/src/libreoffice/include/drawinglayer/processor2d/baseprocessor2d.hxx

Source
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
/*
 * This file is part of the LibreOffice project.
 *
 * 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/.
 *
 * This file incorporates work covered by the following license notice:
 *
 *   Licensed to the Apache Software Foundation (ASF) under one or more
 *   contributor license agreements. See the NOTICE file distributed
 *   with this work for additional information regarding copyright
 *   ownership. The ASF licenses this file to you under the Apache
 *   License, Version 2.0 (the "License"); you may not use this file
 *   except in compliance with the License. You may obtain a copy of
 *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
 */

#ifndef INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX
#define INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX

#include <drawinglayer/drawinglayerdllapi.h>

#include <drawinglayer/primitive2d/Primitive2DVisitor.hxx>
#include <drawinglayer/primitive2d/baseprimitive2d.hxx>
#include <drawinglayer/geometry/viewinformation2d.hxx>


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

/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

Line	Count	Source
1		/* -- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -- */
2		/*
3		* This file is part of the LibreOffice project.
4		*
5		* This Source Code Form is subject to the terms of the Mozilla Public
6		* License, v. 2.0. If a copy of the MPL was not distributed with this
7		* file, You can obtain one at http://mozilla.org/MPL/2.0/.
8		*
9		* This file incorporates work covered by the following license notice:
10		*
11		* Licensed to the Apache Software Foundation (ASF) under one or more
12		* contributor license agreements. See the NOTICE file distributed
13		* with this work for additional information regarding copyright
14		* ownership. The ASF licenses this file to you under the Apache
15		* License, Version 2.0 (the "License"); you may not use this file
16		* except in compliance with the License. You may obtain a copy of
17		* the License at http://www.apache.org/licenses/LICENSE-2.0 .
18		*/
19
20		#ifndef INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX
21		#define INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX
22
23		#include <drawinglayer/drawinglayerdllapi.h>
24
25		#include <drawinglayer/primitive2d/Primitive2DVisitor.hxx>
26		#include <drawinglayer/primitive2d/baseprimitive2d.hxx>
27		#include <drawinglayer/geometry/viewinformation2d.hxx>
28
29
30		namespace drawinglayer::processor2d
31		{
32		/** BaseProcessor2D class
33
34		Base class for all C++ implementations of instances which process
35		primitives.
36
37		Instances which process primitives can be renderers, but also stuff
38		for HitTests, BoundRect calculations and/or animation processing. The
39		main usage are renderers, but they are supposed to handle any primitive
40		processing.
41
42		The base implementation is constructed with a ViewInformation2D which
43		is accessible throughout the processor implementations. The idea is
44		to construct any processor with a given ViewInformation2D. To be able
45		to handle primitives which need to change the current transformation
46		(as e.g. TransformPrimitive2D) it is allowed for the processor implementation
47		to change its local value using setViewInformation2D.
48
49		The basic processing method is process(..) which gets handed over the
50		sequence of primitives to process. For convenience of the C++ implementations,
51		the default implementation of process(..) maps all accesses to primitives to
52		single calls to processBasePrimitive2D(..) where the primitive in question is
53		already casted to the C++ implementation class.
54
55		The process(..) implementation makes a complete iteration over the given
56		sequence of primitives. If the Primitive is not derived from BasePrimitive2D
57		and thus not part of the C++ implementations, it converts ViewInformation2D
58		to the corresponding API implementation (a uno::Sequence< beans::PropertyValue >)
59		and recursively calls the method process(..) at the primitive with the decomposition
60		derived from that primitive. This is the preparation to handle unknown implementations
61		of the css::graphic::XPrimitive2D interface in the future.
62
63		So, to implement a basic processor, it is necessary to override and implement the
64		processBasePrimitive2D(..) method. A minimal renderer has to support the
65		Basic Primitives (see baseprimitive2d.hxx) and the Grouping Primitives (see
66		groupprimitive2d.hxx). These are (currently):
67
68		Basic Primitives:
69
70		- BitmapPrimitive2D (bitmap data, possibly with transparency)
71		- PointArrayPrimitive2D (single points)
72		- PolygonHairlinePrimitive2D (hairline curves/polygons)
73		- PolyPolygonColorPrimitive2D (colored polygons)
74
75		Grouping Primitives:
76
77		- TransparencePrimitive2D (objects with freely defined transparence)
78		- InvertPrimitive2D (for XOR)
79		- MaskPrimitive2D (for masking)
80		- ModifiedColorPrimitive2D (for a stack of color modifications)
81		- TransformPrimitive2D (for a transformation stack)
82
83		A processor doing so is a minimal processor. Of course a processor may
84		handle any higher-level primitive (that has a decomposition implementation)
85		for more direct data access or performance reasons, too.
86
87		The main part of a processBasePrimitive2D implementation is a switch..case
88		construct, looking like the following:
89
90		void foo::processBasePrimitive2D(const BasePrimitive2D& rCandidate)
91		{
92		switch(rCandidate.getPrimitive2DID())
93		{
94		case PRIMITIVE2D_ID_??? :
95		{
96		// process PRIMITIVE2D_ID_??? here...
97
98		...
99
100		break;
101		}
102
103		...
104
105		default :
106		{
107		// process recursively
108		process(rCandidate.get2DDecomposition(getViewInformation2D()));
109		break;
110		}
111		}
112		}
113
114		The default case makes the processor work with all complex primitives
115		by recursively using their decomposition.
116
117		You can also add a case for ignoring primitives by using:
118
119		case PRIMITIVE2D_ID_...IGNORE.A.. :
120		case PRIMITIVE2D_ID_...IGNORE.B.. :
121		case PRIMITIVE2D_ID_...IGNORE.C.. :
122		{
123		// ignore these primitives by neither processing nor
124		// recursively processing their decomposition
125		break;
126		}
127
128		Another useful case is embedding the processing of a complex primitive by
129		bracketing it with some actions:
130
131		case PRIMITIVE2D_ID_SOME_TEXT :
132		{
133		// encapsulate e.g. with changing local variables, e.g.
134		// sometimes it's good to know if a basic primitive is
135		// part of a text, especially when not handling the text
136		// self but by purpose want to handle the decomposed
137		// geometries in the processor
138		startText();
139		process(rCandidate.get2DDecomposition(getViewInformation2D()));
140		endText();
141		break;
142		}
143
144		As an example a processor collecting the outlines of a sequence of primitives
145		only needs to handle some Basic Primitives and create outline and collect
146		outline polygons e.g. for primitives with area like BitmapPrimitive2D (a
147		rectangle) and PolyPolygonColorPrimitive2D. When also handling the Grouping
148		Primitives MaskPrimitive2D (e.g. ignoring its content, using the mask polyPolygon)
149		and TransformPrimitive2D (to have the correct local transformation), a processor
150		creating the outline can be written using just four (4) primitives. As a tipp, it can
151		be helpful to add many for the purpose not interesting higher level primitives
152		to not force their decomposition to be created and/or parsed.
153		*/
154		class DRAWINGLAYER_DLLPUBLIC BaseProcessor2D : public drawinglayer::primitive2d::Primitive2DDecompositionVisitor
155		{
156		private:
157		/// The ViewInformation2D itself. It's private to isolate accesses to it
158		geometry::ViewInformation2D maViewInformation2D;
159
160		protected:
161		/* callback method to allow the implementations to react on changes
162		to the current ViewInformation2D if needed (e.g. when your impl/
163		derivation needs to react on AA change)
164		*/
165	0	virtual void onViewInformation2DChanged() {}
166
167		/* as tooling, the process() implementation takes over API handling and calls this
168		virtual render method when the primitive implementation is BasePrimitive2D-based.
169		Default implementation does nothing
170		*/
171		virtual void processBasePrimitive2D(const primitive2d::BasePrimitive2D& rCandidate);
172
173		void process(const primitive2d::BasePrimitive2D& rCandidate);
174
175		// Primitive2DDecompositionVisitor
176		virtual void visit(const primitive2d::Primitive2DReference&) override final;
177		virtual void visit(const primitive2d::Primitive2DContainer&) override final;
178		virtual void visit(primitive2d::Primitive2DContainer&&) override final;
179
180		public:
181		/// constructor/destructor
182		explicit BaseProcessor2D(geometry::ViewInformation2D aViewInformation);
183		virtual ~BaseProcessor2D();
184
185		/// the central processing method
186		void process(const primitive2d::Primitive2DContainer& rSource);
187
188		/// data read/write access to ViewInformation2D
189	436k	const geometry::ViewInformation2D& getViewInformation2D() const { return maViewInformation2D; }
190		void setViewInformation2D(const geometry::ViewInformation2D& rNew);
191		};
192
193		} // end of namespace drawinglayer::processor2d
194
195
196		#endif //INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX
197
198		/* vim:set shiftwidth=4 softtabstop=4 expandtab: */

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Created: 2025-12-08 09:28