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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/. */
+
+#ifndef MOZ_UNIT_TRANSFORMS_H_
+#define MOZ_UNIT_TRANSFORMS_H_
+
+#include "Units.h"
+#include "mozilla/gfx/Matrix.h"
+#include "mozilla/Maybe.h"
+#include "nsRegion.h"
+
+namespace mozilla {
+
+// Convenience functions for converting an entity from one strongly-typed
+// coordinate system to another without changing the values it stores (this
+// can be thought of as a cast).
+// To use these functions, you must provide a justification for each use!
+// Feel free to add more justifications to PixelCastJustification, along with
+// a comment that explains under what circumstances it is appropriate to use.
+
+enum class PixelCastJustification : uint8_t {
+ // For the root layer, Screen Pixel = Parent Layer Pixel.
+ ScreenIsParentLayerForRoot,
+ // On the layout side, Screen Pixel = LayoutDevice at the outer-window level.
+ LayoutDeviceIsScreenForBounds,
+ // For the root layer, Render Target Pixel = Parent Layer Pixel.
+ RenderTargetIsParentLayerForRoot,
+ // For the root composition size we want to view it as layer pixels in any
+ // layer
+ ParentLayerToLayerForRootComposition,
+ // The Layer coordinate space for one layer is the ParentLayer coordinate
+ // space for its children
+ MovingDownToChildren,
+ // The transform that is usually used to convert between two coordinate
+ // systems is not available (for example, because the object that stores it
+ // is being destroyed), so fall back to the identity.
+ TransformNotAvailable,
+ // When an OS event is initially constructed, its reference point is
+ // technically in screen pixels, as it has not yet accounted for any
+ // asynchronous transforms. This justification is for viewing the initial
+ // reference point as a screen point. The reverse is useful when synthetically
+ // created WidgetEvents need to be converted back to InputData.
+ LayoutDeviceIsScreenForUntransformedEvent,
+ // Similar to LayoutDeviceIsScreenForUntransformedEvent, PBrowser handles
+ // some widget/tab dimension information as the OS does -- in screen units.
+ LayoutDeviceIsScreenForTabDims,
+ // A combination of LayoutDeviceIsScreenForBounds and
+ // ScreenIsParentLayerForRoot, which is how we're using it.
+ LayoutDeviceIsParentLayerForRCDRSF,
+ // Used to treat the product of AsyncTransformComponentMatrix objects
+ // as an AsyncTransformMatrix. See the definitions of these matrices in
+ // LayersTypes.h for details.
+ MultipleAsyncTransforms,
+ // We have reason to believe a layer doesn't have a local transform.
+ // Should only be used if we've already checked or asserted this.
+ NoTransformOnLayer,
+ // LayerPixels are ImagePixels
+ LayerIsImage,
+ // External pixels are the same scale as screen pixels
+ ExternalIsScreen,
+ // LayerToScreenMatrix is used as LayoutDeviceToLayoutDevice, because
+ // out-of-process iframes uses LayoutDevicePixels as the type system-visible
+ // type of their top-level event coordinate space even if technically
+ // inaccurate.
+ ContentProcessIsLayerInUiProcess,
+ // Propagating TransformToAncestorScale to a child process.
+ PropagatingToChildProcess,
+ // A quantity represents a proportion of a page length, e.g. "0.5 pages".
+ // The proportion does not need to be scaled when converting between
+ // units (the page length that it's mutlipled by will be scaled instead).
+ DeltaIsPageProportion,
+ // Used to cast between CSS and OuterCSS pixels when moving between code
+ // that deals with content outside a scroll frame generically (which would
+ // use CSS pixels) and code related to the scroll frame in APZ (which wants
+ // such quantities in OuterCSS pixels).
+ CSSPixelsOfSurroundingContent,
+};
+
+template <class TargetUnits, class SourceUnits>
+gfx::CoordTyped<TargetUnits> ViewAs(const gfx::CoordTyped<SourceUnits>& aCoord,
+ PixelCastJustification) {
+ return gfx::CoordTyped<TargetUnits>(aCoord.value);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntCoordTyped<TargetUnits> ViewAs(
+ const gfx::IntCoordTyped<SourceUnits>& aCoord, PixelCastJustification) {
+ return gfx::IntCoordTyped<TargetUnits>(aCoord.value);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::SizeTyped<TargetUnits> ViewAs(const gfx::SizeTyped<SourceUnits>& aSize,
+ PixelCastJustification) {
+ return gfx::SizeTyped<TargetUnits>(aSize.width, aSize.height);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntSizeTyped<TargetUnits> ViewAs(
+ const gfx::IntSizeTyped<SourceUnits>& aSize, PixelCastJustification) {
+ return gfx::IntSizeTyped<TargetUnits>(aSize.width, aSize.height);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::PointTyped<TargetUnits> ViewAs(const gfx::PointTyped<SourceUnits>& aPoint,
+ PixelCastJustification) {
+ return gfx::PointTyped<TargetUnits>(aPoint.x, aPoint.y);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntPointTyped<TargetUnits> ViewAs(
+ const gfx::IntPointTyped<SourceUnits>& aPoint, PixelCastJustification) {
+ return gfx::IntPointTyped<TargetUnits>(aPoint.x, aPoint.y);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::RectTyped<TargetUnits> ViewAs(const gfx::RectTyped<SourceUnits>& aRect,
+ PixelCastJustification) {
+ return gfx::RectTyped<TargetUnits>(aRect.x, aRect.y, aRect.Width(),
+ aRect.Height());
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntRectTyped<TargetUnits> ViewAs(
+ const gfx::IntRectTyped<SourceUnits>& aRect, PixelCastJustification) {
+ return gfx::IntRectTyped<TargetUnits>(aRect.x, aRect.y, aRect.Width(),
+ aRect.Height());
+}
+template <class TargetUnits, class SourceUnits>
+gfx::MarginTyped<TargetUnits> ViewAs(
+ const gfx::MarginTyped<SourceUnits>& aMargin, PixelCastJustification) {
+ return gfx::MarginTyped<TargetUnits>(aMargin.top, aMargin.right,
+ aMargin.bottom, aMargin.left);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntMarginTyped<TargetUnits> ViewAs(
+ const gfx::IntMarginTyped<SourceUnits>& aMargin, PixelCastJustification) {
+ return gfx::IntMarginTyped<TargetUnits>(aMargin.top, aMargin.right,
+ aMargin.bottom, aMargin.left);
+}
+template <class TargetUnits, class SourceUnits>
+gfx::IntRegionTyped<TargetUnits> ViewAs(
+ const gfx::IntRegionTyped<SourceUnits>& aRegion, PixelCastJustification) {
+ return gfx::IntRegionTyped<TargetUnits>::FromUnknownRegion(
+ aRegion.ToUnknownRegion());
+}
+template <class NewTargetUnits, class OldTargetUnits, class SourceUnits>
+gfx::ScaleFactor<SourceUnits, NewTargetUnits> ViewTargetAs(
+ const gfx::ScaleFactor<SourceUnits, OldTargetUnits>& aScaleFactor,
+ PixelCastJustification) {
+ return gfx::ScaleFactor<SourceUnits, NewTargetUnits>(aScaleFactor.scale);
+}
+template <class NewTargetUnits, class OldTargetUnits, class SourceUnits>
+gfx::ScaleFactors2D<SourceUnits, NewTargetUnits> ViewTargetAs(
+ const gfx::ScaleFactors2D<SourceUnits, OldTargetUnits>& aScaleFactors,
+ PixelCastJustification) {
+ return gfx::ScaleFactors2D<SourceUnits, NewTargetUnits>(aScaleFactors.xScale,
+ aScaleFactors.yScale);
+}
+template <class TargetUnits, class SourceUnits>
+Maybe<gfx::IntRectTyped<TargetUnits>> ViewAs(
+ const Maybe<gfx::IntRectTyped<SourceUnits>>& aRect,
+ PixelCastJustification aJustification) {
+ if (aRect.isSome()) {
+ return Some(ViewAs<TargetUnits>(aRect.value(), aJustification));
+ }
+ return Nothing();
+}
+// Unlike the other functions in this category, these functions take the
+// target matrix or scale type, rather than its source and target unit types, as
+// the explicit template argument, so an example invocation is:
+// ViewAs<ScreenToLayerMatrix4x4>(otherTypedMatrix, justification)
+// The reason is that if it took the source and target unit types as two
+// template arguments, there may be some confusion as to which is the
+// source and which is the target.
+template <class TargetMatrix, class SourceMatrixSourceUnits,
+ class SourceMatrixTargetUnits>
+TargetMatrix ViewAs(const gfx::Matrix4x4Typed<SourceMatrixSourceUnits,
+ SourceMatrixTargetUnits>& aMatrix,
+ PixelCastJustification) {
+ return TargetMatrix::FromUnknownMatrix(aMatrix.ToUnknownMatrix());
+}
+template <class TargetMatrix, class SourceMatrixSourceUnits,
+ class SourceMatrixTargetUnits>
+Maybe<TargetMatrix> ViewAs(
+ const Maybe<gfx::Matrix4x4Typed<SourceMatrixSourceUnits,
+ SourceMatrixTargetUnits>>& aMatrix,
+ PixelCastJustification) {
+ if (aMatrix.isSome()) {
+ return Some(TargetMatrix::FromUnknownMatrix(aMatrix->ToUnknownMatrix()));
+ }
+ return Nothing();
+}
+template <class TargetScale, class SourceScaleSourceUnits,
+ class SourceScaleTargetUnits>
+TargetScale ViewAs(const gfx::ScaleFactor<SourceScaleSourceUnits,
+ SourceScaleTargetUnits>& aScale,
+ PixelCastJustification) {
+ return TargetScale{aScale.scale};
+}
+
+// A non-member overload of ToUnknownMatrix() for use on a Maybe<Matrix>.
+// We can't make this a member because we can't inject a member into Maybe.
+template <typename SourceUnits, typename TargetUnits>
+Maybe<gfx::Matrix4x4> ToUnknownMatrix(
+ const Maybe<gfx::Matrix4x4Typed<SourceUnits, TargetUnits>>& aMatrix) {
+ if (aMatrix.isSome()) {
+ return Some(aMatrix->ToUnknownMatrix());
+ }
+ return Nothing();
+}
+
+// Convenience functions for casting untyped entities to typed entities.
+// Using these functions does not require a justification, but once we convert
+// all code to use strongly typed units they should not be needed any longer.
+template <class TargetUnits>
+gfx::PointTyped<TargetUnits> ViewAs(const gfxPoint& aPoint) {
+ return gfx::PointTyped<TargetUnits>(aPoint.x, aPoint.y);
+}
+template <class TargetUnits>
+gfx::PointTyped<TargetUnits> ViewAs(const gfx::Point& aPoint) {
+ return gfx::PointTyped<TargetUnits>(aPoint.x, aPoint.y);
+}
+template <class TargetUnits>
+gfx::RectTyped<TargetUnits> ViewAs(const gfx::Rect& aRect) {
+ return gfx::RectTyped<TargetUnits>(aRect.x, aRect.y, aRect.Width(),
+ aRect.Height());
+}
+template <class TargetUnits>
+gfx::IntSizeTyped<TargetUnits> ViewAs(const nsIntSize& aSize) {
+ return gfx::IntSizeTyped<TargetUnits>(aSize.width, aSize.height);
+}
+template <class TargetUnits>
+gfx::IntPointTyped<TargetUnits> ViewAs(const nsIntPoint& aPoint) {
+ return gfx::IntPointTyped<TargetUnits>(aPoint.x, aPoint.y);
+}
+template <class TargetUnits>
+gfx::IntRectTyped<TargetUnits> ViewAs(const nsIntRect& aRect) {
+ return gfx::IntRectTyped<TargetUnits>(aRect.x, aRect.y, aRect.Width(),
+ aRect.Height());
+}
+template <class TargetUnits>
+gfx::IntRegionTyped<TargetUnits> ViewAs(const nsIntRegion& aRegion) {
+ return gfx::IntRegionTyped<TargetUnits>::FromUnknownRegion(aRegion);
+}
+// Unlike the other functions in this category, these functions take the
+// target matrix or scale type, rather than its source and target unit
+// types, as the template argument, so an example invocation is:
+// ViewAs<ScreenToLayerMatrix4x4>(untypedMatrix)
+// The reason is that if it took the source and target unit types as two
+// template arguments, there may be some confusion as to which is the
+// source and which is the target.
+template <class TypedScale>
+TypedScale ViewAs(const Scale2D& aScale) {
+ return TypedScale(aScale.xScale, aScale.yScale);
+}
+template <class TypedMatrix>
+TypedMatrix ViewAs(const gfx::Matrix4x4& aMatrix) {
+ return TypedMatrix::FromUnknownMatrix(aMatrix);
+}
+
+// Convenience functions for transforming an entity from one strongly-typed
+// coordinate system to another using the provided transformation matrix.
+template <typename TargetUnits, typename SourceUnits>
+static gfx::PointTyped<TargetUnits> TransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::PointTyped<SourceUnits>& aPoint) {
+ return aTransform.TransformPoint(aPoint);
+}
+template <typename TargetUnits, typename SourceUnits>
+static gfx::IntPointTyped<TargetUnits> TransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::IntPointTyped<SourceUnits>& aPoint) {
+ return RoundedToInt(
+ TransformBy(aTransform, gfx::PointTyped<SourceUnits>(aPoint)));
+}
+template <typename TargetUnits, typename SourceUnits>
+static gfx::RectTyped<TargetUnits> TransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::RectTyped<SourceUnits>& aRect) {
+ return aTransform.TransformBounds(aRect);
+}
+template <typename TargetUnits, typename SourceUnits>
+static gfx::IntRectTyped<TargetUnits> TransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::IntRectTyped<SourceUnits>& aRect) {
+ return RoundedToInt(
+ TransformBy(aTransform, gfx::RectTyped<SourceUnits>(aRect)));
+}
+template <typename TargetUnits, typename SourceUnits>
+static gfx::IntRegionTyped<TargetUnits> TransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::IntRegionTyped<SourceUnits>& aRegion) {
+ return ViewAs<TargetUnits>(
+ aRegion.ToUnknownRegion().Transform(aTransform.ToUnknownMatrix()));
+}
+
+// Transform |aVector|, which is anchored at |aAnchor|, by the given transform
+// matrix, yielding a point in |TargetUnits|.
+// The anchor is necessary because with 3D tranforms, the location of the
+// vector can affect the result of the transform.
+template <typename TargetUnits, typename SourceUnits>
+static gfx::PointTyped<TargetUnits> TransformVector(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::PointTyped<SourceUnits>& aVector,
+ const gfx::PointTyped<SourceUnits>& aAnchor) {
+ gfx::PointTyped<TargetUnits> transformedStart =
+ TransformBy(aTransform, aAnchor);
+ gfx::PointTyped<TargetUnits> transformedEnd =
+ TransformBy(aTransform, aAnchor + aVector);
+ return transformedEnd - transformedStart;
+}
+
+// UntransformBy() and UntransformVector() are like TransformBy() and
+// TransformVector(), respectively, but are intended for cases where
+// the transformation matrix is the inverse of a 3D projection. When
+// using such transforms, the resulting Point4D is only meaningful
+// if it has a positive w-coordinate. To handle this, these functions
+// return a Maybe object which contains a value if and only if the
+// result is meaningful
+template <typename TargetUnits, typename SourceUnits>
+static Maybe<gfx::PointTyped<TargetUnits>> UntransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::PointTyped<SourceUnits>& aPoint) {
+ gfx::Point4DTyped<TargetUnits> point = aTransform.ProjectPoint(aPoint);
+ if (!point.HasPositiveWCoord()) {
+ return Nothing();
+ }
+ return Some(point.As2DPoint());
+}
+template <typename TargetUnits, typename SourceUnits>
+static Maybe<gfx::IntPointTyped<TargetUnits>> UntransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::IntPointTyped<SourceUnits>& aPoint) {
+ gfx::PointTyped<SourceUnits> p = aPoint;
+ gfx::Point4DTyped<TargetUnits> point = aTransform.ProjectPoint(p);
+ if (!point.HasPositiveWCoord()) {
+ return Nothing();
+ }
+ return Some(RoundedToInt(point.As2DPoint()));
+}
+
+// The versions of UntransformBy() that take a rectangle also take a clip,
+// which represents the bounds within which the target must fall. The
+// result of the transform is intersected with this clip, and is considered
+// meaningful if the intersection is not empty.
+template <typename TargetUnits, typename SourceUnits>
+static Maybe<gfx::RectTyped<TargetUnits>> UntransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::RectTyped<SourceUnits>& aRect,
+ const gfx::RectTyped<TargetUnits>& aClip) {
+ gfx::RectTyped<TargetUnits> rect = aTransform.ProjectRectBounds(aRect, aClip);
+ if (rect.IsEmpty()) {
+ return Nothing();
+ }
+ return Some(rect);
+}
+template <typename TargetUnits, typename SourceUnits>
+static Maybe<gfx::IntRectTyped<TargetUnits>> UntransformBy(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::IntRectTyped<SourceUnits>& aRect,
+ const gfx::IntRectTyped<TargetUnits>& aClip) {
+ gfx::RectTyped<TargetUnits> rect = aTransform.ProjectRectBounds(aRect, aClip);
+ if (rect.IsEmpty()) {
+ return Nothing();
+ }
+ return Some(RoundedToInt(rect));
+}
+
+template <typename TargetUnits, typename SourceUnits>
+static Maybe<gfx::PointTyped<TargetUnits>> UntransformVector(
+ const gfx::Matrix4x4Typed<SourceUnits, TargetUnits>& aTransform,
+ const gfx::PointTyped<SourceUnits>& aVector,
+ const gfx::PointTyped<SourceUnits>& aAnchor) {
+ gfx::Point4DTyped<TargetUnits> projectedAnchor =
+ aTransform.ProjectPoint(aAnchor);
+ gfx::Point4DTyped<TargetUnits> projectedTarget =
+ aTransform.ProjectPoint(aAnchor + aVector);
+ if (!projectedAnchor.HasPositiveWCoord() ||
+ !projectedTarget.HasPositiveWCoord()) {
+ return Nothing();
+ }
+ return Some(projectedTarget.As2DPoint() - projectedAnchor.As2DPoint());
+}
+
+} // namespace mozilla
+
+#endif