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LibWeb: Implement "distribute height to rows" step in TFC

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This commit implements following missing steps in table layout:
- Calculate final table height
- Resolve percentage height of cells and rows using final table height
- Distribute avilable height to table rows
This commit is contained in:
Aliaksandr Kalenik 2023-04-29 00:43:05 +03:00 • committed by Andreas Kling
parent 9fd51a59ff
commit d9f0c2a806
10 changed files with 320 additions and 12 deletions
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152
Userland/Libraries/LibWeb/Layout/TableFormattingContext.cpp
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@ -394,8 +394,20 @@ void TableFormattingContext::determine_intrisic_size_of_table_container(Availabl
}
}
void TableFormattingContext::calculate_row_heights(LayoutMode layout_mode)
void TableFormattingContext::compute_table_height(LayoutMode layout_mode)
{
// First pass of row height calculation:
for (auto& row : m_rows) {
auto row_computed_height = row.box->computed_values().height();
if (row_computed_height.is_length()) {
auto height_of_containing_block = m_state.get(*row.box->containing_block()).content_height();
auto height_of_containing_block_as_length = CSS::Length::make_px(height_of_containing_block);
auto row_used_height = row_computed_height.resolved(row.box, height_of_containing_block_as_length).to_px(row.box);
row.base_height = max(row.base_height, row_used_height);
}
}
// First pass of cells layout:
for (auto& cell : m_cells) {
auto& row = m_rows[cell.row_index];
auto& cell_state = m_state.get_mutable(cell.box);
@ -430,7 +442,7 @@ void TableFormattingContext::calculate_row_heights(LayoutMode layout_mode)
auto cell_used_height = cell_computed_height.resolved(cell.box, height_of_containing_block_as_length).to_px(cell.box);
cell_state.set_content_height(cell_used_height - cell_state.border_box_top() - cell_state.border_box_bottom());
row.used_height = max(row.used_height, cell_used_height);
row.base_height = max(row.base_height, cell_used_height);
}
cell_state.set_content_width((span_width - cell_state.border_box_left() - cell_state.border_box_right()));
@ -441,17 +453,134 @@ void TableFormattingContext::calculate_row_heights(LayoutMode layout_mode)
cell.baseline = box_baseline(m_state, cell.box);
row.used_height = max(row.used_height, cell_state.border_box_height());
row.base_height = max(row.base_height, cell_state.border_box_height());
row.baseline = max(row.baseline, cell.baseline);
}
CSSPixels sum_rows_height = 0;
for (auto& row : m_rows) {
sum_rows_height += row.base_height;
}
// The height of a table is the sum of the row heights plus any cell spacing or borders.
m_table_height = sum_rows_height;
if (!table_box().computed_values().height().is_auto()) {
// If the table has a height property with a value other than auto, it is treated as a minimum height for the
// table grid, and will eventually be distributed to the height of the rows if their collective minimum height
// ends up smaller than this number.
CSSPixels height_of_table_containing_block = m_state.get(*table_wrapper().containing_block()).content_height();
auto specified_table_height = table_box().computed_values().height().resolved(table_box(), CSS::Length::make_px(height_of_table_containing_block)).to_px(table_box());
if (m_table_height < specified_table_height) {
m_table_height = specified_table_height;
}
}
for (auto& row : m_rows) {
// Reference size is the largest of
// - its initial base height and
// - its new base height (the one evaluated during the second layout pass, where percentages used in
// rowgroups/rows/cells' specified heights were resolved according to the table height, instead of
// being ignored as 0px).
// Assign reference size to base size. Later reference size might change to largee value during
// second pass of rows layout.
row.reference_height = row.base_height;
}
// Second pass of rows height calculation:
// At this point percentage row height can be resolved because final table height is calculated.
for (auto& row : m_rows) {
auto row_computed_height = row.box->computed_values().height();
if (row_computed_height.is_length()) {
auto height_of_containing_block = m_state.get(*row.box->containing_block()).content_height();
auto height_of_containing_block_as_length = CSS::Length::make_px(height_of_containing_block);
auto row_used_height = row_computed_height.resolved(row.box, height_of_containing_block_as_length).to_px(row.box);
row.used_height = max(row.used_height, row_used_height);
if (row_computed_height.is_percentage()) {
auto row_used_height = row_computed_height.resolved(row.box, CSS::Length::make_px(m_table_height)).to_px(row.box);
row.reference_height = max(row.reference_height, row_used_height);
} else {
continue;
}
}
// Second pass cells layout:
// At this point percantage cell height can be resolved because final table heigh is calculated.
for (auto& cell : m_cells) {
auto& row = m_rows[cell.row_index];
auto& cell_state = m_state.get_mutable(cell.box);
CSSPixels span_width = 0;
for (size_t i = 0; i < cell.column_span; ++i)
span_width += m_columns[cell.column_index + i].used_width;
auto height_of_containing_block_as_length = CSS::Length::make_px(m_table_height);
auto cell_computed_height = cell.box->computed_values().height();
if (cell_computed_height.is_percentage()) {
auto cell_used_height = cell_computed_height.resolved(cell.box, height_of_containing_block_as_length).to_px(cell.box);
cell_state.set_content_height(cell_used_height - cell_state.border_box_top() - cell_state.border_box_bottom());
row.reference_height = max(row.reference_height, cell_used_height);
} else {
continue;
}
cell_state.set_content_width((span_width - cell_state.border_box_left() - cell_state.border_box_right()));
if (auto independent_formatting_context = layout_inside(cell.box, layout_mode, cell_state.available_inner_space_or_constraints_from(*m_available_space))) {
independent_formatting_context->parent_context_did_dimension_child_root_box();
}
cell.baseline = box_baseline(m_state, cell.box);
row.reference_height = max(row.reference_height, cell_state.border_box_height());
row.baseline = max(row.baseline, cell.baseline);
}
}
void TableFormattingContext::distribute_height_to_rows()
{
CSSPixels sum_reference_height = 0;
for (auto& row : m_rows) {
sum_reference_height += row.reference_height;
}
if (sum_reference_height == 0)
return;
Vector<Row&> rows_with_auto_height;
for (auto& row : m_rows) {
if (row.box->computed_values().height().is_auto()) {
rows_with_auto_height.append(row);
}
}
if (m_table_height <= sum_reference_height) {
// If the table height is equal or smaller than sum of reference sizes, the final height assigned to each row
// will be the weighted mean of the base and the reference size that yields the correct total height.
for (auto& row : m_rows) {
auto weight = row.reference_height / sum_reference_height;
auto final_height = m_table_height * weight;
row.final_height = final_height;
}
} else if (rows_with_auto_height.size() > 0) {
// Else, if the table owns any “auto-height” row (a row whose size is only determined by its content size and
// none of the specified heights), each non-auto-height row receives its reference height and auto-height rows
// receive their reference size plus some increment which is equal to the height missing to amount to the
// specified table height divided by the amount of such rows.
for (auto& row : m_rows) {
row.final_height = row.reference_height;
}
auto auto_height_rows_increment = (m_table_height - sum_reference_height) / rows_with_auto_height.size();
for (auto& row : rows_with_auto_height) {
row.final_height += auto_height_rows_increment;
}
} else {
// Else, all rows receive their reference size plus some increment which is equal to the height missing to
// amount to the specified table height divided by the amount of rows.
auto increment = (m_table_height - sum_reference_height) / m_rows.size();
for (auto& row : m_rows) {
row.final_height = row.reference_height + increment;
}
}
}
@ -470,7 +599,7 @@ void TableFormattingContext::position_row_boxes(CSSPixels& total_content_height)
row_width += column.used_width;
}
row_state.set_content_height(row.used_height);
row_state.set_content_height(row.final_height);
row_state.set_content_width(row_width);
row_state.set_content_x(row_left_offset);
row_state.set_content_y(row_top_offset);
@ -563,7 +692,10 @@ void TableFormattingContext::run(Box const& box, LayoutMode layout_mode, Availab
// Distribute the width of the table among columns.
distribute_width_to_columns();
calculate_row_heights(layout_mode);
compute_table_height(layout_mode);
distribute_height_to_rows();
position_row_boxes(total_content_height);
position_cell_boxes();