Linux: make gfx::Canvas honor GTK font settings.

app/gfx/canvas_linux.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "app/gfx/canvas.h"
 
 #include <cairo/cairo.h>
+#include <gtk/gtk.h>
 #include <pango/pango.h>
 #include <pango/pangocairo.h>
 
 #include "app/gfx/font.h"
 #include "base/gfx/rect.h"
 #include "base/logging.h"
 #include "base/string_util.h"
 
 namespace {
 
+// Font settings that we initialize once and then use when drawing text in
+// DrawStringInt().
+static cairo_font_options_t* cairo_font_options = NULL;

[Daniel Erat, 2009/08/05 22:36:03]

Is there a better place to be doing this?  I could make it a static var in
DrawStringInt(), but it seems plausible that another method could need this
someday.  Am I going to cause Valgrind warnings with a one-time "leak" like
this?

[agl, 2009/08/05 22:45:57]

I think it's ok where it is. You shouldn't trigger valgrind warnings as long as
you don't lose the pointer to it.

+
 // Returns a new pango font, free with pango_font_description_free().
 PangoFontDescription* PangoFontFromGfxFont(const gfx::Font& gfx_font) {
   gfx::Font font = gfx_font;  // Copy so we can call non-const methods.
   PangoFontDescription* pfd = pango_font_description_new();
   pango_font_description_set_family(pfd, WideToUTF8(font.FontName()).c_str());
   pango_font_description_set_size(pfd, font.FontSize() * PANGO_SCALE);
 
   switch (font.style()) {
     case gfx::Font::NORMAL:
       // Nothing to do, should already be PANGO_STYLE_NORMAL.
       break;
     case gfx::Font::BOLD:
       pango_font_description_set_weight(pfd, PANGO_WEIGHT_BOLD);
       break;
     case gfx::Font::ITALIC:
       pango_font_description_set_style(pfd, PANGO_STYLE_ITALIC);
       break;
     case gfx::Font::UNDERLINED:
       // TODO(deanm): How to do underlined?  Where do we use it?  Probably have
       // to paint it ourselves, see pango_font_metrics_get_underline_position.
       break;
   }
 
   return pfd;
 }
 
+// Update |cairo_font_options| based on GtkSettings, allocating it if needed.
+static void UpdateCairoFontOptions() {
+  if (!cairo_font_options)
+    cairo_font_options = cairo_font_options_create();
+
+  GtkSettings* gtk_settings = gtk_settings_get_default();
+  gint antialias = 0;
+  gint hinting = 0;
+  gchar* hint_style = NULL;
+  gchar* rgba_style = NULL;
+  g_object_get(gtk_settings,
+               "gtk-xft-antialias", &antialias,
+               "gtk-xft-hinting", &hinting,
+               "gtk-xft-hintstyle", &hint_style,
+               "gtk-xft-rgba", &rgba_style,
+               NULL);
+
+  // g_object_get() doesn't tell us whether the properties were present or not,
+  // but if they aren't (because gnome-settings-daemon isn't running), we'll get
+  // NULL values for the strings.
+  if (hint_style && rgba_style) {
+    if (!antialias) {
+      cairo_font_options_set_antialias(cairo_font_options,
+                                       CAIRO_ANTIALIAS_NONE);
+    } else if (strcmp(rgba_style, "none") == 0) {
+      cairo_font_options_set_antialias(cairo_font_options,
+                                       CAIRO_ANTIALIAS_GRAY);
+    } else {
+      cairo_font_options_set_antialias(cairo_font_options,
+                                       CAIRO_ANTIALIAS_SUBPIXEL);
+      cairo_subpixel_order_t cairo_subpixel_order =
+          CAIRO_SUBPIXEL_ORDER_DEFAULT;
+      if (strcmp(rgba_style, "rgb") == 0) {
+        cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_RGB;
+      } else if (strcmp(rgba_style, "bgr") == 0) {
+        cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_BGR;
+      } else if (strcmp(rgba_style, "vrgb") == 0) {
+        cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_VRGB;
+      } else if (strcmp(rgba_style, "vbgr") == 0) {
+        cairo_subpixel_order = CAIRO_SUBPIXEL_ORDER_VBGR;
+      }
+      cairo_font_options_set_subpixel_order(cairo_font_options,
+                                            cairo_subpixel_order);
+    }
+
+    cairo_hint_style_t cairo_hint_style = CAIRO_HINT_STYLE_DEFAULT;
+    if (hinting == 0 || strcmp(hint_style, "hintnone") == 0) {
+      cairo_hint_style = CAIRO_HINT_STYLE_NONE;
+    } else if (strcmp(hint_style, "hintslight") == 0) {
+      cairo_hint_style = CAIRO_HINT_STYLE_SLIGHT;
+    } else if (strcmp(hint_style, "hintmedium") == 0) {
+      cairo_hint_style = CAIRO_HINT_STYLE_MEDIUM;
+    } else if (strcmp(hint_style, "hintfull") == 0) {
+      cairo_hint_style = CAIRO_HINT_STYLE_FULL;
+    }
+    cairo_font_options_set_hint_style(cairo_font_options, cairo_hint_style);
+  }
+
+  if (hint_style)
+    g_free(hint_style);
+  if (rgba_style)
+    g_free(rgba_style);
+}
+
 }  // namespace
 
 namespace gfx {
 
 Canvas::Canvas(int width, int height, bool is_opaque)
     : skia::PlatformCanvas(width, height, is_opaque) {
 }
 
 Canvas::Canvas() : skia::PlatformCanvas() {
 }
@@ skipping 41 matching lines @@
   cairo_surface_destroy(surface);
 }
 
 void Canvas::DrawStringInt(const std::wstring& text,
                            const gfx::Font& font,
                            const SkColor& color, int x, int y, int w, int h,
                            int flags) {
   cairo_t* cr = beginPlatformPaint();
   PangoLayout* layout = pango_cairo_create_layout(cr);
 
+  if (!cairo_font_options)
+    UpdateCairoFontOptions();
+  // This needs to be done early on; it has no effect when called just before
+  // pango_cairo_show_layout().
+  pango_cairo_context_set_font_options(
+      pango_layout_get_context(layout), cairo_font_options);
+
   // Callers of DrawStringInt handle RTL layout themselves, so tell pango to not
   // scope out RTL characters.
   pango_layout_set_auto_dir(layout, FALSE);
 
   cairo_set_source_rgb(cr,
                        SkColorGetR(color) / 255.0,
                        SkColorGetG(color) / 255.0,
                        SkColorGetB(color) / 255.0);
 
   // TODO(deanm): Implement the rest of the Canvas flags.
@@ skipping 37 matching lines @@
   }
 
   cairo_move_to(cr, x, y);
   pango_cairo_show_layout(cr, layout);
 
   g_object_unref(layout);
   // NOTE: beginPlatformPaint returned its surface, we shouldn't destroy it.
 }
 
 }  // namespace gfx