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LibWeb: Parse double-position linear-gradient() color stops

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The only accepted syntax for these seems to be
<color> <length percentage> <length percentage>, no other order.

But that's just gathered from looking at other browsers as though
these are supported by all major browsers, they don't appear in
the W3C spec.
This commit is contained in:
MacDue 2022-08-22 21:37:53 +01:00 • committed by Andreas Kling
parent ec3d8a7a18
commit 3a1f8d714a
4 changed files with 30 additions and 22 deletions
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16
Userland/Libraries/LibWeb/CSS/Parser/Parser.cpp
View file

@ -2509,15 +2509,16 @@ RefPtr<StyleValue> Parser::parse_linear_gradient_function(ComponentValue const&
auto& token = tokens.next_token();
Gfx::Color color;
Optional<LengthPercentage> length;
Optional<LengthPercentage> position;
Optional<LengthPercentage> second_position;
auto dimension = parse_dimension(token);
if (dimension.has_value() && dimension->is_length_percentage()) {
// [<length-percentage> <color>] or [<length-percentage>]
length = dimension->length_percentage();
position = dimension->length_percentage();
tokens.skip_whitespace();
// <length-percentage>
if (!tokens.has_next_token() || tokens.peek_token().is(Token::Type::Comma)) {
element.transition_hint = GradientColorHint { *length };
element.transition_hint = GradientColorHint { *position };
return ElementType::ColorHint;
}
// <length-percentage> <color>
@ -2532,16 +2533,21 @@ RefPtr<StyleValue> Parser::parse_linear_gradient_function(ComponentValue const&
return ElementType::Garbage;
color = *maybe_color;
tokens.skip_whitespace();
// Allow up to [<color> <length-percentage> <length-percentage>] (double-position color stops)
// Note: Double-position color stops only appear to be valid in this order.
for (auto stop_position : Array { &position, &second_position }) {
if (tokens.has_next_token() && !tokens.peek_token().is(Token::Type::Comma)) {
auto token = tokens.next_token();
auto dimension = parse_dimension(token);
if (!dimension.has_value() || !dimension->is_length_percentage())
return ElementType::Garbage;
length = dimension->length_percentage();
*stop_position = dimension->length_percentage();
tokens.skip_whitespace();
}
}
}
element.color_stop = GradientColorStop { color, length };
element.color_stop = GradientColorStop { color, position, second_position };
return ElementType::ColorStop;
};

7
Userland/Libraries/LibWeb/CSS/StyleValue.cpp
View file

@ -1512,8 +1512,9 @@ String LinearGradientStyleValue::to_string() const
}
serialize_a_srgb_value(builder, element.color_stop.color);
if (element.color_stop.length.has_value()) {
builder.appendff(" {}"sv, element.color_stop.length->to_string());
for (auto position : Array { &element.color_stop.position, &element.color_stop.second_position }) {
if (position->has_value())
builder.appendff(" {}"sv, (*position)->to_string());
}
first = false;
}
@ -1537,7 +1538,7 @@ static bool operator==(GradientColorHint a, GradientColorHint b)
static bool operator==(GradientColorStop a, GradientColorStop b)
{
return a.color == b.color && a.length == b.length;
return a.color == b.color && a.position == b.position && a.second_position == b.second_position;
}
static bool operator==(ColorStopListElement a, ColorStopListElement b)

3
Userland/Libraries/LibWeb/CSS/StyleValue.h
View file

@ -74,7 +74,8 @@ enum class SideOrCorner {
struct GradientColorStop {
Color color;
Optional<LengthPercentage> length;
Optional<LengthPercentage> position;
Optional<LengthPercentage> second_position = {};
};
struct GradientColorHint {

16
Userland/Libraries/LibWeb/Painting/GradientPainting.cpp
View file

@ -49,13 +49,13 @@ LinearGradientData resolve_linear_gradient_data(Layout::Node const& node, Gfx::F
// 1. If the first color stop does not have a position, set its position to 0%.
auto& first_stop = color_stop_list.first().color_stop;
resolved_color_stops.first().position = first_stop.length.has_value()
? first_stop.length->resolved(node, gradient_length).to_px(node)
resolved_color_stops.first().position = first_stop.position.has_value()
? first_stop.position->resolved(node, gradient_length).to_px(node)
: 0;
// If the last color stop does not have a position, set its position to 100%
auto& last_stop = color_stop_list.last().color_stop;
resolved_color_stops.last().position = last_stop.length.has_value()
? last_stop.length->resolved(node, gradient_length).to_px(node)
resolved_color_stops.last().position = last_stop.position.has_value()
? last_stop.position->resolved(node, gradient_length).to_px(node)
: gradient_length_px;
// 2. If a color stop or transition hint has a position that is less than the
@ -71,8 +71,8 @@ LinearGradientData resolve_linear_gradient_data(Layout::Node const& node, Gfx::F
resolved_color_stops[i].transition_hint = value;
max_previous_color_stop_or_hint = value;
}
if (stop.color_stop.length.has_value()) {
float value = stop.color_stop.length->resolved(node, gradient_length).to_px(node);
if (stop.color_stop.position.has_value()) {
float value = stop.color_stop.position->resolved(node, gradient_length).to_px(node);
value = max(value, max_previous_color_stop_or_hint);
resolved_color_stops[i].position = value;
max_previous_color_stop_or_hint = value;
@ -86,7 +86,7 @@ LinearGradientData resolve_linear_gradient_data(Layout::Node const& node, Gfx::F
size_t i = 1;
auto find_run_end = [&] {
auto color_stop_has_position = [](auto& color_stop) {
return color_stop.transition_hint.has_value() || color_stop.color_stop.length.has_value();
return color_stop.transition_hint.has_value() || color_stop.color_stop.position.has_value();
};
while (i < color_stop_list.size() - 1 && !color_stop_has_position(color_stop_list[i])) {
i++;
@ -95,7 +95,7 @@ LinearGradientData resolve_linear_gradient_data(Layout::Node const& node, Gfx::F
};
while (i < color_stop_list.size() - 1) {
auto& stop = color_stop_list[i];
if (!stop.color_stop.length.has_value()) {
if (!stop.color_stop.position.has_value()) {
auto run_start = i - 1;
auto start_position = resolved_color_stops[i++].transition_hint.value_or(resolved_color_stops[run_start].position);
auto run_end = find_run_end();