Fixes to FrTime dynamic value snips (for textual content, at least).
* Expect DrRacket to make a copy of the copy of the snip we give it. * Add documentation explaining some of the trickiness involved in this code and how it might be possible to make it less brittle. * Add a note about editor-snip% not behaving as expected when non-textual elements are inserted and subsequently removed (or the underlying editor object is replaced).
This commit is contained in:
Gregory Cooper
parent
f15ca607ed
commit
f418805c32
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@ -35,33 +35,33 @@
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(send current draw dc x y left top right bottom dx dy draw-caret))
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(super-instantiate (" "))))
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(define make-snip
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(case-lambda
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[(bhvr)
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(make-object string-snip%
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(let ([tmp (cond
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[(behavior? bhvr) (value-now bhvr)]
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[(event? bhvr) (signal-value bhvr)]
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[else bhvr])])
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(cond
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[(event-set? tmp) (format "#<event (last: ~a@~a)>"
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(event-set-events tmp) (event-set-time tmp))]
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[(undefined? tmp) "<undefined>"]
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[else (format "~a" tmp)])))]
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[(bhvr super-render-fun)
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(get-rendering (value-now bhvr) super-render-fun)]))
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(define (make-snip bhvr)
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(make-object string-snip%
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(let ([tmp (cond
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[(behavior? bhvr) (value-now bhvr)]
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[(event? bhvr) (signal-value bhvr)]
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[else bhvr])])
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(cond
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[(event-set? tmp) (format "#<event (last: ~a@~a)>"
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(event-set-events tmp) (event-set-time tmp))]
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[(undefined? tmp) "<undefined>"]
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[else (format "~a" tmp)]))))
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(define value-snip%
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(class string-snip%
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(init-field bhvr)
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(init-field bhvr [ignore-copy-count 1])
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(field [copies empty]
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[loc-bhvr (proc->signal (lambda () (update)) bhvr)]
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[current (make-snip bhvr)])
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[current (make-snip bhvr)]
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[loc-bhvr (proc->signal (lambda () (update)) bhvr)])
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(define/override (copy)
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(let ([ret (make-object value-snip-copy% current this)])
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(set! copies (cons ret copies))
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ret))
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(if (> ignore-copy-count 0)
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(begin
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(set! ignore-copy-count (sub1 ignore-copy-count))
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this)
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(let ([ret (make-object value-snip-copy% current this)])
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(set! copies (cons ret copies))
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ret)))
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(define/public (update)
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(set! current (make-snip bhvr))
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@ -71,19 +71,27 @@
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(define dynamic-snip-copy%
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(class editor-snip%
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(init-field current parent)
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(inherit get-editor)
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(define/public (set-current c)
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(init-field initial-content parent)
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(inherit get-editor set-editor)
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(define/public (update content)
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(parameterize ([current-eventspace drs-eventspace])
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(queue-callback
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(lambda ()
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(send (get-editor) lock #f)
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(send (get-editor) delete 0 (send (get-editor) last-position))
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(for-each (lambda (thing)
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(send (get-editor) insert thing
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(send (get-editor) last-position) (send (get-editor) last-position)))
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c)
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(send (get-editor) lock #t)))))
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;; TODO(ghcooper): Figure out why this doesn't work properly for non-
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;; textual content. (Image snips don't seem to be deleted from the
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;; editor.) It doesn't even work if we create a completely new
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;; racket:text% each time, which suggests it's a bug in the snip
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;; rather than the editor itself.
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(let ([editor (get-editor)])
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(send editor lock #f)
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(send editor delete 0 (send editor last-position))
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(for-each (lambda (thing)
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(send editor insert thing
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(send editor last-position)
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(send editor last-position)))
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content)
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(send editor lock #t))))))
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(super-new
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[editor (new racket:text%)]
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@ -92,24 +100,53 @@
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[right-margin 0]
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[top-margin 0]
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[bottom-margin 0])
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(set-current current)))
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(update initial-content)))
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;; Class of objects to be given to DrRacket for rendering a signal in the
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;; interactions window. However, DrRacket won't actually embed this snip
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;; directly into the interactions window; instead it makes a copy, and then a
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;; copy of the copy, and the second copy is what's really rendered. This makes
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;; life challenging for us, because what we want (I believe) is ultimately an
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;; editor-snip% whose contents we can rewrite whenever the signal changes.
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;; We can't make this class inherit from editor-snip%, though, because we need
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;; custom copy behavior, and editor-snip%'s copy method is final. Instead, this
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;; class is designed NOT to be rendered, but just to be copied, to keep track of
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;; the copy that's actually displayed, and to make sure the copy gets updated
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;; when the signal changes. The displayed "copy" is not, in fact, a copy at all
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;; but an instance of the dynamic-snip-copy% class defined above.
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;;
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;; TODO(ghcooper): This code is very brittle; it breaks whenever DrRacket
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;; changes the length of the chain of copies it makes. A better approach might
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;; be to have a single class that HAS an editor-snip% (instead of inheriting
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;; from editor-snip%), delegates all relevant calls to the editor-snip%, and has
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;; a copy method that makes a proper copy of itself and (like this class) keeps
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;; track of copies so it can notify them when they need to be redrawn.
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(define dynamic-snip%
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(class snip%
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(init-field bhvr super-render-fun)
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(init-field
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;; The behavior we want to render dynamically.
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bhvr
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;; Procedure that generates a rendering of the current value of bhvr.
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super-render-fun
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;; Number of times the copy method will just return this object. Ick!
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[ignore-copy-count 1])
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(field [copies empty]
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[loc-bhvr (proc->signal (lambda () (update)) bhvr)]
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[current (make-snip bhvr super-render-fun)])
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(field [copies empty] ; "Copies" of this snip that we need to update.
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[current (get-rendering (value-now bhvr) super-render-fun)]
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[loc-bhvr (proc->signal (lambda () (update)) bhvr)])
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(define/override (copy)
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(let ([ret (make-object dynamic-snip-copy% current this)])
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(set! copies (cons ret copies))
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ret))
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(if (> ignore-copy-count 0)
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(begin
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(set! ignore-copy-count (sub1 ignore-copy-count))
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this)
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(let ([ret (make-object dynamic-snip-copy% current this)])
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(set! copies (cons ret copies))
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ret)))
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(define/public (update)
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(set! current (make-snip bhvr super-render-fun))
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(for-each (lambda (copy) (send copy set-current current)) copies))
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(set! current (get-rendering (value-now bhvr) super-render-fun))
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(for-each (lambda (copy) (send copy update current)) copies))
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(define/override (size-cache-invalid)
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(for-each
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@ -138,6 +175,9 @@
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; easy case
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(super-render-fun val)))
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;; get-rendering : any (any port -> void) -> (listof (string U snip%))
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;; Applies super-render-fun to val and a port. Returns the sequence of values
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;; written to the port.
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(define (get-rendering val super-render-fun)
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(let-values ([(in out) (make-pipe-with-specials)])
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(thread (lambda () (super-render-fun val out) (close-output-port out)))
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