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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* 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/gfx/Matrix.h"
+#include "mozilla/EnumeratedArray.h"
+#include "mozilla/ServoStyleConsts.h"
+#include "nsSize.h"
+#include "Units.h" // for CSSPoint
+#include <limits>
+
+class nsIFrame;
+class nsPresContext;
+struct gfxQuaternion;
+struct nsRect;
+
+namespace mozilla {
+struct ResolvedMotionPathData;
+}
+
+/**
+ * A helper to generate gfxMatrixes from css transform functions.
+ */
+namespace nsStyleTransformMatrix {
+// The operator passed to Servo backend.
+enum class MatrixTransformOperator : uint8_t { Interpolate, Accumulate };
+
+/**
+ * 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),
+ mX(0),
+ mY(0),
+ mWidth(0),
+ mHeight(0),
+ mIsCached(false) {}
+
+ explicit TransformReferenceBox(const nsIFrame* aFrame)
+ : mFrame(aFrame), mX(0), mY(0), mWidth(0), mHeight(0), mIsCached(false) {
+ MOZ_ASSERT(mFrame);
+ }
+
+ explicit TransformReferenceBox(const nsIFrame* aFrame,
+ const nsRect& aFallbackDimensions)
+ : mX(0), mY(0), mWidth(0), mHeight(0) {
+ mFrame = aFrame;
+ mIsCached = false;
+ if (!mFrame) {
+ Init(aFallbackDimensions);
+ }
+ }
+
+ void Init(const nsIFrame* aFrame) {
+ MOZ_ASSERT(!mFrame && !mIsCached);
+ mFrame = aFrame;
+ }
+
+ void Init(const nsRect& 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;
+};
+
+float ProcessTranslatePart(
+ const mozilla::LengthPercentage& aValue, TransformReferenceBox* aRefBox,
+ TransformReferenceBox::DimensionGetter aDimensionGetter = nullptr);
+
+void ProcessInterpolateMatrix(mozilla::gfx::Matrix4x4& aMatrix,
+ const mozilla::StyleTransformOperation& aOp,
+ TransformReferenceBox& aBounds);
+
+void ProcessAccumulateMatrix(mozilla::gfx::Matrix4x4& aMatrix,
+ const mozilla::StyleTransformOperation& aOp,
+ TransformReferenceBox& aBounds);
+
+/**
+ * Given a StyleTransform containing transform functions, returns a matrix
+ * containing the value of those functions.
+ *
+ * @param aList the transform operation list.
+ * @param aBounds The frame's bounding rectangle.
+ * @param aAppUnitsPerMatrixUnit The number of app units per device pixel.
+ */
+mozilla::gfx::Matrix4x4 ReadTransforms(const mozilla::StyleTransform& aList,
+ TransformReferenceBox& aBounds,
+ float aAppUnitsPerMatrixUnit);
+
+// Generate the gfx::Matrix for CSS Transform Module Level 2.
+// https://drafts.csswg.org/css-transforms-2/#ctm
+mozilla::gfx::Matrix4x4 ReadTransforms(
+ const mozilla::StyleTranslate&, const mozilla::StyleRotate&,
+ const mozilla::StyleScale&,
+ const mozilla::Maybe<mozilla::ResolvedMotionPathData>& aMotion,
+ const mozilla::StyleTransform&, TransformReferenceBox& aRefBox,
+ float aAppUnitsPerMatrixUnit);
+
+/**
+ * Given the x and y values, compute the 2d position with respect to the given
+ * a reference box size that these values describe, in CSS pixels.
+ */
+mozilla::CSSPoint Convert2DPosition(const mozilla::LengthPercentage& aX,
+ const mozilla::LengthPercentage& aY,
+ const mozilla::CSSSize& aSize);
+
+/**
+ * Given the x and y values, compute the 2d position with respect to the given
+ * TransformReferenceBox that these values describe, in CSS pixels.
+ */
+mozilla::CSSPoint Convert2DPosition(const mozilla::LengthPercentage& aX,
+ const mozilla::LengthPercentage& aY,
+ TransformReferenceBox& aRefBox);
+
+/**
+ * Given the x and y values, compute the 2d position with respect to the given
+ * TransformReferenceBox that these values describe, in device pixels.
+ */
+mozilla::gfx::Point Convert2DPosition(const mozilla::LengthPercentage& aX,
+ const mozilla::LengthPercentage& aY,
+ TransformReferenceBox& aRefBox,
+ int32_t aAppUnitsPerDevPixel);
+
+// Shear type for decomposition.
+enum class ShearType { XY, XZ, YZ, 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);
+
+} // namespace nsStyleTransformMatrix
+
+#endif
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