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Painter: Improve draw_scaled_bitmap() performance.

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- Removed extra bounds checking.
- Converted it to use integer math for the scale factors.
- Using blend() for everything.

Patch contributed by "pd"
This commit is contained in:
Andreas Kling 2019-05-11 02:55:42 +02:00
parent 1ff7f76172
commit e491dd2125
1 changed files with 7 additions and 16 deletions
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23
SharedGraphics/Painter.cpp
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@ -349,27 +349,18 @@ void Painter::draw_scaled_bitmap(const Rect& a_dst_rect, const GraphicsBitmap& s
if (clipped_rect.is_empty())
return;
float hscale = (float)src_rect.width() / (float)dst_rect.width();
float vscale = (float)src_rect.height() / (float)dst_rect.height();
int hscale = (src_rect.width() << 16) / dst_rect.width();
int vscale = (src_rect.height() << 16) / dst_rect.height();
for (int y = dst_rect.top(); y <= dst_rect.bottom(); ++y) {
if (y < clipped_rect.top() || y > clipped_rect.bottom())
continue;
for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); ++y) {
auto* scanline = (Color*)m_target->scanline(y);
for (int x = dst_rect.left(); x <= dst_rect.right(); ++x) {
if (x < clipped_rect.left() || x >= clipped_rect.right())
continue;
for (int x = clipped_rect.left(); x <= clipped_rect.right(); ++x) {
auto scaled_x = (float)(x - dst_rect.x()) * hscale;
auto scaled_y = (float)(y - dst_rect.y()) * vscale;
auto scaled_x = ((x - dst_rect.x()) * hscale) >> 16;
auto scaled_y = ((y - dst_rect.y()) * vscale) >> 16;
auto src_pixel = source.get_pixel(scaled_x, scaled_y);
if (!src_pixel.alpha())
continue;
if (src_pixel.alpha() == 0xff)
scanline[x] = src_pixel;
else
scanline[x] = scanline[x].blend(scanline[x]);
scanline[x] = scanline[x].blend(src_pixel);
}
}
}