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LibGUI/TreeView: Implement Home/End/PageUp/PageDn navigation

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This adds an implementation for the Home, End, Page Up and Page Down
cursor movements for TreeView.

Also, the Up and Down movement implementations are replaced by a more
efficient traversal mechanism: whereas the old code would walk over all
visible nodes every time, the new code only evaluates relevant sibling
and parent indices.
This commit is contained in:
Jelle Raaijmakers 2021-05-29 00:50:10 +02:00 • committed by Ali Mohammad Pur
parent 3cf835af6d
commit 80a84f726e
1 changed files with 105 additions and 41 deletions
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146
Userland/Libraries/LibGUI/TreeView.cpp
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@ -472,54 +472,118 @@ void TreeView::keydown_event(KeyEvent& event)
void TreeView::move_cursor(CursorMovement movement, SelectionUpdate selection_update)
{
auto& model = *this->model();
auto find_last_index_in_tree = [&](const ModelIndex tree_index) -> ModelIndex {
auto last_index = tree_index;
size_t row_count = model.row_count(last_index);
while (row_count > 0) {
last_index = model.index(row_count - 1, model.tree_column(), last_index);
if (last_index.is_valid()) {
if (model.row_count(last_index) == 0)
break;
auto& metadata = ensure_metadata_for_index(last_index);
if (!metadata.open)
break;
}
row_count = model.row_count(last_index);
}
return last_index;
};
auto step_up = [&](const ModelIndex current_index) -> ModelIndex {
// Traverse into parent index if we're at the top of our subtree
if (current_index.row() == 0) {
auto parent_index = current_index.parent();
if (parent_index.is_valid())
return parent_index;
return current_index;
}
// If previous index is closed, move to it immediately
auto previous_index = model.index(current_index.row() - 1, model.tree_column(), current_index.parent());
if (model.row_count(previous_index) == 0)
return previous_index;
auto& metadata = ensure_metadata_for_index(previous_index);
if (!metadata.open)
return previous_index;
// Return very last index inside of open previous index
return find_last_index_in_tree(previous_index);
};
auto step_down = [&](const ModelIndex current_index) -> ModelIndex {
if (!current_index.is_valid())
return current_index;
// Step in when node is open
if (model.row_count(current_index) > 0) {
auto& metadata = ensure_metadata_for_index(current_index);
if (metadata.open)
return model.index(0, model.tree_column(), current_index);
}
// Find the parent index in which we must step one down
auto child_index = current_index;
auto parent_index = child_index.parent();
int row_count = model.row_count(parent_index);
while (child_index.is_valid() && child_index.row() >= row_count - 1) {
child_index = parent_index;
parent_index = parent_index.parent();
row_count = model.row_count(parent_index);
}
// Step one down
if (!child_index.is_valid())
return current_index;
return model.index(child_index.row() + 1, child_index.column(), parent_index);
};
switch (movement) {
case CursorMovement::Up: {
ModelIndex previous_index;
ModelIndex found_index;
traverse_in_paint_order([&](const ModelIndex& index, const Gfx::IntRect&, const Gfx::IntRect&, int) {
if (index == cursor_index()) {
found_index = previous_index;
return IterationDecision::Break;
}
previous_index = index;
return IterationDecision::Continue;
});
if (found_index.is_valid())
set_cursor(found_index, selection_update);
auto new_index = step_up(cursor_index());
if (new_index.is_valid())
set_cursor(new_index, selection_update);
break;
}
case CursorMovement::Down: {
ModelIndex previous_index;
ModelIndex found_index;
traverse_in_paint_order([&](const ModelIndex& index, const Gfx::IntRect&, const Gfx::IntRect&, int) {
if (previous_index == cursor_index()) {
found_index = index;
return IterationDecision::Break;
}
previous_index = index;
return IterationDecision::Continue;
});
if (found_index.is_valid())
set_cursor(found_index, selection_update);
auto new_index = step_down(cursor_index());
if (new_index.is_valid())
set_cursor(new_index, selection_update);
return;
}
case CursorMovement::Home: {
ModelIndex first_index = model.index(0, model.tree_column(), ModelIndex());
if (first_index.is_valid())
set_cursor(first_index, selection_update);
return;
}
case CursorMovement::End: {
auto last_index = find_last_index_in_tree({});
if (last_index.is_valid())
set_cursor(last_index, selection_update);
return;
}
case CursorMovement::PageUp: {
const int items_per_page = visible_content_rect().height() / row_height();
auto new_index = cursor_index();
for (int step = 0; step < items_per_page; ++step)
new_index = step_up(new_index);
if (new_index.is_valid())
set_cursor(new_index, selection_update);
return;
}
case CursorMovement::PageDown: {
const int items_per_page = visible_content_rect().height() / row_height();
auto new_index = cursor_index();
for (int step = 0; step < items_per_page; ++step)
new_index = step_down(new_index);
if (new_index.is_valid())
set_cursor(new_index, selection_update);
return;
}
case CursorMovement::Home:
// FIXME: Implement.
break;
case CursorMovement::End:
// FIXME: Implement.
break;
case CursorMovement::PageUp:
// FIXME: Implement.
break;
case CursorMovement::PageDown:
// FIXME: Implement.
break;
case CursorMovement::Left:
case CursorMovement::Right:
// There is no left/right in a treeview, those keys expand/collapse items instead.