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LibGfx: Give Bitmap a scale factor

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Gfx::Bitmap can now store its scale factor. Normally it's 1, but
in high dpi mode it can be 2.

If a Bitmap with a scale factor of 2 is blitted to a Painter with
scale factor of 2, the pixels can be copied over without any resampling.
(When blitting a Bitmap with a scale factor of 1 to a Painter with scale
factor of 2, the Bitmap is painted at twice its width and height at
paint time. Blitting a Bitmap with a scale factor of 2 to a Painter with
scale factor 1 is not supported.)

A Bitmap with scale factor of 2 reports the same width() and height() as
one with scale factor 1. That's important because many places in the
codebase use a bitmap's width() and height() to layout Widgets, and all
widget coordinates are in logical coordinates as well, per
Documentation/HighDPI.md.

Bitmap grows physical_width() / physical_height() to access the actual
pixel size. Update a few callers that work with pixels to call this
instead.

Make Painter's constructor take its scale factor from the target bitmap
that's passed in, and update its various blit() methods to handle
blitting a 2x bitmap to a 2x painter. This allows removing some gnarly
code in Compositor. (In return, put some new gnarly code in
LibGfxScaleDemo to preserve behavior there.)

No intended behavior change.
This commit is contained in:
Nico Weber 2021-01-19 12:10:47 -05:00 • committed by Andreas Kling
parent c6726f331e
commit 5f9c42c404
14 changed files with 192 additions and 174 deletions
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72
Userland/Libraries/LibGfx/Painter.cpp
View file

@ -68,15 +68,16 @@ ALWAYS_INLINE Color get_pixel(const Gfx::Bitmap& bitmap, int x, int y)
return bitmap.get_pixel(x, y);
}
Painter::Painter(Gfx::Bitmap& bitmap, int scale)
Painter::Painter(Gfx::Bitmap& bitmap)
: m_target(bitmap)
{
int scale = bitmap.scale();
ASSERT(bitmap.format() == Gfx::BitmapFormat::RGB32 || bitmap.format() == Gfx::BitmapFormat::RGBA32);
ASSERT(bitmap.width() % scale == 0);
ASSERT(bitmap.height() % scale == 0);
ASSERT(bitmap.physical_width() % scale == 0);
ASSERT(bitmap.physical_height() % scale == 0);
m_state_stack.append(State());
state().font = &FontDatabase::default_font();
state().clip_rect = { { 0, 0 }, bitmap.size() };
state().clip_rect = { { 0, 0 }, bitmap.physical_size() };
state().scale = scale;
m_clip_origin = state().clip_rect;
}
@ -109,7 +110,7 @@ void Painter::clear_rect(const IntRect& a_rect, Color color)
if (rect.is_empty())
return;
ASSERT(m_target->rect().contains(rect));
ASSERT(m_target->physical_rect().contains(rect));
RGBA32* dst = m_target->scanline(rect.top()) + rect.left();
const size_t dst_skip = m_target->pitch() / sizeof(RGBA32);
@ -120,12 +121,12 @@ void Painter::clear_rect(const IntRect& a_rect, Color color)
}
}
void Painter::fill_physical_rect(const IntRect& a_rect, Color color)
void Painter::fill_physical_rect(const IntRect& a_physical_rect, Color color)
{
auto rect = a_rect.intersected(clip_rect());
auto rect = a_physical_rect.intersected(clip_rect());
if (rect.is_empty())
return;
ASSERT(m_target->rect().contains(rect));
ASSERT(m_target->physical_rect().contains(rect));
RGBA32* dst = m_target->scanline(rect.top()) + rect.left();
const size_t dst_skip = m_target->pitch() / sizeof(RGBA32);
@ -693,14 +694,16 @@ void Painter::blit_offset(const IntPoint& position, const Gfx::Bitmap& source, c
ASSERT_NOT_REACHED();
}
void Painter::blit_with_alpha(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& src_rect)
void Painter::blit_with_alpha(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& a_src_rect)
{
if (scale() != 1)
return draw_scaled_bitmap({ position, src_rect.size() }, source, src_rect);
if (scale() != source.scale())
return draw_scaled_bitmap({ position, a_src_rect.size() }, source, a_src_rect);
ASSERT(source.has_alpha_channel());
IntRect safe_src_rect = src_rect.intersected(source.rect());
auto dst_rect = IntRect(position, safe_src_rect.size()).translated(translation());
IntRect safe_src_rect = a_src_rect.intersected(source.rect());
auto dst_rect = to_physical(IntRect(position, safe_src_rect.size()));
auto src_rect = a_src_rect * source.scale();
auto clipped_rect = dst_rect.intersected(clip_rect());
if (clipped_rect.is_empty())
return;
@ -728,18 +731,25 @@ void Painter::blit_with_alpha(const IntPoint& position, const Gfx::Bitmap& sourc
}
}
void Painter::blit(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& src_rect, float opacity)
void Painter::blit(const IntPoint& position, const Gfx::Bitmap& source, const IntRect& a_src_rect, float opacity)
{
if (opacity < 1.0f)
return blit_with_opacity(position, source, src_rect, opacity);
if (source.has_alpha_channel())
return blit_with_alpha(position, source, src_rect);
if (scale() != 1)
return draw_scaled_bitmap({ position, src_rect.size() }, source, src_rect, opacity);
assert(scale() >= source.scale() && "painter doesn't support downsampling scale factors");
auto safe_src_rect = src_rect.intersected(source.rect());
if (opacity < 1.0f)
return blit_with_opacity(position, source, a_src_rect, opacity);
if (source.has_alpha_channel())
return blit_with_alpha(position, source, a_src_rect);
if (scale() != source.scale())
return draw_scaled_bitmap({ position, a_src_rect.size() }, source, a_src_rect, opacity);
// If we get here, the Painter might have a scale factor, but the source bitmap has the same scale factor.
// We need to transform from logical to physical coordinates, but we can just copy pixels without resampling.
// All computations below are in physical coordinates (except for safe_src_rect).
auto safe_src_rect = a_src_rect.intersected(source.rect());
ASSERT(source.rect().contains(safe_src_rect));
auto dst_rect = IntRect(position, safe_src_rect.size()).translated(translation());
auto dst_rect = to_physical(IntRect(position, safe_src_rect.size()));
auto src_rect = a_src_rect * source.scale();
auto clipped_rect = dst_rect.intersected(clip_rect());
if (clipped_rect.is_empty())
return;
@ -832,15 +842,13 @@ 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, float opacity)
void Painter::draw_scaled_bitmap(const IntRect& a_dst_rect, const Gfx::Bitmap& source, const IntRect& a_src_rect, float opacity)
{
if (scale() == 1 && a_dst_rect.size() == src_rect.size())
return blit(a_dst_rect.location(), source, src_rect, opacity);
if (scale() == source.scale() && a_dst_rect.size() == a_src_rect.size())
return blit(a_dst_rect.location(), source, a_src_rect, opacity);
auto dst_rect = to_physical(a_dst_rect);
auto safe_src_rect = src_rect.intersected(source.rect());
ASSERT(source.rect().contains(safe_src_rect));
auto src_rect = a_src_rect * source.scale();
auto clipped_rect = dst_rect.intersected(clip_rect());
if (clipped_rect.is_empty())
@ -1232,7 +1240,7 @@ ALWAYS_INLINE void Painter::fill_physical_scanline_with_draw_op(int y, int x, in
}
}
void Painter::draw_physical_pixel(const IntPoint& position, Color color, int thickness)
void Painter::draw_physical_pixel(const IntPoint& physical_position, Color color, int thickness)
{
// This always draws a single physical pixel, independent of scale().
// This should only be called by routines that already handle scale
@ -1240,11 +1248,11 @@ void Painter::draw_physical_pixel(const IntPoint& position, Color color, int thi
ASSERT(draw_op() == DrawOp::Copy);
if (thickness == 1) { // Implies scale() == 1.
auto& pixel = m_target->scanline(position.y())[position.x()];
auto& pixel = m_target->scanline(physical_position.y())[physical_position.x()];
return set_physical_pixel_with_draw_op(pixel, Color::from_rgba(pixel).blend(color));
}
IntRect rect { position, { thickness, thickness } };
IntRect rect { physical_position, { thickness, thickness } };
fill_physical_rect(rect, color);
}
@ -1488,7 +1496,7 @@ void Painter::draw_elliptical_arc(const IntPoint& p1, const IntPoint& p2, const
void Painter::add_clip_rect(const IntRect& rect)
{
state().clip_rect.intersect(to_physical(rect));
state().clip_rect.intersect(m_target->rect()); // FIXME: This shouldn't be necessary?
state().clip_rect.intersect(m_target->physical_rect()); // FIXME: This shouldn't be necessary?
}
void Painter::clear_clip_rect()