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TextMesh.ixx File

Properties for positioning and styling text during rendering. More...

Included Headers​

#include <memory> #include <span> #include <string> #include <limits> #include <algorithm> #include <utility> #include <vector> #include <helios.rendering.shader.UniformValueMap> #include <helios.math> #include <helios.rendering.shader.UniformSemantics> #include <helios.util.Colors> #include <helios.engine.core.data.FontId> #include <helios.rendering.shader.Shader> #include <helios.rendering.text.FontResourceProvider> #include <helios.rendering.text.TypeSetter> #include <helios.rendering.text.Glyph>

Namespaces Index​

namespacehelios
namespacerendering

Graphics rendering infrastructure. More...

namespacetext

Text rendering abstractions and data types. More...

Classes Index​

classTextMesh

Manages text content and caches layout data for efficient rendering. More...

Description​

Properties for positioning and styling text during rendering.

File Listing​

The file content with the documentation metadata removed is:

1/**
2 * @file TextMesh.ixx
3 * @brief Properties for positioning and styling text during rendering.
4 */
5module;
6
7#include <memory>
8#include <span>
9#include <string>
10#include <limits>
11#include <algorithm>
12#include <utility>
13#include <vector>
14
15export module helios.rendering.text.TextMesh;
16
17import helios.rendering.text.Glyph;
18import helios.rendering.text.TypeSetter;
19
20import helios.rendering.text.FontResourceProvider;
21
22import helios.rendering.shader.Shader;
23import helios.engine.core.data.FontId;
24
25import helios.util.Colors;
26import helios.math;
27
28import helios.rendering.shader.UniformValueMap;
29import helios.rendering.shader.UniformSemantics;
30
31export namespace helios::rendering::text {
32
33 /**
34 * @brief Manages text content and caches layout data for efficient rendering.
35 *
36 * `TextMesh` encapsulates a text string along with its font and provides lazy
37 * computation of vertex data and bounding boxes. The layout is computed on-demand
38 * and cached until the text content changes.
39 *
40 * ## Caching Strategy
41 *
42 * - Layout computation is deferred until `vertices()` or `localAABB()` is called.
43 * - The cache is invalidated when `setText()` is called.
44 * - The `TypeSetter` is used internally to compute glyph positions.
45 *
46 * ## Usage
47 *
48 * ```cpp
49 * TextMesh mesh("Score: 0", FontId{1});
50 *
51 * // Access vertices for rendering (triggers layout if needed)
52 * auto verts = mesh.vertices(fontProvider);
53 *
54 * // Update text (invalidates cache)
55 * mesh.setText("Score: 100");
56 * ```
57 *
58 * @see TypeSetter
59 * @see TextRenderable
60 * @see FontResourceProvider
61 */
62 class TextMesh {
63
64 /**
65 * @brief Font identifier for glyph lookup.
66 */
67 helios::engine::core::data::FontId fontId_;
68
69 /**
70 * @brief The text string to render.
71 */
72 std::string text_;
73
74 /**
75 * @brief Flag indicating whether the cached layout needs recomputation.
76 */
77 mutable bool needsUpdate_ = true;
78
79 /**
80 * @brief Cached layout data (AABB and vertices).
81 */
82 mutable TextLayout textLayout_;
83
84 /**
85 * @brief TypeSetter instance for computing text layout.
86 */
87 mutable TypeSetter typeSetter_;
88
89 /**
90 * @brief The scale factor for the font.
91 */
92 float fontScale_ = 1.0f;
93
94 /**
95 * @brief Updates the cached layout if needed.
96 *
97 * @param fontResourceProvider Provider for glyph data.
98 */
99 void updateCache(FontResourceProvider& fontResourceProvider) const {
100
101 if (!needsUpdate_) {
102 return;
103 }
104
105 textLayout_ = typeSetter_.layout(text_, fontScale_, fontId_, fontResourceProvider);
106
107 needsUpdate_ = false;
108 }
109
110 public:
111
112 /**
113 * @brief Constructs a TextMesh with the given text and font.
114 *
115 * @param text The text string to render.
116 * @param fontScale The scale of the font, relative to the pixelHeight it was loaded with.
117 * @param fontId The font identifier for glyph lookup.
118 */
119 explicit TextMesh(
120 std::string text,
121 const float fontScale,
122 const helios::engine::core::data::FontId fontId
123 ) noexcept
124 :
125 text_(std::move(text)),
126 fontScale_(fontScale),
127 fontId_(fontId) {}
128
129
130 /**
131 * @brief Returns the local-space axis-aligned bounding box.
132 *
133 * Triggers layout computation if the cache is invalid.
134 *
135 * @param fontResourceProvider Provider for glyph data.
136 *
137 * @return Reference to the cached AABB.
138 */
139 [[nodiscard]] const helios::math::aabbf& localAABB(FontResourceProvider& fontResourceProvider) const noexcept {
140 updateCache(fontResourceProvider);
141 return textLayout_.aabb;
142 }
143
144 /**
145 * @brief Returns the vertex data for rendering.
146 *
147 * Each glyph is represented as 6 vertices (2 triangles). Triggers layout
148 * computation if the cache is invalid.
149 *
150 * @param fontResourceProvider Provider for glyph data.
151 *
152 * @return A span of vertex data (x, y, texU, texV per vertex).
153 */
154 [[nodiscard]] std::span<helios::math::vec4f> vertices(FontResourceProvider& fontResourceProvider) const noexcept {
155 updateCache(fontResourceProvider);
156 return textLayout_.vertices;
157 }
158
159 /**
160 * @brief Updates the text string.
161 *
162 * Invalidates the cached layout, which will be recomputed on the next
163 * call to `vertices()` or `localAABB()`.
164 *
165 * @param text The new text to render.
166 */
167 void setText(std::string text) noexcept {
168 text_ = std::move(text);
169 needsUpdate_ = true;
170 }
171
172 /**
173 * @brief Returns the current text string.
174 *
175 * @return View of the text string.
176 */
177 [[nodiscard]] std::string_view text() const noexcept {
178 return text_;
179 }
180
181 /**
182 * @brief Sets the font scale factor.
183 *
184 * Invalidates the cached layout, which will be recomputed on the next
185 * call to `vertices()` or `localAABB()`.
186 *
187 * @param scale The new scale factor relative to the font's pixel height.
188 */
189 void setFontScale(const float scale) noexcept {
190 fontScale_ = scale;
191 needsUpdate_ = true;
192 }
193
194 /**
195 * @brief Returns the current font scale factor.
196 *
197 * @return The scale factor relative to the font's pixel height.
198 */
199 [[nodiscard]] float fontScale() const noexcept {
200 return fontScale_;
201 }
202
203 /**
204 * @brief Checks if the cached layout needs recomputation.
205 *
206 * @return True if the layout is invalid and needs to be recomputed.
207 */
208 bool needsUpdate() const noexcept {
209 return needsUpdate_;
210 }
211
212 /**
213 * @brief Returns the font identifier.
214 *
215 * @return The font ID used for glyph lookup.
216 */
217 [[nodiscard]] helios::engine::core::data::FontId fontId() const noexcept {
218 return fontId_;
219 }
220 };
221
222
223}

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