diff options
Diffstat (limited to 'doc/example-smob/image-type.c')
-rw-r--r-- | doc/example-smob/image-type.c | 116 |
1 files changed, 116 insertions, 0 deletions
diff --git a/doc/example-smob/image-type.c b/doc/example-smob/image-type.c new file mode 100644 index 000000000..083d5df94 --- /dev/null +++ b/doc/example-smob/image-type.c @@ -0,0 +1,116 @@ +/* file "image-type.c" */ + +#include <stdlib.h> +#include <libguile.h> + +static long image_tag; + +struct image { + int width, height; + char *pixels; + + /* The name of this image */ + SCM name; + + /* A function to call when this image is + modified, e.g., to update the screen, + or SCM_BOOL_F if no action necessary */ + SCM update_func; +}; + +static SCM +make_image (SCM name, SCM s_width, SCM s_height) +{ + struct image *image; + SCM image_smob; + int width, height; + + SCM_ASSERT (SCM_NIMP (name) && SCM_STRINGP (name), name, + SCM_ARG1, "make-image"); + SCM_ASSERT (SCM_INUMP (s_width), s_width, SCM_ARG2, "make-image"); + SCM_ASSERT (SCM_INUMP (s_height), s_height, SCM_ARG3, "make-image"); + + width = SCM_INUM (s_width); + height = SCM_INUM (s_height); + + image = (struct image *) scm_must_malloc (sizeof (struct image), "image"); + image->width = width; + image->height = height; + image->pixels = scm_must_malloc (width * height, "image pixels"); + image->name = name; + image->update_func = SCM_BOOL_F; + + SCM_NEWCELL (image_smob); + SCM_SETCDR (image_smob, image); + SCM_SETCAR (image_smob, image_tag); + + return image_smob; +} + +static SCM +clear_image (SCM image_smob) +{ + int area; + struct image *image; + + SCM_ASSERT ((SCM_NIMP (image_smob) + && SCM_CAR (image_smob) == image_tag), + image_smob, SCM_ARG1, "clear-image"); + + image = (struct image *) SCM_CDR (image_smob); + area = image->width * image->height; + memset (image->pixels, 0, area); + + /* Invoke the image's update function. */ + if (image->update_func != SCM_BOOL_F) + scm_apply (image->update_func, SCM_EOL, SCM_EOL); + + return SCM_UNSPECIFIED; +} + +static SCM +mark_image (SCM image_smob) +{ + struct image *image = (struct image *) SCM_CDR (image_smob); + + scm_gc_mark (image->name); + return image->update_func; +} + +static scm_sizet +free_image (SCM image_smob) +{ + struct image *image = (struct image *) SCM_CDR (image_smob); + scm_sizet size = image->width * image->height + sizeof (struct image); + + free (image->pixels); + free (image); + + return size; +} + +static int +print_image (SCM image_smob, SCM port, scm_print_state *pstate) +{ + struct image *image = (struct image *) SCM_CDR (image_smob); + + scm_puts ("#<image ", port); + scm_display (image->name, port); + scm_puts (">", port); + + /* non-zero means success */ + return 1; +} + +static scm_smobfuns image_funs = { + mark_image, free_image, print_image, 0 +}; + +void +init_image_type () +{ + image_tag = scm_newsmob (&image_funs); + + scm_make_gsubr ("clear-image", 1, 0, 0, clear_image); + scm_make_gsubr ("make-image", 3, 0, 0, make_image); +} |