164 lines
4.2 KiB
C++
164 lines
4.2 KiB
C++
/*
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* \brief Functor for drawing text on a surface
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* \author Norman Feske
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* \date 2006-08-04
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*/
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/*
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* Copyright (C) 2006-2018 Genode Labs GmbH
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*
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* This file is part of the Genode OS framework, which is distributed
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* under the terms of the GNU Affero General Public License version 3.
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*/
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#ifndef _INCLUDE__NITPICKER_GFX__TEXT_PAINTER_H_
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#define _INCLUDE__NITPICKER_GFX__TEXT_PAINTER_H_
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#include <util/interface.h>
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#include <util/utf8.h>
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#include <nitpicker_gfx/glyph_painter.h>
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struct Text_painter
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{
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typedef Genode::Surface_base::Point Point;
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typedef Genode::Surface_base::Area Area;
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typedef Genode::Surface_base::Rect Rect;
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typedef Genode::Codepoint Codepoint;
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typedef Glyph_painter::Fixpoint_number Fixpoint_number;
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typedef Glyph_painter::Position Position;
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typedef Glyph_painter::Glyph Glyph;
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/***************************************
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** Interface for accessing font data **
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***************************************/
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class Font : public Genode::Interface
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{
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protected:
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struct Apply_fn : Genode::Interface
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{
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virtual void apply(Glyph const &) const = 0;
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};
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virtual void _apply_glyph(Codepoint c, Apply_fn const &) const = 0;
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public:
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template <typename FN>
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void apply_glyph(Codepoint c, FN const &fn) const
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{
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/* helper to pass lambda 'fn' to virtual '_apply_glyph' method */
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struct Wrapped_fn : Apply_fn
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{
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FN const &_fn;
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void apply(Glyph const &glyph) const override { _fn(glyph); }
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Wrapped_fn(FN const &fn) : _fn(fn) { }
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};
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_apply_glyph(c, Wrapped_fn(fn));
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}
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struct Advance_info
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{
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unsigned const width;
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Fixpoint_number const advance;
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};
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virtual Advance_info advance_info(Codepoint c) const = 0;
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/**
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* Return distance from the top of a glyph the baseline of the font
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*/
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virtual unsigned baseline() const = 0;
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/**
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* Return height of text in pixels when rendered with the font
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*/
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virtual unsigned height() const = 0;
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/**
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* Return the bounding box that fits each single glyph of the font
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*/
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virtual Area bounding_box() const = 0;
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/**
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* Compute width of UTF8 string in pixels when rendered with the font
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*/
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Fixpoint_number string_width(Genode::Utf8_ptr utf8, unsigned len = ~0U) const
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{
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Fixpoint_number result { (int)0 };
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for (; utf8.complete() && len--; utf8 = utf8.next())
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result.value += advance_info(utf8.codepoint()).advance.value;
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return result;
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}
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};
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/**
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* Paint UTF8 string to surface
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*/
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template <typename PT>
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static inline void paint(Genode::Surface<PT> &surface,
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Position position,
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Font const &font,
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Genode::Color color,
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char const *string)
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{
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/* use sub-pixel positioning horizontally */
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Fixpoint_number x = position.x();
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Fixpoint_number const y = position.y();
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int const clip_top = surface.clip().y1(),
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clip_bottom = surface.clip().y2() + 1,
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clip_left = surface.clip().x1(),
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clip_right = surface.clip().x2() + 1;
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Genode::Utf8_ptr utf8(string);
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/* skip glyphs hidden behind left clipping border */
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bool skip = true;
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while (skip && utf8.complete()) {
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auto const glyph = font.advance_info(utf8.codepoint());
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skip = x.decimal() + (int)glyph.width < clip_left;
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if (skip) {
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x.value += glyph.advance.value;
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utf8 = utf8.next();
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}
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}
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int const x_start = x.decimal();
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unsigned const dst_line_len = surface.size().w();
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PT * const dst = surface.addr();
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PT const pixel(color.r, color.g, color.b);
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int const alpha = color.a;
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/* draw glyphs */
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for ( ; utf8.complete() && (x.decimal() <= clip_right); utf8 = utf8.next()) {
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font.apply_glyph(utf8.codepoint(), [&] (Glyph const &glyph) {
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Glyph_painter::paint(Position(x, y), glyph, dst, dst_line_len,
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clip_top, clip_bottom, clip_left, clip_right,
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pixel, alpha);
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x.value += glyph.advance.value;
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});
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}
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surface.flush_pixels(Rect(Point(x_start, y.decimal()),
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Area(x.decimal() - x_start + 1,
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font.bounding_box().h())));
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}
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};
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#endif /* _INCLUDE__NITPICKER_GFX__TEXT_PAINTER_H_ */
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