| Flutter Impeller |

text_frame_skia.cc
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1 // Copyright 2013 The Flutter Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4
5 #include "impeller/typographer/backends/skia/text_frame_skia.h"
6
7 #include <vector>
8
9 #include "flutter/fml/logging.h"
10 #include "impeller/typographer/backends/skia/typeface_skia.h"
11 #include "include/core/SkRect.h"
12 #include "third_party/skia/include/core/SkFont.h"
13 #include "third_party/skia/include/core/SkFontMetrics.h"
14 #include "third_party/skia/src/core/SkStrikeSpec.h" // nogncheck
15 #include "third_party/skia/src/core/SkTextBlobPriv.h" // nogncheck
16
17 namespace impeller {
18
19 static Font ToFont(const SkTextBlobRunIterator& run) {
20 auto& font = run.font();
21 auto typeface = std::make_shared<TypefaceSkia>(font.refTypefaceOrDefault());
22
23 SkFontMetrics sk_metrics;
24 font.getMetrics(&sk_metrics);
25
26 Font::Metrics metrics;
27 metrics.point_size = font.getSize();
28 metrics.embolden = font.isEmbolden();
29 metrics.skewX = font.getSkewX();
30 metrics.scaleX = font.getScaleX();
31
32 return Font{std::move(typeface), metrics};
33 }
34
35 static Rect ToRect(const SkRect& rect) {
36 return Rect::MakeLTRB(rect.fLeft, rect.fTop, rect.fRight, rect.fBottom);
37 }
38
39 static constexpr Scalar kScaleSize = 100000.0f;
40
41 std::shared_ptr<TextFrame> MakeTextFrameFromTextBlobSkia(
42 const sk_sp<SkTextBlob>& blob) {
43 bool has_color = false;
44 std::vector<TextRun> runs;
45 for (SkTextBlobRunIterator run(blob.get()); !run.done(); run.next()) {
46 // TODO(jonahwilliams): ask Skia for a public API to look this up.
47 // https://github.com/flutter/flutter/issues/112005
48 SkStrikeSpec strikeSpec = SkStrikeSpec::MakeWithNoDevice(run.font());
49 SkBulkGlyphMetricsAndPaths paths{strikeSpec};
50
51 const auto glyph_count = run.glyphCount();
52 const auto* glyphs = run.glyphs();
53 switch (run.positioning()) {
54 case SkTextBlobRunIterator::kFull_Positioning: {
55 std::vector<SkRect> glyph_bounds;
56 glyph_bounds.resize(glyph_count);
57 SkFont font = run.font();
58 auto font_size = font.getSize();
59 // For some platforms (including Android), `SkFont::getBounds()` snaps
60 // the computed bounds to integers. And so we scale up the font size
61 // prior to fetching the bounds to ensure that the returned bounds are
62 // always precise enough.
63 font.setSize(kScaleSize);
64 font.getBounds(glyphs, glyph_count, glyph_bounds.data(), nullptr);
65
66 std::vector<TextRun::GlyphPosition> positions;
67 positions.reserve(glyph_count);
68 for (auto i = 0u; i < glyph_count; i++) {
69 // kFull_Positioning has two scalars per glyph.
70 const SkPoint* glyph_points = run.points();
71 const auto* point = glyph_points + i;
72 Glyph::Type type = paths.glyph(glyphs[i])->isColor()
73 ? Glyph::Type::kBitmap
74 : Glyph::Type::kPath;
75 has_color |= type == Glyph::Type::kBitmap;
76
77 positions.emplace_back(TextRun::GlyphPosition{
78 Glyph{glyphs[i], type,
79 ToRect(glyph_bounds[i]).Scale(font_size / kScaleSize)},
80 Point{point->x(), point->y()}});
81 }
82 TextRun text_run(ToFont(run), positions);
83 runs.emplace_back(text_run);
84 break;
85 }
86 default:
87 FML_DLOG(ERROR) << "Unimplemented.";
88 continue;
89 }
90 }
91 return std::make_shared<TextFrame>(runs, ToRect(blob->bounds()), has_color);
92 }
93
94 } // namespace impeller
impeller::Glyph::Type
Type
Definition: glyph.h:20
impeller::Scalar
float Scalar
Definition: scalar.h:15
impeller::Font
Describes a typeface along with any modifications to its intrinsic properties.
Definition: font.h:21
impeller::Font::Metrics::embolden
bool embolden
Definition: font.h:35
impeller::kScaleSize
static constexpr Scalar kScaleSize
Definition: text_frame_skia.cc:39
impeller::Glyph::Type::kBitmap
@ kBitmap
impeller::TextRun
Represents a collection of positioned glyphs from a specific font.
Definition: text_run.h:19
text_frame_skia.h
impeller::Font::Metrics::skewX
Scalar skewX
Definition: font.h:36
impeller::Glyph
The glyph index in the typeface.
Definition: glyph.h:19
impeller::TRect::Scale
constexpr TRect Scale(Type scale) const
Definition: rect.h:108
impeller::Font::Metrics::point_size
Scalar point_size
Definition: font.h:34
impeller::ToFont
static Font ToFont(const SkTextBlobRunIterator &run)
Definition: text_frame_skia.cc:19
impeller::MakeTextFrameFromTextBlobSkia
std::shared_ptr< TextFrame > MakeTextFrameFromTextBlobSkia(const sk_sp< SkTextBlob > &blob)
Definition: text_frame_skia.cc:41
impeller::TPoint::x
Type x
Definition: point.h:23
typeface_skia.h
impeller::TPoint< Scalar >
impeller::TextRun::GlyphPosition
Definition: text_run.h:21
impeller::Font::Metrics::scaleX
Scalar scaleX
Definition: font.h:37
impeller::TRect< Scalar >::MakeLTRB
constexpr static TRect MakeLTRB(Type left, Type top, Type right, Type bottom)
Definition: rect.h:40
impeller::Glyph::Type::kPath
@ kPath
impeller::ToRect
static Rect ToRect(const SkRect &rect)
Definition: dl_vertices_geometry.cc:16
impeller
Definition: aiks_context.cc:10
impeller::Font::Metrics
Describes the modifications made to the intrinsic properties of a typeface.
Definition: font.h:30
impeller::TRect
Definition: rect.h:20