/* -*- 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 #include #include namespace drawinglayer { namespace 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 tis local value using updateViewInformation. 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 (an 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 com::sun::star::graphic::XPrimitive2D interface in the future. So, to implement a basic processor, it is necessary to overload 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, eventually 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 varibles, 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 { private: /// The ViewInformation2D itself. It's private to isolate accesses to it geometry::ViewInformation2D maViewInformation2D; protected: /* access method to allow the implementations to change the current ViewInformation2D if needed. This allows isolating these accesses later if needed */ void updateViewInformation(const geometry::ViewInformation2D& rViewInformation2D) { maViewInformation2D = rViewInformation2D; } /* 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); public: /// constructor/destructor explicit BaseProcessor2D(const geometry::ViewInformation2D& rViewInformation); virtual ~BaseProcessor2D(); /// the central processing method virtual void process(const primitive2d::Primitive2DSequence& rSource); /// data read access const geometry::ViewInformation2D& getViewInformation2D() const { return maViewInformation2D; } }; } // end of namespace processor2d } // end of namespace drawinglayer #endif //INCLUDED_DRAWINGLAYER_PROCESSOR2D_BASEPROCESSOR2D_HXX /* vim:set shiftwidth=4 softtabstop=4 expandtab: */