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;;; Sly
;;; Copyright (C) 2013, 2014 David Thompson <dthompson2@worcester.edu>
;;;
;;; 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/>.
;;; Commentary:
;;
;; Font rendering.
;;
;;; Code:
(define-module (sly render font)
#:use-module (rnrs bytevectors)
#:use-module (srfi srfi-2)
#:use-module (srfi srfi-4)
#:use-module (srfi srfi-9)
#:use-module (system foreign)
#:use-module ((sdl sdl) #:prefix SDL:)
#:use-module ((sdl ttf) #:prefix SDL:)
#:use-module (gl)
#:use-module (sly wrappers gl)
#:use-module (sly render color)
#:use-module (sly config)
#:use-module (sly render sprite)
#:use-module (sly render texture)
#:export (enable-fonts
load-font
load-default-font
font?
font-point-size
make-label))
;;;
;;; Font
;;;
(define (enable-fonts)
(SDL:ttf-init))
(define-record-type <font>
(make-font ttf point-size)
font?
(ttf font-ttf)
(point-size font-point-size))
(define (load-font filename point-size)
"Load the TTF font in FILENAME with the given POINT-SIZE."
(if (file-exists? filename)
(make-font (SDL:load-font filename point-size) point-size)
(error "File not found!" filename)))
(define* (load-default-font #:optional (point-size 12))
"Load the Sly default TTF font. POINT-SIZE is an optional
argument with a default value of 12."
(load-font (string-append %pkgdatadir "/fonts/DejaVuSans.ttf") point-size))
(define (flip-pixels-vertically pixels width height)
"Create a new bytevector that reverses the rows in PIXELS, a WIDTH x
HEIGHT, 32 bit color bytevector."
(let ((buffer (make-u8vector (bytevector-length pixels)))
(row-width (* width 4))) ; assuming 32 bit color
(let loop ((y 0))
(when (< y height)
(let* ((y* (- height y 1))
(source-start (* y row-width))
(target-start (* y* row-width)))
(bytevector-copy! pixels source-start buffer target-start row-width)
(loop (1+ y)))))
buffer))
(define (render-text font text)
"Return a new texture with TEXT rendered using FONT."
;; An empty string will result in a surface value of #f, in which
;; case we want to abort the texture creation process.
(and-let* ((surface (SDL:render-utf8 (font-ttf font) text
(SDL:make-color 255 255 255) #t))
(width (SDL:surface:w surface))
(height (SDL:surface:h surface))
;; Need to flip pixels so that origin is on the bottom-left.
(pixels (flip-pixels-vertically (SDL:surface-pixels surface)
width height)))
;; Need to flip pixels so that origin is on the bottom-left.
(bytevector->texture pixels width height 'linear 'linear)))
(define* (make-label font text #:key (anchor 'top-left))
"Create a sprite that displays TEXT rendered using FONT. ANCHOR
defines the sprite's origin, which is 'top-left' by default."
(let ((texture (render-text font text)))
(make-sprite texture #:anchor anchor)))
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