ladybird/Libraries/LibDraw/DisjointRectSet.cpp
Andreas Kling 1c0669f010 LibDraw: Introduce (formerly known as SharedGraphics.)
Instead of LibGUI and WindowServer building their own copies of the drawing
and graphics code, let's it in a separate LibDraw library.

This avoids building the code twice, and will encourage better separation
of concerns. :^)
2019-07-18 10:18:16 +02:00

45 lines
1.3 KiB
C++

#include <LibDraw/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, 32> output;
output.ensure_capacity(m_rects.size());
bool pass_had_intersections = false;
do {
pass_had_intersections = false;
output.clear_with_capacity();
for (int i = 0; i < m_rects.size(); ++i) {
auto& r1 = m_rects[i];
for (int 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;
}
output.append(r1);
}
next_pass:
swap(output, m_rects);
} while (pass_had_intersections);
}