liblbx: Don't scale palette values internally.

Output the 18-bit palette values unadulterated, leaving it up to the
users to do conversion if necessary.  Push the conversion down into the
consumers (currently PNG output and the GTK GUI) where a 24-bit palette
is required.

While we're at it, adjust the conversion to scale to the full output
range of [0, 255].  This is a slight change to the output, so all the
image hashes need to be adjusted in the regression test.

diff --git a/src/gui/render.c b/src/gui/render.c
index e30e6c845623feb011fb8397ce05bb80807a6434..a96cc06a0b0e83f03b6f80ca944d6e48e70186f5 100644 (file)
--- a/src/gui/render.c
+++ b/src/gui/render.c
@@ -29,6 +29,13 @@ struct lbx_colour palette_external[256];
 struct lbx_colour palette_internal[256];
 struct lbx_colour palette_override[256];
 
+static inline unsigned scale6to8(unsigned x)
+{
+       assert(x <= 0x3f);
+
+       return x*0xff / 0x3f;
+}
+
 static void get_colour(unsigned char index, unsigned char out[static 4])
 {
        struct lbx_colour *colour;
@@ -40,11 +47,11 @@ static void get_colour(unsigned char index, unsigned char out[static 4])
        else if (palette_external[index].active)
                colour = palette_external + index;
        else
-               colour = &(struct lbx_colour) { .red = 0xff, .blue = 0xff };
+               colour = &(struct lbx_colour) { .red = 0x3f, .blue = 0x3f };
 
-       out[0] = colour->red;
-       out[1] = colour->green;
-       out[2] = colour->blue;
+       out[0] = scale6to8(colour->red);
+       out[1] = scale6to8(colour->green);
+       out[2] = scale6to8(colour->blue);
        out[3] = -1; /* opaque */
 }
 

diff --git a/src/image.c b/src/image.c
index 4657208a05ae28439496346473c8de7cb1566023..98d1a31118ceb03085d14d860045ef267ed52244 100644 (file)
--- a/src/image.c
+++ b/src/image.c
@@ -413,9 +413,9 @@ lbx_img_loadpalette(void *f, const struct lbx_file_ops *fops,
                }
 
                palette[i] = (struct lbx_colour) {
-                       .red    = entry[1] << 2,
-                       .green  = entry[2] << 2,
-                       .blue   = entry[3] << 2,
+                       .red    = entry[1] & 0x3f,
+                       .green  = entry[2] & 0x3f,
+                       .blue   = entry[3] & 0x3f,
                        .active = 1,
                };
        }
@@ -451,9 +451,9 @@ lbx_img_getpalette(struct lbx_image *pub, struct lbx_colour palette[static 256])
                }
 
                palette[img->palstart + i] = (struct lbx_colour){
-                       .red    = entry[1] << 2,
-                       .green  = entry[2] << 2,
-                       .blue   = entry[3] << 2,
+                       .red    = entry[1],
+                       .green  = entry[2],
+                       .blue   = entry[3],
                        .active = 1,
                };
        }

diff --git a/src/image.h b/src/image.h
index b51b3600dea242e92676c949fab04bc2ef7d0e9e..2057a423e85d035b49e5a34faf5cdb6bd62f2a79 100644 (file)
--- a/src/image.h
+++ b/src/image.h
@@ -11,10 +11,7 @@ struct lbx_image {
 };
 
 struct lbx_colour {
-       unsigned char red;
-       unsigned char green;
-       unsigned char blue;
-       unsigned char active;
+       unsigned red:6, green:6, blue:6, active:1;
 };
 
 struct lbx_imginfo {

diff --git a/src/lbximg.c b/src/lbximg.c
index 085e191fd8101c314100ef7a95486095e3ae7ec3..6c54b0f3b659bbb79371d63efe88252f8053858b 100644 (file)
--- a/src/lbximg.c
+++ b/src/lbximg.c
@@ -180,7 +180,7 @@ static int loadpalette(struct lbx_image *img, struct lbx_imginfo *info,
 
        /* Default the palette to a wonderful pink. */
        for (i = 0; i < 256; i++) {
-               palette[i] = (struct lbx_colour){0xff, 0x00, 0xff};
+               palette[i] = (struct lbx_colour){0x3f, 0x00, 0x3f};
        }
 
        /* Read the external palette, if any. */

diff --git a/src/png.c b/src/png.c
index 288cf7719d227f83dc5c5f8342370149fc6ac9b2..83aeec43583a354834a8e49bd525113fc50a6876 100644 (file)
--- a/src/png.c
+++ b/src/png.c
@@ -23,6 +23,7 @@
 #include <stdarg.h>
 #include <stdbool.h>
 #include <setjmp.h>
+#include <assert.h>
 
 #include <png.h>
 
@@ -93,13 +94,33 @@ static void flush_data(png_structp png)
        }
 }
 
+static inline unsigned scale6to8(unsigned x)
+{
+       assert(x <= 0x3f);
+
+       return x*0xff / 0x3f;
+}
+
+/* Scale the 18-bit LBX palette into a 24-bit PNG palette. */
+static void fill_png_palette(png_color *out, const struct lbx_colour *in)
+{
+       for (unsigned i = 0; i < 256; i++) {
+               out[i] = (struct png_color_struct) {
+                       .red   = scale6to8(in[i].red),
+                       .green = scale6to8(in[i].green),
+                       .blue  = scale6to8(in[i].blue),
+               };
+       }
+}
+
 static void
 write_rgba_frame(png_structp png, png_infop info,
                  unsigned char **framedata, unsigned char **mask,
-                 struct lbx_colour *palette)
+                 struct lbx_colour *lbx_palette)
 {
        png_uint_32 width = png_get_image_width(png, info);
        png_uint_32 height = png_get_image_height(png, info);
+       png_color png_palette[256];
        unsigned char (*row)[4];
        jmp_buf parent;
 
@@ -121,11 +142,12 @@ write_rgba_frame(png_structp png, png_infop info,
        }
 
        png_write_info(png, info);
+       fill_png_palette(png_palette, lbx_palette);
        for (png_uint_32 y = 0; y < height; y++) {
                for (png_uint_32 x = 0; x < width; x++) {
-                       row[x][0] = palette[framedata[y][x]].red;
-                       row[x][1] = palette[framedata[y][x]].green;
-                       row[x][2] = palette[framedata[y][x]].blue;
+                       row[x][0] = png_palette[framedata[y][x]].red;
+                       row[x][1] = png_palette[framedata[y][x]].green;
+                       row[x][2] = png_palette[framedata[y][x]].blue;
                        row[x][3] = mask[y][x] ? -1 : 0;
                }
                png_write_row(png, (void *)row);
@@ -176,18 +198,11 @@ write_masked_index_frame(png_structp png, png_infop info,
 
 static void
 write_palette_frame(png_structp png, png_infop info,
-                    unsigned char **framedata, struct lbx_colour *palette)
+                    unsigned char **framedata, struct lbx_colour *lbx_palette)
 {
        png_color png_palette[256];
 
-       for (unsigned i = 0; i < 256; i++) {
-               png_palette[i] = (png_color) {
-                       .red   = palette[i].red,
-                       .green = palette[i].green,
-                       .blue  = palette[i].blue,
-               };
-       }
-
+       fill_png_palette(png_palette, lbx_palette);
        png_set_PLTE(png, info, png_palette, 256);
        png_set_rows(png, info, framedata);
        png_write_png(png, info, PNG_TRANSFORM_IDENTITY, NULL);

diff --git a/tests/regress.zsh b/tests/regress.zsh
index 041e83f184cfd09b424b1abc30f1cdb00fbb1876..a3a5adf89f9d452bc2d6d6d40a645e9a3f8ac44d 100755 (executable)
--- a/tests/regress.zsh
+++ b/tests/regress.zsh
@@ -43,53 +43,53 @@ $LBXTOOL -xf $DATADIR/mainmenu.lbx mainmenu.lbx.{000,007,021}
 
 echo "mainmenu.lbx.021: single frame, embedded palette:"
 $LBXIMG -df mainmenu.lbx.021
-compare 0 390c49cfd1fe5e2ac0490be976f20936
+compare 0 b5d488667bed557a089c5d8f8b0a3d64
 
 echo "mainmenu.lbx.007: single frame, external palette:"
 $LBXIMG -dp fonts.lbx.006 < mainmenu.lbx.007
-compare 0 76def3e188f666025c62e621e23ab0d0
+compare 0 5b9a1a10e4979531e91a41f02ee40537
 
 echo "mainmenu.lbx.000: multi frame, external palette:"
 $LBXIMG -dp fonts.lbx.006 < mainmenu.lbx.000 0 15 49
-compare  0 cc4ae6d96f6233f3b50bdce8b7ca74ee
-compare 15 cad158da9a015adfcea7809a8a3b6f4b
-compare 49 390c49cfd1fe5e2ac0490be976f20936
+compare  0 6556baafebe441498f33865f2e9eb0de
+compare 15 76a6e8fe18614423f8780ee80f513e8c
+compare 49 b5d488667bed557a089c5d8f8b0a3d64
 
 # Logos
 $LBXTOOL -xf $DATADIR/logo.lbx
 
 echo "logo.lbx.000: single frame, embedded palette, transparency:"
 $LBXIMG -df logo.lbx.000
-compare 0 5cc8d2b761390d15be2738030c658bfc
+compare 0 cf4cbcb834ef35890d1283928b0187bf
 
 echo "logo.lbx.001: multi frame, embedded palette:"
 $LBXIMG -df logo.lbx.001 0 30 63
-compare  0 f3f0859b39f2e76091842c8a7276b2a1
-compare 30 8fb41356a20c68c3be0939ad49256cf9
-compare 63 156f381c5d4bf6178affd3d6a4720118
+compare  0 542778cde51dc821e225ddd4a16dc197
+compare 30 609c2b9be5a1e18f5c36398554f9f2ec
+compare 63 664b12c7259948900ded3ff93e1f4ec7
 
 # Ships
 $LBXTOOL -xf $DATADIR/ships.lbx ships.lbx.{042,049}
 
 echo "ships.lbx.042: single frame, external+override palette, transparency:"
 $LBXIMG -df ships.lbx.042 -p fonts.lbx.012 -O ships.lbx.049
-compare 0 bd643736d46ef387bcffcc8803aabb83
+compare 0 3426ef9c5c8e3dfbd1a95ed9211e2342
 
 # Nebulae
 $LBXTOOL -xf $DATADIR/starbg.lbx starbg.lbx.009
 
 echo "starbg.lbx.009: single frame, raw data:"
 $LBXIMG -df starbg.lbx.009 -p fonts.lbx.005
-compare 0 cfc5d92b6503951c4962498c7dcfea31
+compare 0 2e430234f410ef208f78d99a64fa449f
 
 # Monsters
 $LBXTOOL -xf $DATADIR/monster.lbx monster.lbx.{007,014}
 
 echo "monster.lbx.007: multi frame, chunked:"
 $LBXIMG -df monster.lbx.007 -p fonts.lbx.004 -O monster.lbx.014 0 5 19
-compare  0 59399c8d2d74116ff4b330a2cc1f3cc2
-compare  5 6947e108f7c8d2d2d626c67af3fdb7e2
-compare 19 03d86257527f0d7a91c2cde57059e734
+compare  0 20eb7d52abb3cd718426d4732d9e2286
+compare  5 ea8c7a5fbeb9043fd8f30ae91b13550a
+compare 19 d501ecf1599ea724846625a9711c6ccb
 
 # Clean up
 if [[ $FAILED -eq 0 ]]; then
@@ -97,4 +97,5 @@ if [[ $FAILED -eq 0 ]]; then
        rm -rf -- $SCRATCH
 else
        echo "$FAILED test(s) FAILED"
+       exit 1
 fi