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LibGfx: Add an "opacity" argument to Painter::draw_scaled_bitmap()

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This API is not super perfect as it merely overrides the source alpha
on all source pixels instead of blending the alpha values. There is
room for improvement here for sure.
This commit is contained in:
Andreas Kling 2020-07-23 20:32:39 +02:00
parent 0a95f8d346
commit d7be3faab5
Notes: sideshowbarker 2024-07-19 04:39:20 +09:00 
Author: https://github.com/awesomekling
Commit: https://github.com/SerenityOS/serenity/commit/d7be3faab51
2 changed files with 25 additions and 20 deletions
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43
Libraries/LibGfx/Painter.cpp
View file

@ -690,12 +690,14 @@ void Painter::blit(const IntPoint& position, const Gfx::Bitmap& source, const In
}
template<bool has_alpha_channel, typename GetPixel>
ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const Gfx::Bitmap& source, int hfactor, int vfactor, GetPixel get_pixel)
ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const Gfx::Bitmap& source, int hfactor, int vfactor, GetPixel get_pixel, float opacity)
{
u8 src_alpha = opacity * 255;
for (int y = source.rect().top(); y <= source.rect().bottom(); ++y) {
int dst_y = dst_rect.y() + y * vfactor;
for (int x = source.rect().left(); x <= source.rect().right(); ++x) {
auto src_pixel = get_pixel(source, x, y);
src_pixel.set_alpha(src_alpha);
for (int yo = 0; yo < vfactor; ++yo) {
auto* scanline = (Color*)target.scanline(dst_y + yo);
int dst_x = dst_rect.x() + x * hfactor;
@ -711,26 +713,29 @@ ALWAYS_INLINE static void do_draw_integer_scaled_bitmap(Gfx::Bitmap& target, con
}
template<bool has_alpha_channel, typename GetPixel>
ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const IntRect& clipped_rect, const Gfx::Bitmap& source, const IntRect& src_rect, int hscale, int vscale, GetPixel get_pixel)
ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRect& dst_rect, const IntRect& clipped_rect, const Gfx::Bitmap& source, const IntRect& src_rect, int hscale, int vscale, GetPixel get_pixel, float opacity)
{
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, source, 2, 2, get_pixel);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, 2, 2, get_pixel, opacity);
if (hfactor == 3 && vfactor == 3)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, 3, 3, get_pixel);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, 3, 3, get_pixel, opacity);
if (hfactor == 4 && vfactor == 4)
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, 4, 4, get_pixel);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, hfactor, vfactor, get_pixel);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, 4, 4, get_pixel, opacity);
return do_draw_integer_scaled_bitmap<has_alpha_channel>(target, dst_rect, source, hfactor, vfactor, get_pixel, opacity);
}
u8 src_alpha = opacity * 255;
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) {
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);
src_pixel.set_alpha(src_alpha);
if constexpr (has_alpha_channel) {
scanline[x] = scanline[x].blend(src_pixel);
@ -740,11 +745,11 @@ ALWAYS_INLINE static void do_draw_scaled_bitmap(Gfx::Bitmap& target, const IntRe
}
}
void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& source, const IntRect& src_rect)
void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& source, const IntRect& src_rect, float opacity)
{
auto dst_rect = a_dst_rect;
if (dst_rect.size() == src_rect.size())
return blit(dst_rect.location(), source, src_rect);
return blit(dst_rect.location(), source, src_rect, opacity);
auto safe_src_rect = src_rect.intersected(source.rect());
ASSERT(source.rect().contains(safe_src_rect));
@ -759,40 +764,40 @@ void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& s
if (source.has_alpha_channel()) {
switch (source.format()) {
case BitmapFormat::RGB32:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGB32>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGB32>, opacity);
break;
case BitmapFormat::RGBA32:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGBA32>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGBA32>, opacity);
break;
case BitmapFormat::Indexed8:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed8>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed8>, opacity);
break;
case BitmapFormat::Indexed4:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed4>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed4>, opacity);
break;
case BitmapFormat::Indexed2:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed2>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed2>, opacity);
break;
case BitmapFormat::Indexed1:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed1>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed1>, opacity);
break;
default:
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Invalid>);
do_draw_scaled_bitmap<true>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Invalid>, opacity);
break;
}
} else {
switch (source.format()) {
case BitmapFormat::RGB32:
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGB32>);
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGB32>, opacity);
break;
case BitmapFormat::RGBA32:
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGBA32>);
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::RGBA32>, opacity);
break;
case BitmapFormat::Indexed8:
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed8>);
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Indexed8>, opacity);
break;
default:
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Invalid>);
do_draw_scaled_bitmap<false>(*m_target, dst_rect, clipped_rect, source, src_rect, hscale, vscale, get_pixel<BitmapFormat::Invalid>, opacity);
break;
}
}

2
Libraries/LibGfx/Painter.h
View file

@ -65,7 +65,7 @@ public:
void set_pixel(const IntPoint&, Color);
void draw_line(const IntPoint&, const IntPoint&, Color, int thickness = 1, LineStyle style = LineStyle::Solid);
void draw_quadratic_bezier_curve(const IntPoint& control_point, const IntPoint&, const IntPoint&, Color, int thickness = 1, LineStyle style = LineStyle::Solid);
void draw_scaled_bitmap(const IntRect& dst_rect, const Gfx::Bitmap&, const IntRect& src_rect);
void draw_scaled_bitmap(const IntRect& dst_rect, const Gfx::Bitmap&, const IntRect& src_rect, float opacity = 1.0f);
void blit(const IntPoint&, const Gfx::Bitmap&, const IntRect& src_rect, float opacity = 1.0f);
void blit_dimmed(const IntPoint&, const Gfx::Bitmap&, const IntRect& src_rect);
void blit_brightened(const IntPoint&, const Gfx::Bitmap&, const IntRect& src_rect);