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Userland: Piano: Optimize repaints

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The Piano application used to perform very poorly due to unnecessary
draw calls. This is solved with two optimziations:

1. Don't draw the widgets as often as possible. The widgets are instead
   at least updated every 150ms, except for other events.
2. Don't re-draw the entire piano roll sheet. The piano roll background,
   excluding in-motion objects (notes, the play cursor), is only re-drawn
   when its "viewport" changes.

A minor drawback of this change is that notes will appear on top of the
pitch labels if placed at the left edge of the roll. This is IMO
acceptable or may be changed by moving the text to the "foreground".
This commit is contained in:
kleines Filmröllchen 2021-04-19 19:10:24 +02:00 • committed by Andreas Kling
parent 511ffa8d68
commit c1345bda3e
3 changed files with 79 additions and 19 deletions
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7
Userland/Applications/Piano/main.cpp
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@ -1,6 +1,7 @@
/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* Copyright (c) 2019-2020, William McPherson <willmcpherson2@gmail.com>
* Copyright (c) 2021, kleines Filmröllchen <malu.bertsch@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
@ -64,7 +65,6 @@ int main(int argc, char** argv)
while (!Core::EventLoop::current().was_exit_requested()) {
track_manager.fill_buffer(buffer);
audio->write(reinterpret_cast<u8*>(buffer.data()), buffer_size);
Core::EventLoop::current().post_event(main_widget, make<Core::CustomEvent>(0));
Core::EventLoop::wake();
if (need_to_write_wav) {
@ -84,6 +84,11 @@ int main(int argc, char** argv)
});
audio_thread->start();
auto main_widget_updater = Core::Timer::construct(150, [&] {
Core::EventLoop::current().post_event(main_widget, make<Core::CustomEvent>(0));
});
main_widget_updater->start();
auto menubar = GUI::Menubar::construct();
auto& app_menu = menubar->add_menu("File");