PixelRect
ButtonPanel::BottomLayout(PixelRect rc)
{
assert(!buttons.empty());
const UPixelScalar total_width = rc.right - rc.left;
unsigned end = buttons.size();
while (end > 0) {
unsigned start = end - 1;
UPixelScalar max_width = Width(start);
while (start > 0) {
--start;
UPixelScalar width = Width(start);
UPixelScalar new_width = std::max(width, max_width);
if ((end - start) * new_width > total_width) {
++start;
break;
}
max_width = new_width;
}
rc = HorizontalRange(rc, start, end);
end = start;
}
return rc;
}
PixelRect
ButtonPanel::BottomLayout(PixelRect rc)
{
assert(!buttons.empty());
const unsigned n_buttons = buttons.size();
const unsigned total_width = rc.GetWidth();
/* naive button distribution algorithm: distribute as many buttons
as possible into each row; weakness: the last row may have only
one button */
struct Row {
unsigned start, end;
constexpr unsigned size() const {
return end - start;
}
};
StaticArray<Row, 8u> rows;
for (unsigned i = 0; i < n_buttons;) {
unsigned end = FitButtonRow(i, total_width);
assert(end > i);
auto &row = rows.append();
row.start = i;
row.end = i = end;
}
assert(!rows.empty());
/* optimise the naive result: try to move buttons down until we see
no further chance for improvement */
bool modified;
do {
modified = false;
for (unsigned i = rows.size() - 1; i > 0; --i) {
auto &dest_row = rows[i];
auto &src_row = rows[i - 1];
/* the upper row has many more buttons than the lower row */
if (dest_row.size() + 2 <= src_row.size()) {
unsigned max_width = RangeMaxWidth(dest_row.start - 1, dest_row.end);
unsigned row_width = (dest_row.size() + 1) * max_width;
/* yes, we can move one button down */
if (row_width <= total_width) {
--src_row.end;
--dest_row.start;
modified = true;
}
}
}
} while (modified);
/* now do the actual layout based on row metadata */
for (int i = rows.size() - 1; i >= 0; --i) {
const auto &row = rows[i];
rc = HorizontalRange(rc, row.start, row.end);
}
return rc;
}
