The Battle for Wesnoth  1.17.0-dev
text.hpp
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1 /*
2  Copyright (C) 2008 - 2018 by Mark de Wever <koraq@xs4all.nl>
3  Part of the Battle for Wesnoth Project https://www.wesnoth.org/
4 
5  This program is free software; you can redistribute it and/or modify
6  it under the terms of the GNU General Public License as published by
7  the Free Software Foundation; either version 2 of the License, or
8  (at your option) any later version.
9  This program is distributed in the hope that it will be useful,
10  but WITHOUT ANY WARRANTY.
11 
12  See the COPYING file for more details.
13 */
14 
15 #pragma once
16 
17 #include "font/font_options.hpp"
18 #include "color.hpp"
19 #include "sdl/surface.hpp"
21 
22 #include <pango/pango.h>
23 #include <pango/pangocairo.h>
24 
25 #include <functional>
26 #include <memory>
27 #include <string>
28 #include <vector>
29 
30 /***
31  * Note: This is the cairo-pango code path, not the SDL_TTF code path.
32  */
33 
34 struct language_def;
35 struct point;
36 
37 namespace font {
38 
39 // add background color and also font markup.
40 
41 /**
42  * Text class.
43  *
44  * This class represents text which is rendered using Pango.
45  *
46  * It takes text, as a utf-8 std::string, plus formatting options including
47  * font and color. It provides a surface object which holds the rendered text.
48  *
49  * Besides this, it can do some additional calculations using the font layout.
50  *
51  * It can take an index into the text, and convert it to pixel coordinates,
52  * so that if we want to draw a cursor in an editbox, we know where to draw it.
53  *
54  * It can also take a pixel coordinate with respect to the text layout, and
55  * translate it back to an index into the original text. This is useful if the
56  * user clicks on the text, and we want to know where to move the cursor.
57  *
58  * The get_token method takes a pixel coordinate, which we assume represents a
59  * click position, and gets the corresponding "token" from the string. The default
60  * token delimiters are whitespace " \n\r\t". So, this returns the "word" that the
61  * user clicked on.
62  *
63  * Finally, the get_link method represents special support for hyperlinks in text.
64  * A token "looks like a link" if it begins "http://" or "https://".
65  * If a text has link_aware enabled, then any such token is rendered with an
66  * underline and in a special color, see `link_color`.
67  * The get_link method calls get_token and further checks if the clicked token
68  * looks like a link.
69  *
70  * This class stores the text to draw and uses pango with the cairo backend to
71  * render the text. See http://pango.org for more info.
72  *
73  */
75 {
76 public:
77 
78  pango_text();
79 
80  pango_text(const pango_text &) = delete;
81  pango_text & operator = (const pango_text &) = delete;
82 
83  /**
84  * Returns the rendered text.
85  *
86  * @param viewport Only this area needs to be drawn - the returned
87  * surface's origin will correspond to viewport.x and viewport.y, the
88  * width and height will be at least viewport.w and viewport.h (although
89  * they may be larger).
90  */
91  surface& render(const SDL_Rect& viewport);
92 
93  /**
94  * Equivalent to render(viewport), where the viewport's top-left is at
95  * (0,0) and the area is large enough to contain the full text.
96  *
97  * The top-left of the viewport will be at (0,0), regardless of the values
98  * of x and y. If the x or y co-ordinates are non-zero, then x columns and
99  * y rows of blank space are included in the amount of memory allocated.
100  */
101  surface& render();
102 
103  /** Returns the width needed for the text. */
104  int get_width() const;
105 
106  /** Returns the height needed for the text. */
107  int get_height() const;
108 
109  /** Returns the pixel size needed for the text. */
110  point get_size() const;
111 
112  /** Has the text been truncated? This happens if it exceeds max width or height. */
113  bool is_truncated() const;
114 
115  /**
116  * Inserts UTF-8 text.
117  *
118  * @param offset The position to insert the text.
119  * @param text The UTF-8 text to insert.
120  *
121  * @returns The number of characters inserted.
122  */
123  unsigned insert_text(const unsigned offset, const std::string& text);
124 
125  /***** ***** ***** ***** Font flags ***** ***** ***** *****/
126 
127  // NOTE: these values must be powers of 2 in order to be bit-unique
128  enum FONT_STYLE {
133  };
134 
135  /***** ***** ***** ***** Query details ***** ***** ***** *****/
136 
137  /**
138  * Returns the maximum glyph height of a font, in pixels.
139  *
140  * @returns The height of the tallest possible glyph for the selected
141  * font. More specifically, the result is the sum of the maximum
142  * ascent and descent lengths.
143  */
144  int get_max_glyph_height() const;
145 
146  /**
147  * Gets the location for the cursor.
148  *
149  * @param column The column offset of the cursor.
150  * @param line The line offset of the cursor.
151  *
152  * @returns The position of the top of the cursor. It the
153  * requested location is out of range 0,0 is
154  * returned.
155  */
157  const unsigned column, const unsigned line = 0) const;
158 
159  /**
160  * Get maximum length.
161  *
162  * @returns The maximum length of the text. The length of text
163  * should not exceed this value.
164  */
165  std::size_t get_maximum_length() const;
166 
167  /**
168  * Gets the largest collection of characters, including the token at position,
169  * and not including any characters from the delimiters set.
170  *
171  * @param position The pixel position in the text area.
172  * @param delimiters
173  *
174  * @returns The token containing position, and none of the
175  * delimiter characters. If position is out of bounds,
176  * it returns the empty string.
177  */
178  std::string get_token(const point & position, const char * delimiters = " \n\r\t") const;
179 
180  /**
181  * Checks if position points to a character in a link in the text, returns it
182  * if so, empty string otherwise. Link-awareness must be enabled to get results.
183  * @param position The pixel position in the text area.
184  *
185  * @returns The link if one is found, the empty string otherwise.
186  */
187  std::string get_link(const point & position) const;
188 
189  /**
190  * Gets the column of line of the character at the position.
191  *
192  * @param position The pixel position in the text area.
193  *
194  * @returns A point with the x value the column and the y
195  * value the line of the character found (or last
196  * character if not found.
197  */
198  point get_column_line(const point& position) const;
199 
200  /**
201  * Retrieves a list of strings with contents for each rendered line.
202  *
203  * This method is not const because it requires rendering the text.
204  *
205  * @note This is only intended for renderer implementation details. This
206  * is a rather expensive function because it copies everything at
207  * least once.
208  */
209  std::vector<std::string> get_lines() const;
210 
211  /**
212  * Gets the length of the text in bytes.
213  *
214  * The text set is UTF-8 so the length of the string might not be the length
215  * of the text.
216  */
217  std::size_t get_length() const { return length_; }
218 
219  /**
220  * Sets the text to render.
221  *
222  * @param text The text to render.
223  * @param markedup Should the text be rendered with pango
224  * markup. If the markup is invalid it's
225  * rendered as text without markup.
226  *
227  * @returns The status, if rendered as markup and the
228  * markup contains errors, false is returned
229  * else true.
230  */
231  bool set_text(const std::string& text, const bool markedup);
232 
233  /***** ***** ***** ***** Setters / getters ***** ***** ***** *****/
234 
235  const std::string& text() const { return text_; }
236 
238 
239  pango_text& set_font_size(const unsigned font_size);
240 
241  pango_text& set_font_style(const FONT_STYLE font_style);
242 
243  pango_text& set_foreground_color(const color_t& color);
244 
245  pango_text& set_maximum_width(int width);
246 
247  pango_text& set_characters_per_line(const unsigned characters_per_line);
248 
249  pango_text& set_maximum_height(int height, bool multiline);
250 
251  pango_text& set_ellipse_mode(const PangoEllipsizeMode ellipse_mode);
252 
253  pango_text& set_alignment(const PangoAlignment alignment);
254 
255  pango_text& set_maximum_length(const std::size_t maximum_length);
256 
257  bool link_aware() const { return link_aware_; }
258 
259  pango_text& set_link_aware(bool b);
260 
261  pango_text& set_link_color(const color_t& color);
262 
263  pango_text& set_add_outline(bool do_add);
264 
265 private:
266 
267  /***** ***** ***** ***** Pango variables ***** ***** ***** *****/
268  std::unique_ptr<PangoContext, std::function<void(void*)>> context_;
269  std::unique_ptr<PangoLayout, std::function<void(void*)>> layout_;
270  mutable PangoRectangle rect_;
271 
272  /** The SDL surface to render upon used as a cache. */
273  mutable surface surface_;
274 
275 
276  /** The text to draw (stored as UTF-8). */
277  std::string text_;
278 
279  /** Does the text contain pango markup? If different render routines must be used. */
281 
282  /** Are hyperlinks in the text marked-up, and will get_link return them. */
284 
285  /**
286  * The color to render links in.
287  *
288  * Links are formatted using pango &lt;span> as follows:
289  *
290  * &lt;span underline="single" color=" + link_color_ + ">
291  */
293 
294  /** The font family class used. */
296 
297  /** The font size to draw. */
298  unsigned font_size_;
299 
300  /** The style of the font, this is an orred mask of the font flags. */
302 
303  /** The foreground color. */
305 
306  /** Whether to add an outline effect. */
308 
309  /**
310  * The maximum width of the text.
311  *
312  * Values less or equal to 0 mean no maximum and are internally stored as
313  * -1, since that's the value pango uses for it.
314  *
315  * See @ref characters_per_line_.
316  */
318 
319  /**
320  * The number of characters per line.
321  *
322  * This can be used as an alternative of @ref maximum_width_. The user can
323  * select a number of characters on a line for wrapping. When the value is
324  * non-zero it determines the maximum width based on the average character
325  * width.
326  *
327  * If both @ref maximum_width_ and @ref characters_per_line_ are set the
328  * minimum of the two will be the maximum.
329  *
330  * @note Long lines are often harder to read, setting this value can
331  * automatically wrap on a number of characters regardless of the font
332  * size. Often 66 characters is considered the optimal value for a one
333  * column text.
334  */
336 
337  /**
338  * The maximum height of the text.
339  *
340  * Values less or equal to 0 mean no maximum and are internally stored as
341  * -1, since that's the value pango uses for it.
342  */
344 
345  /** The way too long text is shown depends on this mode. */
346  PangoEllipsizeMode ellipse_mode_;
347 
348  /** The alignment of the text. */
349  PangoAlignment alignment_;
350 
351  /** The maximum length of the text. */
352  std::size_t maximum_length_;
353 
354  /**
355  * The text has two dirty states:
356  * - The setting of the state and the size calculations.
357  * - The rendering of the surface.
358  */
359 
360  /** The dirty state of the calculations. */
361  mutable bool calculation_dirty_;
362 
363  /** Length of the text. */
364  mutable std::size_t length_;
365 
366  /**
367  * Recalculates the text layout.
368  */
369  void recalculate() const;
370 
371  /** Calculates surface size. */
372  PangoRectangle calculate_size(PangoLayout& layout) const;
373 
374  /** The dirty state of the surface. */
375  mutable bool surface_dirty_;
376 
377  /** The area that's cached in surface_, which is the area that was rendered when surface_dirty_ was last set to false. */
379 
380  /**
381  * Renders the text.
382  *
383  * It will do a recalculation first so no need to call both.
384  */
385  void rerender(const SDL_Rect& viewport);
386 
387  void render(PangoLayout& layout, const SDL_Rect& viewport, const unsigned stride);
388 
389  /**
390  * Buffer to store the image on.
391  *
392  * We use a cairo surface to draw on this buffer and then use the buffer as
393  * data source for the SDL_Surface. This means the buffer needs to be stored
394  * in the object, since SDL_Surface doesn't own its buffer.
395  */
396  mutable std::vector<uint8_t> surface_buffer_;
397 
398  /**
399  * Sets the markup'ed text.
400  *
401  * It tries to set the text as markup. If the markup is invalid it will try
402  * a bit harder to recover from the errors and still set the markup.
403  *
404  * @param text The text to set as markup.
405  * @param layout
406  *
407  * @returns Whether the markup was set or an
408  * unrecoverable error occurred and the text is
409  * set as plain text with an error message.
410  */
411  bool set_markup(std::string_view text, PangoLayout& layout);
412 
413  bool validate_markup(std::string_view text, char** raw_text, std::string& semi_escaped) const;
414 
415  static void copy_layout_properties(PangoLayout& src, PangoLayout& dst);
416 
417  std::string format_links(std::string_view text) const;
418 };
419 
420 /**
421  * Returns a reference to a static pango_text object.
422  *
423  * Since the class is essentially a render pipeline, there's no need for individual
424  * areas of the game to own their own renderers. Not to mention it isn't a trivial
425  * class; constructing one is likely to be expensive.
426  */
428 
429 /**
430  * Returns the maximum glyph height of a font, in pixels.
431  *
432  * @param size Desired font size in pixels.
433  * @param fclass Font family to use for measurement.
434  * @param style Font style to select the correct variant for measurement.
435  *
436  * @returns The height of the tallest possible glyph for the selected
437  * font. More specifically, the result is the sum of the maximum
438  * ascent and descent lengths.
439  */
441 
442 } // namespace font
void recalculate() const
Recalculates the text layout.
Definition: text.cpp:499
unsigned font_size_
The font size to draw.
Definition: text.hpp:298
family_class
Font classes for get_font_families().
std::size_t get_length() const
Gets the length of the text in bytes.
Definition: text.hpp:217
bool set_text(const std::string &text, const bool markedup)
Sets the text to render.
Definition: text.cpp:282
Collection of helper functions relating to Pango formatting.
bool set_markup(std::string_view text, PangoLayout &layout)
Sets the markup&#39;ed text.
Definition: text.cpp:752
int get_width() const
Returns the width needed for the text.
Definition: text.cpp:107
int maximum_height_
The maximum height of the text.
Definition: text.hpp:343
unsigned characters_per_line_
The number of characters per line.
Definition: text.hpp:335
std::size_t length_
Length of the text.
Definition: text.hpp:364
std::vector< std::string > get_lines() const
Retrieves a list of strings with contents for each rendered line.
Definition: text.cpp:864
pango_text & set_link_aware(bool b)
Definition: text.cpp:447
bool link_aware() const
Definition: text.hpp:257
std::size_t maximum_length_
The maximum length of the text.
Definition: text.hpp:352
void rerender(const SDL_Rect &viewport)
Renders the text.
Definition: text.cpp:701
std::size_t get_maximum_length() const
Get maximum length.
Definition: text.cpp:196
font::family_class font_class_
The font family class used.
Definition: text.hpp:295
pango_text & set_font_style(const FONT_STYLE font_style)
Definition: text.cpp:342
pango_text & get_text_renderer()
Returns a reference to a static pango_text object.
Definition: text.cpp:890
int get_max_height(unsigned size, font::family_class fclass, pango_text::FONT_STYLE style)
Returns the maximum glyph height of a font, in pixels.
Definition: text.cpp:896
pango_text & set_ellipse_mode(const PangoEllipsizeMode ellipse_mode)
Definition: text.cpp:409
pango_text & set_maximum_length(const std::size_t maximum_length)
Definition: text.cpp:434
std::vector< uint8_t > surface_buffer_
Buffer to store the image on.
Definition: text.hpp:396
bool validate_markup(std::string_view text, char **raw_text, std::string &semi_escaped) const
Definition: text.cpp:819
pango_text & set_alignment(const PangoAlignment alignment)
Definition: text.cpp:423
#define b
point get_cursor_position(const unsigned column, const unsigned line=0) const
Gets the location for the cursor.
Definition: text.cpp:151
std::size_t size(const std::string &str)
Length in characters of a UTF-8 string.
Definition: unicode.cpp:86
std::string get_token(const point &position, const char *delimiters=" \\) const
Gets the largest collection of characters, including the token at position, and not including any cha...
Definition: text.cpp:201
point get_size() const
Returns the pixel size needed for the text.
Definition: text.cpp:117
std::unique_ptr< PangoLayout, std::function< void(void *)> > layout_
Definition: text.hpp:269
std::string format_links(std::string_view text) const
Replaces all instances of URLs in a given string with formatted links and returns the result...
Definition: text.cpp:781
SDL_Rect rendered_viewport_
The area that&#39;s cached in surface_, which is the area that was rendered when surface_dirty_ was last ...
Definition: text.hpp:378
bool is_truncated() const
Has the text been truncated? This happens if it exceeds max width or height.
Definition: text.cpp:124
int maximum_width_
The maximum width of the text.
Definition: text.hpp:317
color_t foreground_color_
The foreground color.
Definition: text.hpp:304
std::string get_link(const point &position) const
Checks if position points to a character in a link in the text, returns it if so, empty string otherw...
Definition: text.cpp:233
pango_text & set_font_size(const unsigned font_size)
Definition: text.cpp:330
PangoEllipsizeMode ellipse_mode_
The way too long text is shown depends on this mode.
Definition: text.hpp:346
pango_text & set_characters_per_line(const unsigned characters_per_line)
Definition: text.cpp:378
bool markedup_text_
Does the text contain pango markup? If different render routines must be used.
Definition: text.hpp:280
PangoRectangle calculate_size(PangoLayout &layout) const
Calculates surface size.
Definition: text.cpp:511
bool surface_dirty_
The dirty state of the surface.
Definition: text.hpp:375
PangoRectangle rect_
Definition: text.hpp:270
bool calculation_dirty_
The text has two dirty states:
Definition: text.hpp:361
unsigned insert_text(const unsigned offset, const std::string &text)
Inserts UTF-8 text.
Definition: text.cpp:131
pango_text & set_family_class(font::family_class fclass)
Definition: text.cpp:319
std::unique_ptr< PangoContext, std::function< void(void *)> > context_
Definition: text.hpp:268
bool link_aware_
Are hyperlinks in the text marked-up, and will get_link return them.
Definition: text.hpp:283
point get_column_line(const point &position) const
Gets the column of line of the character at the position.
Definition: text.cpp:248
FONT_STYLE font_style_
The style of the font, this is an orred mask of the font flags.
Definition: text.hpp:301
int get_max_glyph_height() const
Returns the maximum glyph height of a font, in pixels.
Definition: text.cpp:479
bool add_outline_
Whether to add an outline effect.
Definition: text.hpp:307
Holds a 2D point.
Definition: point.hpp:23
pango_text & set_link_color(const color_t &color)
Definition: text.cpp:457
int get_height() const
Returns the height needed for the text.
Definition: text.cpp:112
const std::string & text() const
Definition: text.hpp:235
color_t link_color_
The color to render links in.
Definition: text.hpp:292
Text class.
Definition: text.hpp:74
pango_text & set_maximum_width(int width)
Definition: text.cpp:363
surface surface_
The SDL surface to render upon used as a cache.
Definition: text.hpp:273
surface & render()
Equivalent to render(viewport), where the viewport&#39;s top-left is at (0,0) and the area is large enoug...
Definition: text.cpp:99
pango_text & set_maximum_height(int height, bool multiline)
Definition: text.cpp:390
std::string text_
The text to draw (stored as UTF-8).
Definition: text.hpp:277
pango_text & set_foreground_color(const color_t &color)
Definition: text.cpp:353
PangoAlignment alignment_
The alignment of the text.
Definition: text.hpp:349
pango_text & set_add_outline(bool do_add)
Definition: text.cpp:468
static void copy_layout_properties(PangoLayout &src, PangoLayout &dst)
Definition: text.cpp:857
pango_text & operator=(const pango_text &)=delete