| Flutter Impeller |

text_frame.h
Go to the documentation of this file.
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 #ifndef FLUTTER_IMPELLER_TYPOGRAPHER_TEXT_FRAME_H_
6 #define FLUTTER_IMPELLER_TYPOGRAPHER_TEXT_FRAME_H_
7
8 #include <cstdint>
9
10 #include "flutter/display_list/geometry/dl_path.h"
11 #include "fml/status_or.h"
12 #include "impeller/geometry/rational.h"
13 #include "impeller/typographer/glyph.h"
14 #include "impeller/typographer/glyph_atlas.h"
15 #include "impeller/typographer/text_run.h"
16
17 namespace impeller {
18
19 using PathCreator = std::function<fml::StatusOr<flutter::DlPath>()>;
20
21 //------------------------------------------------------------------------------
22 /// @brief Represents a collection of shaped text runs.
23 ///
24 /// This object is typically the entrypoint in the Impeller type
25 /// rendering subsystem.
26 ///
27 /// A text frame should not be reused in multiple places within a single frame,
28 /// as internally it is used as a cache for various glyph properties.
29 class TextFrame {
30 public:
31 TextFrame();
32
33 TextFrame(std::vector<TextRun>& runs,
34 Rect bounds,
35 bool has_color,
36 const PathCreator& path_creator = {});
37
38 ~TextFrame();
39
40 static SubpixelPosition ComputeSubpixelPosition(
41 const TextRun::GlyphPosition& glyph_position,
42 AxisAlignment alignment,
43 const Matrix& transform);
44
45 static Rational RoundScaledFontSize(Scalar scale);
46 static Rational RoundScaledFontSize(Rational scale);
47
48 //----------------------------------------------------------------------------
49 /// @brief The conservative bounding box for this text frame.
50 ///
51 /// @return The bounds rectangle. If there are no glyphs in this text
52 /// frame and empty Rectangle is returned instead.
53 ///
54 Rect GetBounds() const;
55
56 //----------------------------------------------------------------------------
57 /// @brief The number of runs in this text frame.
58 ///
59 /// @return The run count.
60 ///
61 size_t GetRunCount() const;
62
63 //----------------------------------------------------------------------------
64 /// @brief Returns a reference to all the text runs in this frame.
65 ///
66 /// @return The runs in this frame.
67 ///
68 const std::vector<TextRun>& GetRuns() const;
69
70 //----------------------------------------------------------------------------
71 /// @brief Returns the paint color this text frame was recorded with.
72 ///
73 /// Non-bitmap/COLR fonts always use a black text color here, but
74 /// COLR fonts can potentially use the paint color in the glyph
75 /// atlas, so this color must be considered as part of the cache
76 /// key.
77 bool HasColor() const;
78
79 //----------------------------------------------------------------------------
80 /// @brief The type of atlas this run should be place in.
81 GlyphAtlas::Type GetAtlasType() const;
82
83 /// @brief Verifies that all glyphs in this text frame have computed bounds
84 /// information.
85 bool IsFrameComplete() const;
86
87 /// @brief Retrieve the frame bounds for the glyph at [index].
88 ///
89 /// This method is only valid if [IsFrameComplete] returns true.
90 const FrameBounds& GetFrameBounds(size_t index) const;
91
92 /// @brief If this text frame contains a single glyph (such as for an Icon),
93 /// then return it, otherwise std::nullopt.
94 std::optional<Glyph> AsSingleGlyph() const;
95
96 /// @brief Return the font of the first glyph run.
97 const Font& GetFont() const;
98
99 /// @brief Store text frame scale, offset, and properties for hashing in th
100 /// glyph atlas.
101 void SetPerFrameData(Rational scale,
102 Point offset,
103 const Matrix& transform,
104 std::optional<GlyphProperties> properties);
105
106 // A generation id for the glyph atlas this text run was associated
107 // with. As long as the frame generation matches the atlas generation,
108 // the contents are guaranteed to be populated and do not need to be
109 // processed.
110 std::pair<size_t, intptr_t> GetAtlasGenerationAndID() const;
111
112 Rational GetScale() const;
113
114 const Matrix& GetTransform() const { return transform_; }
115
116 fml::StatusOr<flutter::DlPath> GetPath() const;
117
118 Point GetOffset() const;
119
120 Matrix GetOffsetTransform() const;
121
122 private:
123 friend class TypographerContextSkia;
124 friend class LazyGlyphAtlas;
125
126 std::optional<GlyphProperties> GetProperties() const;
127
128 void AppendFrameBounds(const FrameBounds& frame_bounds);
129
130 void ClearFrameBounds();
131
132 void SetAtlasGeneration(size_t value, intptr_t atlas_id);
133
134 std::vector<TextRun> runs_;
135 Rect bounds_;
136 bool has_color_;
137 const PathCreator path_creator_;
138
139 // Data that is cached when rendering the text frame and is only
140 // valid for the current atlas generation.
141 std::vector<FrameBounds> bound_values_;
142 Rational scale_ = Rational(0, 1);
143 size_t generation_ = 0;
144 intptr_t atlas_id_ = 0;
145 Point offset_;
146 std::optional<GlyphProperties> properties_;
147 Matrix transform_;
148 };
149
150 } // namespace impeller
151
152 #endif // FLUTTER_IMPELLER_TYPOGRAPHER_TEXT_FRAME_H_
impeller::Font
Describes a typeface along with any modifications to its intrinsic properties.
Definition: font.h:35
impeller::GlyphAtlas::Type
Type
Describes how the glyphs are represented in the texture.
Definition: glyph_atlas.h:74
impeller::LazyGlyphAtlas
Definition: lazy_glyph_atlas.h:16
impeller::Rational
Definition: rational.h:13
impeller::TextFrame
Represents a collection of shaped text runs.
Definition: text_frame.h:29
impeller::TextFrame::RoundScaledFontSize
static Rational RoundScaledFontSize(Scalar scale)
Definition: text_frame.cc:55
impeller::TextFrame::GetBounds
Rect GetBounds() const
The conservative bounding box for this text frame.
Definition: text_frame.cc:27
impeller::TextFrame::TextFrame
TextFrame()
impeller::TextFrame::IsFrameComplete
bool IsFrameComplete() const
Verifies that all glyphs in this text frame have computed bounds information.
Definition: text_frame.cc:156
impeller::TextFrame::GetAtlasType
GlyphAtlas::Type GetAtlasType() const
The type of atlas this run should be place in.
Definition: text_frame.cc:39
impeller::TextFrame::AsSingleGlyph
std::optional< Glyph > AsSingleGlyph() const
If this text frame contains a single glyph (such as for an Icon), then return it, otherwise std::null...
Definition: text_frame.cc:168
impeller::TextFrame::HasColor
bool HasColor() const
Returns the paint color this text frame was recorded with.
Definition: text_frame.cc:44
impeller::TextFrame::GetScale
Rational GetScale() const
Definition: text_frame.cc:129
impeller::TextFrame::GetFrameBounds
const FrameBounds & GetFrameBounds(size_t index) const
Retrieve the frame bounds for the glyph at [index].
Definition: text_frame.cc:175
impeller::TextFrame::GetTransform
const Matrix & GetTransform() const
Definition: text_frame.h:114
impeller::TextFrame::GetFont
const Font & GetFont() const
Return the font of the first glyph run.
Definition: text_frame.cc:164
impeller::TextFrame::GetAtlasGenerationAndID
std::pair< size_t, intptr_t > GetAtlasGenerationAndID() const
Definition: text_frame.cc:180
impeller::TextFrame::GetRunCount
size_t GetRunCount() const
The number of runs in this text frame.
Definition: text_frame.cc:31
impeller::TextFrame::GetOffset
Point GetOffset() const
Definition: text_frame.cc:133
impeller::TextFrame::SetPerFrameData
void SetPerFrameData(Rational scale, Point offset, const Matrix &transform, std::optional< GlyphProperties > properties)
Store text frame scale, offset, and properties for hashing in th glyph atlas.
Definition: text_frame.cc:118
impeller::TextFrame::GetOffsetTransform
Matrix GetOffsetTransform() const
Definition: text_frame.cc:114
impeller::TextFrame::GetPath
fml::StatusOr< flutter::DlPath > GetPath() const
Definition: text_frame.cc:149
impeller::TextFrame::ComputeSubpixelPosition
static SubpixelPosition ComputeSubpixelPosition(const TextRun::GlyphPosition &glyph_position, AxisAlignment alignment, const Matrix &transform)
Definition: text_frame.cc:94
impeller::TextFrame::GetRuns
const std::vector< TextRun > & GetRuns() const
Returns a reference to all the text runs in this frame.
Definition: text_frame.cc:35
impeller::TextFrame::~TextFrame
~TextFrame()
impeller::TypographerContextSkia
Definition: typographer_context_skia.h:12
value
int32_t value
Definition: dl_golden_unittests.cc:459
transform
Matrix transform
Definition: gaussian_blur_filter_contents.cc:214
glyph.h
glyph_atlas.h
impeller
Definition: allocation.cc:12
impeller::Scalar
float Scalar
Definition: scalar.h:19
impeller::AxisAlignment
AxisAlignment
Determines the axis along which there is subpixel positioning.
Definition: font.h:20
impeller::PathCreator
std::function< fml::StatusOr< flutter::DlPath >()> PathCreator
Definition: text_frame.h:19
impeller::SubpixelPosition
SubpixelPosition
Definition: font_glyph_pair.h:56
rational.h
impeller::FrameBounds
Definition: glyph_atlas.h:55
impeller::Matrix
A 4x4 matrix using column-major storage.
Definition: matrix.h:37
impeller::TPoint< Scalar >
impeller::TRect< Scalar >
impeller::TextRun::GlyphPosition
Definition: text_run.h:22
text_run.h