renderFile(qrCode, "png", new File("output.png"));
+ * }</pre>
+ *
+ * <p>
+ * Here's an example of tweaking the defaults and rendering a PNG to an OutputStream:
+ * </p>
+ * <pre>{@code
+ *  QrCode qr = QrCode.encodeText( "Hello World!", QrCode.Ecc.MEDIUM );
+ *  ByteArrayOutputStream baos = new ByteArrayOutputStream();
+ *  File target = new QrCodeRenderer()
+ *      .scale(4)
+ *      .border(10)
+ *      .colors(Color.BLUE, Color.WHITE)
+ *      .renderStream(qrCode, "png", baos);
+ * }</pre>
+ *
+ * <p>
+ * Here's an example, for rendering to SVG:
+ * </p>
+ * <pre>{@code
+ *  QrCode qr = QrCode.encodeText( "Hello World!", QrCode.Ecc.MEDIUM );
+ *  String svg = new QrCodeRenderer().renderSvg(qrCode);
+ * }</pre>
+ */
+public class QrCodeRenderer {
+
+    /**
+     * The scale to use when rendering bitmap based images.  Default is 5.
+     */
+    private int scale = 5;
+
+    /**
+     * The size of border in pixels.  THe border will be scaled by the scale factor.
+     * This provides some whitespace around QR code. This area will be rendered using
+     * the light color.  Default is 2.
+     */
+    private int border = 2;
+
+    /**
+     * This the dark color used to render the QR code.  The default is black.
+     */
+    private Color darkColor = Color.BLACK;
+
+    /**
+     * This is the light color used to render the background of the QR Code.
+     */
+    private Color lightColor = Color.WHITE;
+
+    /**
+     * Renders a BufferedImage of the given QRCode object.
+     * @param qrCode the QR code to use to render into a BufferedImage.
+     * @return The bitmap rendering of the given QR Code.
+     */
+    public BufferedImage renderImage(QrCode qrCode) {
+        BufferedImage img = new BufferedImage((qrCode.size + border * 2) * scale, (qrCode.size + border * 2) * scale, BufferedImage.TYPE_INT_RGB);
+        for( int y = 0; y < img.getHeight(); y++ ) {
+            for( int x = 0; x < img.getWidth(); x++ ) {
+                int sx = x / scale - border;
+                int sy = y / scale - border;
+                boolean color = qrCode.getModule(sx,sy);
+                img.setRGB(x, y, color ? darkColor.getRGB() : lightColor.getRGB() );
+            }
+        }
+        return img;
+    }
+
+    /**
+     * Renders an SVG document of the given QR Code.
+     * @param qrCode the QRCode to render into the SVG document.
+     * @return a String that contains the SVG markup of the QR Code.
+     */
+    public String renderSvg(QrCode qrCode) {
+        long brd = border;
+
+        StringBuilder buffer = new StringBuilder()
+                .append("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n")
+                .append("<!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\">\n")
+                .append(String.format("<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" viewBox=\"0 0 %1$d %1$d\" stroke=\"none\">\n",
+                        qrCode.size + brd * 2))
+                .append("\t<rect width=\"100%\" height=\"100%\" fill=\"").append(toRgb(lightColor)).append("\"/>\n")
+                .append("\t<path d=\"");
+        for (int y = 0; y < qrCode.size; y++) {
+            for (int x = 0; x < qrCode.size; x++) {
+                if (qrCode.getModule(x, y)) {
+                    if (x != 0 || y != 0)
+                        buffer.append(" ");
+                    buffer.append(String.format("M%d,%dh1v1h-1z", x + brd, y + brd));
+                }
+            }
+        }
+
+        return buffer
+                .append("\" fill=\"").append(toRgb(darkColor)).append("\"/>\n")
+                .append("</svg>\n")
+                .toString();
+    }
+
+    /**
+     * Renders the QR Code to a bitmap and writes that to the given file in the given format provided.
+     * @param qrCode The QRCode to generate the bitmap of.
+     * @param formatName The image format to write (png, jpeg, etc).  These are the same formats supported by {@see javax.imageio.ImageIO}.
+     * @param output A java.io.File you want to write the given QRCode in the given format into.
+     * @return Returns the given File for convenience that contains the bitmap of the QRCode.
+     * @throws IOException if any IOException happens while writing to the given File.
+     * @throws IllegalArgumentException if the given formatName cannot be found in ImageIO library.
+     */
+    public File renderFile(QrCode qrCode, String formatName, File output) throws IOException {
+        BufferedImage img = renderImage(qrCode);
+        if( ImageIO.write( img, formatName, output ) ) {
+            return output;
+        } else {
+            throw new IllegalArgumentException("No appropriate writer found for formatName=" + formatName );
+        }
+    }
+
+    /**
+     * Renders the QR Code to a bitmap and writes that to the given OutputStream in the given format provided.
+     * @param qrCode The QRCode to generate the bitmap of.
+     * @param formatName The image format to write (png, jpeg, etc).  These are the same formats supported by {@see javax.imageio.ImageIO}.
+     * @param stream The OutputStream in which to write the bitmap image of the given QRCode in the given formatName into.
+     * @throws IOException if any IOException happens while writing to the given OutputStream.
+     * @throws IllegalArgumentException if the given formatName cannot be found in ImageIO library.
+     */
+    public void renderStream(QrCode qrCode, String formatName, OutputStream stream ) throws IOException {
+        BufferedImage img = renderImage( qrCode );
+        if( !ImageIO.write( img, formatName, stream ) ) {
+            throw new IllegalArgumentException("No appropriate writer found for formatName=" + formatName );
+        }
+    }
+
+    private String toRgb(Color color) {
+        return "rgb(" + color.getRed() + " " + color.getGreen() + " " + color.getBlue() + ")";
+    }
+
+    /**
+     * Overwrite the border default by specifying the number of pixels to use as a border.  This is
+     * the number of pixels to use before scaling is applied so the resulting border will be scaled
+     * up if scale > 1.
+     * @param border pixels to add around the resulting QRCode bitmap
+     * @return this
+     */
+    public QrCodeRenderer border( int border ) {
+        if( border < 0 ) throw new IllegalArgumentException("Border must be non-negative: " + border );
+        if( border > Integer.MAX_VALUE / 2 ) throw new IllegalArgumentException("Border size is too large.");
+        this.border = border;
+        return this;
+    }
+
+    /**
+     * Sets the scale to use when writing into the Bitmap image.
+     *
+     * @param scale the amount to scale the image by.  1 performs no sale, 2 doubles it, 3 triples, etc.
+     * @return this
+     */
+    public QrCodeRenderer scale( int scale ) {
+        if( scale < 0 ) throw new IllegalArgumentException("Scale must be non-negative: " + scale );
+        if( (QrCode.MAX_VERSION * 4 + 17) * scale + border*2 > Integer.MAX_VALUE / scale ) throw new IllegalArgumentException("Scale is too large: " + scale);
+        this.scale = scale;
+        return this;
+    }
+
+    /**
+     * Sets the colors to use when rendering the QRCode.  The dark color will be used to write
+     * the QR Code, and the light color will be used as the background.
+     * @param darkColor the color to use for the QRCode
+     * @param lightColor the color to use as the background color.
+     * @return this
+     */
+    public QrCodeRenderer colors( Color darkColor, Color lightColor ) {
+        this.darkColor = darkColor;
+        this.lightColor = lightColor;
+        return this;
+    }
+}