Add flag to not compress fonts in the APK

Font assets can be mmap'ed if they're not compressed.
This is much more efficient than decompressing them first.

Bug: 395153140
Bug: 393177415
Flag: EXEMPT Aconfig not supported on host tools
Change-Id: I7163746e05a637962d48c0c5a1eb47517435ebf7

4 files changed, 56 insertions, 0 deletions

diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index ff4d8ef2ec25..0a5cb1ff4956 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -2649,6 +2649,10 @@ int LinkCommand::Action(const std::vector<std::string>& args) {
       ".mpg", ".mpeg", ".mp4", ".m4a", ".m4v", ".3gp", ".3gpp", ".3g2", ".3gpp2", ".wma", ".wmv",
       ".webm", ".mkv"});
 
+  if (options_.no_compress_fonts) {
+    options_.extensions_to_not_compress.insert({".ttf", ".otf", ".ttc"});
+  }
+
   // Turn off auto versioning for static-libs.
   if (context.GetPackageType() == PackageType::kStaticLib) {
     options_.no_auto_version = true;
diff --git a/tools/aapt2/cmd/Link.h b/tools/aapt2/cmd/Link.h
index 2f17853718ec..977978834fcd 100644
--- a/tools/aapt2/cmd/Link.h
+++ b/tools/aapt2/cmd/Link.h
@@ -78,6 +78,7 @@ struct LinkOptions {
   bool use_sparse_encoding = false;
   std::unordered_set<std::string> extensions_to_not_compress;
   std::optional<std::regex> regex_to_not_compress;
+  bool no_compress_fonts = false;
   FeatureFlagValues feature_flag_values;
 
   // Static lib options.
@@ -300,6 +301,14 @@ class LinkCommand : public Command {
             "use the '$' symbol for end of line. Uses a case-sensitive ECMAScript"
             "regular expression grammar.",
         &no_compress_regex);
+    AddOptionalSwitch("--no-compress-fonts",
+        "Do not compress files with common extensions for fonts.\n"
+            "This allows loading fonts directly from the APK, without needing to\n"
+            "decompress them first. Loading fonts will be faster and use less memory.\n"
+            "The downside is that the APK will be larger.\n"
+            "Passing this flag is functionally equivalent to passing the following flags:\n"
+            "-0 .ttf -0 .otf -0 .ttc",
+        &options_.no_compress_fonts);
     AddOptionalSwitch("--warn-manifest-validation",
         "Treat manifest validation errors as warnings.",
         &options_.manifest_fixer_options.warn_validation);
diff --git a/tools/aapt2/cmd/Link_test.cpp b/tools/aapt2/cmd/Link_test.cpp
index a2dc8f8ce0fd..41f8e250efd7 100644
--- a/tools/aapt2/cmd/Link_test.cpp
+++ b/tools/aapt2/cmd/Link_test.cpp
@@ -98,6 +98,7 @@ TEST_F(LinkTest, NoCompressAssets) {
   WriteFile(GetTestPath("assets/test.txt"), content);
   WriteFile(GetTestPath("assets/test.hello.txt"), content);
   WriteFile(GetTestPath("assets/test.hello.xml"), content);
+  WriteFile(GetTestPath("assets/fonts/myfont.ttf"), content);
 
   const std::string out_apk = GetTestPath("out.apk");
   std::vector<std::string> link_args = {
@@ -136,6 +137,10 @@ TEST_F(LinkTest, NoCompressAssets) {
   file = zip->FindFile("assets/test.hello.xml");
   ASSERT_THAT(file, Ne(nullptr));
   EXPECT_FALSE(file->WasCompressed());
+
+  file = zip->FindFile("assets/fonts/myfont.ttf");
+  ASSERT_THAT(file, Ne(nullptr));
+  EXPECT_TRUE(file->WasCompressed());
 }
 
 TEST_F(LinkTest, NoCompressResources) {
@@ -182,6 +187,42 @@ TEST_F(LinkTest, NoCompressResources) {
   EXPECT_FALSE(file->WasCompressed());
 }
 
+TEST_F(LinkTest, NoCompressFonts) {
+  StdErrDiagnostics diag;
+  std::string content(500, 'a');
+  const std::string compiled_files_dir = GetTestPath("compiled");
+  ASSERT_TRUE(CompileFile(GetTestPath("res/raw/test.txt"), content, compiled_files_dir, &diag));
+  WriteFile(GetTestPath("assets/fonts/myfont1.ttf"), content);
+  WriteFile(GetTestPath("assets/fonts/myfont2.ttf"), content);
+
+  const std::string out_apk = GetTestPath("out.apk");
+  std::vector<std::string> link_args = {
+      "--manifest", GetDefaultManifest(),
+      "-o", out_apk,
+      "--no-compress-fonts",
+      "-A", GetTestPath("assets")
+  };
+
+  ASSERT_TRUE(Link(link_args, compiled_files_dir, &diag));
+
+  std::unique_ptr<LoadedApk> apk = LoadedApk::LoadApkFromPath(out_apk, &diag);
+  ASSERT_THAT(apk, Ne(nullptr));
+  io::IFileCollection* zip = apk->GetFileCollection();
+  ASSERT_THAT(zip, Ne(nullptr));
+
+  auto file = zip->FindFile("res/raw/test.txt");
+  ASSERT_THAT(file, Ne(nullptr));
+  EXPECT_TRUE(file->WasCompressed());
+
+  file = zip->FindFile("assets/fonts/myfont1.ttf");
+  ASSERT_THAT(file, Ne(nullptr));
+  EXPECT_FALSE(file->WasCompressed());
+
+  file = zip->FindFile("assets/fonts/myfont2.ttf");
+  ASSERT_THAT(file, Ne(nullptr));
+  EXPECT_FALSE(file->WasCompressed());
+}
+
 TEST_F(LinkTest, OverlayStyles) {
   StdErrDiagnostics diag;
   const std::string compiled_files_dir = GetTestPath("compiled");
diff --git a/tools/aapt2/readme.md b/tools/aapt2/readme.md
index 5c3dfdcadfec..6bdbaaed9858 100644
--- a/tools/aapt2/readme.md
+++ b/tools/aapt2/readme.md
@@ -3,6 +3,8 @@
 ## Version 2.20
 - Too many features, bug fixes, and improvements to list since the last minor version update in
   2017. This README will be updated more frequently in the future.
+- Added a new flag `--no-compress-fonts`. This can significantly speed up loading fonts from APK
+  assets, at the cost of increasing the storage size of the APK.
 
 ## Version 2.19
 - Added navigation resource type.