SVGMotionSMILPathUtils.h

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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/. */

/* Helper class to help with generating anonymous path elements for

   <animateMotion> elements to use. */

#ifndef DOM_SVG_SVGMOTIONSMILPATHUTILS_H_

#define DOM_SVG_SVGMOTIONSMILPATHUTILS_H_

#include "mozilla/Attributes.h"

#include "mozilla/RefPtr.h"

#include "mozilla/SMILParserUtils.h"

#include "mozilla/gfx/2D.h"

#include "gfxPlatform.h"

#include "nsDebug.h"

#include "nsStringFwd.h"

#include "nsTArray.h"

namespace mozilla {

namespace dom {

class SVGElement;

class SVGMotionSMILPathUtils {

  using DrawTarget = mozilla::gfx::DrawTarget;

  using Path = mozilla::gfx::Path;

  using PathBuilder = mozilla::gfx::PathBuilder;

 public:

  // Class to assist in generating a Path, based on

  // coordinates in the <animateMotion> from/by/to/values attributes.

  class PathGenerator {

   public:

    explicit PathGenerator(const dom::SVGElement* aSVGElement)

        : mSVGElement(aSVGElement), mHaveReceivedCommands(false) {

      RefPtr<DrawTarget> drawTarget =

          gfxPlatform::GetPlatform()->ScreenReferenceDrawTarget();

      NS_ASSERTION(

          gfxPlatform::GetPlatform()->SupportsAzureContentForDrawTarget(

              drawTarget),

          "Should support Moz2D content drawing");

      mPathBuilder = drawTarget->CreatePathBuilder();

    // Methods for adding various path commands to output path.

    // Note: aCoordPairStr is expected to be a whitespace and/or

    // comma-separated x,y coordinate-pair -- see description of

    // "the specified values for from, by, to, and values" at

    //    http://www.w3.org/TR/SVG11/animate.html#AnimateMotionElement

    void MoveToOrigin();

    bool MoveToAbsolute(const nsAString& aCoordPairStr);

    bool LineToAbsolute(const nsAString& aCoordPairStr,

                        double& aSegmentDistance);

    bool LineToRelative(const nsAString& aCoordPairStr,

                        double& aSegmentDistance);

    // Accessor to let clients check if we've received any commands yet.

    inline bool HaveReceivedCommands() { return mHaveReceivedCommands; }

    // Accessor to get the finalized path

    already_AddRefed<Path> GetResultingPath();

   protected:

    // Helper methods

    bool ParseCoordinatePair(const nsAString& aCoordPairStr, float& aXVal,

                             float& aYVal);

    // Member data

    const dom::SVGElement* mSVGElement;  // context for converting to user units

    RefPtr<PathBuilder> mPathBuilder;

    bool mHaveReceivedCommands;

};

  // Class to assist in passing each subcomponent of a |values| attribute to

  // a PathGenerator, for generating a corresponding Path.

  class MOZ_STACK_CLASS MotionValueParser

      : public SMILParserUtils::GenericValueParser {

   public:

    MotionValueParser(PathGenerator* aPathGenerator,

                      FallibleTArray<double>* aPointDistances)

        : mPathGenerator(aPathGenerator),

          mPointDistances(aPointDistances),

          mDistanceSoFar(0.0) {

      MOZ_ASSERT(mPointDistances->IsEmpty(),

                 "expecting point distances array to start empty");

    // SMILParserUtils::GenericValueParser interface

    bool Parse(const nsAString& aValueStr) override;

   protected:

    PathGenerator* mPathGenerator;

    FallibleTArray<double>* mPointDistances;

    double mDistanceSoFar;

};

};

}  // namespace mozilla

#endif  // DOM_SVG_SVGMOTIONSMILPATHUTILS_H_