Implement Pango RenderText for Linux.

ui/gfx/pango_util.cc

+#include "ui/gfx/pango_util.h"

[msw, 2011/08/24 08:55:30]

Add a copyright notice.

[xji, 2011/08/25 03:15:19]

Done.

+
+#include <cairo/cairo.h>
+#include <gtk/gtk.h>
+#include <pango/pango.h>
+#include <pango/pangocairo.h>
+
+#include "base/logging.h"
+#include "base/utf_string_conversions.h"
+#include "ui/gfx/canvas.h"
+#include "ui/gfx/font.h"
+#include "ui/gfx/gtk_util.h"
+#include "ui/gfx/skia_util.h"
+
+namespace {
+
+// Marker for accelerators in the text.
+const gunichar kAcceleratorChar = '&';
+
+// Font settings that we initialize once and then use when drawing text in
+// DrawStringInt().
+cairo_font_options_t* cairo_font_options = NULL;

[msw, 2011/08/24 08:55:30]

I meant to say that this is a global class pointer, which violates our style
guide, even if it's in an anonymous namespace. I think a better singleton
pattern is to make this a static pointer declared inside UpdateCairoFontOptions.
I might be wrong, perhaps oshima can weigh in.

[oshima, 2011/08/24 21:12:30]

This is allowed in anonymous namespace, although I'd probably do something like
this:

GetCairoFontOptions and do everything in there including check and creation. 

cairo_font_options_t* GetCairoFontOptions() {
  static cairo_font_options_t* cfo = NULL;
  if (cfo)
    return cfo;
  cfo = ...
  return cfo;
}

[xji, 2011/08/25 03:15:19]

Done.

+
+// Update |cairo_font_options| based on GtkSettings, allocating it if needed.
+void UpdateCairoFontOptions() {
+  if (!cairo_font_options)
+    cairo_font_options = cairo_font_options_create();
+
+  gint antialias = 0;
+  gint hinting = 0;
+  gchar* hint_style = NULL;
+  gchar* rgba_style = NULL;
+
+#if !defined(USE_WAYLAND)
+  // TODO(xji): still has gtk dependency.
+  GtkSettings* gtk_settings = gtk_settings_get_default();
+  g_object_get(gtk_settings,
+               "gtk-xft-antialias", &antialias,
+               "gtk-xft-hinting", &hinting,
+               "gtk-xft-hintstyle", &hint_style,
+               "gtk-xft-rgba", &rgba_style,
+               NULL);
+#endif
+
+  // 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 {
+
+// Pass a width greater than 0 to force wrapping and eliding.
+void SetupPangoLayout(PangoLayout* layout,
+                      const string16& text,
+                      const Font& font,
+                      int width,
+                      base::i18n::TextDirection text_direction,
+                      int flags) {
+  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);
+
+  if (width > 0)
+    pango_layout_set_width(layout, width * PANGO_SCALE);
+
+  if (flags & Canvas::TEXT_ALIGN_CENTER) {
+    // We don't support center aligned w/ eliding.
+    DCHECK(gfx::Canvas::NO_ELLIPSIS);
+    pango_layout_set_alignment(layout, PANGO_ALIGN_CENTER);
+  } else if (flags & Canvas::TEXT_ALIGN_RIGHT) {
+    pango_layout_set_alignment(layout, PANGO_ALIGN_RIGHT);
+  }
+
+  if (flags & Canvas::NO_ELLIPSIS) {
+    pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_NONE);
+    if (flags & Canvas::MULTI_LINE) {
+      pango_layout_set_wrap(layout,
+          (flags & Canvas::CHARACTER_BREAK) ?
+              PANGO_WRAP_WORD_CHAR : PANGO_WRAP_WORD);
+    }
+  } else if (text_direction == base::i18n::RIGHT_TO_LEFT) {
+    pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_END);
+  } else {
+    // Fading the text will be handled in the draw operation.
+    // Ensure that the text is only on one line.
+    pango_layout_set_ellipsize(layout, PANGO_ELLIPSIZE_NONE);
+    pango_layout_set_width(layout, -1);
+  }
+
+  // Set the resolution to match that used by Gtk. If we don't set the
+  // resolution and the resolution differs from the default, Gtk and Chrome end
+  // up drawing at different sizes.
+  double resolution = GetPangoResolution();
+  if (resolution > 0) {
+    pango_cairo_context_set_resolution(pango_layout_get_context(layout),
+                                       resolution);
+  }
+
+  PangoFontDescription* desc = font.GetNativeFont();
+  pango_layout_set_font_description(layout, desc);
+  pango_font_description_free(desc);
+
+  // Set text and accelerator character if needed.
+  std::string utf8 = UTF16ToUTF8(text);
+  if (flags & Canvas::SHOW_PREFIX) {
+    // Escape the text string to be used as markup.
+    gchar* escaped_text = g_markup_escape_text(utf8.c_str(), utf8.size());
+    pango_layout_set_markup_with_accel(layout,
+                                       escaped_text,
+                                       strlen(escaped_text),
+                                       kAcceleratorChar, NULL);
+    g_free(escaped_text);
+  } else if (flags & Canvas::HIDE_PREFIX) {
+    // Remove the ampersand character.  A double ampersand is output as
+    // a single ampersand.
+    DCHECK_EQ(1, g_unichar_to_utf8(kAcceleratorChar, NULL));
+    const std::string accelerator_removed =
+        RemoveAcceleratorChar(utf8, static_cast<char>(kAcceleratorChar));
+
+    pango_layout_set_text(layout,
+        accelerator_removed.data(), accelerator_removed.size());
+  } else {
+    pango_layout_set_text(layout, utf8.data(), utf8.size());
+  }
+}
+
+}