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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:
;;
;; SDL surface manipulation.
;;
;;; Code:
(define-module (sdl2 surface)
#:use-module (ice-9 format)
#:use-module (ice-9 match)
#:use-module (rnrs bytevectors)
#:use-module (system foreign)
#:use-module ((sdl2 bindings) #:prefix ffi:)
#:use-module (sdl2)
#:export (surface?
delete-surface!
call-with-surface
load-bmp
surface-width
surface-height
surface-pitch
surface-pixels))
(define-wrapped-pointer-type <surface>
surface?
wrap-surface unwrap-surface
(lambda (surface port)
(format port "#<surface ~x>"
(pointer-address (unwrap-surface surface)))))
(define (delete-surface! surface)
"Free the memory used by SURFACE."
(ffi:sdl-free-surface (unwrap-surface surface)))
(define (call-with-surface surface proc)
"Call PROC, passing it SURFACE and deleting SURFACE upon exit of
PROC."
(dynamic-wind
(const #t)
(lambda ()
(proc surface))
(lambda ()
(delete-surface! surface))))
;; The equivalent of the SDL_LoadBMP C macro.
(define (load-bmp file)
"Create a new surface from the bitmap data in FILE."
(let ((ptr (ffi:sdl-load-bmp-rw (ffi:sdl-rw-from-file (string->pointer file)
(string->pointer "rb"))
1)))
(if (null-pointer? ptr)
(sdl-error "load-bmp" "failed to load bitmap")
(wrap-surface ptr))))
(define %int-size (sizeof int))
(define %pointer-size (sizeof '*))
(define (pointer-int-ref pointer offset)
(bytevector-sint-ref (pointer->bytevector pointer %int-size offset)
0 (native-endianness) %int-size))
;; The offsets below correspond to the SDL_Surface struct elements
;; that come before the element in question.
(define %width-offset (sizeof (list uint32 '*)))
(define %height-offset (sizeof (list uint32 '* int)))
(define %pitch-offset (sizeof (list uint32 '* int int)))
(define %pixels-offset 32)
(define (surface-width surface)
"Return the width of SURFACE in pixels."
(pointer-int-ref (unwrap-surface surface) %width-offset))
(define (surface-height surface)
"Return the height of SURFACE in pixels."
(pointer-int-ref (unwrap-surface surface) %height-offset))
(define (surface-pitch surface)
"Return the length of a row of pixels in SURFACE in bytes."
(pointer-int-ref (unwrap-surface surface) %pitch-offset))
(define (surface-pixels surface)
"Return a bytevector containing the raw pixel data in SURFACE."
(let* ((ptr (unwrap-surface surface))
(height (pointer-int-ref ptr %height-offset))
(pitch (pointer-int-ref ptr %pitch-offset))
(pixels-ptr (pointer->bytevector ptr %pointer-size %pixels-offset))
(pixels (make-pointer
(bytevector-uint-ref pixels-ptr
0
(native-endianness)
%pointer-size))))
(pointer->bytevector pixels (* height pitch))))
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