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Implement grayscale DMG palette specs (#1709)

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This commit is contained in:
Rangi
2025-06-30 14:53:05 -04:00
committed by GitHub
parent 5942117ac3
commit 7054d81650
21 changed files with 166 additions and 76 deletions
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79
src/gfx/pal_spec.cpp
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@@ -28,6 +28,27 @@ static void skipWhitespace(Str const &str, size_t &pos) {
pos = std::min(str.find_first_not_of(" \t"sv, pos), str.length());
}
static constexpr uint8_t nibble(char c) {
if (c >= 'a') {
assume(c <= 'f');
return c - 'a' + 10;
} else if (c >= 'A') {
assume(c <= 'F');
return c - 'A' + 10;
} else {
assume(c >= '0' && c <= '9');
return c - '0';
}
}
static constexpr uint8_t toHex(char c1, char c2) {
return nibble(c1) * 16 + nibble(c2);
}
static constexpr uint8_t singleToHex(char c) {
return toHex(c, c);
}
void parseInlinePalSpec(char const * const rawArg) {
// List of #rrggbb/#rgb colors (or #none); comma-separated.
// Palettes are separated by colons.
@@ -595,3 +616,61 @@ void parseExternalPalSpec(char const *arg) {
std::get<1> (*iter)(file);
}
void parseDmgPalSpec(char const * const rawArg) {
// Two hex digit DMG palette spec
std::string_view arg(rawArg);
if (arg.length() != 2
|| arg.find_first_not_of("0123456789ABCDEFabcdef"sv) != std::string_view::npos) {
error("Unknown DMG palette specification \"%s\"", rawArg);
return;
}
options.palSpecDmg = toHex(arg[0], arg[1]);
// Map gray shades to their DMG color indexes for fast lookup by `Rgba::grayIndex`
for (uint8_t i = 0; i < 4; ++i) {
options.dmgColors[options.dmgValue(i)] = i;
}
// Validate that DMG palette spec does not have conflicting colors
for (uint8_t i = 0; i < 3; ++i) {
for (uint8_t j = i + 1; j < 4; ++j) {
if (options.dmgValue(i) == options.dmgValue(j)) {
error("DMG palette specification maps two gray shades to the same color index");
return;
}
}
}
}
void parseBackgroundPalSpec(char const *arg) {
if (strcasecmp(arg, "transparent") == 0) {
options.bgColor = Rgba(0x00, 0x00, 0x00, 0x00);
return;
}
if (arg[0] != '#') {
error("Background color specification must be `#rgb`, `#rrggbb`, or `transparent`");
return;
}
size_t size = strspn(&arg[1], "0123456789ABCDEFabcdef");
switch (size) {
case 3:
options.bgColor = Rgba(singleToHex(arg[1]), singleToHex(arg[2]), singleToHex(arg[3]), 0xFF);
break;
case 6:
options.bgColor =
Rgba(toHex(arg[1], arg[2]), toHex(arg[3], arg[4]), toHex(arg[5], arg[6]), 0xFF);
break;
default:
error("Unknown background color specification \"%s\"", arg);
}
if (arg[size + 1] != '\0') {
error("Unexpected text \"%s\" after background color specification", &arg[size + 1]);
}
}