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Colour handling: Support modern hsl(a) syntax #12

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Merged
merged 5 commits into from
Jul 13, 2025
Merged

Colour handling: Support modern hsl(a) syntax #12

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8e71e0f
parse: properties: utils: hsl: Allow <angle> for hue
tlsa Jul 12, 2025
bf5ec81
parse: properties: utils: hsl and hsla are interchangable
tlsa Jul 12, 2025
73002db
parse: properties: utils: hsl: Alpha can be percentage
tlsa Jul 13, 2025
ea9ffb9
parse: properties: utils: hsl: Support modern syntax
tlsa Jul 13, 2025
6194a24
parse: properties: utils: hsl: Percentage optional with modern syntax
tlsa Jul 13, 2025
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131 changes: 98 additions & 33 deletions src/parse/properties/utils.c
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Original file line number Diff line number Diff line change
Expand Up @@ -487,34 +487,75 @@ static bool parse_rgb(
*
* \param vector Vector of tokens to process
* \param ctx Pointer to vector iteration context
* \param colour_channels Number of colour channels to expect
* \param result Pointer to location to receive result (AARRGGBB)
* \return true on success, false on error.
*/
static bool parse_hsl(
const parserutils_vector *vector,
int32_t *ctx,
int colour_channels,
uint32_t *result)
{
const css_token *token;
size_t consumed = 0;
css_fixed hue, sat, lit;
int32_t alpha = 255;
bool legacy = false;
css_error error;
uint8_t r = 0, g = 0, b = 0, a = 0xff;

/* hue is a number without a unit representing an
* angle (0-360) degrees
* angle (0-360) degrees, or it can be an angle dimension.
*/
consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if ((token == NULL) || (token->type != CSS_TOKEN_NUMBER))
if ((token == NULL) ||
(token->type != CSS_TOKEN_NUMBER &&
token->type != CSS_TOKEN_DIMENSION)) {
return false;
}

hue = css__number_from_lwc_string(token->idata, false, &consumed);
if (consumed != lwc_string_length(token->idata))
return false; /* failed to consume the whole string as a number */

switch (token->type) {
case CSS_TOKEN_NUMBER:
if (consumed != lwc_string_length(token->idata)) {
return false; /* failed to consume the whole string as a number */
}
break;
case CSS_TOKEN_DIMENSION: {
size_t len = lwc_string_length(token->idata);
const char *data = lwc_string_data(token->idata);
uint32_t unit = UNIT_DEG;

error = css__parse_unit_keyword(
data + consumed,
len - consumed,
&unit);
if (error != CSS_OK) {
return false;
}

switch (unit) {
case UNIT_DEG:
break;
case UNIT_RAD:
hue = FDIV(FMUL(hue, F_180), F_PI);
break;
case UNIT_GRAD:
hue = FMUL(hue, FLTTOFIX(0.9));
break;
case UNIT_TURN:
hue = FMUL(hue, F_360);
break;
default:
return false;
}
}
break;
default:
return false; /* unexpected token type */
}

/* Normalise hue to the range [0, 360) */
while (hue < 0)
Expand All @@ -524,21 +565,32 @@ static bool parse_hsl(

consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if (!tokenIsChar(token, ','))
token = parserutils_vector_peek(vector, *ctx);
if (token == NULL) {
return false;
}

if (tokenIsChar(token, ',')) {
parserutils_vector_iterate(vector, ctx);
consumeWhitespace(vector, ctx);
legacy = true;
}

/* saturation */
consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if ((token == NULL) || (token->type != CSS_TOKEN_PERCENTAGE))
if (token == NULL)
return false;

if ((token->type != CSS_TOKEN_PERCENTAGE) &&
(token->type != CSS_TOKEN_NUMBER || legacy)) {
return false;
}

sat = css__number_from_lwc_string(token->idata, false, &consumed);
if (consumed != lwc_string_length(token->idata))
return false; /* failed to consume the whole string as a number */
if (consumed != lwc_string_length(token->idata)) {
/* failed to consume the whole string as a number */
return false;
}

/* Normalise saturation to the range [0, 100] */
if (sat < INTTOFIX(0))
Expand All @@ -548,21 +600,30 @@ static bool parse_hsl(

consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if (!tokenIsChar(token, ','))
return false;
if (legacy) {
token = parserutils_vector_iterate(vector, ctx);
if (token == NULL || !tokenIsChar(token, ',')) {
return false;
}

consumeWhitespace(vector, ctx);
}

/* lightness */
consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if ((token == NULL) || (token->type != CSS_TOKEN_PERCENTAGE))
if (token == NULL)
return false;

if ((token->type != CSS_TOKEN_PERCENTAGE) &&
(token->type != CSS_TOKEN_NUMBER || legacy)) {
return false;
}

lit = css__number_from_lwc_string(token->idata, false, &consumed);
if (consumed != lwc_string_length(token->idata))
return false; /* failed to consume the whole string as a number */
if (consumed != lwc_string_length(token->idata)) {
/* failed to consume the whole string as a number */
return false;
}

/* Normalise lightness to the range [0, 100] */
if (lit < INTTOFIX(0))
Expand All @@ -574,28 +635,32 @@ static bool parse_hsl(

token = parserutils_vector_iterate(vector, ctx);

if (colour_channels == 6) {
/* alpha */

if (!tokenIsChar(token, ','))
return false;

if (( legacy && tokenIsChar(token, ',')) ||
(!legacy && tokenIsChar(token, '/'))) {
consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);
if ((token == NULL) || (token->type != CSS_TOKEN_NUMBER))
if ((token == NULL) ||
(token->type != CSS_TOKEN_NUMBER &&
token->type != CSS_TOKEN_PERCENTAGE)) {
return false;
}

alpha = css__number_from_lwc_string(token->idata, false, &consumed);
if (consumed != lwc_string_length(token->idata))
return false; /* failed to consume the whole string as a number */
if (consumed != lwc_string_length(token->idata)) {
/* failed to consume the whole string as a number */
return false;
}

alpha = FIXTOINT(FMUL(alpha, F_255));
if (token->type != CSS_TOKEN_NUMBER) {
alpha = FIXTOINT(FMUL(alpha, F_255));
} else {
alpha = FIXTOINT(FDIV(FMUL(alpha, F_255), F_100));
}

consumeWhitespace(vector, ctx);

token = parserutils_vector_iterate(vector, ctx);

}

if (!tokenIsChar(token, ')'))
Expand Down Expand Up @@ -731,7 +796,7 @@ css_error css__parse_colour_specifier(css_language *c,
goto invalid;
}
} else if (colour_channels == 5 || colour_channels == 6) {
if (!parse_hsl(vector, ctx, colour_channels, result)) {
if (!parse_hsl(vector, ctx, result)) {
goto invalid;
}
} else {
Expand Down
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