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;;; guile-sdl2 --- FFI bindings for SDL2
;;; Copyright © 2015 David Thompson <davet@gnu.org>
;;;
;;; This file is part of guile-sdl2.
;;;
;;; Guile-sdl2 is free software; you can redistribute it and/or modify
;;; it under the terms of the GNU Lesser General Public License as
;;; published by the Free Software Foundation; either version 3 of the
;;; License, or (at your option) any later version.
;;;
;;; Guile-sdl2 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 Lesser General Public
;;; License along with guile-sdl2. If not, see
;;; <http://www.gnu.org/licenses/>.
;;; Commentary:
;;
;; Font rendering.
;;
;;; Code:
(define-module (sdl2 ttf)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (srfi srfi-1)
#:use-module (system foreign)
#:use-module (sdl2)
#:use-module ((sdl2 bindings ttf) #:prefix ffi:)
#:export (ttf-init
ttf-quit
font?
load-font
delete-font!
font-height
font-ascent
font-descent
font-line-skip
font-size
font-glyph-index
font-glyph-metrics
font-style
set-font-style!
render-font-solid
render-font-blended))
(define (ttf-init)
"Initialize the TTF system."
(unless (zero? (ffi:ttf-init))
(sdl-error "ttf-init" "failed to initialize TTF library")))
(define (ttf-quit)
"Shut down and clean up the TTF system."
(ffi:ttf-quit))
(define-wrapped-pointer-type <font>
font?
wrap-font unwrap-font
(lambda (font port)
(format port "#<font ~x>"
(pointer-address (unwrap-font font)))))
(define (load-font file point-size)
"Load TTF font from FILE and return a new font object whose glyph
size is POINT-SIZE."
(let ((ptr (ffi:ttf-open-font (string->pointer file) point-size)))
(if (null-pointer? ptr)
(sdl-error "load-font" "failed to load font" file)
(wrap-font ptr))))
(define (delete-font! font)
"Delete the memory allocated for FONT."
(ffi:ttf-close-font (unwrap-font font)))
(define (font-height font)
"Return the maximum height of FONT."
(ffi:ttf-font-height (unwrap-font font)))
(define (font-ascent font)
"Return the maximum pixel ascent of all glyphs in FONT."
(ffi:ttf-font-ascent (unwrap-font font)))
(define (font-descent font)
"Return the maximum pixel descent of all glyphs in FONT."
(ffi:ttf-font-descent (unwrap-font font)))
(define (font-line-skip font)
"Return the recommended pixel height of a line in FONT."
(ffi:ttf-font-line-skip (unwrap-font font)))
(define (font-size font text)
"Return 2 values for the resulting surface size of the string TEXT
using FONT."
(let ((bv (make-s32vector 2)))
(if (zero? (ffi:ttf-size-utf8 (unwrap-font font)
(string->pointer text)
(bytevector->pointer bv)
(bytevector->pointer bv 4)))
(values (s32vector-ref bv 0) (s32vector-ref bv 1))
(sdl-error "size-utf8" "failed to get size utf8"))))
(define (font-glyph-index font char)
"Return the index of the glyph for CHAR in FONT, or #f if CHAR is
not present."
(let ((result (ffi:ttf-glyph-is-provided (unwrap-font font) (char->integer char))))
(if (eq? result 0) #f result)))
(define (font-glyph-metrics font char)
"Return 5 values for the metrics of CHAR in FONT: min x, max x, min y,
max y, and advance."
(let ((bv (make-s32vector 5)))
(if (zero? (ffi:ttf-glyph-metrics (unwrap-font font)
(char->integer char)
(bytevector->pointer bv)
(bytevector->pointer bv 4)
(bytevector->pointer bv 8)
(bytevector->pointer bv 12)
(bytevector->pointer bv 16)))
(values (s32vector-ref bv 0)
(s32vector-ref bv 1)
(s32vector-ref bv 2)
(s32vector-ref bv 3)
(s32vector-ref bv 4))
(sdl-error "font-glyph-metrics" "failed to get glyph metrics"))))
(define (font-style font)
"Return the rendering style of FONT. Return a list that may contain
any of the following symbols:
- bold
- italic
- underline
- strikethrough
The empty list returned if no there is no style applied."
(let ((bitmask (ffi:ttf-get-font-style (unwrap-font font))))
(filter-map (match-lambda
((sym . bit)
(and (not (zero? (logand bitmask bit))) sym)))
`((bold . ,ffi:SDL_TTF_STYLE_BOLD)
(italic . ,ffi:SDL_TTF_STYLE_ITALIC)
(underline . ,ffi:SDL_TTF_STYLE_UNDERLINE)
(strikethrough . ,ffi:SDL_TTF_STYLE_STRIKETHROUGH)))))
(define (set-font-style! font style)
"Set the rendering style of FONT to STYLE, a list that may contain
any of the following symbols:
- bold
- italic
- underline
- strikethrough
Use an empty list to set the normal style."
(let ((bitmask
(fold (lambda (flag prev)
(logior prev
(match flag
('bold ffi:SDL_TTF_STYLE_BOLD)
('italic ffi:SDL_TTF_STYLE_ITALIC)
('underline ffi:SDL_TTF_STYLE_UNDERLINE)
('strikethrough ffi:SDL_TTF_STYLE_STRIKETHROUGH))))
0
style)))
(ffi:ttf-set-font-style (unwrap-font font) bitmask)))
(define (render-font-solid font text color)
"Render TEXT, a UTF-8 encoded string, using FONT and COLOR, the
foreground color, and return a surface containing the results."
(let ((ptr (ffi:ttf-render-utf8-solid (unwrap-font font)
(string->pointer text)
((@@ (sdl2) color->struct) color))))
(if (null-pointer? ptr)
(sdl-error "render-font-solid" "failed to render text")
((@@ (sdl2 surface) wrap-surface) ptr))))
(define (render-font-blended font text color)
"Render TEXT, a UTF-8 encoded string, using FONT and COLOR, the
foreground color, and return a high-quality alpha-blended surface
containing the results."
(let ((ptr (ffi:ttf-render-utf8-blended (unwrap-font font)
(string->pointer text)
((@@ (sdl2) color->struct) color))))
(if (null-pointer? ptr)
(sdl-error "render-font-blended" "failed to render text")
((@@ (sdl2 surface) wrap-surface) ptr))))
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