firefox/layout/svg/ISVGDisplayableFrame.h

/* 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 LAYOUT_SVG_ISVGDISPLAYABLEFRAME_H_
#define LAYOUT_SVG_ISVGDISPLAYABLEFRAME_H_

#include "gfxMatrix.h"
#include "gfxPoint.h"
#include "gfxRect.h"
#include "mozilla/EnumSet.h"
#include "mozilla/gfx/MatrixFwd.h"
#include "nsQueryFrame.h"
#include "nsRect.h"

class gfxContext;
class nsIFrame;

namespace mozilla {
class SVGAnimatedLengthList;
class SVGAnimatedNumberList;
class SVGBBox;
class SVGLengthList;
class SVGNumberList;
class SVGUserUnitList;

namespace image {
struct imgDrawingParams;
}  // namespace image

enum class SVGBBoxFlag : uint16_t {
  // Include the geometry of the fill even when the fill does not
  // actually render (e.g. when fill="none" or fill-opacity="0")
  IncludeFillGeometry,
  IncludeStroke,
  // Include the geometry of the stroke even when the stroke does not
  // actually render (e.g. when stroke="none" or stroke-opacity="0")
  IncludeStrokeGeometry,
  IncludeMarkers,
  IncludeClipped,
  // Normally a getBBox call on outer-<svg> should only return the
  // bounds of the elements children. This flag will cause the
  // element's bounds to be returned instead.
  UseFrameBoundsForOuterSVG,
  // Normally GetBBox will return values that apply CSS Zoom.
  // This flag will cause the unzoomed element's bounds to be returned instead.
  DisregardCSSZoom,
  // https://developer.mozilla.org/en-US/docs/Web/API/Element/getBoundingClientRect
  ForGetClientRects,
  // If the given frame is an HTML element, only include the region of the
  // given frame, instead of all continuations of it, while computing bbox if
  // this flag is set.
  IncludeOnlyCurrentFrameForNonSVGElement,
  // This flag is only has an effect when the target is a <use> element.
  // getBBox returns the bounds of the elements children in user space if
  // this flag is set; Otherwise, getBBox returns the union bounds in
  // the coordinate system formed by the <use> element.
  UseUserSpaceOfUseElement,
  // For a frame with a clip-path, if this flag is set then the result
  // will not be clipped to the bbox of the content inside the clip-path.
  DoNotClipToBBoxOfContentInsideClipPath,
  // For some cases, e.g. when using transform-box: stroke-box, we may have
  // the cyclical dependency if any of the elements in the subtree has
  // non-scaling-stroke. In this case, we should break it and use
  // transform-box:fill-box instead.
  // https://github.com/w3c/csswg-drafts/issues/9640
  AvoidCycleIfNonScalingStroke
};
using SVGBBoxFlags = EnumSet<SVGBBoxFlag>;

/**
 * This class is used for elements that can be part of a directly displayable
 * section of a document.  This includes SVGGeometryFrame and SVGGFrame.
 * (Even though the latter doesn't display anything itself, if it contains
 * SVGGeometryFrame descendants it is can still be part of a displayable
 * section of a document)  This class is not used for elements that can never
 * display directly, including SVGGradientFrame and SVGPatternFrame.  (The
 * latter may contain displayable content, but it and its content are never
 * *directly* displayed in a document.  It can only end up being displayed by
 * means of a reference from other content.)
 *
 * Note specifically that SVG frames that inherit SVGContainerFrame do *not*
 * implement this class (only those that inherit SVGDisplayContainerFrame
 * do.)
 */
class ISVGDisplayableFrame : public nsQueryFrame {
 public:
  using imgDrawingParams = image::imgDrawingParams;

  NS_DECL_QUERYFRAME_TARGET(ISVGDisplayableFrame)

  /**
   * Paint this frame.
   *
   * SVG is painted using a combination of display lists (trees of
   * nsDisplayItem built by BuildDisplayList() implementations) and recursive
   * PaintSVG calls.  SVG frames with the NS_FRAME_IS_NONDISPLAY bit set are
   * always painted using recursive PaintSVG calls since display list painting
   * would provide no advantages (they wouldn't be retained for invalidation).
   * Displayed SVG is normally painted via a display list tree created under
   * SVGOuterSVGFrame::BuildDisplayList, In future we may use a PaintSVG() call
   * that recurses over the entire SVG frame tree on SVG container frames to
   * avoid display list construction when it is expensive and unnecessary (see
   * bug 934411).
   *
   * @param aTransform The transform that has to be multiplied onto the
   *   DrawTarget in order for drawing to be in this frame's SVG user space.
   *   Implementations of this method should avoid multiplying aTransform onto
   *   the DrawTarget when possible and instead just pass a transform down to
   *   their children.  This is preferable because changing the transform is
   *   very expensive for certain DrawTarget backends so it is best to minimize
   *   the number of transform changes.
   *
   * @param aImgParams imagelib parameters that may be used when painting
   *   feImage.
   */
  virtual void PaintSVG(gfxContext& aContext, const gfxMatrix& aTransform,
                        imgDrawingParams& aImgParams) = 0;

  /**
   * Returns the frame that should handle pointer events at aPoint.  aPoint is
   * expected to be in the SVG user space of the frame on which this method is
   * called.  The frame returned may be the frame on which this method is
   * called, any of its descendants or else nullptr.
   */
  virtual nsIFrame* GetFrameForPoint(const gfxPoint& aPoint) = 0;

  // Called on SVG child frames (except NS_FRAME_IS_NONDISPLAY frames)
  // to update and then invalidate their cached bounds. This method is not
  // called until after the SVGOuterSVGFrame has had its initial reflow
  // (i.e. once the SVG viewport dimensions are known). It should also only
  // be called by SVGOuterSVGFrame during its reflow.
  virtual void ReflowSVG() = 0;

  // Flags to pass to NotifySVGChange:
  //
  // TransformChanged:
  //   the current transform matrix for this frame has changed
  // CoordContextChanged:
  //   the dimensions of this frame's coordinate context has changed (percentage
  //   lengths must be reevaluated)
  // FullZoomChanged:
  //   the page's zoom level has changed
  enum class ChangeFlag {
    TransformChanged,
    CoordContextChanged,
    FullZoomChanged
  };
  using ChangeFlags = EnumSet<ChangeFlag>;

  /**
   * This is called on a frame when there has been a change to one of its
   * ancestors that might affect the frame too. ChangeFlags are passed
   * to indicate what changed.
   *
   * Implementations do not need to invalidate, since the caller will
   * invalidate the entire area of the ancestor that changed. However, they
   * may need to update their bounds.
   */
  virtual void NotifySVGChanged(ChangeFlags aFlags) = 0;

  /**
   * Get this frame's contribution to the rect returned by a GetBBox() call
   * that occurred either on this element, or on one of its ancestors.
   *
   * SVG defines an element's bbox to be the element's fill bounds in the
   * userspace established by that element. By allowing callers to pass in the
   * transform from the userspace established by this element to the userspace
   * established by an ancestor, this method allows callers to obtain this
   * element's fill bounds in the userspace established by that ancestor
   * instead. In that case, since we return the bounds in a different userspace
   * (the ancestor's), the bounds we return are not this element's bbox, but
   * rather this element's contribution to the bbox of the ancestor.
   *
   * @param aToBBoxUserspace The transform from the userspace established by
   *   this element to the userspace established by the ancestor on which
   *   getBBox was called. This will be the identity matrix if we are the
   *   element on which getBBox was called.
   *
   * @param aFlags Flags indicating whether, stroke, for example, should be
   *   included in the bbox calculation.
   */
  virtual SVGBBox GetBBoxContribution(const gfx::Matrix& aToBBoxUserspace,
                                      SVGBBoxFlags aFlags) = 0;

  // Are we a container frame?
  virtual bool IsDisplayContainer() = 0;
};

}  // namespace mozilla

#endif  // LAYOUT_SVG_ISVGDISPLAYABLEFRAME_H_