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Mandelbrot: Only recalculate missing areas after panning

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We can reuse the areas that we have from before and just recalculate
the areas that are fresh. This makes panning super smooth. :^)
This commit is contained in:
sin-ack 2021-08-08 15:04:43 +00:00 • committed by Gunnar Beutner
parent d28802ad22
commit 1be59d663a
1 changed files with 57 additions and 3 deletions
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60
Userland/Demos/Mandelbrot/Mandelbrot.cpp
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@ -61,7 +61,23 @@ public:
m_x_end - delta.x() * relative_width_pixel,
m_y_start - delta.y() * relative_height_pixel,
m_y_end - delta.y() * relative_height_pixel);
calculate();
Gfx::IntRect horizontal_missing, vertical_missing;
if (delta.y() >= 0) {
horizontal_missing = { 0, 0, m_bitmap->width(), delta.y() };
} else {
horizontal_missing = { 0, m_bitmap->height() + delta.y(), m_bitmap->width(), -delta.y() };
}
if (delta.x() >= 0) {
vertical_missing = { 0, 0, delta.x(), m_bitmap->height() };
} else {
vertical_missing = { m_bitmap->width() + delta.x(), 0, -delta.x(), m_bitmap->height() };
}
move_contents_by(delta);
calculate_rect(horizontal_missing);
calculate_rect(vertical_missing);
}
double mandelbrot(double px, double py, i32 max_iterations)
@ -116,8 +132,18 @@ public:
{
VERIFY(m_bitmap);
for (int py = 0; py < m_bitmap->height(); py++)
for (int px = 0; px < m_bitmap->width(); px++)
calculate_rect(m_bitmap->rect(), max_iterations);
}
void calculate_rect(Gfx::IntRect const& rect, int max_iterations = 100)
{
VERIFY(m_bitmap);
if (rect.is_empty())
return;
for (int py = rect.top(); py <= rect.bottom(); py++)
for (int px = rect.left(); px <= rect.right(); px++)
calculate_pixel(px, py, max_iterations);
}
@ -148,6 +174,34 @@ private:
m_y_start = y_mid - aspect_corrected_y_length / 2;
m_y_end = y_mid + aspect_corrected_y_length / 2;
}
void move_contents_by(Gfx::IntPoint const& delta)
{
// If we're moving down we paint upwards, else we paint downwards, to
// avoid overwriting.
if (delta.y() >= 0) {
for (int row = m_bitmap->physical_height() - 1; row >= delta.y(); row--)
move_row(row - delta.y(), row, delta.x());
} else {
for (int row = 0; row < m_bitmap->physical_height() + delta.y(); row++)
move_row(row - delta.y(), row, delta.x());
}
}
void move_row(int from, int to, int x_delta)
{
// If we're moving right we paint RTL, else we paint LTR, to avoid
// overwriting.
if (x_delta >= 0) {
for (int column = m_bitmap->physical_width() - 1; column >= x_delta; column--) {
m_bitmap->set_pixel(column, to, m_bitmap->get_pixel(column - x_delta, from));
}
} else {
for (int column = 0; column < m_bitmap->physical_width() + x_delta; column++) {
m_bitmap->set_pixel(column, to, m_bitmap->get_pixel(column - x_delta, from));
}
}
}
};
class Mandelbrot : public GUI::Frame {