Add option to control recompression of images by actool.

During compilation of assets catalogs, actool has the option of
recompressing the images (likely with pngcrush as used by older
version of Xcode). Add an option to wrapper script to control
whether this is enabled and disable it on iOS (as images have
already been optimised with imageoptim).

Bug: 738359
Change-Id: I8a2b855798bf5f2d221fe9dc1098f8649f77e5a4
Reviewed-on: https://chromium-review.googlesource.com/561777Reviewed-by: Dirk Pranke <dpranke@chromium.org>
Reviewed-by: Justin Cohen <justincohen@chromium.org>
Commit-Queue: Sylvain Defresne <sdefresne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#485208}

build/toolchain/mac/BUILD.gn

@@ -431,14 +431,17 @@ template("mac_toolchain") {
       if (is_ios) {
         _sdk_name = ios_sdk_name
         _min_deployment_target = ios_deployment_target
+        _compress_pngs = ""
       } else {
         _sdk_name = mac_sdk_name
         _min_deployment_target = mac_deployment_target
+        _compress_pngs = " -c "
       }
       command = "$env_wrapper rm -f {{output}} && " +
                 "TOOL_VERSION=${tool_versions.compile_xcassets} " +
                 "python $_tool -p $_sdk_name -t $_min_deployment_target " +
-                "-T {{bundle_product_type}} -o {{output}} {{inputs}}"
+                "$_compress_pngs -T {{bundle_product_type}} -o {{output}} " +
+                "{{inputs}}"
 
       description = "COMPILE_XCASSETS {{output}}"
       pool = ":bundle_pool($default_toolchain)"

build/toolchain/mac/compile_xcassets.py

@@ -76,8 +76,8 @@ def FilterCompilerOutput(compiler_output, relative_paths):
   return ''.join(filtered_output)
 
 
-def CompileAssetCatalog(
-    output, platform, product_type, min_deployment_target, inputs):
+def CompileAssetCatalog(output, platform, product_type, min_deployment_target,
+    inputs, compress_pngs):
   """Compile the .xcassets bundles to an asset catalog using actool.
 
   Args:
@@ -86,14 +86,17 @@ def CompileAssetCatalog(
     product_type: the bundle type
     min_deployment_target: minimum deployment target
     inputs: list of absolute paths to .xcassets bundles
+    compress_pngs: whether to enable compression of pngs
   """
   command = [
       'xcrun', 'actool', '--output-format=human-readable-text',
-      '--compress-pngs', '--notices', '--warnings', '--errors',
-      '--platform', platform, '--minimum-deployment-target',
-      min_deployment_target,
+      '--notices', '--warnings', '--errors', '--platform', platform,
+      '--minimum-deployment-target', min_deployment_target,
   ]
 
+  if compress_pngs:
+    command.extend(['--compress-pngs'])
+
   if product_type != '':
     command.extend(['--product-type', product_type])
 
@@ -144,6 +147,9 @@ def Main():
   parser.add_argument(
       '--output', '-o', required=True,
       help='path to the compiled assets catalog')
+  parser.add_argument(
+      '--compress-pngs', '-c', action='store_true', default=False,
+      help='recompress PNGs while compiling assets catalog')
   parser.add_argument(
       '--product-type', '-T',
       help='type of the containing bundle')
@@ -163,7 +169,8 @@ def Main():
       args.platform,
       args.product_type,
       args.minimum_deployment_target,
-      args.inputs)
+      args.inputs,
+      args.compress_pngs)
 
 
 if __name__ == '__main__':