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#ifndef INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX

#define INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX

#include <drawinglayer/drawinglayerdllapi.h>

#include <drawinglayer/primitive2d/Primitive2DVisitor.hxx>

#include <drawinglayer/geometry/viewinformation2d.hxx>

namespace drawinglayer::primitive2d { class BasePrimitive2D; }

namespace drawinglayer::primitive2d { class Primitive2DContainer; }

namespace drawinglayer::processor2d

    {

        /** BaseProcessor2D class

            Base class for all C++ implementations of instances which process

            primitives.

            Instances which process primitives can be renderers, but also stuff

            for HitTests, BoundRect calculations and/or animation processing. The

            main usage are renderers, but they are supposed to handle any primitive

            processing.

            The base implementation is constructed with a ViewInformation2D which

            is accessible throughout the processor implementations. The idea is

            to construct any processor with a given ViewInformation2D. To be able

            to handle primitives which need to change the current transformation

            (as e.g. TransformPrimitive2D) it is allowed for the processor implementation

            to change its local value using setViewInformation2D.

            The basic processing method is process(..) which gets handed over the

            sequence of primitives to process. For convenience of the C++ implementations,

            the default implementation of process(..) maps all accesses to primitives to

            single calls to processBasePrimitive2D(..) where the primitive in question is

            already casted to the C++ implementation class.

            The process(..) implementation makes a complete iteration over the given

            sequence of primitives. If the Primitive is not derived from BasePrimitive2D

            and thus not part of the C++ implementations, it converts ViewInformation2D

            to the corresponding API implementation (a uno::Sequence< beans::PropertyValue >)

            and recursively calls the method process(..) at the primitive with the decomposition

            derived from that primitive. This is the preparation to handle unknown implementations

            of the css::graphic::XPrimitive2D interface in the future.

            So, to implement a basic processor, it is necessary to override and implement the

            processBasePrimitive2D(..) method. A minimal renderer has to support the

            Basic Primitives (see baseprimitive2d.hxx) and the Grouping Primitives (see

            groupprimitive2d.hxx). These are (currently):

            Basic Primitives:

            - BitmapPrimitive2D (bitmap data, possibly with transparency)

            - PointArrayPrimitive2D (single points)

            - PolygonHairlinePrimitive2D (hairline curves/polygons)

            - PolyPolygonColorPrimitive2D (colored polygons)

            Grouping Primitives:

            - TransparencePrimitive2D (objects with freely defined transparence)

            - InvertPrimitive2D (for XOR)

            - MaskPrimitive2D (for masking)

            - ModifiedColorPrimitive2D (for a stack of color modifications)

            - TransformPrimitive2D (for a transformation stack)

            A processor doing so is a minimal processor. Of course a processor may

            handle any higher-level primitive (that has a decomposition implementation)

            for more direct data access or performance reasons, too.

            The main part of a processBasePrimitive2D implementation is a switch..case

            construct, looking like the following:

            void foo::processBasePrimitive2D(const BasePrimitive2D& rCandidate)

            {

                switch(rCandidate.getPrimitive2DID())

                {

                    case PRIMITIVE2D_ID_??? :

                    {

                        // process PRIMITIVE2D_ID_??? here...

                        ...

                        break;

                    }

                    ...

                    default :

                    {

                        // process recursively

                        process(rCandidate.get2DDecomposition(getViewInformation2D()));

                        break;

                    }

                }

            }

            The default case makes the processor work with all complex primitives

            by recursively using their decomposition.

            You can also add a case for ignoring primitives by using:

                    case PRIMITIVE2D_ID_...IGNORE.A.. :

                    case PRIMITIVE2D_ID_...IGNORE.B.. :

                    case PRIMITIVE2D_ID_...IGNORE.C.. :

                    {

                        // ignore these primitives by neither processing nor

                        // recursively processing their decomposition

                        break;

                    }

            Another useful case is embedding the processing of a complex primitive by

            bracketing it with some actions:

                    case PRIMITIVE2D_ID_SOME_TEXT :

                    {

                        // encapsulate e.g. with changing local variables, e.g.

                        // sometimes it's good to know if a basic primitive is

                        // part of a text, especially when not handling the text

                        // self but by purpose want to handle the decomposed

                        // geometries in the processor

                        startText();

                        process(rCandidate.get2DDecomposition(getViewInformation2D()));

                        endText();

                        break;

                    }

            As an example a processor collecting the outlines of a sequence of primitives

            only needs to handle some Basic Primitives and create outline and collect

            outline polygons e.g. for primitives with area like BitmapPrimitive2D (a

            rectangle) and PolyPolygonColorPrimitive2D. When also handling the Grouping

            Primitives MaskPrimitive2D (e.g. ignoring its content, using the mask polyPolygon)

            and TransformPrimitive2D (to have the correct local transformation), a processor

            creating the outline can be written using just four (4) primitives. As a tipp, it can

            be helpful to add many for the purpose not interesting higher level primitives

            to not force their decomposition to be created and/or parsed.

         */

        class DRAWINGLAYER_DLLPUBLIC BaseProcessor2D : public  drawinglayer::primitive2d::Primitive2DDecompositionVisitor

        {

        private:

            /// The ViewInformation2D itself. It's private to isolate accesses to it

            geometry::ViewInformation2D                     maViewInformation2D;

        protected:

            /*  callback method to allow the implementations to react on changes

                to the current ViewInformation2D if needed (e.g. when your impl/

                derivation needs to react on AA change)

             */

            virtual void onViewInformation2DChanged() {}

            /*  as tooling, the process() implementation takes over API handling and calls this

                virtual render method when the primitive implementation is BasePrimitive2D-based.

                Default implementation does nothing

             */

            virtual void processBasePrimitive2D(const primitive2d::BasePrimitive2D& rCandidate);

            void process(const primitive2d::BasePrimitive2D& rCandidate);

            // Primitive2DDecompositionVisitor

            virtual void visit(const primitive2d::Primitive2DReference&) override final;

            virtual void visit(const primitive2d::Primitive2DContainer&) override final;

            virtual void visit(primitive2d::Primitive2DContainer&&) override final;

        public:

            /// constructor/destructor

            explicit BaseProcessor2D(geometry::ViewInformation2D aViewInformation);

            virtual ~BaseProcessor2D();

            /// the central processing method

            void process(const primitive2d::Primitive2DContainer& rSource);

            /// data read/write access to ViewInformation2D

            const geometry::ViewInformation2D& getViewInformation2D() const { return maViewInformation2D; }

            void setViewInformation2D(const geometry::ViewInformation2D& rNew);

        };

} // end of namespace drawinglayer::processor2d

#endif //INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX

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