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Painter: Add a fast path for draw_scaled_bitmap() with integer scale.

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When both the x and y scale factors are integers, we can avoid a whole bunch
of the pixel lookups in the source image.

This makes 2x scaling a 320x200 bitmap another ~25% faster. :^)
This commit is contained in:
Andreas Kling 2019-05-11 05:34:20 +02:00
parent 91a4b60d66
commit e2c2a4c6d7
1 changed files with 43 additions and 9 deletions
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52
SharedGraphics/Painter.cpp
View file

@ -349,8 +349,42 @@ void Painter::blit(const Point& position, const GraphicsBitmap& source, const Re
}
template<bool has_alpha_channel, typename GetPixel>
ALWAYS_INLINE static void do_draw_scaled_bitmap(GraphicsBitmap& target, const Rect& dst_rect, const Rect& clipped_rect, const GraphicsBitmap& source, int hscale, int vscale, GetPixel get_pixel)
ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(GraphicsBitmap& target, const Rect& dst_rect, const Rect& clipped_rect, const GraphicsBitmap& source, int hscale, int vscale, int hfactor, int vfactor, GetPixel get_pixel)
{
for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); y += vfactor) {
for (int x = clipped_rect.left(); x <= clipped_rect.right(); x += hfactor) {
auto scaled_x = ((x - dst_rect.x()) * hscale) >> 16;
auto scaled_y = ((y - dst_rect.y()) * vscale) >> 16;
auto src_pixel = get_pixel(source, scaled_x, scaled_y);
for (int yo = 0; yo < vfactor; ++yo) {
auto* scanline = (Color*)target.scanline(y + yo);
for (int xo = 0; xo < hfactor; ++xo) {
if constexpr (has_alpha_channel)
scanline[x + xo] = scanline[x].blend(src_pixel);
else
scanline[x + xo] = src_pixel;
}
}
}
}
}
template<bool has_alpha_channel, typename GetPixel>
ALWAYS_INLINE static void do_draw_scaled_bitmap(GraphicsBitmap& target, const Rect& dst_rect, const Rect& clipped_rect, const GraphicsBitmap& source, const Rect& src_rect, int hscale, int vscale, GetPixel get_pixel)
{
if (dst_rect == clipped_rect && !(dst_rect.width() % src_rect.width()) && !(dst_rect.height() % src_rect.height())) {
int hfactor = dst_rect.width() / src_rect.width();
int vfactor = dst_rect.height() / src_rect.height();
if (hfactor == 2 && vfactor == 2)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, clipped_rect, source, hscale, vscale, 2, 2, get_pixel);
if (hfactor == 3 && vfactor == 3)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, clipped_rect, source, hscale, vscale, 3, 3, get_pixel);
if (hfactor == 4 && vfactor == 4)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, clipped_rect, source, hscale, vscale, 3, 3, get_pixel);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, clipped_rect, source, hscale, vscale, hfactor, vfactor, get_pixel);
}
for (int y = clipped_rect.top(); y <= clipped_rect.bottom(); ++y) {
auto* scanline = (Color*)target.scanline(y);
for (int x = clipped_rect.left(); x <= clipped_rect.right(); ++x) {
@ -384,17 +418,17 @@ void Painter::draw_scaled_bitmap(const Rect& a_dst_rect, const GraphicsBitmap& s
if (source.has_alpha_channel()) {
switch (source.format()) {
case GraphicsBitmap::Format::RGB32: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::RGBA32: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::Indexed8: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::Indexed8>); break;
default: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::Invalid>); break;
case GraphicsBitmap::Format::RGB32: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::RGBA32: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::Indexed8: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::Indexed8>); break;
default: do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::Invalid>); break;
}
} else {
switch (source.format()) {
case GraphicsBitmap::Format::RGB32: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::RGBA32: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::Indexed8: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::Indexed8>); break;
default: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, hscale, vscale, get_pixel<GraphicsBitmap::Format::Invalid>); break;
case GraphicsBitmap::Format::RGB32: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::RGBA32: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::RGB32>); break;
case GraphicsBitmap::Format::Indexed8: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::Indexed8>); break;
default: do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<GraphicsBitmap::Format::Invalid>); break;
}
}
}