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Boost drawing speed of ItemLists with many items

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This commit is contained in:
Bernhard Liebl 2018-01-03 21:11:50 +01:00
parent fab0d53f7e
commit 85ecd79012
1 changed files with 48 additions and 4 deletions
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52
scene/gui/item_list.cpp
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@ -961,12 +961,36 @@ void ItemList::_notification(int p_what) {
Vector2 base_ofs = bg->get_offset();
base_ofs.y -= int(scroll_bar->get_value());
Rect2 clip(Point2(), size - bg->get_minimum_size() + Vector2(0, scroll_bar->get_value()));
const Rect2 clip(-base_ofs, size); // visible frame, don't need to draw outside of there
for (int i = 0; i < items.size(); i++) {
int first_item_visible;
{
// do a binary search to find the first item whose rect reaches below clip.position.y
int lo = 0;
int hi = items.size();
while (lo < hi) {
const int mid = (lo + hi) / 2;
const Rect2 &rcache = items[mid].rect_cache;
if (rcache.position.y + rcache.size.y < clip.position.y) {
lo = mid + 1;
} else {
hi = mid;
}
}
// we might have ended up with column 2, or 3, ..., so let's find the first column
while (lo > 0 && items[lo - 1].rect_cache.position.y == items[lo].rect_cache.position.y) {
lo -= 1;
}
first_item_visible = lo;
}
for (int i = first_item_visible; i < items.size(); i++) {
Rect2 rcache = items[i].rect_cache;
if (rcache.position.y > clip.position.y + clip.size.y)
break; // done
if (!clip.intersects(rcache))
continue;
@ -1138,8 +1162,28 @@ void ItemList::_notification(int p_what) {
}
}
for (int i = 0; i < separators.size(); i++) {
draw_line(Vector2(bg->get_margin(MARGIN_LEFT), base_ofs.y + separators[i]), Vector2(width, base_ofs.y + separators[i]), guide_color);
int first_visible_separator = 0;
{
// do a binary search to find the first separator that is below clip_position.y
int lo = 0;
int hi = separators.size();
while (lo < hi) {
const int mid = (lo + hi) / 2;
if (separators[mid] < clip.position.y) {
lo = mid + 1;
} else {
hi = mid;
}
}
first_visible_separator = lo;
}
for (int i = first_visible_separator; i < separators.size(); i++) {
if (separators[i] > clip.position.y + clip.size.y)
break; // done
const int y = base_ofs.y + separators[i];
draw_line(Vector2(bg->get_margin(MARGIN_LEFT), y), Vector2(width, y), guide_color);
}
}
}