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SharedGraphics: Add Painter::draw_scaled_bitmap().

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It's just a simple nearest-neighbor scale with alpha blending but it gets
the job done.
This commit is contained in:
Andreas Kling 2019-03-22 04:20:10 +01:00
parent e4498194c2
commit 86570d3b1a
2 changed files with 39 additions and 0 deletions
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38
SharedGraphics/Painter.cpp
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@ -321,6 +321,44 @@ void Painter::blit(const Point& position, const GraphicsBitmap& source, const Re
}
}
void Painter::draw_scaled_bitmap(const Rect& a_dst_rect, const GraphicsBitmap& source, const Rect& src_rect)
{
auto dst_rect = a_dst_rect;
if (dst_rect.size() == src_rect.size())
return blit(dst_rect.location(), source, src_rect);
auto safe_src_rect = Rect::intersection(src_rect, source.rect());
ASSERT(source.rect().contains(safe_src_rect));
dst_rect.move_by(state().translation);
auto clipped_rect = Rect::intersection(dst_rect, clip_rect());
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();
for (int y = dst_rect.top(); y <= dst_rect.bottom(); ++y) {
if (y < clipped_rect.top() || y > clipped_rect.bottom())
continue;
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;
auto scaled_x = (float)(x - dst_rect.x()) * hscale;
auto scaled_y = (float)(y - dst_rect.y()) * vscale;
auto src_pixel = Color::from_rgba(source.scanline((int)scaled_y)[(int)scaled_x]);
if (!src_pixel.alpha())
continue;
if (src_pixel.alpha() == 0xff)
scanline[x] = src_pixel;
else
scanline[x] = scanline[x].blend(scanline[x]);
}
}
}
[[gnu::flatten]] void Painter::draw_glyph(const Point& point, char ch, Color color)
{
draw_glyph(point, ch, font(), color);