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LibWeb: Fix building of areas spanning multiple rows in GFC

Rewrites the grid area building to accurately identify areas that span
multiple rows. Also now we can recognize invalid areas but do not
handle them yet.
This commit is contained in:
Aliaksandr Kalenik 2023-10-22 18:48:35 +02:00 committed by Andreas Kling
parent 8eab44896a
commit 122d847720
8 changed files with 194 additions and 24 deletions

View file

@ -1323,33 +1323,35 @@ void GridFormattingContext::build_grid_areas()
// https://www.w3.org/TR/css-grid-2/#grid-template-areas-property
// If a named grid area spans multiple grid cells, but those cells do not form a single
// filled-in rectangle, the declaration is invalid.
for (size_t y = 0; y < grid_container().computed_values().grid_template_areas().size(); y++) {
for (size_t x = 0; x < grid_container().computed_values().grid_template_areas()[y].size(); x++) {
auto grid_area_name = grid_container().computed_values().grid_template_areas()[y][x];
auto maybe_grid_area = m_grid_areas.get(grid_area_name);
if (!maybe_grid_area.has_value()) {
m_grid_areas.set(grid_area_name, { grid_area_name, y, y + 1, x, x + 1 });
} else {
auto& grid_area = maybe_grid_area.value();
if (grid_area.row_start == y) {
if (grid_area.column_end == x)
grid_area.column_end = grid_area.column_end + 1;
else
return;
} else {
if (grid_area.row_end == y) {
if (grid_area.column_start != x)
return;
grid_area.row_end = grid_area.row_end + 1;
} else if (grid_area.row_end == y + 1) {
if (grid_area.column_end < x || grid_area.column_end > x + 1)
return;
} else {
return;
}
auto const& rows = grid_container().computed_values().grid_template_areas();
auto find_area_rectangle = [&](size_t x_start, size_t y_start, String const& name) {
bool invalid = false;
size_t x_end = x_start;
size_t y_end = y_start;
while (x_end < rows[y_start].size() && rows[y_start][x_end] == name)
x_end++;
while (y_end < rows.size() && rows[y_end][x_start] == name)
y_end++;
for (size_t y = y_start; y < y_end; y++) {
for (size_t x = x_start; x < x_end; x++) {
if (rows[y][x] != name) {
// If a named grid area spans multiple grid cells, but those cells do not form a single filled-in rectangle, the declaration is invalid.
invalid = true;
break;
}
}
}
m_grid_areas.set(name, { name, y_start, y_end, x_start, x_end, invalid });
};
for (size_t y = 0; y < rows.size(); y++) {
for (size_t x = 0; x < rows[y].size(); x++) {
auto name = rows[y][x];
if (auto grid_area = m_grid_areas.get(name); grid_area.has_value())
continue;
find_area_rectangle(x, y, name);
}
}
}