Bug 1479173 - Add a static constexpr function returns an nsCSSPropertyIDSet being consist of CSS properties set can be run on the compositor. r=heycam,birtles

Also add a script to generate the CSS properties set by looking at
CanAnimateOnCompositor flag in servo's property definitions.

Differential Revision: https://phabricator.services.mozilla.com/D10687

--HG--
extra : moz-landing-system : lando

layout/style/GenerateCompositorAnimatableProperties.py

@@ -0,0 +1,23 @@
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this file,
+# You can obtain one at http://mozilla.org/MPL/2.0/.
+
+import runpy
+
+def generate(output, dataFile):
+    output.write("""/* THIS IS AN AUTOGENERATED FILE.  DO NOT EDIT */
+#ifndef COMPOSITOR_ANIMATABLE_PROPERTY_LIST
+#define COMPOSITOR_ANIMATABLE_PROPERTY_LIST { \\
+""")
+
+    def can_animate_on_compositor(p):
+        return "CanAnimateOnCompositor" in p.flags
+
+    properties = runpy.run_path(dataFile)["data"]
+    properties = filter(can_animate_on_compositor, properties)
+
+    for p in properties:
+        output.write("  eCSSProperty_{}, \\\n".format(p.id))
+
+    output.write("}\n")
+    output.write("#endif /* COMPOSITOR_ANIMATABLE_PROPERTY_LIST */\n")

layout/style/moz.build

@@ -291,15 +291,23 @@ servo_props.inputs = [
 
 if CONFIG['COMPILE_ENVIRONMENT']:
     GENERATED_FILES += [
+        'CompositorAnimatableProperties.h',
         'nsComputedDOMStyleGenerated.cpp',
         'nsCSSPropsGenerated.inc',
         'ServoStyleConsts.h',
     ]
 
     EXPORTS.mozilla += [
+        '!CompositorAnimatableProperties.h',
         '!ServoStyleConsts.h',
     ]
 
+    compositor = GENERATED_FILES['CompositorAnimatableProperties.h']
+    compositor.script = 'GenerateCompositorAnimatableProperties.py:generate'
+    compositor.inputs = [
+        '!ServoCSSPropList.py',
+    ]
+
     computed = GENERATED_FILES['nsComputedDOMStyleGenerated.cpp']
     computed.script = 'GenerateComputedDOMStyleGenerated.py:generate'
     computed.inputs = [

layout/style/nsCSSPropertyIDSet.h

@@ -11,6 +11,10 @@
 
 #include "nsCSSPropertyID.h"
 #include <limits.h> // for CHAR_BIT
+#include <initializer_list>
+
+// For COMPOSITOR_ANIMATABLE_PROPERTY_LIST
+#include "mozilla/CompositorAnimatableProperties.h"
 
 /**
  * nsCSSPropertyIDSet maintains a set of non-shorthand CSS properties.  In
@@ -22,6 +26,17 @@ public:
     nsCSSPropertyIDSet() { Empty(); }
     // auto-generated copy-constructor OK
 
+    explicit constexpr nsCSSPropertyIDSet(
+        std::initializer_list<nsCSSPropertyID> aProperties)
+      : mProperties{0}
+    {
+      for (auto property : aProperties) {
+        size_t p = property;
+        mProperties[p / kBitsInChunk] |=
+          property_set_type(1) << (p % kBitsInChunk);
+      }
+    }
+
     void AssertInSetRange(nsCSSPropertyID aProperty) const {
         NS_ASSERTION(0 <= aProperty &&
                      aProperty < eCSSProperty_COUNT_no_shorthands,
@@ -52,6 +67,19 @@ public:
                 (property_set_type(1) << (p % kBitsInChunk))) != 0;
     }
 
+    // Returns an nsCSSPropertyIDSet including all properties that can be run
+    // on the compositor.
+    static constexpr nsCSSPropertyIDSet CompositorAnimatables()
+    {
+      return nsCSSPropertyIDSet(COMPOSITOR_ANIMATABLE_PROPERTY_LIST);
+    }
+
+    static constexpr size_t CompositorAnimatableCount()
+    {
+      auto list = COMPOSITOR_ANIMATABLE_PROPERTY_LIST;
+      return list.size();
+    }
+
     void Empty() {
         memset(mProperties, 0, sizeof(mProperties));
     }