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LibGfx: Don't use target's alpha if it doesn't have one (#5888)

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Oleg 2021-03-21 11:40:14 +03:00 • committed by GitHub
parent 8560108717
commit d0e7d45b85
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1 changed files with 59 additions and 28 deletions
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87
Userland/Libraries/LibGfx/Painter.cpp
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@ -532,6 +532,45 @@ void Painter::draw_triangle(const IntPoint& a, const IntPoint& b, const IntPoint
}
}
struct BlitState {
enum AlphaState {
NoAlpha = 0,
SrcAlpha = 1,
DstAlpha = 2,
BothAlpha = SrcAlpha | DstAlpha
};
const RGBA32* src;
RGBA32* dst;
size_t src_pitch;
size_t dst_pitch;
int row_count;
int column_count;
float opacity;
};
template<BlitState::AlphaState has_alpha>
static void do_blit_with_opacity(BlitState& state)
{
for (int row = 0; row < state.row_count; ++row) {
for (int x = 0; x < state.column_count; ++x) {
Color dest_color = (has_alpha & BlitState::DstAlpha) ? Color::from_rgba(state.dst[x]) : Color::from_rgb(state.dst[x]);
if constexpr (has_alpha & BlitState::SrcAlpha) {
Color src_color_with_alpha = Color::from_rgba(state.src[x]);
float pixel_opacity = src_color_with_alpha.alpha() / 255.0;
src_color_with_alpha.set_alpha(255 * (state.opacity * pixel_opacity));
state.dst[x] = dest_color.blend(src_color_with_alpha).value();
} else {
Color src_color_with_alpha = Color::from_rgb(state.src[x]);
src_color_with_alpha.set_alpha(state.opacity * 255);
state.dst[x] = dest_color.blend(src_color_with_alpha).value();
}
}
state.dst += state.dst_pitch;
state.src += state.src_pitch;
}
}
void Painter::blit_with_opacity(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& a_src_rect, float opacity, bool apply_alpha)
{
VERIFY(scale() >= source.scale() && "painter doesn't support downsampling scale factors");
@ -539,8 +578,6 @@ void Painter::blit_with_opacity(const IntPoint& position, const Gfx::Bitmap& sou
if (opacity >= 1.0f && !(source.has_alpha_channel() && apply_alpha))
return blit(position, source, a_src_rect);
u8 alpha = 255 * opacity;
IntRect safe_src_rect = IntRect::intersection(a_src_rect, source.rect());
if (scale() != source.scale())
return draw_scaled_bitmap({ position, safe_src_rect.size() }, source, safe_src_rect, opacity);
@ -559,34 +596,28 @@ void Painter::blit_with_opacity(const IntPoint& position, const Gfx::Bitmap& sou
const int last_row = clipped_rect.bottom() - dst_rect.top();
const int first_column = clipped_rect.left() - dst_rect.left();
const int last_column = clipped_rect.right() - dst_rect.left();
RGBA32* dst = m_target->scanline(clipped_rect.y()) + clipped_rect.x();
const size_t dst_skip = m_target->pitch() / sizeof(RGBA32);
const RGBA32* src = source.scanline(src_rect.top() + first_row) + src_rect.left() + first_column;
const unsigned src_skip = source.pitch() / sizeof(RGBA32);
auto do_blit = [&]<bool with_src_alpha>() {
for (int row = first_row; row <= last_row; ++row) {
for (int x = 0; x <= (last_column - first_column); ++x) {
if constexpr (with_src_alpha) {
Color src_color_with_alpha = Color::from_rgba(src[x]);
float pixel_opacity = src_color_with_alpha.alpha() / 255.0;
src_color_with_alpha.set_alpha(255 * (opacity * pixel_opacity));
dst[x] = Color::from_rgba(dst[x]).blend(src_color_with_alpha).value();
} else {
Color src_color_with_alpha = Color::from_rgb(src[x]);
src_color_with_alpha.set_alpha(alpha);
dst[x] = Color::from_rgb(dst[x]).blend(src_color_with_alpha).value();
}
}
dst += dst_skip;
src += src_skip;
}
BlitState blit_state {
.src = source.scanline(src_rect.top() + first_row) + src_rect.left() + first_column,
.dst = m_target->scanline(clipped_rect.y()) + clipped_rect.x(),
.src_pitch = source.pitch() / sizeof(RGBA32),
.dst_pitch = m_target->pitch() / sizeof(RGBA32),
.row_count = last_row - first_row + 1,
.column_count = last_column - first_column + 1,
.opacity = opacity
};
if (source.has_alpha_channel() && apply_alpha)
do_blit.template operator()<true>();
else
do_blit.template operator()<false>();
if (source.has_alpha_channel() && apply_alpha) {
if (m_target->has_alpha_channel())
do_blit_with_opacity<BlitState::BothAlpha>(blit_state);
else
do_blit_with_opacity<BlitState::SrcAlpha>(blit_state);
} else {
if (m_target->has_alpha_channel())
do_blit_with_opacity<BlitState::DstAlpha>(blit_state);
else
do_blit_with_opacity<BlitState::NoAlpha>(blit_state);
}
}
void Painter::blit_filtered(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& src_rect, Function<Color(Color)> filter)