Backed out changeset b7e1a728dfd2 (bug 1717161) for causing failures at perspective-zero-2.html. CLOSED TREE

layout/painting/nsDisplayList.cpp

@@ -7649,9 +7649,10 @@ bool nsDisplayTransform::ComputePerspectiveMatrix(const nsIFrame* aFrame,
   }
 
   MOZ_ASSERT(perspectiveDisplay->mChildPerspective.IsLength());
-  float perspective =
-      perspectiveDisplay->mChildPerspective.length._0.ToCSSPixels();
-  perspective = std::max(1.0f, perspective);
+  // TODO(emilio): Seems quite silly to go through app units just to convert to
+  // float pixels below.
+  nscoord perspective =
+      perspectiveDisplay->mChildPerspective.length._0.ToAppUnits();
   if (perspective < std::numeric_limits<Float>::epsilon()) {
     return true;
   }
@@ -7678,8 +7679,7 @@ bool nsDisplayTransform::ComputePerspectiveMatrix(const nsIFrame* aFrame,
   perspectiveOrigin += frameToPerspectiveGfxOffset;
 
   aOutMatrix._34 =
-      -1.0 / NSAppUnitsToFloatPixels(CSSPixel::ToAppUnits(perspective),
-                                     aAppUnitsPerPixel);
+      -1.0 / NSAppUnitsToFloatPixels(perspective, aAppUnitsPerPixel);
 
   aOutMatrix.ChangeBasis(Point3D(perspectiveOrigin.x, perspectiveOrigin.y, 0));
   return true;

layout/style/nsStyleTransformMatrix.h

@@ -39,8 +39,8 @@ enum class MatrixTransformOperator : uint8_t { Interpolate, Accumulate };
 // follows CSSWG's resolution on perspective(0). See bug 1316236.
 inline void ApplyPerspectiveToMatrix(mozilla::gfx::Matrix4x4& aMatrix,
                                      float aDepth) {
-  if (aDepth > 0) {
-    aMatrix.Perspective(std::max(aDepth, 1.0f));
+  if (aDepth >= std::numeric_limits<float>::epsilon()) {
+    aMatrix.Perspective(aDepth);
   }
 }
 

servo/components/style/values/animated/transform.rs

@@ -1204,8 +1204,8 @@ impl ComputeSquaredDistance for ComputedTransformOperation {
                 // FIXME(emilio): Is this right? Why interpolating this with
                 // Perspective but not with anything else?
                 let mut p_matrix = Matrix3D::identity();
-                if p.px() >= 0. {
-                    p_matrix.m34 = -1. / p.px().max(1.);
+                if p.px() > 0. {
+                    p_matrix.m34 = -1. / p.px();
                 }
                 p_matrix.compute_squared_distance(&m)
             },

servo/components/style/values/generics/transform.rs

@@ -582,10 +582,17 @@ impl<T: ToMatrix> Transform<T> {
 /// Return the transform matrix from a perspective length.
 #[inline]
 pub fn create_perspective_matrix(d: CSSFloat) -> Transform3D<CSSFloat> {
-    if d < 0.0 {
+    // TODO(gw): The transforms spec says that perspective length must
+    // be positive. However, there is some confusion between the spec
+    // and browser implementations as to handling the case of 0 for the
+    // perspective value. Until the spec bug is resolved, at least ensure
+    // that a provided perspective value of <= 0.0 doesn't cause panics
+    // and behaves as it does in other browsers.
+    // See https://lists.w3.org/Archives/Public/www-style/2016Jan/0020.html for more details.
+    if d <= 0.0 {
         Transform3D::identity()
     } else {
-        Transform3D::perspective(d.max(1.))
+        Transform3D::perspective(d)
     }
 }
 

testing/web-platform/meta/css/css-transforms/perspective-zero-2.html.ini

@@ -0,0 +1,2 @@
+[perspective-zero-2.html]
+  expected: FAIL

testing/web-platform/meta/css/css-transforms/perspective-zero-3.html.ini

@@ -0,0 +1,2 @@
+[perspective-zero-3.html]
+  expected: FAIL

testing/web-platform/meta/css/css-transforms/perspective-zero.html.ini

@@ -0,0 +1,2 @@
+[perspective-zero.html]
+  expected: FAIL

testing/web-platform/meta/css/css-transforms/transform3d-perspective-005.html.ini

@@ -0,0 +1,2 @@
+[transform3d-perspective-005.html]
+  expected: FAIL

testing/web-platform/meta/web-animations/animation-model/animation-types/interpolation-per-property-002.html.ini

@@ -0,0 +1,4 @@
+[interpolation-per-property-002.html]
+  [transform: perspective]
+    expected: FAIL
+