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LibGUI+WindowServer: Improve window resizing performance

The old `GUI::Window` resizing behavior created a new backing store for
each resize event (i.e. every visible window size). This caused a lot of
trashing and on my machine, caused up to 25% of CPU time spent in
creating new backing stores.

The new behavior is a bit more sensible:

  * If the window size is shrinking, the backing store is already large
    enough to contain the entire window - so we don't create a new one.

  * If the window size is growing, as soon as the backing store can no
    longer contain the window, it is inflated with a large margin (of an
    arbitrary chosen 64 pixels) in both directions to accommodate some
    leeway in resizing before an even larger backing store is required.

  * When the user stops resizing the window, the backing store is
    resized to the exact dimensions of the window.

For me, this brings the CPU time for creating backing stores down to 0%.
This commit is contained in:
Jelle Raaijmakers 2023-01-11 21:46:14 +01:00 committed by Andreas Kling
parent 45e85d20b6
commit 634d1e0197
8 changed files with 73 additions and 39 deletions

View file

@ -733,7 +733,7 @@ void ConnectionFromClient::did_finish_painting(i32 window_id, Vector<Gfx::IntRec
void ConnectionFromClient::set_window_backing_store(i32 window_id, [[maybe_unused]] i32 bpp,
[[maybe_unused]] i32 pitch, IPC::File const& anon_file, i32 serial, bool has_alpha_channel,
Gfx::IntSize size, bool flush_immediately)
Gfx::IntSize size, Gfx::IntSize visible_size, bool flush_immediately)
{
auto it = m_windows.find(window_id);
if (it == m_windows.end()) {
@ -761,6 +761,7 @@ void ConnectionFromClient::set_window_backing_store(i32 window_id, [[maybe_unuse
}
window.set_backing_store(backing_store_or_error.release_value(), serial);
}
window.set_backing_store_visible_size(visible_size);
if (flush_immediately)
window.invalidate(false);