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ladybird/Libraries/LibTTF/Glyf.cpp
Luke 0f66589007 Everywhere: Fix more typos
2020-12-31 01:47:41 +01:00

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/*
* Copyright (c) 2020, Srimanta Barua <srimanta.barua1@gmail.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <LibGfx/Path.h>
#include <LibGfx/Point.h>
#include <LibTTF/Glyf.h>
namespace TTF {
extern u16 be_u16(const u8* ptr);
extern u32 be_u32(const u8* ptr);
extern i16 be_i16(const u8* ptr);
extern float be_fword(const u8* ptr);
enum class SimpleGlyfFlags {
// From spec.
OnCurve = 0x01,
XShortVector = 0x02,
YShortVector = 0x04,
RepeatFlag = 0x08,
XIsSameOrPositiveXShortVector = 0x10,
YIsSameOrPositiveYShortVector = 0x20,
// Combinations
XMask = 0x12,
YMask = 0x24,
XLongVector = 0x00,
YLongVector = 0x00,
XNegativeShortVector = 0x02,
YNegativeShortVector = 0x04,
XPositiveShortVector = 0x12,
YPositiveShortVector = 0x24,
};
enum class CompositeGlyfFlags {
Arg1AndArg2AreWords = 0x0001,
ArgsAreXYValues = 0x0002,
RoundXYToGrid = 0x0004,
WeHaveAScale = 0x0008,
MoreComponents = 0x0020,
WeHaveAnXAndYScale = 0x0040,
WeHaveATwoByTwo = 0x0080,
WeHaveInstructions = 0x0100,
UseMyMetrics = 0x0200,
OverlapCompound = 0x0400, // Not relevant - can overlap without this set
ScaledComponentOffset = 0x0800,
UnscaledComponentOffset = 0x1000,
};
class PointIterator {
public:
struct Item {
bool on_curve;
Gfx::FloatPoint point;
};
PointIterator(const ReadonlyBytes& slice, u16 num_points, u32 flags_offset, u32 x_offset, u32 y_offset, Gfx::AffineTransform affine)
: m_slice(slice)
, m_points_remaining(num_points)
, m_flags_offset(flags_offset)
, m_x_offset(x_offset)
, m_y_offset(y_offset)
, m_affine(affine)
{
}
Optional<Item> next()
{
if (m_points_remaining == 0) {
return {};
}
if (m_flags_remaining > 0) {
m_flags_remaining--;
} else {
m_flag = m_slice[m_flags_offset++];
if (m_flag & (u8)SimpleGlyfFlags::RepeatFlag) {
m_flags_remaining = m_slice[m_flags_offset++];
}
}
switch (m_flag & (u8)SimpleGlyfFlags::XMask) {
case (u8)SimpleGlyfFlags::XLongVector:
m_last_point.set_x(m_last_point.x() + be_i16(m_slice.offset_pointer(m_x_offset)));
m_x_offset += 2;
break;
case (u8)SimpleGlyfFlags::XNegativeShortVector:
m_last_point.set_x(m_last_point.x() - m_slice[m_x_offset++]);
break;
case (u8)SimpleGlyfFlags::XPositiveShortVector:
m_last_point.set_x(m_last_point.x() + m_slice[m_x_offset++]);
break;
default:
break;
}
switch (m_flag & (u8)SimpleGlyfFlags::YMask) {
case (u8)SimpleGlyfFlags::YLongVector:
m_last_point.set_y(m_last_point.y() + be_i16(m_slice.offset_pointer(m_y_offset)));
m_y_offset += 2;
break;
case (u8)SimpleGlyfFlags::YNegativeShortVector:
m_last_point.set_y(m_last_point.y() - m_slice[m_y_offset++]);
break;
case (u8)SimpleGlyfFlags::YPositiveShortVector:
m_last_point.set_y(m_last_point.y() + m_slice[m_y_offset++]);
break;
default:
break;
}
m_points_remaining--;
Item ret = {
.on_curve = (m_flag & (u8)SimpleGlyfFlags::OnCurve) != 0,
.point = m_affine.map(m_last_point),
};
return ret;
}
private:
ReadonlyBytes m_slice;
u16 m_points_remaining;
u8 m_flag { 0 };
Gfx::FloatPoint m_last_point = { 0.0f, 0.0f };
u32 m_flags_remaining = { 0 };
u32 m_flags_offset;
u32 m_x_offset;
u32 m_y_offset;
Gfx::AffineTransform m_affine;
};
Optional<Glyf::Glyph::ComponentIterator::Item> Glyf::Glyph::ComponentIterator::next()
{
if (!m_has_more) {
return {};
}
u16 flags = be_u16(m_slice.offset_pointer(m_offset));
m_offset += 2;
u16 glyph_id = be_u16(m_slice.offset_pointer(m_offset));
m_offset += 2;
i16 arg1 = 0, arg2 = 0;
if (flags & (u16)CompositeGlyfFlags::Arg1AndArg2AreWords) {
arg1 = be_i16(m_slice.offset_pointer(m_offset));
m_offset += 2;
arg2 = be_i16(m_slice.offset_pointer(m_offset));
m_offset += 2;
} else {
arg1 = (i8)m_slice[m_offset++];
arg2 = (i8)m_slice[m_offset++];
}
float a = 1.0, b = 0.0, c = 0.0, d = 1.0, e = 0.0, f = 0.0;
if (flags & (u16)CompositeGlyfFlags::WeHaveATwoByTwo) {
a = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
b = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
c = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
d = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
} else if (flags & (u16)CompositeGlyfFlags::WeHaveAnXAndYScale) {
a = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
d = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
} else if (flags & (u16)CompositeGlyfFlags::WeHaveAScale) {
a = be_fword(m_slice.offset_pointer(m_offset));
m_offset += 2;
d = a;
}
// FIXME: Handle UseMyMetrics, ScaledComponentOffset, UnscaledComponentOffset, non-ArgsAreXYValues
if (flags & (u16)CompositeGlyfFlags::ArgsAreXYValues) {
e = arg1;
f = arg2;
} else {
TODO();
}
if (flags & (u16)CompositeGlyfFlags::UseMyMetrics) {
TODO();
}
if (flags & (u16)CompositeGlyfFlags::ScaledComponentOffset) {
TODO();
}
if (flags & (u16)CompositeGlyfFlags::UnscaledComponentOffset) {
TODO();
}
m_has_more = (flags & (u16)CompositeGlyfFlags::MoreComponents);
return Item {
.glyph_id = glyph_id,
.affine = Gfx::AffineTransform(a, b, c, d, e, f),
};
}
Rasterizer::Rasterizer(Gfx::IntSize size)
: m_size(size)
{
m_data.resize(m_size.width() * m_size.height());
for (int i = 0; i < m_size.width() * m_size.height(); i++) {
m_data[i] = 0.0;
}
}
void Rasterizer::draw_path(Gfx::Path& path)
{
for (auto& line : path.split_lines()) {
draw_line(line.from, line.to);
}
}
RefPtr<Gfx::Bitmap> Rasterizer::accumulate()
{
auto bitmap = Gfx::Bitmap::create(Gfx::BitmapFormat::RGBA32, m_size);
Color base_color = Color::from_rgb(0xffffff);
for (int y = 0; y < m_size.height(); y++) {
float accumulator = 0.0;
for (int x = 0; x < m_size.width(); x++) {
accumulator += m_data[y * m_size.width() + x];
float value = accumulator;
if (value < 0.0) {
value = -value;
}
if (value > 1.0) {
value = 1.0;
}
u8 alpha = value * 255.0;
bitmap->set_pixel(x, y, base_color.with_alpha(alpha));
}
}
return bitmap;
}
void Rasterizer::draw_line(Gfx::FloatPoint p0, Gfx::FloatPoint p1)
{
// FIXME: Shift x and y according to dy/dx
if (p0.x() < 0.0) {
p0.set_x(roundf(p0.x()));
}
if (p0.y() < 0.0) {
p0.set_y(roundf(p0.y()));
}
if (p1.x() < 0.0) {
p1.set_x(roundf(p1.x()));
}
if (p1.y() < 0.0) {
p1.set_y(roundf(p1.y()));
}
if (!(p0.x() >= 0.0 && p0.y() >= 0.0 && p0.x() <= m_size.width() && p0.y() <= m_size.height())) {
dbgln("!P0({},{})", p0.x(), p0.y());
return;
}
if (!(p1.x() >= 0.0 && p1.y() >= 0.0 && p1.x() <= m_size.width() && p1.y() <= m_size.height())) {
dbgln("!P1({},{})", p1.x(), p1.y());
return;
}
ASSERT(p0.x() >= 0.0 && p0.y() >= 0.0 && p0.x() <= m_size.width() && p0.y() <= m_size.height());
ASSERT(p1.x() >= 0.0 && p1.y() >= 0.0 && p1.x() <= m_size.width() && p1.y() <= m_size.height());
// If we're on the same Y, there's no need to draw
if (p0.y() == p1.y()) {
return;
}
float direction = -1.0;
if (p1.y() < p0.y()) {
direction = 1.0;
auto tmp = p0;
p0 = p1;
p1 = tmp;
}
float dxdy = (p1.x() - p0.x()) / (p1.y() - p0.y());
u32 y0 = floor(p0.y());
u32 y1 = ceil(p1.y());
float x_cur = p0.x();
for (u32 y = y0; y < y1; y++) {
u32 line_offset = m_size.width() * y;
float dy = min(y + 1.0f, p1.y()) - max((float)y, p0.y());
float directed_dy = dy * direction;
float x_next = x_cur + dy * dxdy;
if (x_next < 0.0) {
x_next = 0.0;
}
float x0 = x_cur;
float x1 = x_next;
if (x1 < x0) {
x1 = x_cur;
x0 = x_next;
}
float x0_floor = floor(x0);
float x1_ceil = ceil(x1);
u32 x0i = x0_floor;
if (x1_ceil <= x0_floor + 1.0) {
// If x0 and x1 are within the same pixel, then area to the right is (1 - (mid(x0, x1) - x0_floor)) * dy
float area = ((x0 + x1) * 0.5) - x0_floor;
m_data[line_offset + x0i] += directed_dy * (1.0 - area);
m_data[line_offset + x0i + 1] += directed_dy * area;
} else {
float dydx = 1.0 / dxdy;
float x0_right = 1.0 - (x0 - x0_floor);
u32 x1_floor_i = floor(x1);
float area_upto_here = 0.5 * x0_right * x0_right * dydx;
m_data[line_offset + x0i] += direction * area_upto_here;
for (u32 x = x0i + 1; x < x1_floor_i; x++) {
x0_right += 1.0;
float total_area_here = 0.5 * x0_right * x0_right * dydx;
m_data[line_offset + x] += direction * (total_area_here - area_upto_here);
area_upto_here = total_area_here;
}
m_data[line_offset + x1_floor_i] += direction * (dy - area_upto_here);
}
x_cur = x_next;
}
}
Optional<Loca> Loca::from_slice(const ReadonlyBytes& slice, u32 num_glyphs, IndexToLocFormat index_to_loc_format)
{
switch (index_to_loc_format) {
case IndexToLocFormat::Offset16:
if (slice.size() < num_glyphs * 2) {
return {};
}
break;
case IndexToLocFormat::Offset32:
if (slice.size() < num_glyphs * 4) {
return {};
}
break;
}
return Loca(slice, num_glyphs, index_to_loc_format);
}
u32 Loca::get_glyph_offset(u32 glyph_id) const
{
ASSERT(glyph_id < m_num_glyphs);
switch (m_index_to_loc_format) {
case IndexToLocFormat::Offset16:
return ((u32)be_u16(m_slice.offset_pointer(glyph_id * 2))) * 2;
case IndexToLocFormat::Offset32:
return be_u32(m_slice.offset_pointer(glyph_id * 4));
default:
ASSERT_NOT_REACHED();
}
}
static void get_ttglyph_offsets(const ReadonlyBytes& slice, u32 num_points, u32 flags_offset, u32* x_offset, u32* y_offset)
{
u32 flags_size = 0;
u32 x_size = 0;
u32 repeat_count;
while (num_points > 0) {
u8 flag = slice[flags_offset + flags_size];
if (flag & (u8)SimpleGlyfFlags::RepeatFlag) {
flags_size++;
repeat_count = slice[flags_offset + flags_size] + 1;
} else {
repeat_count = 1;
}
flags_size++;
switch (flag & (u8)SimpleGlyfFlags::XMask) {
case (u8)SimpleGlyfFlags::XLongVector:
x_size += repeat_count * 2;
break;
case (u8)SimpleGlyfFlags::XNegativeShortVector:
case (u8)SimpleGlyfFlags::XPositiveShortVector:
x_size += repeat_count;
break;
default:
break;
}
num_points -= repeat_count;
}
*x_offset = flags_offset + flags_size;
*y_offset = *x_offset + x_size;
}
void Glyf::Glyph::raster_inner(Rasterizer& rasterizer, Gfx::AffineTransform& affine) const
{
// Get offset for flags, x, and y.
u16 num_points = be_u16(m_slice.offset_pointer((m_num_contours - 1) * 2)) + 1;
u16 num_instructions = be_u16(m_slice.offset_pointer(m_num_contours * 2));
u32 flags_offset = m_num_contours * 2 + 2 + num_instructions;
u32 x_offset = 0;
u32 y_offset = 0;
get_ttglyph_offsets(m_slice, num_points, flags_offset, &x_offset, &y_offset);
// Prepare to render glyph.
Gfx::Path path;
PointIterator point_iterator(m_slice, num_points, flags_offset, x_offset, y_offset, affine);
int last_contour_end = -1;
i32 contour_index = 0;
u32 contour_size = 0;
Optional<Gfx::FloatPoint> contour_start = {};
Optional<Gfx::FloatPoint> last_offcurve_point = {};
// Render glyph
while (true) {
if (!contour_start.has_value()) {
if (contour_index >= m_num_contours) {
break;
}
int current_contour_end = be_u16(m_slice.offset_pointer(contour_index++ * 2));
contour_size = current_contour_end - last_contour_end;
last_contour_end = current_contour_end;
auto opt_item = point_iterator.next();
ASSERT(opt_item.has_value());
contour_start = opt_item.value().point;
path.move_to(contour_start.value());
contour_size--;
} else if (!last_offcurve_point.has_value()) {
if (contour_size > 0) {
auto opt_item = point_iterator.next();
// FIXME: Should we draw a line to the first point here?
if (!opt_item.has_value()) {
break;
}
auto item = opt_item.value();
contour_size--;
if (item.on_curve) {
path.line_to(item.point);
} else if (contour_size > 0) {
auto opt_next_item = point_iterator.next();
// FIXME: Should we draw a quadratic bezier to the first point here?
if (!opt_next_item.has_value()) {
break;
}
auto next_item = opt_next_item.value();
contour_size--;
if (next_item.on_curve) {
path.quadratic_bezier_curve_to(item.point, next_item.point);
} else {
auto mid_point = (item.point + next_item.point) * 0.5f;
path.quadratic_bezier_curve_to(item.point, mid_point);
last_offcurve_point = next_item.point;
}
} else {
path.quadratic_bezier_curve_to(item.point, contour_start.value());
contour_start = {};
}
} else {
path.line_to(contour_start.value());
contour_start = {};
}
} else {
auto point0 = last_offcurve_point.value();
last_offcurve_point = {};
if (contour_size > 0) {
auto opt_item = point_iterator.next();
// FIXME: Should we draw a quadratic bezier to the first point here?
if (!opt_item.has_value()) {
break;
}
auto item = opt_item.value();
contour_size--;
if (item.on_curve) {
path.quadratic_bezier_curve_to(point0, item.point);
} else {
auto mid_point = (point0 + item.point) * 0.5f;
path.quadratic_bezier_curve_to(point0, mid_point);
last_offcurve_point = item.point;
}
} else {
path.quadratic_bezier_curve_to(point0, contour_start.value());
contour_start = {};
}
}
}
rasterizer.draw_path(path);
}
RefPtr<Gfx::Bitmap> Glyf::Glyph::raster_simple(float x_scale, float y_scale) const
{
u32 width = (u32)(ceil((m_xmax - m_xmin) * x_scale)) + 2;
u32 height = (u32)(ceil((m_ymax - m_ymin) * y_scale)) + 2;
Rasterizer rasterizer(Gfx::IntSize(width, height));
auto affine = Gfx::AffineTransform().scale(x_scale, -y_scale).translate(-m_xmin, -m_ymax);
raster_inner(rasterizer, affine);
return rasterizer.accumulate();
}
Glyf::Glyph Glyf::glyph(u32 offset) const
{
ASSERT(m_slice.size() >= offset + (u32)Sizes::GlyphHeader);
i16 num_contours = be_i16(m_slice.offset_pointer(offset));
i16 xmin = be_i16(m_slice.offset_pointer(offset + (u32)Offsets::XMin));
i16 ymin = be_i16(m_slice.offset_pointer(offset + (u32)Offsets::YMin));
i16 xmax = be_i16(m_slice.offset_pointer(offset + (u32)Offsets::XMax));
i16 ymax = be_i16(m_slice.offset_pointer(offset + (u32)Offsets::YMax));
auto slice = ReadonlyBytes(m_slice.offset_pointer(offset + (u32)Sizes::GlyphHeader), m_slice.size() - offset - (u32)Sizes::GlyphHeader);
return Glyph(slice, xmin, ymin, xmax, ymax, num_contours);
}
}
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