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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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/. */
+
+/*
+ * A class representing three matrices that can be used for style transforms.
+ */
+
+#ifndef nsStyleTransformMatrix_h_
+#define nsStyleTransformMatrix_h_
+
+#include "mozilla/EnumeratedArray.h"
+#include "nsCSSValue.h"
+
+#include <limits>
+
+class nsIFrame;
+class nsStyleContext;
+class nsPresContext;
+struct gfxQuaternion;
+struct nsRect;
+namespace mozilla {
+class RuleNodeCacheConditions;
+} // namespace mozilla
+
+/**
+ * A helper to generate gfxMatrixes from css transform functions.
+ */
+namespace nsStyleTransformMatrix {
+
+ // Function for applying perspective() transform function. We treat
+ // any value smaller than epsilon as perspective(infinity), which
+ // follows CSSWG's resolution on perspective(0). See bug 1316236.
+ inline void ApplyPerspectiveToMatrix(mozilla::gfx::Matrix4x4& aMatrix,
+ float aDepth)
+ {
+ if (aDepth >= std::numeric_limits<float>::epsilon()) {
+ aMatrix.Perspective(aDepth);
+ }
+ }
+
+ /**
+ * This class provides on-demand access to the 'reference box' for CSS
+ * transforms (needed to resolve percentage values in 'transform',
+ * 'transform-origin', etc.):
+ *
+ * http://dev.w3.org/csswg/css-transforms/#reference-box
+ *
+ * This class helps us to avoid calculating the reference box unless and
+ * until it is actually needed. This is important for performance when
+ * transforms are applied to SVG elements since the reference box for SVG is
+ * much more expensive to calculate (than for elements with a CSS layout box
+ * where we can use the nsIFrame's cached mRect), much more common (than on
+ * HTML), and yet very rarely have percentage values that require the
+ * reference box to be resolved. We also don't want to cause SVG frames to
+ * cache lots of ObjectBoundingBoxProperty objects that aren't needed.
+ *
+ * If UNIFIED_CONTINUATIONS (experimental, and currently broke) is defined,
+ * we consider the reference box for non-SVG frames to be the smallest
+ * rectangle containing a frame and all of its continuations. For example,
+ * if there is a <span> element with several continuations split over
+ * several lines, this function will return the rectangle containing all of
+ * those continuations. (This behavior is not currently in a spec.)
+ */
+ class MOZ_STACK_CLASS TransformReferenceBox final {
+ public:
+ typedef nscoord (TransformReferenceBox::*DimensionGetter)();
+
+ explicit TransformReferenceBox()
+ : mFrame(nullptr)
+ , mIsCached(false)
+ {}
+
+ explicit TransformReferenceBox(const nsIFrame* aFrame)
+ : mFrame(aFrame)
+ , mIsCached(false)
+ {
+ MOZ_ASSERT(mFrame);
+ }
+
+ explicit TransformReferenceBox(const nsIFrame* aFrame,
+ const nsSize& aFallbackDimensions)
+ {
+ mFrame = aFrame;
+ mIsCached = false;
+ if (!mFrame) {
+ Init(aFallbackDimensions);
+ }
+ }
+
+ void Init(const nsIFrame* aFrame) {
+ MOZ_ASSERT(!mFrame && !mIsCached);
+ mFrame = aFrame;
+ }
+
+ void Init(const nsSize& aDimensions);
+
+ /**
+ * The offset of the reference box from the nsIFrame's TopLeft(). This
+ * is non-zero only in the case of SVG content. If we can successfully
+ * implement UNIFIED_CONTINUATIONS at some point in the future then it
+ * may also be non-zero for non-SVG content.
+ */
+ nscoord X() {
+ EnsureDimensionsAreCached();
+ return mX;
+ }
+ nscoord Y() {
+ EnsureDimensionsAreCached();
+ return mY;
+ }
+
+ /**
+ * The size of the reference box.
+ */
+ nscoord Width() {
+ EnsureDimensionsAreCached();
+ return mWidth;
+ }
+ nscoord Height() {
+ EnsureDimensionsAreCached();
+ return mHeight;
+ }
+
+ bool IsEmpty() {
+ return !mFrame;
+ }
+
+ private:
+ // We don't really need to prevent copying, but since none of our consumers
+ // currently need to copy, preventing copying may allow us to catch some
+ // cases where we use pass-by-value instead of pass-by-reference.
+ TransformReferenceBox(const TransformReferenceBox&) = delete;
+
+ void EnsureDimensionsAreCached();
+
+ const nsIFrame* mFrame;
+ nscoord mX, mY, mWidth, mHeight;
+ bool mIsCached;
+ };
+
+ /**
+ * Return the transform function, as an nsCSSKeyword, for the given
+ * nsCSSValue::Array from a transform list.
+ */
+ nsCSSKeyword TransformFunctionOf(const nsCSSValue::Array* aData);
+
+ void SetIdentityMatrix(nsCSSValue::Array* aMatrix);
+
+ float ProcessTranslatePart(const nsCSSValue& aValue,
+ nsStyleContext* aContext,
+ nsPresContext* aPresContext,
+ mozilla::RuleNodeCacheConditions& aConditions,
+ TransformReferenceBox* aRefBox,
+ TransformReferenceBox::DimensionGetter aDimensionGetter = nullptr);
+
+ void
+ ProcessInterpolateMatrix(mozilla::gfx::Matrix4x4& aMatrix,
+ const nsCSSValue::Array* aData,
+ nsStyleContext* aContext,
+ nsPresContext* aPresContext,
+ mozilla::RuleNodeCacheConditions& aConditions,
+ TransformReferenceBox& aBounds,
+ bool* aContains3dTransform);
+
+ /**
+ * Given an nsCSSValueList containing -moz-transform functions,
+ * returns a matrix containing the value of those functions.
+ *
+ * @param aData The nsCSSValueList containing the transform functions
+ * @param aContext The style context, used for unit conversion.
+ * @param aPresContext The presentation context, used for unit conversion.
+ * @param aConditions Set to uncachable (by calling SetUncacheable()) if the
+ * result cannot be cached in the rule tree, otherwise untouched.
+ * @param aBounds The frame's bounding rectangle.
+ * @param aAppUnitsPerMatrixUnit The number of app units per device pixel.
+ * @param aContains3dTransform [out] Set to true if aList contains at least
+ * one 3d transform function (as defined in the CSS transforms
+ * specification), false otherwise.
+ *
+ * aContext and aPresContext may be null if all of the (non-percent)
+ * length values in aData are already known to have been converted to
+ * eCSSUnit_Pixel (as they are in an StyleAnimationValue)
+ */
+ mozilla::gfx::Matrix4x4 ReadTransforms(const nsCSSValueList* aList,
+ nsStyleContext* aContext,
+ nsPresContext* aPresContext,
+ mozilla::RuleNodeCacheConditions& aConditions,
+ TransformReferenceBox& aBounds,
+ float aAppUnitsPerMatrixUnit,
+ bool* aContains3dTransform);
+
+ // Shear type for decomposition.
+ enum class ShearType {
+ XYSHEAR,
+ XZSHEAR,
+ YZSHEAR,
+ Count
+ };
+ using ShearArray =
+ mozilla::EnumeratedArray<ShearType, ShearType::Count, float>;
+
+ /*
+ * Implements the 2d transform matrix decomposition algorithm.
+ */
+ bool Decompose2DMatrix(const mozilla::gfx::Matrix& aMatrix,
+ mozilla::gfx::Point3D& aScale,
+ ShearArray& aShear,
+ gfxQuaternion& aRotate,
+ mozilla::gfx::Point3D& aTranslate);
+ /*
+ * Implements the 3d transform matrix decomposition algorithm.
+ */
+ bool Decompose3DMatrix(const mozilla::gfx::Matrix4x4& aMatrix,
+ mozilla::gfx::Point3D& aScale,
+ ShearArray& aShear,
+ gfxQuaternion& aRotate,
+ mozilla::gfx::Point3D& aTranslate,
+ mozilla::gfx::Point4D& aPerspective);
+
+ mozilla::gfx::Matrix CSSValueArrayTo2DMatrix(nsCSSValue::Array* aArray);
+ mozilla::gfx::Matrix4x4 CSSValueArrayTo3DMatrix(nsCSSValue::Array* aArray);
+} // namespace nsStyleTransformMatrix
+
+#endif