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WindowServer: Avoid overdraw by shattering dirty rects into unique shards.

The algorithm I came up with is O(n^2) but given the small numbers of rects
we're typically working with, it doesn't really matter. May need to revisit
this in the future if we find ourselves with a huge number of rects.
This commit is contained in:
Andreas Kling 2019-02-19 14:49:23 +01:00
parent 420b7bd55f
commit 98784ad3cb
7 changed files with 127 additions and 21 deletions

View file

@ -0,0 +1,46 @@
#include <SharedGraphics/DisjointRectSet.h>
void DisjointRectSet::add(const Rect& new_rect)
{
for (auto& rect : m_rects) {
if (rect.contains(new_rect))
return;
}
m_rects.append(new_rect);
if (m_rects.size() > 1)
shatter();
}
void DisjointRectSet::shatter()
{
Vector<Rect> output;
bool pass_had_intersections = false;
do {
pass_had_intersections = false;
output.clear_with_capacity();
for (size_t i = 0; i < m_rects.size(); ++i) {
auto& r1 = m_rects[i];
bool r1_had_intersections = false;
for (size_t j = 0; j < m_rects.size(); ++j) {
if (i == j)
continue;
auto& r2 = m_rects[j];
if (!r1.intersects(r2))
continue;
pass_had_intersections = true;
auto pieces = r1.shatter(r2);
for (auto& piece : pieces)
output.append(piece);
m_rects.remove(i);
for (; i < m_rects.size(); ++i)
output.append(m_rects[i]);
goto next_pass;
}
if (!r1_had_intersections)
output.append(r1);
}
next_pass:
swap(output, m_rects);
} while(pass_had_intersections);
}

View file

@ -0,0 +1,23 @@
#pragma once
#include <AK/Vector.h>
#include <SharedGraphics/Rect.h>
class DisjointRectSet {
public:
DisjointRectSet() { }
~DisjointRectSet() { }
DisjointRectSet(DisjointRectSet&& other) : m_rects(move(other.m_rects)) { }
void add(const Rect&);
void clear() { m_rects.clear(); }
void clear_with_capacity() { m_rects.clear_with_capacity(); }
const Vector<Rect>& rects() const { return m_rects; }
private:
void shatter();
Vector<Rect> m_rects;
};

View file

@ -33,3 +33,47 @@ Rect Rect::united(const Rect& other) const
rect.set_bottom(max(bottom(), other.bottom()));
return rect;
}
Vector<Rect> Rect::shatter(const Rect& hammer) const
{
Vector<Rect> pieces;
if (!intersects(hammer)) {
pieces.append(*this);
pieces.append(hammer);
return pieces;
}
Rect top_shard {
x(),
y(),
width(),
hammer.y() - y()
};
Rect bottom_shard {
x(),
hammer.y() + hammer.height(),
width(),
(y() + height()) - (hammer.y() + hammer.height())
};
Rect left_shard {
x(),
max(hammer.y(), y()),
hammer.x() - x(),
min((hammer.y() + hammer.height()), (y() + height())) - max(hammer.y(), y())
};
Rect right_shard {
hammer.x() + hammer.width(),
max(hammer.y(), y()),
(x() + width() - 1) - (hammer.x() + hammer.width() - 1),
min((hammer.y() + hammer.height()), (y() + height())) - max(hammer.y(), y())
};
if (intersects(top_shard))
pieces.append(top_shard);
if (intersects(bottom_shard))
pieces.append(bottom_shard);
if (intersects(left_shard))
pieces.append(left_shard);
if (intersects(right_shard))
pieces.append(right_shard);
return pieces;
}

View file

@ -170,6 +170,8 @@ public:
Point location() const { return m_location; }
Size size() const { return m_size; }
Vector<Rect> shatter(const Rect& hammer) const;
operator WSAPI_Rect() const;
bool operator==(const Rect& other) const

View file

@ -4,6 +4,7 @@ SHAREDGRAPHICS_OBJS = \
../SharedGraphics/Rect.o \
../SharedGraphics/GraphicsBitmap.o \
../SharedGraphics/CharacterBitmap.o \
../SharedGraphics/DisjointRectSet.o \
../SharedGraphics/Color.o
WINDOWSERVER_OBJS = \

View file

@ -614,10 +614,10 @@ void WSWindowManager::compose()
{
auto dirty_rects = move(m_dirty_rects);
auto cursor_location = m_screen.cursor_location();
dirty_rects.append(m_last_cursor_rect);
dirty_rects.append({ cursor_location.x(), cursor_location.y(), (int)m_cursor_bitmap_inner->width(), (int)m_cursor_bitmap_inner->height() });
dirty_rects.add(m_last_cursor_rect);
dirty_rects.add({ cursor_location.x(), cursor_location.y(), (int)m_cursor_bitmap_inner->width(), (int)m_cursor_bitmap_inner->height() });
#ifdef DEBUG_COUNTERS
dbgprintf("[WM] compose #%u (%u rects)\n", ++m_compose_count, dirty_rects.size());
dbgprintf("[WM] compose #%u (%u rects)\n", ++m_compose_count, dirty_rects.rects().size());
#endif
auto any_opaque_window_contains_rect = [this] (const Rect& r) {
@ -639,14 +639,14 @@ void WSWindowManager::compose()
auto any_dirty_rect_intersects_window = [&dirty_rects] (const WSWindow& window) {
auto window_rect = outer_window_rect(window.rect());
for (auto& dirty_rect : dirty_rects) {
for (auto& dirty_rect : dirty_rects.rects()) {
if (dirty_rect.intersects(window_rect))
return true;
}
return false;
};
for (auto& dirty_rect : dirty_rects) {
for (auto& dirty_rect : dirty_rects.rects()) {
if (any_opaque_window_contains_rect(dirty_rect))
continue;
if (!m_wallpaper)
@ -661,7 +661,7 @@ void WSWindowManager::compose()
return IterationDecision::Continue;
if (!any_dirty_rect_intersects_window(window))
return IterationDecision::Continue;
for (auto& dirty_rect : dirty_rects) {
for (auto& dirty_rect : dirty_rects.rects()) {
m_back_painter->set_clip_rect(dirty_rect);
paint_window_frame(window);
Rect dirty_rect_in_window_coordinates = Rect::intersection(dirty_rect, window.rect());
@ -685,12 +685,12 @@ void WSWindowManager::compose()
draw_cursor();
if (m_flash_flush) {
for (auto& rect : dirty_rects)
for (auto& rect : dirty_rects.rects())
m_front_painter->fill_rect(rect, Color::Yellow);
}
flip_buffers();
for (auto& r : dirty_rects)
for (auto& r : dirty_rects.rects())
flush(r);
}
@ -808,18 +808,7 @@ void WSWindowManager::invalidate(const Rect& a_rect, bool should_schedule_compos
if (rect.is_empty())
return;
for (auto& r : m_dirty_rects) {
if (r.contains(rect))
return;
if (r.intersects(rect)) {
// Unite with the existing dirty rect.
// FIXME: It would be much nicer to compute the exact rects needing repaint.
r = r.united(rect);
return;
}
}
m_dirty_rects.append(rect);
m_dirty_rects.add(rect);
if (should_schedule_compose_event && !m_pending_compose_event) {
WSMessageLoop::the().post_message(this, make<WSMessage>(WSMessage::WM_DeferredCompose));

View file

@ -3,6 +3,7 @@
#include <SharedGraphics/Rect.h>
#include <SharedGraphics/Color.h>
#include <SharedGraphics/Painter.h>
#include <SharedGraphics/DisjointRectSet.h>
#include <AK/HashTable.h>
#include <AK/InlineLinkedList.h>
#include <AK/WeakPtr.h>
@ -127,7 +128,7 @@ private:
RetainPtr<GraphicsBitmap> m_front_bitmap;
RetainPtr<GraphicsBitmap> m_back_bitmap;
Vector<Rect> m_dirty_rects;
DisjointRectSet m_dirty_rects;
bool m_pending_compose_event { false };