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1113 discussions

How do I approxmate C pointer dereferencing?
by Joeish W 05 Oct '13

05 Oct '13

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

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test 5 pls disregard
by Joeish W 05 Oct '13

05 Oct '13

(defun create-trackbar-example (&optional (camera-index 0) (width *default-width*) (height *default-height*)) "Creates a trackbar and attaches it to the specified window. Move the slider to adjust the brightess of the camera output" (with-capture (capture (create-camera-capture camera-index)) (let ((window-name "CREATE-TRACKBAR Example") (contrast (cffi:foreign-alloc :int :initial-contents '(50)))) (set-capture-property capture +cap-prop-frame-width+ width) (set-capture-property capture +cap-prop-frame-height+ height) (named-window window-name) (move-window window-name 600 175) (do* ((frame (query-frame capture) (query-frame capture)) (dest (clone-image frame)) (scalar 0)) ((plusp (wait-key *millis-per-frame*)) nil) (format t "Trackbar level: ~a~%~%" (cffi:mem-ref contrast :int)) (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest)) (setf scalar (scalar (- (cffi:mem-ref contrast :int 50)) (- (cffi:mem-ref contrast :int) 50) (- (cffi:mem-ref contrast :int) 50))) (add-s frame scalar dest) (show-image window-name dest)) (destroy-window window-name)))) (defun create-trackbar-example (&optional (camera-index 0) (width *default-width*) (height *default-height*)) "Creates a trackbar and attaches it to the specified window. Move the slider to adjust the brightess of the camera output" (with-capture (capture (create-camera-capture camera-index)) (let ((window-name "CREATE-TRACKBAR Example") (contrast (cffi:foreign-alloc :int :initial-contents '(50)))) (set-capture-property capture +cap-prop-frame-width+ width) (set-capture-property capture +cap-prop-frame-height+ height) (named-window window-name) (move-window window-name 600 175) (do* ((frame (query-frame capture) (query-frame capture)) (dest (clone-image frame)) (scalar 0)) ((plusp (wait-key *millis-per-frame*)) nil) (format t "Trackbar level: ~a~%~%" (cffi:mem-ref contrast :int)) (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest)) (setf scalar (scalar (- (cffi:mem-ref contrast :int 50)) (- (cffi:mem-ref contrast :int) 50) (- (cffi:mem-ref contrast :int) 50))) (add-s frame scalar dest) (show-image window-name dest)) (destroy-window window-name)))) (defun create-trackbar-example (&optional (camera-index 0) (width *default-width*) (height *default-height*)) "Creates a trackbar and attaches it to the specified window. Move the slider to adjust the brightess of the camera output" (with-capture (capture (create-camera-capture camera-index)) (let ((window-name "CREATE-TRACKBAR Example") (contrast (cffi:foreign-alloc :int :initial-contents '(50)))) (set-capture-property capture +cap-prop-frame-width+ width) (set-capture-property capture +cap-prop-frame-height+ height) (named-window window-name) (move-window window-name 600 175) (do* ((frame (query-frame capture) (query-frame capture)) (dest (clone-image frame)) (scalar 0)) ((plusp (wait-key *millis-per-frame*)) nil) (format t "Trackbar level: ~a~%~%" (cffi:mem-ref contrast :int)) (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest)) (setf scalar (scalar (- (cffi:mem-ref contrast :int 50)) (- (cffi:mem-ref contrast :int) 50) (- (cffi:mem-ref contrast :int) 50))) (add-s frame scalar dest) (show-image window-name dest)) (destroy-window window-name)))) (defun create-trackbar-example (&optional (camera-index 0) (width *default-width*) (height *default-height*)) "Creates a trackbar and attaches it to the specified window. Move the slider to adjust the brightess of the camera output" (with-capture (capture (create-camera-capture camera-index)) (let ((window-name "CREATE-TRACKBAR Example") (contrast (cffi:foreign-alloc :int :initial-contents '(50)))) (set-capture-property capture +cap-prop-frame-width+ width) (set-capture-property capture +cap-prop-frame-height+ height) (named-window window-name) (move-window window-name 600 175) (do* ((frame (query-frame capture) (query-frame capture)) (dest (clone-image frame)) (scalar 0)) ((plusp (wait-key *millis-per-frame*)) nil) (format t "Trackbar level: ~a~%~%" (cffi:mem-ref contrast :int)) (create-trackbar "Brightness" window-name contrast 100 (change-contrast contrast window-name frame dest)) (setf scalar (scalar (- (cffi:mem-ref contrast :int 50)) (- (cffi:mem-ref contrast :int) 50) (- (cffi:mem-ref contrast :int) 50))) (add-s frame scalar dest) (show-image window-name dest)) (destroy-window window-name))))

1 0

test 4 pls disregarde
by Joeish W 05 Oct '13

05 Oct '13

<code>(cffi:defcstruct (cv-size :classcv-size-type)(width :int)(height :int))(defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height))))</code> and my opencv wrappers for CvGetSize and cvCreateImage, get-size and create-image, are defined like this ;;CvSizecvGetSize(constCvArr*arr)(cffi:defcfun ("cvGetSize"get-size)(:structcv-size)(arr cv-arr));;IplImage*cvCreateImage(CvSizesize,intdepth,intchannels)(cffi:defcfun ("cvCreateImage"%create-image)ipl-image (size :int64)(depth :int)(channels :int))(defun create-image (size depth channels)"Create an image with dimensions given by SIZE, DEPTH bits per channel, and CHANNELS number of channels."(let((nsize (size->int64 size)))(%create-image nsize depth channels))) here is the definition of size->int64 (DEFUN SIZE->INT64 (S)(+(SIZE-WIDTH S)(ASH (SIZE-HEIGHT S)32)))it converts get-size output which isa structure here:#S(SIZE :WIDTH 640 :HEIGHT 480)into64-bit integer,which CFFI can handle but i love the idea of the translate-foreign defmethod's so i was wondering if you can show my how to make the translate-into-foreign version of the below from method this would really make my library awesome (defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height))))

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could i get help with code formatting
by Joeish W 05 Oct '13

05 Oct '13

as you can see my last attempts were unsuccessful I indented my code as i normally do when i add to a site but it didnt work how does everyone else add code so neatly

1 0

test 3 pls disregard
by Joeish W 05 Oct '13

05 Oct '13

CL-OPENCV>;;(cffi:foreign-type-size '(:struct cv-size)) = 8 (cffi:defcstruct (cv-size :class cv-size-type) (width :int) (height :int)) (defmethod cffi:translate-from-foreign (p (type cv-size-type)) (let ((plist (call-next-method))) (make-size :width (getf plist 'width):height (getf plist 'height)))) (defmethod cffi:translate-to-foreign (value (type cv-size-type)) (let ((plist ())) (setf (getf plist 'width)(size-width value)(getf plist 'height) (size-height value)) (call-next-method plist type))) ;; CvSize cvGetSize(const CvArr* arr) (cffi:defcfun ("cvGetSize" get-size) (:struct cv-size) (arr (:pointer cv-arr))) ;; IplImage* cvCreateImage(CvSize size, int depth, int channels) (cffi:defcfun ("cvCreateImage" create-image) (:pointer (:struct ipl-image)) (size (:struct cv-size)) (depth :int) (channels :int)) STYLE-WARNING: redefining CL-OPENCV:GET-SIZE in DEFUN STYLE-WARNING: redefining CL-OPENCV:CREATE-IMAGE in DEFUN CREATE-IMAGE 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))

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test 2 pls disregard
by Joeish W 05 Oct '13

05 Oct '13

(cffi:defcstruct (cv-size :classcv-size-type)(width :int)(height :int))(defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height)))) and my opencv wrappers for CvGetSize and cvCreateImage, get-size and create-image, are defined like this ;;CvSizecvGetSize(constCvArr*arr)(cffi:defcfun ("cvGetSize"get-size)(:structcv-size)(arr cv-arr));;IplImage*cvCreateImage(CvSizesize,intdepth,intchannels)(cffi:defcfun ("cvCreateImage"%create-image)ipl-image (size :int64)(depth :int)(channels :int))(defun create-image (size depth channels)"Create an image with dimensions given by SIZE, DEPTH bits per channel, and CHANNELS number of channels."(let((nsize (size->int64 size)))(%create-image nsize depth channels))) here is the definition of size->int64 (DEFUN SIZE->INT64 (S)(+(SIZE-WIDTH S)(ASH (SIZE-HEIGHT S)32)))it converts get-size output which isa structure here:#S(SIZE :WIDTH 640 :HEIGHT 480)into64-bit integer,which CFFI can handle but i love the idea of the translate-foreign defmethod's so i was wondering if you can show my how to make the translate-into-foreign version of the below from method this would really make my library awesome (defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height)))) I was going to try stuff and add it but for the get-size output structure, it isnt a plist so not really sure what to put there for the (let((plist (call-next-method))) part, for the (make-size :width (getf plist 'width) :height (getf plist 'height))))

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just quick test my formatting was destoyed on last post
by Joeish W 05 Oct '13

05 Oct '13

arbitrary code to test <code></code> tags to see if thats how i add code <code>(cffi:with-foreign-object (img-size '(:struct cv-size)) ;; Initialize the slots ;; Return a list with the coordinates (cffi:with-foreign-slots ((width height) img-size (:struct cv-size)) (list width height))) </code> any guidance on formatting would be appreciated pls disregard last post....the translat-into one it is non-sensical

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Can some one help me with this Stackoverflow?
by Joeish W 05 Oct '13

05 Oct '13

here is the link....http://stackoverflow.com/questions/18807500/how-would-i-go-about-wr… Im not sure if its ok 2 to this bit it would save me some typing pls let me know either way....The nice gentleman at StackOverflow keep refferring me here so i'd thought i'd try it....and i'm looking forward to talking to like minded people a myself =).

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How do i write a comparable cffi:translate-into foreign defmethod for this cffi:translate-from-foreign?
by Joeish W 05 Oct '13

05 Oct '13

How do i write a comparable cffi:translate-into foreign defmethod for this cffi:translate-from-foreign? up vote 0 down vote favorite ok I tried this translate-from-foreign method and it did work i have these defined in my structs.lisp file in my library which loads first before all my other dependencies (cffi:defcstruct (cv-size :classcv-size-type)(width :int)(height :int))(defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height)))) and my opencv wrappers for CvGetSize and cvCreateImage, get-size and create-image, are defined like this ;;CvSizecvGetSize(constCvArr*arr)(cffi:defcfun ("cvGetSize"get-size)(:structcv-size)(arr cv-arr));;IplImage*cvCreateImage(CvSizesize,intdepth,intchannels)(cffi:defcfun ("cvCreateImage"%create-image)ipl-image (size :int64)(depth :int)(channels :int))(defun create-image (size depth channels)"Create an image with dimensions given by SIZE, DEPTH bits per channel, and CHANNELS number of channels."(let((nsize (size->int64 size)))(%create-image nsize depth channels))) here is the definition of size->int64 (DEFUN SIZE->INT64 (S)(+(SIZE-WIDTH S)(ASH (SIZE-HEIGHT S)32)))it converts get-size output which isa structure here:#S(SIZE :WIDTH 640 :HEIGHT 480)into64-bit integer,which CFFI can handle but i love the idea of the translate-foreign defmethod's so i was wondering if you can show my how to make the translate-into-foreign version of the below from method this would really make my library awesome (defmethod cffi:translate-from-foreign (p (type cv-size-type))(let((plist (call-next-method)))(make-size :width (getf plist 'width) :height (getf plist 'height)))) I was going to try stuff and add it but for the get-size output structure, it isnt a plist so not really sure what to put there for the (let((plist (call-next-method))) part, for the (make-size :width (getf plist 'width) :height (getf plist 'height)))) part, i was hoping to find another method other than the size->64 function because that was made 2 years ago when cl-opencv https://github.com/ryepup/cl-opencv first came out and i would like to make an even better wrapper than that...i've already taken cl-opencv added 100 new function 5000 lines of code samples and documentation and a new structs.lisp file so i would love if someone could help me with all the latest cffi tools so i could do something else than int64...plus the if i have a funtion to wrap where the int64 thing wouldnt work ill be ready Thanks again to all the answerers cffi-devel. you all really have helped my library great. Edit: I also tried it this way, Below is my repl history showing my steps CL-OPENCV>;;(cffi:foreign-type-size '(:struct cv-size)) = 8 (cffi:defcstruct (cv-size :class cv-size-type) (width :int) (height :int)) (defmethod cffi:translate-from-foreign (p (type cv-size-type)) (let ((plist (call-next-method))) (make-size :width (getf plist 'width):height (getf plist 'height)))) (defmethod cffi:translate-to-foreign (value (type cv-size-type)) (let ((plist ())) (setf (getf plist 'width)(size-width value)(getf plist 'height) (size-height value)) (call-next-method plist type))) ;; CvSize cvGetSize(const CvArr* arr) (cffi:defcfun ("cvGetSize" get-size) (:struct cv-size) (arr (:pointer cv-arr))) ;; IplImage* cvCreateImage(CvSize size, int depth, int channels) (cffi:defcfun ("cvCreateImage" create-image) (:pointer (:struct ipl-image)) (size (:struct cv-size)) (depth :int) (channels :int)) CREATE-IMAGE 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)) but i get error Thereisnoapplicable method forthe genericfunction#<STANDARD-GENERIC-FUNCTIONCFFI:TRANSLATE-INTO-FOREIGN-MEMORY (5)>whencalled witharguments (#S(SIZE :WIDTH 640:HEIGHT 480)#<CV-SIZE-TYPE CV-SIZE>#.(SB-SYS:INT-SAP #X7FFFE5427FF0)).[Conditionof type SIMPLE-ERROR] because the translate-from-foreign function i have is converting the output from cv-size into a structure CL-OPENCV>img-size #S(SIZE :WIDTH 640 :HEIGHT 480) I appreciate the translate-into foreign function but with the old translate-from-foreign function it isnt woking, because of the make-size part...would you help me figure out what cvCreateImage needs to satisfy it ....here is the link 4 that: http://docs.opencv.org/modules/core/doc/old_basic_structures.html?highlight… I can get this version below to run right(i show the repl session) 5CL-OPENCV>;TODO SIZE-WIDTH AND HEIGHT ;;CvSizecvGetSize(constCvArr*arr)(cffi:defcfun ("cvGetSize"get-size)(:pointer (:structcv-size))(arr cv-arr));;IplImage*cvCreateImage(CvSizesize,intdepth,intchannels)(cffi:defcfun ("cvCreateImage"create-image)(:pointer (:structipl-image))(size (:pointer (:structcv-size)))(depth :int)(channels :int))STYLE-WARNING:redefining CL-OPENCV:GET-SIZE inDEFUN STYLE-WARNING:redefining CL-OPENCV:CREATE-IMAGE inDEFUN CREATE-IMAGE 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-constimage-data-origin)img(:structipl-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-constimage-data-origin))n-size =144id =0n-channels =3alpha-channel =0depth =8color-model =4343634channel-seq =5392194data-order =0origin =0align =4width =640height =480roi =#.(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 =921600image-data =width-step =1920border-mode =#.(SB-SYS:INT-SAP #X00000000)border-const=#.(SB-SYS:INT-SAP #X00000000)image-data-origin =NIL NIL so i get data from the slots for ipl-image but this does'nt seem like correct way because id have to be able to derefrence the cv-size poiner output by get-size here is documentation on cvGetSize the function im wrapping http://docs.opencv.org/modules/core/doc/old_basic_structures.html?highlight… as u can see it is a pointer CL-OPENCV>img-size #.(SB-SYS:INT-SAP #X1E000000280) so when i do : (cffi:with-foreign-object(img-size '(:pointer (:struct cv-size))) ;; Initialize the slots ;; Return a list with the coordinates (cffi:with-foreign-slots ((width height) img-size (list width height))) i get Thereisnoapplicable method forthe genericfunction#<STANDARD-GENERIC-FUNCTION CFFI::SLOTS (1)>whencalled witharguments (#<CFFI::FOREIGN-POINTER-TYPE (:POINTER (:STRUCT CV-SIZE))>).[Conditionof type SIMPLE-ERROR] and when i do (cffi:with-foreign-object(img-size '(:struct cv-size)) ;; Initialize the slots ;; Return a list with the coordinates (cffi:with-foreign-slots ((width height) img-size (:struct cv-size)) (list width height))) i get (346539 0) just nonsensical output i try mem-refing and mem-arefing the pointer and get unhandled memory fault errors if you can help me figure out how to write compatible translate-from-foreign and translate-into-foreign functions i would be very grateful =). but if i use make-size or size-width,height anywhere in them the create-image would have to have the size->int64 in it because they work only because that function.

1 0

Collecting native garbage
by Victor 01 Oct '13

01 Oct '13

Hi, Probably this was asked before, or probably you will find this question somewhat stupid, nevertheless. Is there any kind of a tutorial or a guide into how to achieve automatic garbage collection of the native objects referenced from Lisp objects? So far I found just this thread that contains useful information in tiny bits but not a coherent cookbook style guide: http://lists.common-lisp.net/pipermail/cffi-devel/2011-May/003541.html Thanks, Victor

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