kicad/include/preview_items/draw_context.h

/*
 * This program source code file is part of KICAD, a free EDA CAD application.
 *
 * Copyright (C) 2017 Kicad Developers, see change_log.txt for contributors.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you may find one here:
 * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
 * or you may search the http://www.gnu.org website for the version 2 license,
 * or you may write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
 */

#ifndef PREVIEW_PREVIEW_DRAW_CONTEXT__H_
#define PREVIEW_PREVIEW_DRAW_CONTEXT__H_

#include <painter.h>
#include <math/vector2d.h>

namespace KIGFX
{
class GAL;
class VIEW;

namespace PREVIEW
{
    /**
     * A KIGFX::PREVIEW::DRAW_CONTEXT is a wrapper around a GAL and some other
     * settings that makes it easy to draw preview items consistently.
     *
     * This class provides some graphical items that are often used by preview
     * items. Complex items can be composed from these.
     */
    class DRAW_CONTEXT
    {
    public:
        DRAW_CONTEXT( KIGFX::VIEW& aView );

        /**
         * Draw a preview circle on the current layer
         *
         * @param aOrigin circle origin
         * @param aRad    circle radius
         * @param aDeEmphasised draw the circle de-emphasised
         */
        void DrawCircle( const VECTOR2I& aOrigin, double aRad, bool aDeEmphasised );


        /**
         * Draw a simple line on the current layer.
         *
         * @param aStart        line start point
         * @param aEnd          line end point
         * @param aDeEmphasised draw the line de-emphasised
         */
        void DrawLine( const VECTOR2I& aStart, const VECTOR2I& aEnd, bool aDeEmphasised );


        /**
         * Draw a straight line on the current layer, with a special highlight when
         * the line angle is a multiple of 45 degrees.
         *
         * @param aStart        line start point
         * @param aEnd          line end point
         * @param aDeEmphasised draw the line de-emphasised
         */
        void DrawLineWithAngleHighlight(
                const VECTOR2I& aStart, const VECTOR2I& aEnd, bool aDeEmphasised );

        /**
         * Draw an arc on the current layer, with a special highlight when
         * the line angle is a multiple of 45 degrees.
         *
         * @param aOrigin     the arc centre
         * @param aRad        the arc radius
         * @param aStartAngle the arc start angle
         * @param aEndAngle   the arc end angle
         */
        void DrawArcWithAngleHighlight(
                const VECTOR2I& aOrigin, double aRad, double aStartAngle, double aEndAngle );

    private:
        /**
         * @return the colour to use for "special" angles
         */
        COLOR4D getSpecialAngleColour() const;

        ///< The GAL to draw into
        KIGFX::GAL& m_gal;

        const KIGFX::RENDER_SETTINGS& m_render_settings;

        ///< The current layer to draw onto
        GAL_LAYER_ID m_currLayer;

        /// The line width to use for items
        float m_lineWidth;
    };

} // namespace PREVIEW
} // namespace KIGFX

#endif // PREVIEW_PREVIEW_DRAW_CONTEXT__H_