Re: Draw images efficiently

Answering myself:

While I haven’t found a general solution for this, I did find a way to to this on OS X that I would like to share:


(defmethod nsview ((pane capi:simple-pane))
  (slot-value (slot-value pane 'capi-internals:representation) 'capi-cocoa-library::main-view))

(defun cocoa-set-background (pane image)
  (let* ((view (nsview pane))
         (image (gp:load-image pane image))
         (nsimage (slot-value (slot-value image 'gp::representation) 'gp::image)))
    (objc:invoke view "setWantsLayer:" 1)  ; enable backing layer
    (objc:invoke (objc:invoke view "layer") "setBackgroundColor:" (objc:invoke (objc:invoke "NSColor" "colorWithPatternImage:" nsimage) "CGColor"))))

(setf *pane* (capi:contain (make-instance 'capi:output-pane :background :transparent :display-callback
                                          (lambda (port x y w h)
                                            (gp:draw-rectangle port 10 10 50 50 :filled t :foreground :green)))))

(capi:apply-in-pane-process *pane* 'cocoa-set-background *pane* 'some-image)


This enables a backing layer for the output-pane, that ”shines through” if the background of the pane is set to :transparent.

So far I haven’t yet checked out whether the NSImage needs to be retained, or if the code leeks memory. But it seems to work well at least on my Mac with OS X 10.11.

Erik





> 11 dec. 2017 kl. 10:53 skrev Erik Ronström <erik.ronstrom@doremir.com>:
> 
> Hi,
> 
> I’m using an image as a background for an output-pane, and in order to fill the entire pane, I’ve been using a naïve tile approach:
> 
> (loop for nx from 0 below (ceiling width image-width) do
>      (loop for ny from 0 below (ceiling height image-height) do
>            (gp:draw-image port image (+ x (* nx image-width)) (+ y (* ny image-height))))
> 
> However, this is pretty slow. I tried experimenting with various image sizes, but drawing a bigger image fewer times seems to take about the same time as drawing a smaller image more times. That suggests the cost of drawing images is (to some extent) proportional to the amount of data being drawn.
> 
> Is there any way to optimize image drawing in CAPI?
> 
> Erik
> 
> 


_______________________________________________
Lisp Hug - the mailing list for LispWorks users
lisp-hug@lispworks.com
http://www.lispworks.com/support/lisp-hug.html