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Add client-side double buffering of window backing stores.

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This prevents flicker and looks rather good. The main downside is that
resizing gets even more sluggish. That's the price we pay for now.
This commit is contained in:
Andreas Kling 2019-03-17 04:23:54 +01:00
parent 2ac4f54724
commit 4e451c1e92
12 changed files with 95 additions and 39 deletions
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87
LibGUI/GWindow.cpp
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@ -3,6 +3,7 @@
#include "GEventLoop.h"
#include "GWidget.h"
#include <SharedGraphics/GraphicsBitmap.h>
#include <SharedGraphics/Painter.h>
#include <LibC/stdio.h>
#include <LibC/stdlib.h>
#include <LibC/unistd.h>
@ -166,33 +167,19 @@ void GWindow::event(GEvent& event)
return;
auto& paint_event = static_cast<GPaintEvent&>(event);
auto rect = paint_event.rect();
bool created_new_backing_store = !m_backing;
if (!m_backing) {
ASSERT(GEventLoop::main().server_pid());
ASSERT(!paint_event.window_size().is_empty());
Size new_backing_store_size = paint_event.window_size();
size_t size_in_bytes = new_backing_store_size.area() * sizeof(RGBA32);
auto shared_buffer = SharedBuffer::create(GEventLoop::main().server_pid(), size_in_bytes);
ASSERT(shared_buffer);
m_backing = GraphicsBitmap::create_with_shared_buffer(
m_has_alpha_channel ? GraphicsBitmap::Format::RGBA32 : GraphicsBitmap::Format::RGB32,
*shared_buffer,
new_backing_store_size);
}
bool created_new_backing_store = !m_back_bitmap;
if (!m_back_bitmap)
m_back_bitmap = create_backing_bitmap(paint_event.window_size());
if (rect.is_empty() || created_new_backing_store)
rect = m_main_widget->rect();
m_main_widget->event(*make<GPaintEvent>(rect));
if (created_new_backing_store) {
WSAPI_ClientMessage message;
message.type = WSAPI_ClientMessage::Type::SetWindowBackingStore;
message.window_id = m_window_id;
message.backing.bpp = 32;
message.backing.pitch = m_backing->pitch();
message.backing.shared_buffer_id = m_backing->shared_buffer_id();
message.backing.has_alpha_channel = m_backing->has_alpha_channel();
message.backing.size = m_backing->size();
GEventLoop::main().post_message_to_server(message);
}
if (m_double_buffering_enabled)
flip(rect);
else if (created_new_backing_store)
set_current_backing_bitmap(*m_back_bitmap, true);
if (m_window_id) {
WSAPI_ClientMessage message;
message.type = WSAPI_ClientMessage::Type::DidFinishPainting;
@ -232,8 +219,8 @@ void GWindow::event(GEvent& event)
if (event.type() == GEvent::Resize) {
auto new_size = static_cast<GResizeEvent&>(event).size();
if (m_backing && m_backing->size() != new_size)
m_backing = nullptr;
if (m_back_bitmap && m_back_bitmap->size() != new_size)
m_back_bitmap = nullptr;
m_pending_paint_event_rects.clear();
m_rect_when_windowless = { { }, new_size };
m_main_widget->set_relative_rect({ { }, new_size });
@ -328,6 +315,12 @@ void GWindow::set_has_alpha_channel(bool value)
m_has_alpha_channel = value;
}
void GWindow::set_double_buffering_enabled(bool value)
{
ASSERT(!m_window_id);
m_double_buffering_enabled = value;
}
void GWindow::set_opacity(float opacity)
{
m_opacity_when_windowless = opacity;
@ -354,3 +347,45 @@ void GWindow::set_hovered_widget(GWidget* widget)
if (m_hovered_widget)
GEventLoop::main().post_event(*m_hovered_widget, make<GEvent>(GEvent::Enter));
}
void GWindow::set_current_backing_bitmap(GraphicsBitmap& bitmap, bool flush_immediately)
{
WSAPI_ClientMessage message;
message.type = WSAPI_ClientMessage::Type::SetWindowBackingStore;
message.window_id = m_window_id;
message.backing.bpp = 32;
message.backing.pitch = bitmap.pitch();
message.backing.shared_buffer_id = bitmap.shared_buffer_id();
message.backing.has_alpha_channel = bitmap.has_alpha_channel();
message.backing.size = bitmap.size();
message.backing.flush_immediately = flush_immediately;
GEventLoop::main().sync_request(message, WSAPI_ServerMessage::Type::DidSetWindowBackingStore);
}
void GWindow::flip(const Rect& dirty_rect)
{
swap(m_front_bitmap, m_back_bitmap);
set_current_backing_bitmap(*m_front_bitmap);
if (!m_back_bitmap || m_back_bitmap->size() != m_front_bitmap->size()) {
m_back_bitmap = create_backing_bitmap(m_front_bitmap->size());
memcpy(m_back_bitmap->scanline(0), m_front_bitmap->scanline(0), m_front_bitmap->size().area() * sizeof(RGBA32));
return;
}
// Copy whatever was painted from the front to the back.
Painter painter(*m_back_bitmap);
painter.blit(dirty_rect.location(), *m_front_bitmap, dirty_rect);
}
Retained<GraphicsBitmap> GWindow::create_backing_bitmap(const Size& size)
{
ASSERT(GEventLoop::server_pid());
ASSERT(!size.is_empty());
size_t size_in_bytes = size.area() * sizeof(RGBA32);
auto shared_buffer = SharedBuffer::create(GEventLoop::server_pid(), size_in_bytes);
ASSERT(shared_buffer);
auto format = m_has_alpha_channel ? GraphicsBitmap::Format::RGBA32 : GraphicsBitmap::Format::RGB32;
return GraphicsBitmap::create_with_shared_buffer(format, *shared_buffer, size);
}