From ef6fcd2a9eb117f7a0e36e84e5c8024526353f78 Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sun, 21 Sep 2014 18:45:43 +0200
Subject: [PATCH 1/5] Correctly sized col in color_set

---
 qrenc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/qrenc.c b/qrenc.c
index 78f1c120..796ab01b 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -189,7 +189,7 @@ static int color_set(unsigned char color[4], const char *value)
 {
 	int len = strlen(value);
 	int i, count;
-	unsigned int col[3];
+	unsigned int col[4];
 	if(len == 6) {
 		count = sscanf(value, "%02x%02x%02x%n", &col[0], &col[1], &col[2], &len);
 		if(count < 3 || len != 6) {

From 3bd690b5fa165a5a79ea44ea54919eb58afef187 Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sat, 8 Feb 2014 13:14:09 +0100
Subject: [PATCH 2/5] SVG write: use styles instead of tag attributes

This produces a smaller SVG (about 30% smaller for SVG without
alpha channels, closer to 50% with alpha channels).
---
 qrenc.c | 50 ++++++++++++++++++++++++++++++--------------------
 1 file changed, 30 insertions(+), 20 deletions(-)

diff --git a/qrenc.c b/qrenc.c
index 796ab01b..f9c1bf77 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -494,17 +494,10 @@ static int writeEPS(const QRcode *qrcode, const char *outfile)
 	return 0;
 }
 
-static void writeSVG_writeRect(FILE *fp, int x, int y, int width, const char* col, float opacity)
+static void writeSVG_writeRect(FILE *fp, int x, int y, int width)
 {
-	if(fg_color[3] != 255) {
-		fprintf(fp, "\t\t\t<rect x=\"%d\" y=\"%d\" width=\"%d\" height=\"1\" "\
-				"fill=\"#%s\" fill-opacity=\"%f\" />\n", 
-				x, y, width, col, opacity );
-	} else {
-		fprintf(fp, "\t\t\t<rect x=\"%d\" y=\"%d\" width=\"%d\" height=\"1\" "\
-				"fill=\"#%s\" />\n", 
-				x, y, width, col );
-	}
+	fprintf(fp, "\t\t\t<rect x=\"%d\" y=\"%d\" width=\"%d\" height=\"1\" />\n",
+		x, y, width);
 }
 
 static int writeSVG(const QRcode *qrcode, const char *outfile)
@@ -552,16 +545,35 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 			" xmlns=\"http://www.w3.org/2000/svg\">\n", 
 			realwidth / scale, realwidth / scale, symwidth, symwidth
 		   );
+	/* SVG CSS for styling */
+	fputs( "\t<style>", fp );
+
+	/* rects by default will be styled as foreground */
+	if(fg_color[3] != 255) {
+		fprintf(fp, "rect{fill:#%s;fill-opacity:%f}", fg, fg_opacity);
+	} else {
+		fprintf(fp, "rect{fill:#%s}", fg);
+	}
+
+	/* add style specification for the background as 'bg' class. fill-opacity
+	 * must be declared whenever the background opacity is different from
+	 * the foreground opacity.
+	 */
+
+	if(bg_color[3] != fg_color[3]) {
+		fprintf(fp, ".bg{fill:#%s;fill-opacity:%f}", bg, bg_opacity);
+	} else {
+		fprintf(fp, ".bg{fill:#%s}", bg);
+	}
+
+	fputs( "</style>\n", fp );
 
 	/* Make named group */
 	fputs( "\t<g id=\"QRcode\">\n", fp );
 
 	/* Make solid background */
-	if(bg_color[3] != 255) {
-		fprintf(fp, "\t\t<rect x=\"0\" y=\"0\" width=\"%d\" height=\"%d\" fill=\"#%s\" fill-opacity=\"%f\" />\n", symwidth, symwidth, bg, bg_opacity);
-	} else {
-		fprintf(fp, "\t\t<rect x=\"0\" y=\"0\" width=\"%d\" height=\"%d\" fill=\"#%s\" />\n", symwidth, symwidth, bg);
-	}
+	fprintf(fp, "\t\t<rect x=\"0\" y=\"0\" width=\"%d\" height=\"%d\" class=\"bg\" />\n",
+		symwidth, symwidth);
 
 	/* Create new viewbox for QR data */
 	fputs( "\t\t<g id=\"Pattern\">\n", fp);
@@ -575,9 +587,7 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 			/* no RLE */
 			for(x=0; x<qrcode->width; x++) {
 				if(*(row+x)&0x1) {
-					writeSVG_writeRect(fp,	margin + x,
-								margin + y, 1,
-								fg, fg_opacity);
+					writeSVG_writeRect(fp,	margin + x, margin + y, 1);
 				}
 			}
 		} else {
@@ -590,13 +600,13 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 					x0 = x;
 				} else {
 					if(!(*(row+x)&0x1)) {
-						writeSVG_writeRect(fp, x0 + margin, y + margin, x-x0, fg, fg_opacity);
+						writeSVG_writeRect(fp, x0 + margin, y + margin, x-x0);
 						pen = 0;
 					}
 				}
 			}
 			if( pen ) {
-				writeSVG_writeRect(fp, x0 + margin, y + margin, qrcode->width - x0, fg, fg_opacity);
+				writeSVG_writeRect(fp, x0 + margin, y + margin, qrcode->width - x0);
 			}
 		}
 	}

From e6acce9d991cbe553f8c75c72102449d45514a7b Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sat, 8 Feb 2014 13:43:27 +0100
Subject: [PATCH 3/5] Dimensionless SVG when DPI is zero

Allow the generation of SVGs without explicit dimensions set by setting
DPI to 0. Since SVGs are perfectly scalable, there is no need to set the
size, in general.
---
 qrenc.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/qrenc.c b/qrenc.c
index f9c1bf77..a74d6b6c 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -540,11 +540,19 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 			QRcode_APIVersionString() );
 
 	/* SVG code start */
-	fprintf( fp, "<svg width=\"%0.2fcm\" height=\"%0.2fcm\" viewBox=\"0 0 %d %d\""\
+	/* Only set the width/height if dpi was non-zero */
+	if (scale != 0) {
+		fprintf( fp, "<svg width=\"%0.2fcm\" height=\"%0.2fcm\" viewBox=\"0 0 %d %d\""\
 			" preserveAspectRatio=\"none\" version=\"1.1\""\
 			" xmlns=\"http://www.w3.org/2000/svg\">\n", 
 			realwidth / scale, realwidth / scale, symwidth, symwidth
-		   );
+		       );
+	} else {
+		fprintf( fp, "<svg viewBox=\"0 0 %d %d\""\
+			" version=\"1.1\""\
+			" xmlns=\"http://www.w3.org/2000/svg\">\n",
+			symwidth, symwidth);
+	}
 	/* SVG CSS for styling */
 	fputs( "\t<style>", fp );
 

From 4c72ad1c38a70ba89ffc066f7e9d7a8218e7bff5 Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sat, 8 Feb 2014 18:13:24 +0100
Subject: [PATCH 4/5] SVG: use a single path instead of multiple rects for RLE

This reduces the SVG output size by nearly a factor of 7. As a bonus,
rendering of the resulting SVG at high resolutions does not show the
striping which was clearly visible with the previous approach.
---
 qrenc.c | 53 +++++++++++++++++++++++++++++++++++++++--------------
 1 file changed, 39 insertions(+), 14 deletions(-)

diff --git a/qrenc.c b/qrenc.c
index a74d6b6c..0e5df582 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -553,22 +553,32 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 			" xmlns=\"http://www.w3.org/2000/svg\">\n",
 			symwidth, symwidth);
 	}
+
 	/* SVG CSS for styling */
 	fputs( "\t<style>", fp );
 
-	/* rects by default will be styled as foreground */
-	if(fg_color[3] != 255) {
-		fprintf(fp, "rect{fill:#%s;fill-opacity:%f}", fg, fg_opacity);
-	} else {
-		fprintf(fp, "rect{fill:#%s}", fg);
-	}
-
-	/* add style specification for the background as 'bg' class. fill-opacity
-	 * must be declared whenever the background opacity is different from
-	 * the foreground opacity.
+	/* Style for the foreground elements. They are assumed to be the most
+	 * numerous, so we set their style without class specification.
+	 * When using RLE, we create a single path element for the foreground.
+	 * Otherwise, the foreground is assembled as collection of rectangle elements.
 	 */
-
-	if(bg_color[3] != fg_color[3]) {
+	const char* const fg_css_spec[] = {
+		"rect{fill:#%s;fill-opacity:%f}",
+		"rect{fill:#%s}",
+		"path{fill:none;stroke:#%s;stroke-opacity:%f}",
+		"path{fill:none;stroke:#%s}"
+	};
+	/* abuse x as index into fg_css_spec */
+	x = rle ? 2 : 0;
+	if (fg_color[3] == 255)
+		++x;
+	fprintf(fp, fg_css_spec[x], fg, fg_opacity);
+
+	/* Style for the background ('bg' class). In RLE mode, the opacity
+	 * only needs to be specified when it's not full; in non-RLE mode,
+	 * it must be declared if it's different from the foreground opacity.
+	 */
+	if( (rle && bg_color[3] != 255) || (!rle && bg_color[3] != fg_color[3])) {
 		fprintf(fp, ".bg{fill:#%s;fill-opacity:%f}", bg, bg_opacity);
 	} else {
 		fprintf(fp, ".bg{fill:#%s}", bg);
@@ -586,6 +596,13 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 	/* Create new viewbox for QR data */
 	fputs( "\t\t<g id=\"Pattern\">\n", fp);
 
+	/* If in RLE mode, start the path. We will draw it margin-less but translate it by the margin width.
+	 * Note that the y translation has an additional .5 because the path is stroked, so
+	 * it must be _centered_ in its coordinate. Horizontally this is not needed because
+	 * of the butt cap used by default. */
+	if (rle)
+		fprintf(fp, "\t\t\t<path transform=\"translate(%d,%d.5)\" d=\"", margin, margin);
+
 	/* Write data */
 	p = qrcode->data;
 	for(y=0; y<qrcode->width; y++) {
@@ -608,16 +625,24 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 					x0 = x;
 				} else {
 					if(!(*(row+x)&0x1)) {
-						writeSVG_writeRect(fp, x0 + margin, y + margin, x-x0);
+						fprintf(fp, "M%d,%dh%d", x0, y, x - x0);
 						pen = 0;
 					}
 				}
 			}
 			if( pen ) {
-				writeSVG_writeRect(fp, x0 + margin, y + margin, qrcode->width - x0);
+				fprintf(fp, "M%d,%dh%d", x0, y, qrcode->width - x0);
+			}
+			if (y < qrcode->width - 1) {
+				fprintf( fp, "\n\t\t\t\t" );
 			}
 		}
 	}
+
+	/* Close the path */
+	if (rle)
+		fputs( "\"/>\n", fp );
+
 	/* Close QR data viewbox */
 	fputs( "\t\t</g>\n", fp );
 

From 1e91256a56eed996ec515acb857e5299589f7f21 Mon Sep 17 00:00:00 2001
From: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Date: Sun, 9 Feb 2014 14:30:53 +0100
Subject: [PATCH 5/5] SVG: use relative path motion in scanlines

Most scanlines are built from alternating small strides of black and
white pixels, therefore using relative motions results in smaller
numbers passed to the `m` command. On the larger QR Codes this can lead
to savings of as much as 30% of the previous output file size in RLE
mode.
---
 qrenc.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/qrenc.c b/qrenc.c
index 0e5df582..52529fab 100644
--- a/qrenc.c
+++ b/qrenc.c
@@ -504,7 +504,7 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 {
 	FILE *fp;
 	unsigned char *row, *p;
-	int x, y, x0, pen;
+	int x, y, x0, x1, pen, abs;
 	int symwidth, realwidth;
 	float scale;
 	char fg[7], bg[7];
@@ -619,19 +619,26 @@ static int writeSVG(const QRcode *qrcode, const char *outfile)
 			/* simple RLE */
 			pen = 0;
 			x0  = 0;
+			x1  = 0;
 			for(x=0; x<qrcode->width; x++) {
 				if( !pen ) {
 					pen = *(row+x)&0x1;
 					x0 = x;
 				} else {
 					if(!(*(row+x)&0x1)) {
-						fprintf(fp, "M%d,%dh%d", x0, y, x - x0);
+						/* motion is initially absolute */
+						abs = (x1 == 0);
+						fprintf(fp, "%c%d,%dh%d", abs ? 'M' : 'm',
+							(x0 - x1), abs ? y : 0, x - x0);
+						x1 = x;
 						pen = 0;
 					}
 				}
 			}
 			if( pen ) {
-				fprintf(fp, "M%d,%dh%d", x0, y, qrcode->width - x0);
+				abs = (x1 == 0);
+				fprintf(fp, "%c%d,%dh%d", abs ? 'M' : 'm',
+					(x0 - x1), abs ? y : 0, qrcode->width - x0);
 			}
 			if (y < qrcode->width - 1) {
 				fprintf( fp, "\n\t\t\t\t" );