CSS Motion Path: calculate transform for simple ray() paths

third_party/WebKit/Source/core/style/ComputedStyle.cpp

 /*
  * Copyright (C) 1999 Antti Koivisto (koivisto@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights
  * reserved.
  * Copyright (C) 2011 Adobe Systems Incorporated. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
@@ skipping 27 matching lines @@
 #include "core/style/ComputedStyleConstants.h"
 #include "core/style/ContentData.h"
 #include "core/style/CursorData.h"
 #include "core/style/DataEquivalency.h"
 #include "core/style/QuotesData.h"
 #include "core/style/ShadowList.h"
 #include "core/style/StyleImage.h"
 #include "core/style/StyleInheritedData.h"
 #include "core/style/StyleInheritedVariables.h"
 #include "core/style/StyleNonInheritedVariables.h"
+#include "core/style/StyleRay.h"
 #include "platform/LengthFunctions.h"
 #include "platform/RuntimeEnabledFeatures.h"
 #include "platform/fonts/Font.h"
 #include "platform/fonts/FontSelector.h"
 #include "platform/geometry/FloatRoundedRect.h"
 #include "platform/graphics/GraphicsContext.h"
 #include "platform/transforms/RotateTransformOperation.h"
 #include "platform/transforms/ScaleTransformOperation.h"
 #include "platform/transforms/TranslateTransformOperation.h"
 #include "platform/wtf/MathExtras.h"
@@ skipping 1266 matching lines @@
     const FloatRect& bounding_box,
     TransformationMatrix& transform) const {
   const StyleMotionData& motion_data =
       rare_non_inherited_data_->transform_->motion_;
   // TODO(ericwilligers): crbug.com/638055 Apply offset-position.
   if (!motion_data.path_) {
     return;
   }
   const LengthPoint& position = OffsetPosition();
   const LengthPoint& anchor = OffsetAnchor();
-  if (motion_data.path_->GetType() == BasicShape::kStyleRayType) {
-    // TODO(ericwilligers): crbug.com/641245 Support ray paths.
-    return;
-  }
-  const StylePath& motion_path = ToStylePath(*motion_data.path_);
-  float path_length = motion_path.length();
-  float distance = FloatValueForLength(motion_data.distance_, path_length);
-  float computed_distance;
-  if (motion_path.IsClosed() && path_length > 0) {
-    computed_distance = fmod(distance, path_length);
-    if (computed_distance < 0)
-      computed_distance += path_length;
-  } else {
-    computed_distance = clampTo<float>(distance, 0, path_length);
-  }
 
   FloatPoint point;
   float angle;
-  motion_path.GetPath().PointAndNormalAtLength(computed_distance, point, angle);
+  if (motion_data.path_->GetType() == BasicShape::kStyleRayType) {
+    // TODO(ericwilligers): crbug.com/641245 Support <size> for ray paths.
+    float distance = FloatValueForLength(motion_data.distance_, 0);
+
+    angle = ToStyleRay(*motion_data.path_).Angle() - 90;
+    point.SetX(distance * cos(deg2rad(angle)));
+    point.SetY(distance * sin(deg2rad(angle)));
+  } else {
+    const StylePath& motion_path = ToStylePath(*motion_data.path_);

[pdr., 2017/05/16 22:51:19]

Would it be useful to add the following?
DCHECK(motion_data.path_->GetType() == kStylePathType);

[Eric Willigers, 2017/05/17 05:47:00]

ToStylePath is already a debug checked cast, just like ToSVGPath.

+    float path_length = motion_path.length();
+    float distance = FloatValueForLength(motion_data.distance_, path_length);
+    float computed_distance;
+    if (motion_path.IsClosed() && path_length > 0) {
+      computed_distance = fmod(distance, path_length);
+      if (computed_distance < 0)
+        computed_distance += path_length;
+    } else {
+      computed_distance = clampTo<float>(distance, 0, path_length);
+    }
+
+    motion_path.GetPath().PointAndNormalAtLength(computed_distance, point,
+                                                 angle);
+  }
 
   if (motion_data.rotation_.type == kOffsetRotationFixed)
     angle = 0;
 
   float origin_shift_x = 0;
   float origin_shift_y = 0;
   // If offset-Position and offset-anchor properties are not yet enabled,
   // they will have the default value, auto.
   if (position.X() != Length(kAuto) || anchor.X() != Length(kAuto)) {
     // Shift the origin from transform-origin to offset-anchor.
@@ skipping 1146 matching lines @@
     if (value < 0)
       fvalue -= 0.5f;
     else
       fvalue += 0.5f;
   }
 
   return RoundForImpreciseConversion<int>(fvalue / zoom_factor);
 }
 
 }  // namespace blink