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LibWeb: Position grid items with fixed position values

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martinfalisse 2022-09-07 15:33:31 +02:00 committed by Andreas Kling
parent e0cd63f531
commit f143fefca2
Notes: sideshowbarker 2024-07-17 07:11:52 +09:00 
Author: https://github.com/martinfalisse
Commit: https://github.com/SerenityOS/serenity/commit/f143fefca2
Pull-request: https://github.com/SerenityOS/serenity/pull/15155
Reviewed-by: https://github.com/MacDue
1 changed files with 106 additions and 1 deletions
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107
Userland/Libraries/LibWeb/Layout/GridFormattingContext.cpp
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@ -35,12 +35,54 @@ void GridFormattingContext::run(Box const& box, LayoutMode)
return false;
};
auto maybe_add_column_to_occupation_grid = [](int needed_number_of_columns, Vector<Vector<bool>>& occupation_grid) -> void {
int current_column_count = (int)occupation_grid[0].size();
if (needed_number_of_columns <= current_column_count)
return;
for (auto& occupation_grid_row : occupation_grid)
for (int idx = 0; idx < (needed_number_of_columns + 1) - current_column_count; idx++)
occupation_grid_row.append(false);
};
auto maybe_add_row_to_occupation_grid = [](int needed_number_of_rows, Vector<Vector<bool>>& occupation_grid) -> void {
if (needed_number_of_rows <= (int)occupation_grid.size())
return;
Vector<bool> new_occupation_grid_row;
for (int idx = 0; idx < (int)occupation_grid[0].size(); idx++)
new_occupation_grid_row.append(false);
for (int idx = 0; idx < needed_number_of_rows - (int)occupation_grid.size(); idx++)
occupation_grid.append(new_occupation_grid_row);
};
auto set_occupied_cells = [](int row_start, int row_end, int column_start, int column_end, Vector<Vector<bool>>& occupation_grid) -> void {
for (int row_index = 0; row_index < (int)occupation_grid.size(); row_index++) {
if (row_index >= row_start && row_index < row_end) {
for (int column_index = 0; column_index < (int)occupation_grid[0].size(); column_index++) {
if (column_index >= column_start && column_index < column_end) {
occupation_grid[row_index][column_index] = true;
}
}
}
}
};
// https://drafts.csswg.org/css-grid/#overview-placement
// 2.2. Placing Items
// The contents of the grid container are organized into individual grid items (analogous to
// flex items), which are then assigned to predefined areas in the grid. They can be explicitly
// placed using coordinates through the grid-placement properties or implicitly placed into
// empty areas using auto-placement.
struct PositionedBox {
Box const& box;
int row { 0 };
int row_span { 1 };
int column { 0 };
int column_span { 1 };
float computed_height { 0 };
};
Vector<PositionedBox> positioned_boxes;
Vector<Vector<bool>> occupation_grid;
Vector<bool> occupation_grid_row;
@ -60,9 +102,72 @@ void GridFormattingContext::run(Box const& box, LayoutMode)
// https://drafts.csswg.org/css-grid/#auto-placement-algo
// 8.5. Grid Item Placement Algorithm
// 0. Generate anonymous grid items
// FIXME: 0. Generate anonymous grid items
// 1. Position anything that's not auto-positioned.
for (size_t i = 0; i < boxes_to_place.size(); i++) {
auto const& child_box = boxes_to_place[i];
if (child_box.computed_values().grid_row_start().is_auto()
|| child_box.computed_values().grid_row_end().is_auto()
|| child_box.computed_values().grid_column_start().is_auto()
|| child_box.computed_values().grid_column_end().is_auto())
continue;
int row_start = child_box.computed_values().grid_row_start().position();
int row_end = child_box.computed_values().grid_row_end().position();
int column_start = child_box.computed_values().grid_column_start().position();
int column_end = child_box.computed_values().grid_column_end().position();
int row_span = 1;
int column_span = 1;
// https://drafts.csswg.org/css-grid/#grid-placement-int
// [ <integer [−∞,−1]> | <integer [1,∞]> ] && <custom-ident>?
// Contributes the Nth grid line to the grid item’s placement. If a negative integer is given, it
// instead counts in reverse, starting from the end edge of the explicit grid.
if (row_end < 0)
row_end = static_cast<int>(occupation_grid.size()) + row_end + 2;
if (column_end < 0)
column_end = static_cast<int>(occupation_grid[0].size()) + column_end + 2;
// FIXME: If a name is given as a <custom-ident>, only lines with that name are counted. If not enough
// lines with that name exist, all implicit grid lines are assumed to have that name for the purpose
// of finding this position.
// FIXME: An <integer> value of zero makes the declaration invalid.
// https://drafts.csswg.org/css-grid/#grid-placement-errors
// 8.3.1. Grid Placement Conflict Handling
// If the placement for a grid item contains two lines, and the start line is further end-ward than
// the end line, swap the two lines. If the start line is equal to the end line, remove the end
// line.
if (row_start > row_end) {
auto temp = row_end;
row_end = row_start;
row_start = temp;
}
if (column_start > column_end) {
auto temp = column_end;
column_end = column_start;
column_start = temp;
}
if (row_start != row_end)
row_span = row_end - row_start;
if (column_start != column_end)
column_span = column_end - column_start;
// FIXME: If the placement contains two spans, remove the one contributed by the end grid-placement
// property.
// FIXME: If the placement contains only a span for a named line, replace it with a span of 1.
row_start -= 1;
column_start -= 1;
positioned_boxes.append({ child_box, row_start, row_span, column_start, column_span });
maybe_add_row_to_occupation_grid(row_start + row_span, occupation_grid);
maybe_add_column_to_occupation_grid(column_start + column_span, occupation_grid);
set_occupied_cells(row_start, row_start + row_span, column_start, column_start + column_span, occupation_grid);
boxes_to_place.remove(i);
i--;
}
// 2. Process the items locked to a given row.