gecko-dev/layout/svg/nsISVGChildFrame.h

/* -*- 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/. */

#ifndef __NS_ISVGCHILDFRAME_H__
#define __NS_ISVGCHILDFRAME_H__

#include "gfxRect.h"
#include "nsQueryFrame.h"

class gfxContext;
class gfxMatrix;
class nsIFrame;
class SVGBBox;

struct nsRect;

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

namespace gfx {
class Matrix;
} // namespace gfx
} // namespace mozilla

/**
 * This class is not particularly well named. It is inherited by some, but
 * not all SVG frame classes that can be descendants of an
 * nsSVGOuterSVGFrame in the frame tree. Note specifically that SVG container
 * frames that do not inherit nsSVGDisplayContainerFrame do not inherit this
 * class (so that's classes that only inherit nsSVGContainerFrame).
 */
class nsISVGChildFrame : public nsQueryFrame
{
public:
  typedef mozilla::SVGAnimatedNumberList SVGAnimatedNumberList;
  typedef mozilla::SVGNumberList SVGNumberList;
  typedef mozilla::SVGAnimatedLengthList SVGAnimatedLengthList;
  typedef mozilla::SVGLengthList SVGLengthList;
  typedef mozilla::SVGUserUnitList SVGUserUnitList;
  typedef mozilla::image::DrawResult DrawResult;

  NS_DECL_QUERYFRAME_TARGET(nsISVGChildFrame)

  /**
   * 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
   * nsSVGOuterSVGFrame::BuildDisplayList, unless the
   * svg.display-lists.painting.enabled pref has been set to false by the user
   * in which case it is done via an nsSVGOuterSVGFrame::PaintSVG() call that
   * recurses over the entire SVG frame tree.  In future we may use PaintSVG()
   * calls 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 aDirtyRect The area being redrawn, in frame offset pixel
   *   coordinates.
   */
  virtual DrawResult PaintSVG(gfxContext& aContext,
                              const gfxMatrix& aTransform,
                              const nsIntRect* aDirtyRect = nullptr) = 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;

  // Get bounds in our nsSVGOuterSVGFrame's coordinates space (in app units)
  virtual nsRect GetCoveredRegion()=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 nsSVGOuterSVGFrame has had its initial reflow
  // (i.e. once the SVG viewport dimensions are known). It should also only
  // be called by nsSVGOuterSVGFrame during its reflow.
  virtual void ReflowSVG()=0;

  // Flags to pass to NotifySVGChange:
  //
  // DO_NOT_NOTIFY_RENDERING_OBSERVERS - this should only be used when
  //                           updating the descendant frames of a clipPath,
  //                           mask, pattern or marker frame (or other similar
  //                           NS_FRAME_IS_NONDISPLAY frame) immediately
  //                           prior to painting that frame's descendants.
  // TRANSFORM_CHANGED     - the current transform matrix for this frame has changed
  // COORD_CONTEXT_CHANGED - the dimensions of this frame's coordinate context has
  //                           changed (percentage lengths must be reevaluated)
  enum SVGChangedFlags {
    TRANSFORM_CHANGED     = 0x01,
    COORD_CONTEXT_CHANGED = 0x02,
    FULL_ZOOM_CHANGED     = 0x04
  };
  /**
   * This is called on a frame when there has been a change to one of its
   * ancestors that might affect the frame too. SVGChangedFlags 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(uint32_t 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 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 mozilla::gfx::Matrix &aToBBoxUserspace,
                                      uint32_t aFlags) = 0;

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

#endif // __NS_ISVGCHILDFRAME_H__