in my library ive already written wrappers for these opencv functions create-camera-capture query-frame img-size create-image
the struct related to create-image is IplImage and i have it defined like this ;; ;(cffi:foreign-type-size '(:struct ipl-image)) = 144 (cffi:defcstruct ipl-image (n-size :int) (id :int) (n-channels :int) (alpha-channel :int) (depth :int) (color-model :int) ;;Ignored by OpenCV - was :pointer, changed to :int so the struct values would match OpenCV's (channel-seq :int) ;;Ignored by OpenCV - was :pointer, changed to :int so the struct values would match OpenCV's (data-order :int) (origin :int) (align :int) (width :int) (height :int) (roi (:pointer (:struct ipl-roi))) (mask-roi :pointer) (image-id :pointer) (tile-info :pointer) (image-size :int) (image-data :string) (width-step :int) (border-mode :pointer) (border-const :pointer) (image-data-origin :string)) so when i call the above functions and then print the struct values with the below code it looks like this CL-OPENCV> (defparameter capture (create-camera-capture 0)) (defparameter frame (query-frame capture)) (defparameter img-size (get-size frame)) (defparameter img (create-image img-size +ipl-depth-8u+ 3)) IMG CL-OPENCV> (cffi:with-foreign-slots ((n-size id n-channels alpha-channel depth color-model channel-seq data-order origin align width height roi mask-roi image-id tile-info image-size image-data width-step border-mode border-const image-data-origin) img (:struct ipl-image)) (format t "n-size = ~a~%id = ~a~%n-channels = ~a~%alpha-channel = ~a~%depth = ~a~%color-model = ~a~%channel-seq = ~a~%data-order = ~a~%origin = ~a~%align = ~a~%width = ~a~%height = ~a~%roi = ~a~%mask-roi = ~a~%image-id = ~a~%tile-info = ~a~%image-size = ~a~%image-data = ~a~%width-step = ~a~%border-mode = ~a~%border-const = ~a~%image-data-origin = ~a~%" n-size id n-channels alpha-channel depth color-model channel-seq data-order origin align width height roi mask-rOI image-id tile-info image-size image-data width-step border-mode border-const image-data-origin)) n-size = 144 id = 0 n-channels = 3 alpha-channel = 0 depth = 8 color-model = 4343634 channel-seq = 5392194 data-order = 0 origin = 0 align = 4 width = 640 height = 480 roi = #.(SB-SYS:INT-SAP #X00000000) mask-roi = #.(SB-SYS:INT-SAP #X00000000) image-id = #.(SB-SYS:INT-SAP #X00000000) tile-info = #.(SB-SYS:INT-SAP #X00000000) image-size = 921600 image-data = width-step = 1920 border-mode = #.(SB-SYS:INT-SAP #X00000000) border-const = #.(SB-SYS:INT-SAP #X00000000) image-data-origin = NIL NIL I'd rather not have to call the with-foreign-slots function with all that code every time id like to access slot values id rather do exactly like in c and call img->depth for example to access the IplImage struct member depth....Is there a way i can have this exact functionality in lisp with the above struct or any other....if i did have to call (img depth) i guess that would be ok but id rather create some sort of dereferencing operator equivelant to do this as easy as in c....either way can someone show me how to dereference pointers in the tiniest way possible like in c
