1 // Copyright (c) 2012 The Chromium 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 "ui/gfx/pango_util.h"
6
7 #include <cairo/cairo.h>
8 #include <pango/pango.h>
9 #include <pango/pangocairo.h>
10 #include <string>
11
12 #include <algorithm>
13 #include <map>
14
15 #include "base/logging.h"
16 #include "base/strings/utf_string_conversions.h"
17 #include "ui/gfx/canvas.h"
18 #include "ui/gfx/font_list.h"
19 #include "ui/gfx/font_render_params.h"
20 #include "ui/gfx/linux_font_delegate.h"
21 #include "ui/gfx/platform_font_pango.h"
22 #include "ui/gfx/text_utils.h"
23
24 namespace gfx {
25
26 namespace {
27
28 // Marker for accelerators in the text.
29 const gunichar kAcceleratorChar = '&';
30
31 // Creates and returns a PangoContext. The caller owns the context.
GetPangoContext()32 PangoContext* GetPangoContext() {
33 PangoFontMap* font_map = pango_cairo_font_map_get_default();
34 return pango_font_map_create_context(font_map);
35 }
36
37 // Creates a new cairo_font_options_t based on |params|.
CreateCairoFontOptions(const FontRenderParams & params)38 cairo_font_options_t* CreateCairoFontOptions(const FontRenderParams& params) {
39 cairo_font_options_t* cairo_font_options = cairo_font_options_create();
40
41 FontRenderParams::SubpixelRendering subpixel = params.subpixel_rendering;
42 if (!params.antialiasing) {
43 cairo_font_options_set_antialias(cairo_font_options, CAIRO_ANTIALIAS_NONE);
44 } else if (subpixel == FontRenderParams::SUBPIXEL_RENDERING_NONE) {
45 cairo_font_options_set_antialias(cairo_font_options, CAIRO_ANTIALIAS_GRAY);
46 } else {
47 cairo_font_options_set_antialias(cairo_font_options,
48 CAIRO_ANTIALIAS_SUBPIXEL);
49 cairo_subpixel_order_t cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_DEFAULT;
50 if (subpixel == FontRenderParams::SUBPIXEL_RENDERING_RGB)
51 cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_RGB;
52 else if (subpixel == FontRenderParams::SUBPIXEL_RENDERING_BGR)
53 cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_BGR;
54 else if (subpixel == FontRenderParams::SUBPIXEL_RENDERING_VRGB)
55 cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_VRGB;
56 else if (subpixel == FontRenderParams::SUBPIXEL_RENDERING_VBGR)
57 cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_VBGR;
58 else
59 NOTREACHED() << "Unhandled subpixel rendering type " << subpixel;
60 cairo_font_options_set_subpixel_order(cairo_font_options,
61 cairo_subpixel_order);
62 }
63
64 if (params.hinting == FontRenderParams::HINTING_NONE ||
65 params.subpixel_positioning) {
66 cairo_font_options_set_hint_style(cairo_font_options,
67 CAIRO_HINT_STYLE_NONE);
68 cairo_font_options_set_hint_metrics(cairo_font_options,
69 CAIRO_HINT_METRICS_OFF);
70 } else {
71 cairo_hint_style_t cairo_hint_style = CAIRO_HINT_STYLE_DEFAULT;
72 if (params.hinting == FontRenderParams::HINTING_SLIGHT)
73 cairo_hint_style = CAIRO_HINT_STYLE_SLIGHT;
74 else if (params.hinting == FontRenderParams::HINTING_MEDIUM)
75 cairo_hint_style = CAIRO_HINT_STYLE_MEDIUM;
76 else if (params.hinting == FontRenderParams::HINTING_FULL)
77 cairo_hint_style = CAIRO_HINT_STYLE_FULL;
78 else
79 NOTREACHED() << "Unhandled hinting style " << params.hinting;
80 cairo_font_options_set_hint_style(cairo_font_options, cairo_hint_style);
81 cairo_font_options_set_hint_metrics(cairo_font_options,
82 CAIRO_HINT_METRICS_ON);
83 }
84
85 return cairo_font_options;
86 }
87
88 // Returns the DPI that should be used by Pango.
GetPangoDPI()89 double GetPangoDPI() {
90 static double dpi = -1.0;
91 if (dpi < 0.0) {
92 const gfx::LinuxFontDelegate* delegate = gfx::LinuxFontDelegate::instance();
93 if (delegate)
94 dpi = delegate->GetFontDPI();
95 if (dpi <= 0.0)
96 dpi = 96.0;
97 }
98 return dpi;
99 }
100
101 // Returns the number of pixels in a point.
102 // - multiply a point size by this to get pixels ("device units")
103 // - divide a pixel size by this to get points
GetPixelsInPoint()104 double GetPixelsInPoint() {
105 static double pixels_in_point = GetPangoDPI() / 72.0; // 72 points in an inch
106 return pixels_in_point;
107 }
108
109 } // namespace
110
SetUpPangoLayout(PangoLayout * layout,const base::string16 & text,const FontList & font_list,base::i18n::TextDirection text_direction,int flags)111 void SetUpPangoLayout(
112 PangoLayout* layout,
113 const base::string16& text,
114 const FontList& font_list,
115 base::i18n::TextDirection text_direction,
116 int flags) {
117 cairo_font_options_t* cairo_font_options = CreateCairoFontOptions(
118 font_list.GetPrimaryFont().GetFontRenderParams());
119
120 // If we got an explicit request to turn off subpixel rendering, disable it.
121 if ((flags & Canvas::NO_SUBPIXEL_RENDERING) &&
122 (cairo_font_options_get_antialias(cairo_font_options) ==
123 CAIRO_ANTIALIAS_SUBPIXEL))
124 cairo_font_options_set_antialias(cairo_font_options, CAIRO_ANTIALIAS_GRAY);
125
126 // This needs to be done early on; it has no effect when called just before
127 // pango_cairo_show_layout().
128 pango_cairo_context_set_font_options(
129 pango_layout_get_context(layout), cairo_font_options);
130 cairo_font_options_destroy(cairo_font_options);
131 cairo_font_options = NULL;
132
133 // Set Pango's base text direction explicitly from |text_direction|.
134 pango_layout_set_auto_dir(layout, FALSE);
135 pango_context_set_base_dir(pango_layout_get_context(layout),
136 (text_direction == base::i18n::RIGHT_TO_LEFT ?
137 PANGO_DIRECTION_RTL : PANGO_DIRECTION_LTR));
138
139 if (flags & Canvas::TEXT_ALIGN_CENTER) {
140 // We don't support center aligned w/ eliding.
141 DCHECK(gfx::Canvas::NO_ELLIPSIS);
142 pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
143 } else if (flags & Canvas::TEXT_ALIGN_RIGHT) {
144 pango_layout_set_alignment(layout, PANGO_ALIGN_RIGHT);
145 }
146
147 if (flags & Canvas::NO_ELLIPSIS) {
148 pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_NONE);
149 if (flags & Canvas::MULTI_LINE) {
150 pango_layout_set_wrap(layout,
151 (flags & Canvas::CHARACTER_BREAK) ?
152 PANGO_WRAP_WORD_CHAR : PANGO_WRAP_WORD);
153 }
154 } else if (text_direction == base::i18n::RIGHT_TO_LEFT) {
155 pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
156 } else {
157 // Fading the text will be handled in the draw operation.
158 // Ensure that the text is only on one line.
159 pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_NONE);
160 pango_layout_set_width(layout, -1);
161 }
162
163 // Set the layout's resolution to match the resolution used to convert from
164 // points to pixels.
165 pango_cairo_context_set_resolution(pango_layout_get_context(layout),
166 GetPangoDPI());
167
168 // Set text and accelerator character if needed.
169 if (flags & Canvas::SHOW_PREFIX) {
170 // Escape the text string to be used as markup.
171 std::string utf8 = base::UTF16ToUTF8(text);
172 gchar* escaped_text = g_markup_escape_text(utf8.c_str(), utf8.size());
173 pango_layout_set_markup_with_accel(layout,
174 escaped_text,
175 strlen(escaped_text),
176 kAcceleratorChar, NULL);
177 g_free(escaped_text);
178 } else {
179 std::string utf8;
180
181 // Remove the ampersand character. A double ampersand is output as
182 // a single ampersand.
183 if (flags & Canvas::HIDE_PREFIX) {
184 DCHECK_EQ(1, g_unichar_to_utf8(kAcceleratorChar, NULL));
185 base::string16 accelerator_removed =
186 RemoveAcceleratorChar(text,
187 static_cast<base::char16>(kAcceleratorChar),
188 NULL, NULL);
189 utf8 = base::UTF16ToUTF8(accelerator_removed);
190 } else {
191 utf8 = base::UTF16ToUTF8(text);
192 }
193
194 pango_layout_set_text(layout, utf8.data(), utf8.size());
195 }
196
197 ScopedPangoFontDescription desc(pango_font_description_from_string(
198 font_list.GetFontDescriptionString().c_str()));
199 pango_layout_set_font_description(layout, desc.get());
200 }
201
GetPangoFontSizeInPixels(PangoFontDescription * pango_font)202 int GetPangoFontSizeInPixels(PangoFontDescription* pango_font) {
203 // If the size is absolute, then it's in Pango units rather than points. There
204 // are PANGO_SCALE Pango units in a device unit (pixel).
205 if (pango_font_description_get_size_is_absolute(pango_font))
206 return pango_font_description_get_size(pango_font) / PANGO_SCALE;
207
208 // Otherwise, we need to convert from points.
209 return static_cast<int>(GetPixelsInPoint() *
210 pango_font_description_get_size(pango_font) / PANGO_SCALE + 0.5);
211 }
212
GetPangoFontMetrics(PangoFontDescription * desc)213 PangoFontMetrics* GetPangoFontMetrics(PangoFontDescription* desc) {
214 static std::map<int, PangoFontMetrics*>* desc_to_metrics = NULL;
215 static PangoContext* context = NULL;
216
217 if (!context) {
218 context = GetPangoContext();
219 pango_context_set_language(context, pango_language_get_default());
220 }
221
222 if (!desc_to_metrics)
223 desc_to_metrics = new std::map<int, PangoFontMetrics*>();
224
225 const int desc_hash = pango_font_description_hash(desc);
226 std::map<int, PangoFontMetrics*>::iterator i =
227 desc_to_metrics->find(desc_hash);
228
229 if (i == desc_to_metrics->end()) {
230 PangoFontMetrics* metrics = pango_context_get_metrics(context, desc, NULL);
231 desc_to_metrics->insert(std::make_pair(desc_hash, metrics));
232 return metrics;
233 }
234 return i->second;
235 }
236
237 } // namespace gfx
238