Add mechanism for tests to explicitly get a default font.

display_list/BUILD.gn

@@ -127,6 +127,7 @@ if (enable_unittests) {
       ":display_list_fixtures",
       "//flutter/display_list/testing:display_list_testing",
       "//flutter/testing",
+      "//flutter/third_party/txt:txt",
     ]
 
     if (!defined(defines)) {
@@ -222,6 +223,7 @@ source_set("display_list_benchmarks_source") {
     "//flutter/fml",
     "//flutter/testing:skia",
     "//flutter/testing:testing_lib",
+    "//flutter/third_party/txt:txt",
     "//third_party/dart/runtime:libdart_jit",  # for tracing
     "//third_party/skia",
   ]

display_list/benchmarking/dl_benchmarks.cc

@@ -15,6 +15,7 @@
 #include "third_party/skia/include/gpu/GrDirectContext.h"
 #include "third_party/skia/include/gpu/GrRecordingContext.h"
 #include "third_party/skia/include/gpu/GrTypes.h"
+#include "third_party/txt/src/txt/platform.h"
 
 namespace flutter {
 namespace testing {
@@ -1203,7 +1204,7 @@ void BM_DrawTextBlob(benchmark::State& state,
 
   for (size_t i = 0; i < draw_calls; i++) {
     character[0] = 'A' + (i % 26);
-    auto blob = SkTextBlob::MakeFromString(character, SkFont());
+    auto blob = SkTextBlob::MakeFromString(character, txt::DefaultFont());
     builder.DrawTextBlob(blob, 50.0f, 50.0f, paint);
   }
 

display_list/benchmarking/dl_complexity_unittests.cc

@@ -14,6 +14,7 @@
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "third_party/skia/include/core/SkImage.h"
+#include "third_party/txt/src/txt/platform.h"
 
 namespace flutter {
 namespace testing {
@@ -306,7 +307,7 @@ TEST(DisplayListComplexity, DrawVertices) {
 
 TEST(DisplayListComplexity, DrawTextBlob) {
   auto text_blob = SkTextBlob::MakeFromString(
-      "The quick brown fox jumps over the lazy dog.", SkFont());
+      "The quick brown fox jumps over the lazy dog.", txt::DefaultFont());
 
   DisplayListBuilder builder;
   builder.DrawTextBlob(text_blob, 0.0f, 0.0f, DlPaint());

display_list/testing/BUILD.gn

@@ -16,6 +16,7 @@ source_set("display_list_testing") {
 
   deps = [
     "//flutter/testing:testing_lib",
+    "//flutter/third_party/txt:txt",
     "//third_party/skia",
   ]
 

display_list/testing/dl_test_snippets.h

@@ -13,6 +13,7 @@
 #include "third_party/skia/include/effects/SkDashPathEffect.h"
 #include "third_party/skia/include/effects/SkGradientShader.h"
 #include "third_party/skia/include/effects/SkImageFilters.h"
+#include "third_party/txt/src/txt/platform.h"
 
 namespace flutter {
 namespace testing {
@@ -223,8 +224,8 @@ static sk_sp<DisplayList> TestDisplayList2 =
     MakeTestDisplayList(25, 25, SK_ColorBLUE);
 
 static sk_sp<SkTextBlob> MakeTextBlob(std::string string) {
-  return SkTextBlob::MakeFromText(string.c_str(), string.size(), SkFont(),
-                                  SkTextEncoding::kUTF8);
+  return SkTextBlob::MakeFromText(string.c_str(), string.size(),
+                                  txt::DefaultFont(), SkTextEncoding::kUTF8);
 }
 static sk_sp<SkTextBlob> TestBlob1 = MakeTextBlob("TestBlob1");
 static sk_sp<SkTextBlob> TestBlob2 = MakeTextBlob("TestBlob2");

third_party/txt/BUILD.gn

@@ -62,6 +62,7 @@ source_set("txt") {
     "src/txt/placeholder_run.cc",
     "src/txt/placeholder_run.h",
     "src/txt/platform.h",
+    "src/txt/platform_common.cc",
     "src/txt/run_metrics.h",
     "src/txt/test_font_manager.cc",
     "src/txt/test_font_manager.h",

third_party/txt/src/txt/platform.cc

@@ -4,13 +4,17 @@
 
 #include "txt/platform.h"
 
+#include "fml/logging.h"
+
 namespace txt {
 
 std::vector<std::string> GetDefaultFontFamilies() {
   return {"Arial"};
 }
 
 sk_sp<SkFontMgr> GetDefaultFontManager(uint32_t font_initialization_data) {
+  // TODO(b/305780908) Replace this with a singleton that depends on which
+  // platform we are on and which SkFontMgr was compiled in.
   return SkFontMgr::RefDefault();
 }
 

third_party/txt/src/txt/platform.h

@@ -9,14 +9,21 @@
 #include <vector>
 
 #include "flutter/fml/macros.h"
+#include "third_party/skia/include/core/SkFont.h"
 #include "third_party/skia/include/core/SkFontMgr.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
 
 namespace txt {
 
 std::vector<std::string> GetDefaultFontFamilies();
 
+// Returns the platform specific SkFontMgr, which is a singleton.
 sk_sp<SkFontMgr> GetDefaultFontManager(uint32_t font_initialization_data);
 
+// Returns a font using a default typeface returned by a platform-specific
+// SkFontMgr. It may be different on different platforms.
+SkFont DefaultFont();
+
 }  // namespace txt
 
 #endif  // TXT_PLATFORM_H_

third_party/txt/src/txt/platform_common.cc

@@ -0,0 +1,41 @@
+// Copyright 2013 The Flutter 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 "txt/platform.h"
+
+#include "fml/logging.h"
+#include "third_party/skia/include/core/SkFont.h"
+#include "third_party/skia/include/core/SkFontMgr.h"
+#include "third_party/skia/include/core/SkFontStyle.h"
+#include "third_party/skia/include/core/SkRefCnt.h"
+#include "third_party/skia/include/core/SkTypeface.h"
+
+namespace txt {
+
+static sk_sp<SkTypeface> MakeTypefaceFromName(const char* name,
+                                              SkFontStyle style) {
+  sk_sp<SkFontMgr> fm = GetDefaultFontManager(0);
+  FML_CHECK(fm);
+  sk_sp<SkTypeface> face = fm->legacyMakeTypeface(name, style);
+  return face;
+}
+
+static sk_sp<SkTypeface> DefaultTypeface() {
+  sk_sp<SkTypeface> face = MakeTypefaceFromName(nullptr, SkFontStyle());
+  if (face) {
+    return face;
+  }
+  // Due to how SkTypeface::MakeDefault() used to work, many callers of this
+  // depend on the returned SkTypeface being non-null.
+  // TODO(kjlubick) replace this with SkTypeface::MakeEmpty()
+  face = SkTypeface::MakeDefault();
+  FML_CHECK(face);
+  return face;
+}
+
+SkFont DefaultFont() {
+  return SkFont(DefaultTypeface());
+}
+
+}  // namespace txt