gecko-dev/dom/svg/SVGViewportElement.h

/* -*- 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 mozilla_dom_SVGViewportElement_h
#define mozilla_dom_SVGViewportElement_h

#include "mozilla/dom/FromParser.h"
#include "nsAutoPtr.h"
#include "nsIContentInlines.h"
#include "nsISVGPoint.h"
#include "nsSVGEnum.h"
#include "nsSVGLength2.h"
#include "SVGGraphicsElement.h"
#include "SVGImageContext.h"
#include "nsSVGViewBox.h"
#include "SVGPreserveAspectRatio.h"
#include "SVGAnimatedPreserveAspectRatio.h"
#include "mozilla/Attributes.h"

class nsSVGOuterSVGFrame;
class nsSVGViewportFrame;

namespace mozilla {
class AutoPreserveAspectRatioOverride;
class DOMSVGAnimatedPreserveAspectRatio;

namespace dom {
class SVGAnimatedRect;
class SVGTransform;
class SVGViewElement;
class SVGViewportElement;

class svgFloatSize {
public:
  svgFloatSize(float aWidth, float aHeight)
    : width(aWidth)
    , height(aHeight)
  {}
  bool operator!=(const svgFloatSize& rhs) {
    return width != rhs.width || height != rhs.height;
  }
  float width;
  float height;
};

class SVGViewportElement : public SVGGraphicsElement
{
  friend class ::nsSVGOuterSVGFrame;
  friend class ::nsSVGViewportFrame;

protected:

  SVGViewportElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo);
  ~SVGViewportElement();

public:

  // nsIContent interface
  NS_IMETHOD_(bool) IsAttributeMapped(const nsIAtom* aAttribute) const override;

  // nsSVGElement specializations:
  virtual gfxMatrix PrependLocalTransformsTo(
    const gfxMatrix &aMatrix,
    SVGTransformTypes aWhich = eAllTransforms) const override;

  virtual bool HasValidDimensions() const override;

  // SVGViewportElement methods:

  float GetLength(uint8_t mCtxType);

  // public helpers:

  /**
   * Returns true if this element has a base/anim value for its "viewBox"
   * attribute that defines a viewBox rectangle with finite values, or
   * if there is a view element overriding this element's viewBox and it
   * has a valid viewBox.
   *
   * Note that this does not check whether we need to synthesize a viewBox,
   * so you must call ShouldSynthesizeViewBox() if you need to chck that too.
   *
   * Note also that this method does not pay attention to whether the width or
   * height values of the viewBox rect are positive!
   */
  bool HasViewBoxRect() const {
    return GetViewBoxInternal().HasRect();
  }

  /**
   * Returns true if we should synthesize a viewBox for ourselves (that is, if
   * we're the root element in an image document, and we're not currently being
   * painted for an <svg:image> element).
   *
   * Only call this method if HasViewBoxRect() returns false.
   */
  bool ShouldSynthesizeViewBox() const;

  bool HasViewBoxOrSyntheticViewBox() const {
    return HasViewBoxRect() || ShouldSynthesizeViewBox();
  }

  bool HasChildrenOnlyTransform() const {
    return mHasChildrenOnlyTransform;
  }

  void UpdateHasChildrenOnlyTransform();

  enum ChildrenOnlyTransformChangedFlags {
    eDuringReflow = 1
  };

  /**
   * This method notifies the style system that the overflow rects of our
   * immediate childrens' frames need to be updated. It is called by our own
   * frame when changes (e.g. to currentScale) cause our children-only
   * transform to change.
   *
   * The reason we have this method instead of overriding
   * GetAttributeChangeHint is because we need to act on non-attribute (e.g.
   * currentScale) changes in addition to attribute (e.g. viewBox) changes.
   */
  void ChildrenOnlyTransformChanged(uint32_t aFlags = 0);

  gfx::Matrix GetViewBoxTransform() const;

  // WebIDL
  already_AddRefed<SVGAnimatedRect> ViewBox();
  already_AddRefed<DOMSVGAnimatedPreserveAspectRatio> PreserveAspectRatio();
  virtual nsSVGViewBox* GetViewBox() override;

protected:

  // implementation helpers:

  bool IsRoot() const {
    NS_ASSERTION((IsInUncomposedDoc() && !GetParent()) ==
                 (OwnerDoc() && (OwnerDoc()->GetRootElement() == this)),
                 "Can't determine if we're root");
    return IsInUncomposedDoc() && !GetParent();
  }

  /**
   * Returns true if either this is an SVG <svg> element that is the child of
   * another non-foreignObject SVG element, or this is a SVG <symbol> element
   * this is the root of a use-element shadow tree.
   */
  bool IsInner() const {
    const nsIContent *parent = GetFlattenedTreeParent();
    return parent && parent->IsSVGElement() &&
           !parent->IsSVGElement(nsGkAtoms::foreignObject);
  }

  /**
   * Returns the explicit or default preserveAspectRatio, unless we're
   * synthesizing a viewBox, in which case it returns the "none" value.
   */
  virtual SVGPreserveAspectRatio GetPreserveAspectRatioWithOverride() const {
    return mPreserveAspectRatio.GetAnimValue();
  }

  /**
   * Returns the explicit viewBox rect, if specified, or else a synthesized
   * viewBox, if appropriate, or else a viewBox matching the dimensions of the
   * SVG viewport.
   */
  nsSVGViewBoxRect GetViewBoxWithSynthesis(
      float aViewportWidth, float aViewportHeight) const;

  /**
   * Retrieve the value of currentScale and currentTranslate.
   */
  virtual SVGPoint GetCurrentTranslate() const
  { return SVGPoint(0.0f, 0.0f); }
  virtual float GetCurrentScale() const
  { return 1.0f; }

  enum { ATTR_X, ATTR_Y, ATTR_WIDTH, ATTR_HEIGHT };
  nsSVGLength2 mLengthAttributes[4];
  static LengthInfo sLengthInfo[4];
  virtual LengthAttributesInfo GetLengthInfo() override;

  virtual SVGAnimatedPreserveAspectRatio *GetPreserveAspectRatio() override;

  virtual const nsSVGViewBox& GetViewBoxInternal() const { return mViewBox; }
  virtual nsSVGAnimatedTransformList* GetTransformInternal() const {
    return mTransforms;
  }
  nsSVGViewBox                   mViewBox;
  SVGAnimatedPreserveAspectRatio mPreserveAspectRatio;

  // The size of the rectangular SVG viewport into which we render. This is
  // not (necessarily) the same as the content area. See:
  //
  //   http://www.w3.org/TR/SVG11/coords.html#ViewportSpace
  //
  // XXXjwatt Currently only used for outer <svg>, but maybe we could use -1 to
  // flag this as an inner <svg> to save the overhead of GetCtx calls?
  // XXXjwatt our frame should probably reset these when it's destroyed.
  float mViewportWidth, mViewportHeight;

  bool     mHasChildrenOnlyTransform;
};

} // namespace dom

} // namespace mozilla

#endif // SVGViewportElement_h