AOO410/main/basegfx/inc/basegfx/polygon/b2dtrapezoid.hxx

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#ifndef _BGFX_POLYGON_B2DTRAPEZOID_HXX
#define _BGFX_POLYGON_B2DTRAPEZOID_HXX

#include <basegfx/polygon/b2dpolygon.hxx>
#include <basegfx/polygon/b2dpolypolygon.hxx>
#include <vector>

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

namespace basegfx
{
    // class to hold a single trapezoid
	class B2DTrapezoid
	{
	private:
        // Geometry data. YValues are down-oriented, this means bottom should
        // be bigger than top to be below it. The constructor implementation
        // guarantees:
        //
        // - mfBottomY >= mfTopY
        // - mfTopXRight >= mfTopXLeft
        // - mfBottomXRight >= mfBottomXLeft
		double				mfTopXLeft;
		double				mfTopXRight;
		double				mfTopY;
		double				mfBottomXLeft;
		double				mfBottomXRight;
		double				mfBottomY;

	public:
        // constructor
		B2DTrapezoid(
			const double& rfTopXLeft,
			const double& rfTopXRight,
			const double& rfTopY,
			const double& rfBottomXLeft,
			const double& rfBottomXRight,
			const double& rfBottomY);

        // data read access
		const double& getTopXLeft() const { return mfTopXLeft; }
		const double& getTopXRight() const { return mfTopXRight; }
		const double& getTopY() const { return mfTopY; }
		const double& getBottomXLeft() const { return mfBottomXLeft; }
		const double& getBottomXRight() const { return mfBottomXRight; }
		const double& getBottomY() const { return mfBottomY; }

        // convenience method to get content as Polygon
		B2DPolygon getB2DPolygon() const;
	};

    typedef ::std::vector< B2DTrapezoid > B2DTrapezoidVector;

} // end of namespace basegfx

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

namespace basegfx
{
	namespace tools
	{
        // convert SourcePolyPolygon to trapezoids. The trapezoids will be appended to
        // ro_Result. ro_Result will not be cleared. If SourcePolyPolygon contains curves,
        // it's default AdaptiveSubdivision will be used.
        // CAUTION: Trapezoids are oreintation-dependent in the sense that the upper and lower
        // lines have to be parallel to the X-Axis, thus this subdivision is NOT simply usable
        // for primitive decompositions. To use it, the shear and rotate parts of the
        // involved transformations HAVE to be taken into account.
		void trapezoidSubdivide(
            B2DTrapezoidVector& ro_Result, 
            const B2DPolyPolygon& rSourcePolyPolygon);

        // directly create trapezoids from given edge. Depending on the given geometry,
        // none up to three trapezoids will be created
        void createLineTrapezoidFromEdge(
            B2DTrapezoidVector& ro_Result, 
            const B2DPoint& rPointA, 
            const B2DPoint& rPointB, 
            double fLineWidth = 1.0);

        // create trapezoids for all edges of the given polygon. The closed state of
        // the polygon is taken into account. If curves are contaned, the default
        // AdaptiveSubdivision will be used.
        void createLineTrapezoidFromB2DPolygon(
            B2DTrapezoidVector& ro_Result, 
            const B2DPolygon& rPolygon,
            double fLineWidth = 1.0);

        // create trapezoids for all edges of the given polyPolygon. The closed state of
        // the PolyPolygon is taken into account. If curves are contaned, the default
        // AdaptiveSubdivision will be used.
        void createLineTrapezoidFromB2DPolyPolygon(
            B2DTrapezoidVector& ro_Result, 
            const B2DPolyPolygon& rPolyPolygon,
            double fLineWidth = 1.0);

    } // end of namespace tools
} // end of namespace basegfx

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

#endif /* _BGFX_POLYGON_B2DTRAPEZOID_HXX */