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+---- Thread: gimp-drawable-set-pixel giving unspecified error (/Thread-gimp-drawable-set-pixel-giving-unspecified-error)
gimp-drawable-set-pixel giving unspecified error - rgbellotti - 11-24-2024
I generally use some version of GIMP 2.10 on many different distros of Linux, most often Debian-based such Ubuntu, Parrot, Neon, etc
For the most part, I've done my scripting in Scheme because it was the only scripting language I could get to register properly, the python scripts would never load no matter what troubleshooting steps I tried. This is fine though as Scheme is fun and still powerful enough to do just about whatever I need with the proper ideas.
Anyhow, the point being that I came across a hurdle with (gimp-drawable-set-pixel), which is the only function I know where you can explicitly define pixels values to place into an image. And with the following script :
Code:
(define (test-set-pixel)
(let* (
;; Create a new image and drawable
(frame (car (gimp-image-new 10 10 RGB)))
(drawframe (car (gimp-layer-new frame 10 10 RGB "Test Layer" 100 NORMAL-MODE)))
)
;; Add the new layer to the image
(gimp-image-insert-layer frame drawframe 0 -1)
(gimp-drawable-fill drawframe TRANSPARENT-FILL)
;; Test setting a single pixel
(let* (
(x 0)
(y 0)
(new-pixel (vector 255 0 0 255)) ;; Red with full opacity
)
(gimp-message (string-append "Setting pixel at (" (number->string x) ", " (number->string y) ")"))
(gimp-drawable-set-pixel drawframe x y 4 new-pixel))
;; Save the image for inspection
(file-png-save 0 frame drawframe "test.png" "test.png" 1 9 1 1 1 1 1)
(gimp-message "Test image saved.")
(gimp-image-delete frame)
)
)I get the cryptic error message -- "Error: Procedure execution of gimp-drawable-set-pixel failed". As a side note, I don't use python because it's been difficult for me to get Gimp to register python scripts in Linux, so seeing as how I have quite a few Scheme scripts started I'd like to try and resolve this fundamental problem of being able to place a pixel into an image, are there other functions that could give a similar functionality? I've considered sampling pixels with (gimp-drawable-get-pixel) and then creating a new layer with 1x1 pixels, and then applying a paint to the new layer to match the color of sampled picture, and then mixed down a layer group of 320 x 240 layers (for a 320x240 pixel image for example) and then calling that a 'set pixel" alternative, but that would be an extreme work around. Is there anything obvious that I'm overlooking?
RE: gimp-drawable-set-pixel giving unspecified error - rgbellotti - 11-24-2024
I found this work-around to work alright so far, and figured I'd post here in case anyone else ever came across that scenario. This test function will essentially place one pixel on a new image of the color you specify:
Code:
(define (test-set-pixel)
(let* (
;; Create a new image and drawable
(frame (car (gimp-image-new 10 10 RGB)))
(drawframe (car (gimp-layer-new frame 10 10 1 "Test Layer" 100 28)))
)
;; Add the new layer to the image
(gimp-image-insert-layer frame drawframe 0 -1)
;; Set the foreground color to red (the brush color that you will draw)
(gimp-context-set-foreground '(255 0 0))
;; Set the brush size and settings to pixel-perfect accuracy
(gimp-context-set-brush-size 1)
(gimp-context-set-brush-angle 0)
(gimp-context-set-brush-aspect-ratio 0)
(gimp-context-set-brush-hardness 1)
(gimp-context-set-brush-force 1)
;; Use the pencil tool to draw a single pixel
;; NOTE ;; "PRESS" and "RELEASE" are both considered a "stroke" of the pencil
;; so use '2' for the stroke count, for PRESS = (5,5) RELEASE = (5,5)
(gimp-pencil drawframe 2 #(5 5 5 5))
;; Save the image
(file-png-save 1 frame drawframe "test_pixel.png" "test_pixel.png" 1 9 1 1 1 1 1)
(gimp-message "Test image saved.")
(gimp-image-delete frame)
)
)RE: gimp-drawable-set-pixel giving unspecified error - teapot - 11-24-2024
Hi rgbellotti,
You've found an alternative method but just to follow up your first method in your first post:
The number of channels you specified didn't match the layer you created.
You specified 4 channels:
(gimp-drawable-set-pixel drawframe x y 4 new-pixel)
which is rgba.
For 2.10 gimp-layer-new the layer type is
{ RGB-IMAGE (0), RGBA-IMAGE (1), GRAY-IMAGE (2), GRAYA-IMAGE (3), INDEXED-IMAGE (4), INDEXEDA-IMAGE (5) }
Whereas you put RGB which is 0, so no alpha:
(drawframe (car (gimp-layer-new frame 10 10 RGB "Test Layer" 100 NORMAL-MODE)))
RGB is typically used for image type:
{ RGB (0), GRAY (1), INDEXED (2) }
In your second post it was fixed when you hardcoded 1 for type:
(drawframe (car (gimp-layer-new frame 10 10 1 "Test Layer" 100 28)))
Perhaps intead of hardcoding the number of channels you could have used:
(gimp-drawable-bpp drawable)
to get the bytes per pixel.
RE: gimp-drawable-set-pixel giving unspecified error - rgbellotti - 11-24-2024
(3 hours ago)teapot Wrote: Hi rgbellotti,
You've found an alternative method but just to follow up your first method in your first post:
The number of channels you specified didn't match the layer you created.
You specified 4 channels:
(gimp-drawable-set-pixel drawframe x y 4 new-pixel)
which is rgba.
For 2.10 gimp-layer-new the layer type is
{ RGB-IMAGE (0), RGBA-IMAGE (1), GRAY-IMAGE (2), GRAYA-IMAGE (3), INDEXED-IMAGE (4), INDEXEDA-IMAGE (5) }
Whereas you put RGB which is 0, so no alpha:
(drawframe (car (gimp-layer-new frame 10 10 RGB "Test Layer" 100 NORMAL-MODE)))
RGB is typically used for image type:
{ RGB (0), GRAY (1), INDEXED (2) }
In your second post it was fixed when you hardcoded 1 for type:
(drawframe (car (gimp-layer-new frame 10 10 1 "Test Layer" 100 28)))
Perhaps intead of hardcoding the number of channels you could have used:
(gimp-drawable-bpp drawable)
to get the bytes per pixel.
Thank you! This was the problem. I haven't tried (gimp-drawable-bpp drawable) yet but that does sound useful, I'll look into it
