linux: Avoid using unset Fontconfig properties.

ui/gfx/font_render_params_linux_unittest.cc

Index: ui/gfx/font_render_params_linux_unittest.cc
diff --git a/ui/gfx/font_render_params_linux_unittest.cc b/ui/gfx/font_render_params_linux_unittest.cc
index 6d28119206e450446c3931a9fb1e412f397e21c6..2739cc4d5688a56f276d14aba75d94d57f23cba8 100644
--- a/ui/gfx/font_render_params_linux_unittest.cc
+++ b/ui/gfx/font_render_params_linux_unittest.cc
@@ -10,12 +10,42 @@
 #include "base/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "ui/gfx/font.h"
+#include "ui/gfx/linux_font_delegate.h"
+#include "ui/gfx/pango_util.h"

[msw, 2014/07/21 22:19:48]

Should this (and parts of [Test|Linux]FontDelegate) be exclusive to USE_PANGO
builds? And/or is this test file excluded from non-pango configurations?

[Daniel Erat, 2014/07/21 22:54:42]

whoops, sorry for missing this the first time through. :-(

that's a good question. i believe that desktop linux will always link in pango,
as pango is used by gtk+ to configure fonts and lay out text -- the Gtk2UI impl
of LinuxFontDelegate needs pango to get the default font. do you have any plans
to get rid of PlatformFontPango when switching to RenderTextHarfbuzz? if so, i
haven't seen any signs of them. :-)

font_render_params_linux.cc calls LinuxFontDelegate to get the default params,
so everything that uses font_render_params_linux.cc (just desktop linux and
chrome os, as far as i'm aware) is already pulling in pango.

[msw, 2014/07/21 23:38:30]

Okay, I'm not actually worried beyond breaking any configs (Ozone or something?)
that might have been building this test file on Linux without Pango. You can
proceed if that's not a legit concern.

 #include "ui/gfx/test/fontconfig_util_linux.h"
 
 namespace gfx {
 
 namespace {
 
+// Implementation of LinuxFontDelegate that returns a canned FontRenderParams
+// struct. This is used to isolate tests from the system's local configuration.
+class TestFontDelegate : public LinuxFontDelegate {
+ public:
+  TestFontDelegate() {}
+  virtual ~TestFontDelegate() {}
+
+  void set_params(const FontRenderParams& params) { params_ = params; }
+
+  virtual FontRenderParams GetDefaultFontRenderParams() const OVERRIDE {
+    return params_;
+  }
+  virtual scoped_ptr<ScopedPangoFontDescription>
+      GetDefaultPangoFontDescription() const OVERRIDE {
+    NOTIMPLEMENTED();
+    return scoped_ptr<ScopedPangoFontDescription>();
+  }
+  virtual double GetFontDPI() const OVERRIDE {
+    NOTIMPLEMENTED();
+    return 96.0;
+  }
+
+ private:
+  FontRenderParams params_;
+
+  DISALLOW_COPY_AND_ASSIGN(TestFontDelegate);
+};
+
 // Loads the first system font defined by fontconfig_util_linux.h with a base
 // filename of |basename|. Case is ignored.
 bool LoadSystemFont(const std::string& basename) {
@@ -35,14 +65,20 @@ class FontRenderParamsTest : public testing::Test {
   FontRenderParamsTest() {
     SetUpFontconfig();
     CHECK(temp_dir_.CreateUniqueTempDir());
+    orig_font_delegate_ = LinuxFontDelegate::instance();
+    LinuxFontDelegate::SetInstance(&test_font_delegate_);
   }
 
   virtual ~FontRenderParamsTest() {
+    LinuxFontDelegate::SetInstance(
+        const_cast<LinuxFontDelegate*>(orig_font_delegate_));
     TearDownFontconfig();
   }
 
  protected:
   base::ScopedTempDir temp_dir_;
+  const LinuxFontDelegate* orig_font_delegate_;

[msw, 2014/07/21 22:19:48]

optional nit: original

[Daniel Erat, 2014/07/21 22:34:33]

Done.

+  TestFontDelegate test_font_delegate_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FontRenderParamsTest);
@@ -210,4 +246,27 @@ TEST_F(FontRenderParamsTest, UseBitmaps) {
   EXPECT_TRUE(params.use_bitmaps);
 }
 
+TEST_F(FontRenderParamsTest, OnlySetConfiguredValues) {
+  // Configure the LinuxFontDelegate (which queries GtkSettings on desktop
+  // Linux) to request subpixel rendering.
+  FontRenderParams system_params;
+  system_params.subpixel_rendering = FontRenderParams::SUBPIXEL_RENDERING_RGB;
+  test_font_delegate_.set_params(system_params);
+
+  // Load a Fontconfig config that enables antialiasing but doesn't say anything
+  // about subpixel rendering.
+  ASSERT_TRUE(LoadSystemFont("arial.ttf"));
+  ASSERT_TRUE(LoadConfigDataIntoFontconfig(temp_dir_.path(),
+      std::string(kFontconfigFileHeader) +
+      kFontconfigMatchHeader +
+      CreateFontconfigEditStanza("antialias", "bool", "true") +
+      kFontconfigMatchFooter +
+      kFontconfigFileFooter));
+
+  // The subpixel rendering setting from the delegate should make it through.
+  FontRenderParams params = GetCustomFontRenderParams(

[msw, 2014/07/21 22:19:48]

nit: use GetDefaultFontRenderParams.

+      false, NULL, NULL, NULL, NULL, NULL);
+  EXPECT_EQ(system_params.subpixel_rendering, params.subpixel_rendering);
+}
+
 }  // namespace gfx