AOO410/main/basegfx/inc/basegfx/tools/b2dclipstate.hxx

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#ifndef _BGFX_TOOLS_CLIPSTATE_HXX
#define _BGFX_TOOLS_CLIPSTATE_HXX

#include <sal/types.h>
#include <o3tl/cow_wrapper.hxx>

//////////////////////////////////////////////////////////////////////////////

namespace basegfx
{
    class B2DRange;
    class B2DPolyRange;
    class B2DPolygon;
    class B2DPolyPolygon;

    namespace tools
    {
        struct ImplB2DClipState;

        /** This class provides an optimized, symbolic clip state for graphical output

            Having a current 'clip' state is a common attribute of
            almost all graphic output APIs, most of which internally
            represent it via a list of rectangular bands. In contrast,
            this implementation purely uses symbolic clips, but in a
            quite efficient manner, deferring actual evaluation until
            a clip representation is requested, and using faster code
            paths for common special cases (like all-rectangle clips)
         */
        class B2DClipState
        {
        public:
            typedef o3tl::cow_wrapper< ImplB2DClipState > ImplType;

        private:
            ImplType mpImpl;

        public:
            /// Init clip, in 'cleared' state - everything is visible
            B2DClipState();
            ~B2DClipState();
            B2DClipState( const B2DClipState& );
            explicit B2DClipState( const B2DRange& );
            explicit B2DClipState( const B2DPolygon& );
            explicit B2DClipState( const B2DPolyPolygon& );
            B2DClipState& operator=( const B2DClipState& );

            /// unshare this poly-range with all internally shared instances
            void makeUnique();
            
            /// Set clip to 'null' - nothing is visible
            void makeNull();
            /// returns true when clip is 'null' - nothing is visible
            bool isNull() const;

            /// Set clip 'cleared' - everything is visible
            void makeClear();
            /// returns true when clip is 'cleared' - everything is visible
            bool isCleared() const;

            bool operator==(const B2DClipState&) const;
            bool operator!=(const B2DClipState&) const;

            void unionRange(const B2DRange& );
            void unionPolygon(const B2DPolygon& );
            void unionPolyPolygon(const B2DPolyPolygon& );
            void unionClipState(const B2DClipState& );

            void intersectRange(const B2DRange& );
            void intersectPolygon(const B2DPolygon& );
            void intersectPolyPolygon(const B2DPolyPolygon& );
            void intersectClipState(const B2DClipState& );

            void subtractRange(const B2DRange& );
            void subtractPolygon(const B2DPolygon& );
            void subtractPolyPolygon(const B2DPolyPolygon& );
            void subtractClipState(const B2DClipState& );

            void xorRange(const B2DRange& );
            void xorPolygon(const B2DPolygon& );
            void xorPolyPolygon(const B2DPolyPolygon& );
            void xorClipState(const B2DClipState& );

            B2DPolyPolygon getClipPoly() const;
        };
    }
}

#endif // _BGFX_TOOLS_CLIPSTATE_HXX