Add alpha channel support and --nobackground option

Alpha channel for PNG and SVG and option to remove background from EMF

backend/emf.c

@@ -186,6 +186,7 @@ INTERNAL int emf_plot(struct zint_symbol *symbol) {
     int rectangle_count_bycolour[8];
     unsigned char *this_string[6];
     uint32_t spacing;
+    int draw_background = 1;
 
     float ax, ay, bx, by, cx, cy, dx, dy, ex, ey, fx, fy;
 
@@ -224,6 +225,12 @@ INTERNAL int emf_plot(struct zint_symbol *symbol) {
     bggrn = (16 * ctoi(symbol->bgcolour[2])) + ctoi(symbol->bgcolour[3]);
     bgblu = (16 * ctoi(symbol->bgcolour[4])) + ctoi(symbol->bgcolour[5]);
     
+    if (strlen(symbol->bgcolour) > 6) {
+        if ((ctoi(symbol->bgcolour[6]) == 0) && (ctoi(symbol->bgcolour[7]) == 0)) {
+            draw_background = 0;
+        }
+    }
+
     rectangle_count = count_rectangles(symbol);
     circle_count = count_circles(symbol);
     hexagon_count = count_hexagons(symbol);
@@ -372,6 +379,7 @@ INTERNAL int emf_plot(struct zint_symbol *symbol) {
     bytecount += 12;
     recordcount++;
 
+    if (draw_background) {
         /* Make background from a rectangle */
         background.type = 0x0000002b; // EMR_RECTANGLE;
         background.size = 24;
@@ -381,6 +389,7 @@ INTERNAL int emf_plot(struct zint_symbol *symbol) {
         background.box.bottom = emr_header.emf_header.bounds.bottom;
         bytecount += 24;
         recordcount++;
+    }
 
     //Rectangles
     rect = symbol->vector->rectangles;
@@ -578,7 +587,9 @@ INTERNAL int emf_plot(struct zint_symbol *symbol) {
 
     fwrite(&emr_selectobject_bgbrush, sizeof (emr_selectobject_t), 1, emf_file);
     fwrite(&emr_selectobject_pen, sizeof (emr_selectobject_t), 1, emf_file);
+    if (draw_background) {
         fwrite(&background, sizeof (emr_rectangle_t), 1, emf_file);
+    }
 
     if (symbol->symbology == BARCODE_ULTRA) {
         for(i = 0; i < 8; i++) {

backend/library.c

@@ -55,7 +55,9 @@ struct zint_symbol *ZBarcode_Create() {
     symbol->rows = 0;
     symbol->width = 0;
     strcpy(symbol->fgcolour, "000000");
+    symbol->fgcolor = &symbol->fgcolour[0];
     strcpy(symbol->bgcolour, "ffffff");
+    symbol->bgcolor = &symbol->bgcolour[0];
     strcpy(symbol->outfile, "out.png");
     symbol->scale = 1.0;
     symbol->option_1 = -1;
@@ -67,6 +69,7 @@ struct zint_symbol *ZBarcode_Create() {
     symbol->bitmap = NULL;
     symbol->bitmap_width = 0;
     symbol->bitmap_height = 0;
+    symbol->alphamap = NULL;
     symbol->eci = 0; // Default 0 uses ECI 3
     symbol->dot_size = 4.0 / 5.0;
     symbol->vector = NULL;

backend/output.c

@@ -39,11 +39,11 @@
 INTERNAL int output_check_colour_options(struct zint_symbol *symbol) {
     int error_number;
 
-    if (strlen(symbol->fgcolour) != 6) {
+    if ((strlen(symbol->fgcolour) != 6) && (strlen(symbol->fgcolour) != 8)) {
         strcpy(symbol->errtxt, "651: Malformed foreground colour target");
         return ZINT_ERROR_INVALID_OPTION;
     }
-    if (strlen(symbol->bgcolour) != 6) {
+    if ((strlen(symbol->bgcolour) != 6) && (strlen(symbol->bgcolour) != 8)) {
         strcpy(symbol->errtxt, "652: Malformed background colour target");
         return ZINT_ERROR_INVALID_OPTION;
     }
@@ -57,7 +57,7 @@ INTERNAL int output_check_colour_options(struct zint_symbol *symbol) {
         return ZINT_ERROR_INVALID_OPTION;
     }
 
-    error_number = is_sane(SSET, (unsigned char *) symbol->bgcolour, strlen(symbol->fgcolour));
+    error_number = is_sane(SSET, (unsigned char *) symbol->bgcolour, strlen(symbol->bgcolour));
     if (error_number == ZINT_ERROR_INVALID_DATA) {
         strcpy(symbol->errtxt, "654: Malformed background colour target");
         return ZINT_ERROR_INVALID_OPTION;

backend/png.c

@@ -79,11 +79,12 @@ INTERNAL int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
     png_infop info_ptr;
     int i, row, column;
     int fgred, fggrn, fgblu, bgred, bggrn, bgblu;
+    int fgalpha, bgalpha, use_alpha;
 
 #ifndef _MSC_VER
-    unsigned char outdata[symbol->bitmap_width * 3];
+    unsigned char outdata[symbol->bitmap_width * 4];
 #else
-    unsigned char* outdata = (unsigned char*) _alloca(symbol->bitmap_width * 3);
+    unsigned char* outdata = (unsigned char*) _alloca(symbol->bitmap_width * 4);
 #endif
 
     graphic = &wpng_info;
@@ -98,6 +99,22 @@ INTERNAL int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
     bggrn = (16 * ctoi(symbol->bgcolour[2])) + ctoi(symbol->bgcolour[3]);
     bgblu = (16 * ctoi(symbol->bgcolour[4])) + ctoi(symbol->bgcolour[5]);
 
+    use_alpha = 0;
+    
+    if (strlen(symbol->fgcolour) > 6) {
+        fgalpha = (16 * ctoi(symbol->fgcolour[6])) + ctoi(symbol->fgcolour[7]);
+        if (fgalpha != 0xff) use_alpha = 1;
+    } else {
+        fgalpha = 0xff;
+    }
+    
+    if (strlen(symbol->bgcolour) > 6) {
+        bgalpha = (16 * ctoi(symbol->bgcolour[6])) + ctoi(symbol->bgcolour[7]);
+        if (bgalpha != 0xff) use_alpha = 1;
+    } else {
+        bgalpha = 0xff;
+    }
+
     /* Open output file in binary mode */
     if (symbol->output_options & BARCODE_STDOUT) {
 #ifdef _MSC_VER
@@ -142,10 +159,14 @@ INTERNAL int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
     png_set_compression_level(png_ptr, 9);
 
     /* set Header block */
+    if (use_alpha)
+        png_set_IHDR(png_ptr, info_ptr, graphic->width, graphic->height,
+                8, PNG_COLOR_TYPE_RGBA, PNG_INTERLACE_NONE,
+                PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
+    else
         png_set_IHDR(png_ptr, info_ptr, graphic->width, graphic->height,
                 8, PNG_COLOR_TYPE_RGB, PNG_INTERLACE_NONE,
                 PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
-
     /* write all chunks up to (but not including) first IDAT */
     png_write_info(png_ptr, info_ptr);
 
@@ -158,56 +179,67 @@ INTERNAL int png_pixel_plot(struct zint_symbol *symbol, char *pixelbuf) {
         unsigned char *image_data;
         for (column = 0; column < symbol->bitmap_width; column++) {
             i = column * 3;
+            if (use_alpha) i += column;
             switch (*(pixelbuf + (symbol->bitmap_width * row) + column)) {
                 case 'W': // White
                     outdata[i] = 255;
                     outdata[i + 1] = 255;
                     outdata[i + 2] = 255;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'C': // Cyan
                     outdata[i] = 0;
                     outdata[i + 1] = 255;
                     outdata[i + 2] = 255;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'B': // Blue
                     outdata[i] = 0;
                     outdata[i + 1] = 0;
                     outdata[i + 2] = 255;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'M': // Magenta
                     outdata[i] = 255;
                     outdata[i + 1] = 0;
                     outdata[i + 2] = 255;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'R': // Red
                     outdata[i] = 255;
                     outdata[i + 1] = 0;
                     outdata[i + 2] = 0;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'Y': // Yellow
                     outdata[i] = 255;
                     outdata[i + 1] = 255;
                     outdata[i + 2] = 0;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'G': // Green
                     outdata[i] = 0;
                     outdata[i + 1] = 255;
                     outdata[i + 2] = 0;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case 'K': // Black
                     outdata[i] = 0;
                     outdata[i + 1] = 0;
                     outdata[i + 2] = 0;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 case '1':
                     outdata[i] = fgred;
                     outdata[i + 1] = fggrn;
                     outdata[i + 2] = fgblu;
+                    if (use_alpha) outdata[i + 3] = fgalpha;
                     break;
                 default:
                     outdata[i] = bgred;
                     outdata[i + 1] = bggrn;
                     outdata[i + 2] = bgblu;
+                    if (use_alpha) outdata[i + 3] = bgalpha;
                     break;
 
             }

backend/raster.c

@@ -62,6 +62,7 @@ static const char ultra_colour[] = "WCBMRYGK";
 static int buffer_plot(struct zint_symbol *symbol, char *pixelbuf) {
     /* Place pixelbuffer into symbol */
     int fgred, fggrn, fgblu, bgred, bggrn, bgblu;
+    int fgalpha, bgalpha;
     int row, column, i;
 
     /* Free any previous bitmap */
@@ -74,6 +75,11 @@ static int buffer_plot(struct zint_symbol *symbol, char *pixelbuf) {
         strcpy(symbol->errtxt, "661: Insufficient memory for bitmap buffer");
         return ZINT_ERROR_MEMORY;
     }
+    symbol->alphamap = (unsigned char *) malloc(symbol->bitmap_width * symbol->bitmap_height);
+    if (symbol->alphamap == NULL) {
+        strcpy(symbol->errtxt, "662: Insufficient memory for alphamap buffer");
+        return ZINT_ERROR_MEMORY;
+    }
 
     fgred = (16 * ctoi(symbol->fgcolour[0])) + ctoi(symbol->fgcolour[1]);
     fggrn = (16 * ctoi(symbol->fgcolour[2])) + ctoi(symbol->fgcolour[3]);
@@ -82,6 +88,18 @@ static int buffer_plot(struct zint_symbol *symbol, char *pixelbuf) {
     bggrn = (16 * ctoi(symbol->bgcolour[2])) + ctoi(symbol->bgcolour[3]);
     bgblu = (16 * ctoi(symbol->bgcolour[4])) + ctoi(symbol->bgcolour[5]);
     
+    if (strlen(symbol->fgcolour) > 6) {
+        fgalpha = (16 * ctoi(symbol->fgcolour[6])) + ctoi(symbol->fgcolour[7]);
+    } else {
+        fgalpha = 0xff;
+    }
+    
+    if (strlen(symbol->bgcolour) > 6) {
+        bgalpha = (16 * ctoi(symbol->bgcolour[6])) + ctoi(symbol->bgcolour[7]);
+    } else {
+        bgalpha = 0xff;
+    }
+
     for (row = 0; row < symbol->bitmap_height; row++) {
         for (column = 0; column < symbol->bitmap_width; column++) {
             i = ((row * symbol->bitmap_width) + column) * 3;
@@ -90,51 +108,61 @@ static int buffer_plot(struct zint_symbol *symbol, char *pixelbuf) {
                     symbol->bitmap[i] = 255;
                     symbol->bitmap[i + 1] = 255;
                     symbol->bitmap[i + 2] = 255;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'C': // Cyan
                     symbol->bitmap[i] = 0;
                     symbol->bitmap[i + 1] = 255;
                     symbol->bitmap[i + 2] = 255;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'B': // Blue
                     symbol->bitmap[i] = 0;
                     symbol->bitmap[i + 1] = 0;
                     symbol->bitmap[i + 2] = 255;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'M': // Magenta
                     symbol->bitmap[i] = 255;
                     symbol->bitmap[i + 1] = 0;
                     symbol->bitmap[i + 2] = 255;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'R': // Red
                     symbol->bitmap[i] = 255;
                     symbol->bitmap[i + 1] = 0;
                     symbol->bitmap[i + 2] = 0;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'Y': // Yellow
                     symbol->bitmap[i] = 255;
                     symbol->bitmap[i + 1] = 255;
                     symbol->bitmap[i + 2] = 0;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'G': // Green
                     symbol->bitmap[i] = 0;
                     symbol->bitmap[i + 1] = 255;
                     symbol->bitmap[i + 2] = 0;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case 'K': // Black
                     symbol->bitmap[i] = 0;
                     symbol->bitmap[i + 1] = 0;
                     symbol->bitmap[i + 2] = 0;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 case DEFAULT_INK:
                     symbol->bitmap[i] = fgred;
                     symbol->bitmap[i + 1] = fggrn;
                     symbol->bitmap[i + 2] = fgblu;
+                    symbol->alphamap[i / 3] = fgalpha;
                     break;
                 default: // DEFAULT_PAPER
                     symbol->bitmap[i] = bgred;
                     symbol->bitmap[i + 1] = bggrn;
                     symbol->bitmap[i + 2] = bgblu;
+                    symbol->alphamap[i / 3] = bgalpha;
                     break;
             }
         }

backend/svg.c

@@ -121,6 +121,10 @@ INTERNAL int svg_plot(struct zint_symbol *symbol) {
     float ax, ay, bx, by, cx, cy, dx, dy, ex, ey, fx, fy;
     float radius;
     int i;
+    char fgcolour_string[7];
+    char bgcolour_string[7];
+    int bg_alpha = 0xff;
+    int fg_alpha = 0xff;
 
     struct zint_vector_rect *rect;
     struct zint_vector_hexagon *hex;
@@ -133,6 +137,20 @@ INTERNAL int svg_plot(struct zint_symbol *symbol) {
     char* html_string;
 #endif
 
+    for (i = 0; i < 6; i++) {
+        fgcolour_string[i] = symbol->fgcolour[i];
+        bgcolour_string[i] = symbol->bgcolour[i];
+    }
+    fgcolour_string[6] = '\0';
+    bgcolour_string[6] = '\0';
+    
+    if (strlen(symbol->fgcolour) > 6) {
+        fg_alpha = (16 * ctoi(symbol->fgcolour[6])) + ctoi(symbol->fgcolour[7]);
+    }
+    if (strlen(symbol->bgcolour) > 6) {
+        bg_alpha = (16 * ctoi(symbol->bgcolour[6])) + ctoi(symbol->bgcolour[7]);
+    }
+    
     int html_len = strlen((char *)symbol->text) + 1;
 
     for (i = 0; i < (int) strlen((char *)symbol->text); i++) {
@@ -178,18 +196,27 @@ INTERNAL int svg_plot(struct zint_symbol *symbol) {
     fprintf(fsvg, "   xmlns=\"http://www.w3.org/2000/svg\">\n");
     fprintf(fsvg, "   <desc>Zint Generated Symbol\n");
     fprintf(fsvg, "   </desc>\n");
-    fprintf(fsvg, "\n   <g id=\"barcode\" fill=\"#%s\">\n", symbol->fgcolour);
+    fprintf(fsvg, "\n   <g id=\"barcode\" fill=\"#%s\">\n", fgcolour_string);
 
-    fprintf(fsvg, "      <rect x=\"0\" y=\"0\" width=\"%d\" height=\"%d\" fill=\"#%s\" />\n", (int) ceil(symbol->vector->width), (int) ceil(symbol->vector->height), symbol->bgcolour);
+    if (bg_alpha != 0) {
+        fprintf(fsvg, "      <rect x=\"0\" y=\"0\" width=\"%d\" height=\"%d\" fill=\"#%s\"", (int) ceil(symbol->vector->width), (int) ceil(symbol->vector->height), bgcolour_string);
+        if (bg_alpha != 0xff) {
+            fprintf(fsvg, " opacity=\"%.3f\"", (float) bg_alpha / 255.0);
+        }
+        fprintf(fsvg, " />\n");
+    }
 
     rect = symbol->vector->rectangles;
     while (rect) {
-        if (rect->colour == -1) {
+        fprintf(fsvg, "      <rect x=\"%.2f\" y=\"%.2f\" width=\"%.2f\" height=\"%.2f\"", rect->x, rect->y, rect->width, rect->height);
-            fprintf(fsvg, "      <rect x=\"%.2f\" y=\"%.2f\" width=\"%.2f\" height=\"%.2f\" />\n", rect->x, rect->y, rect->width, rect->height);
+        if (rect->colour != -1) {
-        } else {
             pick_colour(rect->colour, colour_code);
-            fprintf(fsvg, "      <rect x=\"%.2f\" y=\"%.2f\" width=\"%.2f\" height=\"%.2f\" fill=\"#%s\" />\n", rect->x, rect->y, rect->width, rect->height, colour_code);
+            fprintf(fsvg, " fill=\"#%s\"", colour_code);
         }
+        if (fg_alpha != 0xff) {
+            fprintf(fsvg, " opacity=\"%.3f\"", (float) fg_alpha / 255.0);
+        }
+        fprintf(fsvg, " />\n");
         rect = rect->next;
     }
 
@@ -208,24 +235,41 @@ INTERNAL int svg_plot(struct zint_symbol *symbol) {
         dx = hex->x;
         ex = hex->x - (0.86 * radius);
         fx = hex->x - (0.86 * radius);
-        fprintf(fsvg, "      <path d=\"M %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f Z\" />\n", ax, ay, bx, by, cx, cy, dx, dy, ex, ey, fx, fy);
+        fprintf(fsvg, "      <path d=\"M %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f L %.2f %.2f Z\"", ax, ay, bx, by, cx, cy, dx, dy, ex, ey, fx, fy);
+        if (fg_alpha != 0xff) {
+            fprintf(fsvg, " opacity=\"%.3f\"", (float) fg_alpha / 255.0);
+        }
+        fprintf(fsvg, " />\n");
         hex = hex->next;
     }
 
     circle = symbol->vector->circles;
     while (circle) {
+        fprintf(fsvg, "      <circle cx=\"%.2f\" cy=\"%.2f\" r=\"%.2f\"", circle->x, circle->y, circle->diameter / 2.0);
+        
         if (circle->colour) {
-            fprintf(fsvg, "      <circle cx=\"%.2f\" cy=\"%.2f\" r=\"%.2f\" fill=\"#%s\" />\n", circle->x, circle->y, circle->diameter / 2.0, symbol->bgcolour);
+            fprintf(fsvg, " fill=\"#%s\"", bgcolour_string);
-        } else {
+            if (bg_alpha != 0xff) {
-            fprintf(fsvg, "      <circle cx=\"%.2f\" cy=\"%.2f\" r=\"%.2f\" fill=\"#%s\" />\n", circle->x, circle->y, circle->diameter / 2.0, symbol->fgcolour);
+                // This doesn't work how the user is likely to expect - more work needed!
+                fprintf(fsvg, " opacity=\"%.3f\"", (float) bg_alpha / 255.0);
             }
+        } else {
+            if (fg_alpha != 0xff) {
+                fprintf(fsvg, " opacity=\"%.3f\"", (float) fg_alpha / 255.0);
+            }
+        }
+        fprintf(fsvg, " />\n");
         circle = circle->next;
     }
 
     string = symbol->vector->strings;
     while (string) {
         fprintf(fsvg, "      <text x=\"%.2f\" y=\"%.2f\" text-anchor=\"middle\"\n", string->x, string->y);
-        fprintf(fsvg, "         font-family=\"Helvetica\" font-size=\"%.1f\" fill=\"#%s\" >\n", string->fsize, symbol->fgcolour);
+        fprintf(fsvg, "         font-family=\"Helvetica\" font-size=\"%.1f\"", string->fsize);
+        if (fg_alpha != 0xff) {
+            fprintf(fsvg, " opacity=\"%.3f\"", (float) fg_alpha / 255.0);
+        }
+        fprintf(fsvg, " >\n");
         make_html_friendly(string->text, html_string);
         fprintf(fsvg, "         %s\n", html_string);
         fprintf(fsvg, "      </text>\n");

backend/zint.h

@@ -37,25 +37,12 @@
 extern "C" {
 #endif /* __cplusplus */
 
-    struct zint_render_line {
-        float x, y, length, width;
-        struct zint_render_line *next; /* Pointer to next line */
-    };
-
     struct zint_vector_rect {
         float x, y, height, width;
         int colour;
         struct zint_vector_rect *next;
     };
     
-    struct zint_render_string {
-        float x, y, fsize;
-        float width; /* Suggested string width, may be 0 if none recommended */
-        int length;
-        unsigned char *text;
-        struct zint_render_string *next; /* Pointer to next character */
-    };
-
     struct zint_vector_string {
         float x, y, fsize;
         float width; /* Suggested string width, may be 0 if none recommended */
@@ -64,35 +51,17 @@ extern "C" {
         struct zint_vector_string *next; /* Pointer to next character */
     };
 
-    struct zint_render_ring {
-        float x, y, radius, line_width;
-        struct zint_render_ring *next; /* Pointer to next ring */
-    };
-
     struct zint_vector_circle {
         float x, y, diameter;
         int colour;
         struct zint_vector_circle *next; /* Pointer to next circle */
     };
 
-    struct zint_render_hexagon {
-        float x, y, height;
-        struct zint_render_hexagon *next; /* Pointer to next hexagon */
-    };
-
     struct zint_vector_hexagon {
         float x, y, diameter;
         struct zint_vector_hexagon *next; /* Pointer to next hexagon */
     };
 
-    struct zint_render {
-        float width, height;
-        struct zint_render_line *lines; /* Pointer to first line */
-        struct zint_render_string *strings; /* Pointer to first string */
-        struct zint_render_ring *rings; /* Pointer to first ring */
-        struct zint_render_hexagon *hexagons; /* Pointer to first hexagon */
-    };
-
     struct zint_vector {
         float width, height;
         struct zint_vector_rect *rectangles; /* Pointer to first rectangle */
@@ -108,7 +77,9 @@ extern "C" {
         int border_width;
         int output_options;
         char fgcolour[10];
+        char *fgcolor; // pointer to fgcolour
         char bgcolour[10];
+        char *bgcolor; // pointer to bgcolour
         char outfile[256];
         float scale;
         int option_1;
@@ -128,6 +99,7 @@ extern "C" {
         unsigned char *bitmap;
         int bitmap_width;
         int bitmap_height;
+        unsigned char *alphamap;
         unsigned int bitmap_byte_length;
         float dot_size;
         struct zint_vector *vector;

docs/manual.txt

@@ -1,6 +1,7 @@
 *******************************************************************************
 * For reference the following is a text-only version of the Zint manual.      *
-* The full version can be accessed at http://zint.org.uk/Manual.aspx          *
+* The HTML version can be accessed at http://zint.org.uk/Manual.aspx          *
+* however this text file is more likely to be up-to-date.                     *
 *******************************************************************************
 
 Zint Barcode Generator and Zint Barcode Studio User Manual
@@ -402,6 +403,24 @@ zint --fg=004700 -d "This"
 
 alters the symbol to a dark green.
 
+Zint also supports RGBA colour information for some output file formats which
+support alpha channels (currently only PNG and SVG) in a RRGGBBAA format.
+For example:
+
+zint --fg=00ff0055 -d "This"
+
+will produce a semi-transparent green foreground with standard (white)
+background. Note that transparency is handled differently for raster and
+vector files so that...
+
+zint --bg=ff0000 --fg=ffffff00 ...
+
+will give different results for PNG and SVG. Experimentation is advised!
+Also note that these options don't work properly with Maxicode yet.
+
+In addition the --nobackground option will simply remove the background from
+PNG, SVG and EMF files.
+
 4.8 Rotating the Symbol
 -----------------------
 The symbol can be rotated through four orientations using the --rotate= option
@@ -827,15 +846,19 @@ output_options    | integer      | Set various output file     | 0 (none)
                   |              |    parameters (see section  |
                   |              |    5.8).                    |
 fgcolour          | character    | Foreground (ink) colour as  | "000000"
-                  |    string    |    RGB hexadecimal string.  |
+                  |    string    |    RGB/RGBA hexadecimal  |
-                  |              |    Must be 6 characters     |
+                  |              |    string. Must be 6 or 8   |
-                  |              |    followed by terminating  |
+                  |              |    characters followed by   |
-                  |              |    \0 character.            |
+                  |              |    terminating \0.          |
+fgcolor           | pointer      | Points to fgcolour allowing |
+                  |              |    alternate spelling.      |
 bgcolour          | character    | Background (paper) colour   | "ffffff"
-                  |    string    |    as RGB hexadecimal       |
+                  |    string    |    as RGB/RGBA hexadecimal  |
-                  |              |    string. Must be 6 chara- |
+                  |              |    string. Must be 6 or 8   |
-                  |              |    ters followed by termin- |
+                  |              |    characters followed by   |
-                  |              |    ating \0 character.      |
+                  |              |    terminating \0.          |
+bgcolor           | pointer      | Points to bgcolour allowing |
+                  |              |    alternate spelling.      |
 outfile           | character    | Contains the name of the    | "out.png"
                   |    string    |    file to output a result- |
                   |              |    ing barcode symbol to.   |
@@ -903,6 +926,11 @@ int main(int argc, char **argv)
     return 0;
 }
 
+Background removal for PNG, SVG and EMF files can be achieved by setting the
+background alpha to "00" where the values for R, G and B will be ignored:
+
+strcpy(my_symbol->bgcolour, "55555500");
+
 5.6 Handling Errors
 -------------------
 If errors occur during encoding an integer value is passed back to the calling

frontend/main.c

@@ -108,6 +108,7 @@ static void usage(void) {
             "  --init                Create reader initialisation/programming symbol\n"
             "  --mirror              Use batch data to determine filename\n"
             "  --mode=NUMBER         Set encoding mode (Maxicode/Composite)\n"
+            "  --nobackground        Remove background (PNG/SVG/EPS only)\n"
             "  --notext              Remove human readable text\n"
             "  -o, --output=FILE     Send output to FILE. Default is out.png\n"
             "  --primary=STRING      Set structured primary message (Maxicode/Composite)\n"
@@ -508,6 +509,7 @@ int main(int argc, char **argv) {
             {"gssep", 0, 0, 0},
             {"binary", 0, 0, 0},
             {"fullmultibyte", 0, 0, 0},
+            {"nobackground", 0, 0, 0},
             {"notext", 0, 0, 0},
             {"square", 0, 0, 0},
             {"dmre", 0, 0, 0},
@@ -574,10 +576,10 @@ int main(int argc, char **argv) {
                     }
                 }
                 if (!strcmp(long_options[option_index].name, "fg")) {
-                    strncpy(my_symbol->fgcolour, optarg, 7);
+                    strncpy(my_symbol->fgcolour, optarg, 9);
                 }
                 if (!strcmp(long_options[option_index].name, "bg")) {
-                    strncpy(my_symbol->bgcolour, optarg, 7);
+                    strncpy(my_symbol->bgcolour, optarg, 9);
                 }
                 if (!strcmp(long_options[option_index].name, "fullmultibyte")) {
                     fullmultibyte = 1;
@@ -806,6 +808,9 @@ int main(int argc, char **argv) {
                         fflush(stderr);
                     }
                 }
+                if (!strcmp(long_options[option_index].name, "nobackground")) {
+                    strcpy(my_symbol->bgcolour, "ffffff00");
+                }
                 break;
 
             case 'h':