ags_font_renderer.h

/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef AGS_SHARED_FONT_AGS_FONT_RENDERER_H
#define AGS_SHARED_FONT_AGS_FONT_RENDERER_H

#include "common/std/utility.h"
#include "ags/shared/core/types.h"
#include "ags/shared/util/string.h"

namespace AGS3 {

class BITMAP;

class IAGSFontRenderer {
public:
    virtual bool LoadFromDisk(int fontNumber, int fontSize) = 0;
    virtual void FreeMemory(int fontNumber) = 0;
    virtual bool SupportsExtendedCharacters(int fontNumber) = 0;
    virtual int GetTextWidth(const char *text, int fontNumber) = 0;
    // Get actual height of the given line of text
    virtual int GetTextHeight(const char *text, int fontNumber) = 0;
    virtual void RenderText(const char *text, int fontNumber, BITMAP *destination, int x, int y, int colour) = 0;
    virtual void AdjustYCoordinateForFont(int *ycoord, int fontNumber) = 0;
    virtual void EnsureTextValidForFont(char *text, int fontNumber) = 0;
protected:
    IAGSFontRenderer() {}
    ~IAGSFontRenderer() {}
};

// Extended font renderer interface.
// WARNING: this interface is exposed for plugins and declared for the second time in agsplugin.h
class IAGSFontRenderer2 : public IAGSFontRenderer {
public:
    // Returns engine API version this font renderer complies to.
    // Must not be lower than 26 (this interface was added at API v26).
    virtual int GetVersion() = 0;
    // Returns an arbitrary renderer name; this is for informational
    // purposes only.
    virtual const char *GetRendererName() = 0;
    // Returns given font's name (if available).
    virtual const char *GetFontName(int fontNumber) = 0;
    // Returns the given font's height: that is the maximal vertical size
    // that the font glyphs may occupy.
    virtual int GetFontHeight(int fontNumber) = 0;
    // Returns the given font's linespacing;
    // is allowed to return 0, telling that no specific linespacing
    // is assigned for this font.
    virtual int GetLineSpacing(int fontNumber) = 0;

protected:
    IAGSFontRenderer2() {}
    ~IAGSFontRenderer2() {}
};

// Font render params, mainly for dealing with various compatibility issues.
struct FontRenderParams {
    // Font's render multiplier
    int SizeMultiplier = 1;
    int LoadMode = 0; // contains font flags from FFLG_LOADMODEMASK
};

// Describes loaded font's properties
struct FontMetrics {
    // Nominal font's height, equals to the game-requested size of the font.
    // This may or not be equal to font's face height; sometimes a font cannot
    // be scaled exactly to particular size, and then nominal height appears different
    // (usually - smaller) than the real one.
    int NominalHeight = 0;
    // Real font's height, equals to reported ascender + descender.
    // This is what you normally think as a font's height.
    int RealHeight = 0;
    // Compatible height, equals to either NominalHeight or RealHeight,
    // selected depending on the game settings.
    // This property is used in calculating linespace, etc.
    int CompatHeight = 0;
    // Maximal vertical extent of a font (top; bottom), this tells the actual
    // graphical bounds that may be occupied by font's glyphs.
    // In a "proper" font this extent is (0; RealHeight-1), but "bad" fonts may
    // have individual glyphs exceeding these bounds, in both directions.
    // Note that "top" may be negative!
    std::pair<int, int> VExtent;

    inline int ExtentHeight() const { return VExtent.second - VExtent.first; }
};

// The strictly internal font renderer interface, not to use in plugin API.
// Contains methods necessary for built-in font renderers.
class IAGSFontRendererInternal : public IAGSFontRenderer2 {
public:
    // Tells if this is a bitmap font (otherwise it's a vector font)
    virtual bool IsBitmapFont() = 0;
    // Load font, applying extended font rendering parameters
    virtual bool LoadFromDiskEx(int fontNumber, int fontSize, AGS::Shared::String *src_filename,
                                const FontRenderParams *params, FontMetrics *metrics) = 0;
    // Fill FontMetrics struct; note that it may be left cleared if this is not supported
    virtual void GetFontMetrics(int fontNumber, FontMetrics *metrics) = 0;
    // Perform any necessary adjustments when the AA mode is toggled
    virtual void AdjustFontForAntiAlias(int fontNumber, bool aa_mode) = 0;

protected:
    IAGSFontRendererInternal() {}
    ~IAGSFontRendererInternal() {}
};

} // namespace AGS3

#endif