linux: Avoid using unset Fontconfig properties.

Check the return values from FcPatternGet*() so unset
properties won't override the defaults from
LinuxFontDelegate. Most properties have default values
assigned to them by Fontconfig, but subpixel rendering
notably doesn't.

BUG=395014

Review URL: https://codereview.chromium.org/407763003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@284697 0039d316-1c4b-4281-b951-d872f2087c98

ui/gfx/BUILD.gn

@@ -394,7 +394,6 @@ source_set("gfx_test_support") {
 
 test("gfx_unittests") {
   sources = [
-    "font_render_params_linux_unittest.cc",
     "geometry/box_unittest.cc",
     "geometry/cubic_bezier_unittest.cc",
     "geometry/insets_unittest.cc",
@@ -423,7 +422,10 @@ test("gfx_unittests") {
   ]
 
   if (use_pango) {
-    sources += [ "platform_font_pango_unittest.cc" ]
+    sources += [
+      "font_render_params_linux_unittest.cc",
+      "platform_font_pango_unittest.cc",
+    ]
     configs += [
       "//build/config/linux:pangocairo",
       "//build/config/linux:pangoft2",

ui/gfx/font_render_params_linux.cc

@@ -86,27 +86,34 @@ bool QueryFontconfig(const std::vector<std::string>* family_list,
 
   if (params_out) {
     FcBool fc_antialias = 0;
-    FcPatternGetBool(match, FC_ANTIALIAS, 0, &fc_antialias);
-    params_out->antialiasing = fc_antialias;
+    if (FcPatternGetBool(match, FC_ANTIALIAS, 0, &fc_antialias) ==
+        FcResultMatch) {
+      params_out->antialiasing = fc_antialias;
+    }
 
     FcBool fc_autohint = 0;
-    FcPatternGetBool(match, FC_AUTOHINT, 0, &fc_autohint);
-    params_out->autohinter = fc_autohint;
+    if (FcPatternGetBool(match, FC_AUTOHINT, 0, &fc_autohint) ==
+        FcResultMatch) {
+      params_out->autohinter = fc_autohint;
+    }
 
     FcBool fc_bitmap = 0;
-    FcPatternGetBool(match, FC_EMBEDDED_BITMAP, 0, &fc_bitmap);
-    params_out->use_bitmaps = fc_bitmap;
+    if (FcPatternGetBool(match, FC_EMBEDDED_BITMAP, 0, &fc_bitmap) ==
+        FcResultMatch) {
+      params_out->use_bitmaps = fc_bitmap;
+    }
 
     FcBool fc_hinting = 0;
-    int fc_hint_style = FC_HINT_NONE;
-    FcPatternGetBool(match, FC_HINTING, 0, &fc_hinting);
-    if (fc_hinting)
-      FcPatternGetInteger(match, FC_HINT_STYLE, 0, &fc_hint_style);
-    params_out->hinting = ConvertFontconfigHintStyle(fc_hint_style);
+    if (FcPatternGetBool(match, FC_HINTING, 0, &fc_hinting) == FcResultMatch) {
+      int fc_hint_style = FC_HINT_NONE;
+      if (fc_hinting)
+        FcPatternGetInteger(match, FC_HINT_STYLE, 0, &fc_hint_style);
+      params_out->hinting = ConvertFontconfigHintStyle(fc_hint_style);
+    }
 
     int fc_rgba = FC_RGBA_NONE;
-    FcPatternGetInteger(match, FC_RGBA, 0, &fc_rgba);
-    params_out->subpixel_rendering = ConvertFontconfigRgba(fc_rgba);
+    if (FcPatternGetInteger(match, FC_RGBA, 0, &fc_rgba) == FcResultMatch)
+      params_out->subpixel_rendering = ConvertFontconfigRgba(fc_rgba);
   }
 
   FcPatternDestroy(match);

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"
 #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());
+    original_font_delegate_ = LinuxFontDelegate::instance();
+    LinuxFontDelegate::SetInstance(&test_font_delegate_);
   }
 
   virtual ~FontRenderParamsTest() {
+    LinuxFontDelegate::SetInstance(
+        const_cast<LinuxFontDelegate*>(original_font_delegate_));
     TearDownFontconfig();
   }
 
  protected:
   base::ScopedTempDir temp_dir_;
+  const LinuxFontDelegate* original_font_delegate_;
+  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(
+      false, NULL, NULL, NULL, NULL, NULL);
+  EXPECT_EQ(system_params.subpixel_rendering, params.subpixel_rendering);
+}
+
 }  // namespace gfx

ui/gfx/gfx_tests.gyp

@@ -43,7 +43,6 @@
         'display_change_notifier_unittest.cc',
         'display_unittest.cc',
         'font_list_unittest.cc',
-        'font_render_params_linux_unittest.cc',
         'geometry/box_unittest.cc',
         'geometry/cubic_bezier_unittest.cc',
         'geometry/insets_unittest.cc',
@@ -104,6 +103,7 @@
             '../../build/linux/system.gyp:pangocairo',
           ],
           'sources': [
+            'font_render_params_linux_unittest.cc',
             'platform_font_pango_unittest.cc',
           ],
           'conditions': [