TextRenderer.h

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/* Copyright (C) 2022 Wildfire Games.
 * This file is part of 0 A.D.
 *
 * 0 A.D. 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.
 *
 * 0 A.D. 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 0 A.D.  If not, see <http://www.gnu.org/licenses/>.
 */

#ifndef INCLUDED_TEXTRENDERER
#define INCLUDED_TEXTRENDERER

#include "graphics/Color.h"
#include "graphics/ShaderProgram.h"
#include "maths/Rect.h"
#include "maths/Vector2D.h"
#include "ps/CStrIntern.h"
#include "renderer/backend/IDeviceCommandContext.h"

#include <list>

class CFont;
class CMatrix3D;

class CTextRenderer
{
public:
    CTextRenderer();

    /**
     * Reset the text transform to the default, with (0,0) in the top-left corner.
     */
    void ResetTranslate(const CVector2D& translate = CVector2D{});

    const CVector2D& GetTranslate() const { return m_Translate; }
    void Translate(float x, float y);

    /**
     * Set clipping rectangle, in pre-transform coordinates (i.e. text is clipped against
     * this rect based purely on the x,y values passed into Put()). Text fully outside the
     * clipping rectangle may not be rendered. Should be used in conjunction with SetScissors
     * for precise clipping - this is just an optimisation.
     */
    void SetClippingRect(const CRect& rect);

    /**
     * Set the color for subsequent print calls.
     */
    void SetCurrentColor(const CColor& color);

    /**
     * Set the font for subsequent print calls.
     */
    void SetCurrentFont(CStrIntern font);

    /**
     * Print formatted text at (0,0) under the current transform,
     * and advance the transform by the width of the text.
     */
    void PrintfAdvance(const wchar_t* fmt, ...);

    /**
     * Print formatted text at (x,y) under the current transform.
     * Does not alter the current transform.
     */
    void PrintfAt(float x, float y, const wchar_t* fmt, ...);

    /**
     * Print text at (0,0) under the current transform,
     * and advance the transform by the width of the text.
     */
    void PutAdvance(const wchar_t* buf);

    /**
     * Print text at (x,y) under the current transform.
     * Does not alter the current transform.
     */
    void Put(float x, float y, const wchar_t* buf);

    /**
     * Print text at (x,y) under the current transform.
     * Does not alter the current transform.
     * @p buf must be a UTF-8 string.
     */
    void Put(float x, float y, const char* buf);

    /**
     * Print text at (x,y) under the current transform.
     * Does not alter the current transform.
     * @p buf must remain valid until Render() is called.
     * (This should be used to minimise memory copies when possible.)
     */
    void Put(float x, float y, const std::wstring* buf);

    /**
     * Render all of the previously printed text calls.
     */
    void Render(
        Renderer::Backend::IDeviceCommandContext* deviceCommandContext,
        Renderer::Backend::IShaderProgram* shader,
        const CVector2D& transformScale, const CVector2D& translation);

private:
    friend struct SBatchCompare;

    /**
     * A string (optionally owned by this object, or else pointing to an
     * externally-owned string) with a position.
     */
    struct SBatchRun
    {
    private:
        SBatchRun& operator=(const SBatchRun&);
    public:
        SBatchRun()
            : text(NULL), owned(false)
        {
        }

        SBatchRun(const SBatchRun& str)
            : x(str.x), y(str.y), owned(str.owned)
        {
            if (owned)
                text = new std::wstring(*str.text);
            else
                text = str.text;
        }

        ~SBatchRun()
        {
            if (owned)
                delete text;
        }

        float x, y;

        const std::wstring* text;
        bool owned;
    };

    /**
     * A list of SBatchRuns, with a single font/color/transform,
     * to be rendered in a single GL call.
     */
    struct SBatch
    {
        size_t chars; // sum of runs[i].text->size()
        CVector2D translate;
        CColor color;
        std::shared_ptr<CFont> font;
        std::list<SBatchRun> runs;
    };

    void PutString(float x, float y, const std::wstring* buf, bool owned);

    CVector2D m_Translate;
    CRect m_Clipping;

    CColor m_Color;
    CStrIntern m_FontName;
    std::shared_ptr<CFont> m_Font;

    bool m_Dirty = true;

    std::list<SBatch> m_Batches;
};

#endif // INCLUDED_TEXTRENDERER