Create mini-skia for RenderEngine

Bug: b/167743764

Android's RenderEngine is now using Skia, but it doesn't need all the
pieces of Skia used by HWUI. Make a smaller version of Skia that
excludes many of those pieces, in particular where they bring in other
dependencies:
- codecs
- text
- pdf
- xml

Add a new cc_defaults to be shared by the new libskia_mini and libskia.

Manually insert fexceptions into libskia, since it is only needed by
SkRawCodec (not needed by mini).

Add a new SkUserConfig for mini, so it can exclude defines like
SK_CODEC_DECODES_PNG.

Continue to link in libpng (and libz, which it depends on) and build
SkPngEncoder, so that SKP captures can include compressed image files.

Switching to the mini-skia reduces the size of surfaceflinger from 7.4M
to 6.0M.

Change-Id: I6843ee43457b5a0feb36ae88a59d1d61770a6247
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/402257
Commit-Queue: Leon Scroggins <scroggo@google.com>
Reviewed-by: Derek Sollenberger <djsollen@google.com>

gn/gn_to_bp.py

@@ -25,9 +25,8 @@ bp = string.Template('''// This file is autogenerated by gn_to_bp.py.
 // files it uses) and submit. The autoroller will then create the updated
 // Android.bp. Or ask a Skia engineer for help.
 
-cc_library_static {
+cc_defaults {
-    name: "libskia",
+    name: "skia_defaults",
-    host_supported: true,
     cflags: [
         $cflags
     ],
@@ -44,10 +43,6 @@ cc_library_static {
         $local_includes
     ],
 
-    srcs: [
-        $srcs
-    ],
-
     arch: {
         arm: {
             srcs: [
@@ -83,13 +78,53 @@ cc_library_static {
     target: {
       android: {
         srcs: [
-          $android_srcs
           "third_party/vulkanmemoryallocator/GrVulkanMemoryAllocator.cpp",
         ],
         local_include_dirs: [
-          "android",
           "third_party/vulkanmemoryallocator/",
         ],
+      },
+    },
+}
+
+cc_library_static {
+    // Smaller version of Skia, without e.g. codecs, intended for use by RenderEngine.
+    name: "libskia_renderengine",
+    defaults: ["skia_defaults",
+               "skia_renderengine_deps"],
+    srcs: [
+        $renderengine_srcs
+    ],
+    local_include_dirs: [
+        "renderengine",
+    ],
+    export_include_dirs: [
+        "renderengine",
+    ],
+}
+
+cc_library_static {
+    name: "libskia",
+    host_supported: true,
+    cppflags:[
+        // Exceptions are necessary for SkRawCodec.
+        // FIXME: Should we split SkRawCodec into a separate target so the rest
+        // of Skia need not be compiled with exceptions?
+        "-fexceptions",
+    ],
+
+    srcs: [
+        $srcs
+    ],
+
+    target: {
+      android: {
+        srcs: [
+          $android_srcs
+        ],
+        local_include_dirs: [
+          "android",
+        ],
         export_include_dirs: [
           "android",
         ],
@@ -142,6 +177,7 @@ cc_library_static {
 
     defaults: ["skia_deps",
                "skia_pgo",
+               "skia_defaults",
     ],
 }
 
@@ -172,23 +208,20 @@ cc_defaults {
 }
 
 cc_defaults {
-    name: "skia_deps",
+    // Subset of the larger "skia_deps", which includes only the dependencies
+    // needed for libskia_renderengine. Note that it includes libpng and libz
+    // for the purposes of MSKP captures, but we could instead leave it up to
+    // RenderEngine to provide its own SkSerializerProcs if another client
+    // wants an even smaller version of libskia.
+    name: "skia_renderengine_deps",
     shared_libs: [
         "libcutils",
-        "libdng_sdk",
-        "libexpat",
-        "libft2",
-        "libjpeg",
         "liblog",
-        "libpiex",
         "libpng",
         "libz",
     ],
     static_libs: [
         "libarect",
-        "libsfntly",
-        "libwebp-decode",
-        "libwebp-encode",
     ],
     group_static_libs: true,
     target: {
@@ -196,7 +229,6 @@ cc_defaults {
         shared_libs: [
             "libEGL",
             "libGLESv2",
-            "libheif",
             "libvulkan",
             "libnativewindow",
         ],
@@ -204,6 +236,30 @@ cc_defaults {
             "libvulkan",
         ],
       },
+    },
+}
+
+cc_defaults {
+    name: "skia_deps",
+    defaults: ["skia_renderengine_deps"],
+    shared_libs: [
+        "libdng_sdk",
+        "libjpeg",
+        "libpiex",
+        "libexpat",
+        "libft2",
+    ],
+    static_libs: [
+        "libwebp-decode",
+        "libwebp-encode",
+        "libsfntly",
+    ],
+    target: {
+      android: {
+        shared_libs: [
+            "libheif",
+        ],
+      },
       darwin: {
         host_ldlibs: [
             "-framework AppKit",
@@ -291,7 +347,7 @@ cc_test {
 }''')
 
 # We'll run GN to get the main source lists and include directories for Skia.
-def generate_args(target_os, enable_gpu):
+def generate_args(target_os, enable_gpu, renderengine = False):
   d = {
     'is_official_build':                    'true',
 
@@ -299,11 +355,9 @@ def generate_args(target_os, enable_gpu):
     # files.
     'target_cpu':                           '"none"',
 
-    'skia_enable_android_utils':            'true',
     # Use the custom FontMgr, as the framework will handle fonts.
     'skia_enable_fontmgr_custom_directory': 'false',
     'skia_enable_fontmgr_custom_embedded':  'false',
-    'skia_enable_fontmgr_custom_empty':     'true',
     'skia_enable_fontmgr_android':          'false',
     'skia_enable_fontmgr_win':              'false',
     'skia_enable_fontmgr_win_gdi':          'false',
@@ -312,19 +366,14 @@ def generate_args(target_os, enable_gpu):
     # enable features used in skia_nanobench
     'skia_tools_require_resources':         'true',
 
-    'skia_use_freetype':                    'true',
     'skia_use_fontconfig':                  'false',
-    'skia_use_fixed_gamma_text':            'true',
     'skia_include_multiframe_procs':        'false',
     'skia_libgifcodec_path':                '"third_party/libgifcodec"',
   }
   d['target_os'] = target_os
   if target_os == '"android"':
     d['skia_enable_tools'] = 'true'
-    d['skia_use_libheif']  = 'true'
     d['skia_include_multiframe_procs'] = 'true'
-  else:
-    d['skia_use_libheif']  = 'false'
 
   if enable_gpu:
     d['skia_use_vulkan']   = 'true'
@@ -342,12 +391,37 @@ def generate_args(target_os, enable_gpu):
     d['win_vc'] = '"placeholder_version"'
     d['win_sdk_version'] = '"placeholder_version"'
     d['win_toolchain_version'] = '"placeholder_version"'
+
+  if target_os == '"android"' and not renderengine:
+    d['skia_use_libheif']  = 'true'
+  else:
+    d['skia_use_libheif']  = 'false'
+
+  if renderengine:
+    d['skia_use_libpng_decode'] = 'false'
+    d['skia_use_libjpeg_turbo_decode'] = 'false'
+    d['skia_use_libjpeg_turbo_encode'] = 'false'
+    d['skia_use_libwebp_decode'] = 'false'
+    d['skia_use_libwebp_encode'] = 'false'
+    d['skia_use_libgifcodec'] = 'false'
+    d['skia_enable_pdf'] = 'false'
+    d['skia_use_freetype'] = 'false'
+    d['skia_use_fixed_gamma_text'] = 'false'
+    d['skia_use_expat'] = 'false'
+    d['skia_enable_fontmgr_custom_empty'] = 'false'
+  else:
+    d['skia_enable_android_utils'] = 'true'
+    d['skia_use_freetype'] = 'true'
+    d['skia_use_fixed_gamma_text'] = 'true'
+    d['skia_enable_fontmgr_custom_empty'] = 'true'
+
   return d
 
 gn_args       = generate_args('"android"', True)
 gn_args_linux = generate_args('"linux"',   False)
 gn_args_mac   = generate_args('"mac"',     False)
 gn_args_win   = generate_args('"win"',     False)
+gn_args_renderengine  = generate_args('"android"', True, True)
 
 js = gn_to_bp_utils.GenerateJSONFromGN(gn_args)
 
@@ -406,6 +480,14 @@ android_srcs    = android_srcs.difference(srcs)
 linux_srcs      =   linux_srcs.difference(srcs)
 mac_srcs        =     mac_srcs.difference(srcs)
 win_srcs        =     win_srcs.difference(srcs)
+
+js_renderengine   = gn_to_bp_utils.GenerateJSONFromGN(gn_args_renderengine)
+renderengine_srcs = strip_slashes(
+    js_renderengine['targets']['//:skia']['sources'])
+gn_to_bp_utils.GrabDependentValues(js_renderengine, '//:skia', 'sources',
+                                   renderengine_srcs, None)
+renderengine_srcs = strip_headers(renderengine_srcs)
+
 dm_srcs         = strip_headers(dm_srcs)
 nanobench_srcs  = strip_headers(nanobench_srcs)
 
@@ -417,10 +499,11 @@ defs = gn_to_bp_utils.GetArchSources(os.path.join(here, 'opts.gni'))
 
 def get_defines(json):
   return {str(d) for d in json['targets']['//:skia']['defines']}
-android_defines = get_defines(js)
+android_defines      = get_defines(js)
-linux_defines   = get_defines(js_linux)
+linux_defines        = get_defines(js_linux)
-mac_defines     = get_defines(js_mac)
+mac_defines          = get_defines(js_mac)
-win_defines     = get_defines(js_win)
+win_defines          = get_defines(js_win)
+renderengine_defines = get_defines(js_renderengine)
 
 def mkdir_if_not_exists(path):
   if not os.path.exists(path):
@@ -429,6 +512,7 @@ mkdir_if_not_exists('android/include/config/')
 mkdir_if_not_exists('linux/include/config/')
 mkdir_if_not_exists('mac/include/config/')
 mkdir_if_not_exists('win/include/config/')
+mkdir_if_not_exists('renderengine/include/config/')
 
 platforms = { 'IOS', 'MAC', 'WIN', 'ANDROID', 'UNIX' }
 
@@ -450,13 +534,16 @@ def append_to_file(config, s):
   with open(config, 'a') as f:
     print(s, file=f)
 
-android_config = 'android/include/config/SkUserConfig.h'
+def write_android_config(config_path, defines):
-gn_to_bp_utils.WriteUserConfig(android_config, android_defines)
+  gn_to_bp_utils.WriteUserConfig(config_path, defines)
-append_to_file(android_config, '''
+  append_to_file(config_path, '''
 #ifndef SK_BUILD_FOR_ANDROID
     #error "SK_BUILD_FOR_ANDROID must be defined!"
 #endif''')
-disallow_platforms(android_config, 'ANDROID')
+  disallow_platforms(config_path, 'ANDROID')
+
+write_android_config('android/include/config/SkUserConfig.h', android_defines)
+write_android_config('renderengine/include/config/SkUserConfig.h', renderengine_defines)
 
 def write_config(config_path, defines, platform):
   gn_to_bp_utils.WriteUserConfig(config_path, defines)
@@ -512,4 +599,6 @@ with open('Android.bp', 'w') as Android_bp:
     'linux_srcs':    bpfmt(10, linux_srcs),
     'mac_srcs':      bpfmt(10, mac_srcs),
     'win_srcs':      bpfmt(10, win_srcs),
+
+    'renderengine_srcs': bpfmt(8, renderengine_srcs),
   }), file=Android_bp)

gn/gn_to_bp_utils.py

@@ -75,10 +75,7 @@ def CleanupCFlags(cflags):
 
 def CleanupCCFlags(cflags_cc):
   # Only use the generated flags related to warnings.
-  cflags_cc       = {s for s in cflags_cc      if s.startswith('-W')}
+  return {s for s in cflags_cc      if s.startswith('-W')}
-  # Add the rest of the flags we want.
-  cflags_cc.add("-fexceptions")
-  return cflags_cc
 
 def _get_path_info(path, kind):
   assert path == "../src"