Correct name of def font on Android and fix bug with coords-to-glyphpos method.

Change-Id: Ib9d2a0a1a54f14c4725e47e00fb547df0a91cd40

engine/src/flutter/BUILD.gn

@@ -21,7 +21,7 @@ config("txt_config") {
 }
 
 source_set("txt") {
-  if (current_toolchain == host_toolchain) {
+  if (current_toolchain == host_toolchain && !is_mac) {
     defines = [ "DIRECTORY_FONT_MANAGER_AVAILABLE" ]
   }
   if (is_android) {

engine/src/flutter/src/font_collection.h

@@ -18,6 +18,12 @@
 #define LIB_TXT_SRC_FONT_COLLECTION_H_
 
 #define DEFAULT_FAMILY_NAME "Roboto"
+#ifdef ANDROID_FONT_MANAGER_AVAILABLE
+#undef DEFAULT_FAMILY_NAME
+// On Android, Roboto is called 'sans-serif'
+#define DEFAULT_FAMILY_NAME "sans-serif"
+#endif
+
 #define DEFAULT_CACHE_CAPACITY 20
 
 #include <list>

engine/src/flutter/src/paragraph.cc

@@ -842,12 +842,10 @@ size_t Paragraph::GetGlyphPositionAtCoordinate(
   prev_count = 0;
   for (size_t x_index = 1; x_index < glyph_position_x_[y_index].size() - 1;
        ++x_index) {
-    // TODO(garyq): Resolve edge case where second to last glyph position is
-    // skipped/unreachable.
     if (dx < glyph_position_x_[y_index][x_index] -
                  (using_glyph_center_as_boundary
-                      ? (glyph_position_x_[y_index][x_index + 1] -
-                         glyph_position_x_[y_index][x_index]) /
+                      ? (glyph_position_x_[y_index][x_index] -
+                         glyph_position_x_[y_index][x_index -1]) /
                             2.0f
                       : 0)) {
       break;

engine/src/flutter/tests/txt/paragraph_unittests.cc

@@ -28,7 +28,7 @@
 namespace txt {
 
 TEST_F(RenderTest, SimpleParagraph) {
-  const char* text = "Hello World";
+  const char* text = "Hello World Text Dialog";
   auto icu_text = icu::UnicodeString::fromUTF8(text);
   std::u16string u16_text(icu_text.getBuffer(),
                           icu_text.getBuffer() + icu_text.length());
@@ -39,6 +39,7 @@ TEST_F(RenderTest, SimpleParagraph) {
 
   txt::TextStyle text_style;
   text_style.color = SK_ColorBLACK;
+  text_style.font_size = 12;
   builder.PushStyle(text_style);
   builder.AddText(u16_text);