125 lines
4.7 KiB
Racket
125 lines
4.7 KiB
Racket
#lang racket/gui
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(require framework
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slideshow/pict
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"display.rkt")
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(provide pict-canvas%)
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(define pict-canvas%
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(class canvas%
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(init pict-builder [hover-handler #f]
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[click-handler #f]
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[overlay-builder #f]
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[redraw-on-resize #f])
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(inherit get-dc get-client-size refresh get-view-start)
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(define bp pict-builder) ;Builds the main pict for the canvas
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(define mh hover-handler) ;Mouse hover handler
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(define ob overlay-builder) ;Hover overlay pict builder
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(define ch click-handler) ;Mouse click handler
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(define redraw-on-size redraw-on-resize) ;Whether we should rebuild the pict for on-size events
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(define scale-factor 1)
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(define/public (set-scale-factor! s)
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(set! scale-factor s))
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(define need-redraw? #f)
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(define delaying-redraw? #f)
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(define cached-base-bitmap #f)
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(define cached-overlay-bitmap #f)
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(define/private (get-viewable-region)
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(define-values (x y) (get-view-start))
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(define-values (w h) (get-client-size))
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(scale-viewable-region (viewable-region x y w h) (/ 1 scale-factor)))
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(define/public (redraw-everything)
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(redraw-the-bitmap/maybe-delayed! (get-viewable-region)))
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;Rebuild both the bottom (base) and overlay (top)
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;pict layers for the canvas
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;;rebuild-the-pict : viewable-region -> void
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(define/private (rebuild-the-pict! vregion #:only-the-overlay? [only-the-overlay? #f])
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(when (or (not cached-base-bitmap) (not only-the-overlay?))
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(set! cached-base-bitmap (pict->bitmap (scale (bp vregion) scale-factor))))
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(when ob
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(define overlay-pict (ob vregion scale-factor))
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(set! cached-overlay-bitmap
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(if overlay-pict
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(pict->bitmap overlay-pict)
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#f))))
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;Rebuilds the pict and stashes in a bitmap
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;to be drawn to the canvas later
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;;redraw-the-bitmap : viewable-region -> void
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(define/private (redraw-the-bitmap! vregion #:only-the-overlay? [only-the-overlay? #f])
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(rebuild-the-pict! vregion #:only-the-overlay? only-the-overlay?)
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(set! need-redraw? #f))
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;;redraw-the-bitmap/maybe-delayed! : viewable-region -> void
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(define/private (redraw-the-bitmap/maybe-delayed! vregion
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#:delay [delay 100]
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#:only-the-overlay? [only-the-overlay? #f])
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(cond
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[need-redraw?
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(redraw-the-bitmap! vregion #:only-the-overlay? only-the-overlay?)
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(set! need-redraw? #f)]
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[(not delaying-redraw?)
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(new timer% [notify-callback (λ ()
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(set! delaying-redraw? #f)
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(set! need-redraw? #t)
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(redraw-the-bitmap/maybe-delayed! (get-viewable-region) #:only-the-overlay? only-the-overlay?)
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(refresh))]
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[interval delay]
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[just-once? #t])
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(set! delaying-redraw? #t)]))
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(define last-vregion #f)
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(define (scroll-or-size-event? vregion)
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(not (equal? vregion last-vregion)))
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(define/override (on-paint)
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(define vregion (get-viewable-region))
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(when (and (not delaying-redraw?) (scroll-or-size-event? vregion))
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(redraw-the-bitmap/maybe-delayed! vregion))
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(set! last-vregion vregion)
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(define dc (get-dc))
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(when cached-base-bitmap
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(send dc
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draw-bitmap
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cached-base-bitmap
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(viewable-region-x vregion)
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(viewable-region-y vregion)))
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(when cached-overlay-bitmap
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(send dc
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draw-bitmap
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cached-overlay-bitmap
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(viewable-region-x vregion)
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(viewable-region-y vregion))))
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(define/override (on-event event)
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(define vregion (get-viewable-region))
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(define x (+ (viewable-region-x vregion) (/ (send event get-x) scale-factor)))
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(define y (+ (viewable-region-y vregion) (/ (send event get-y) scale-factor)))
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(case (send event get-event-type)
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[(motion)
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(when mh
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(when (mh x y vregion) ;Mouse handler returns non-false if a state change requiring redraw occurred
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(redraw-the-bitmap/maybe-delayed! vregion #:delay 0 #:only-the-overlay? #t)))]
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[(left-up)
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(when ch (ch x y vregion)) ;Ditto for click handler
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(redraw-the-bitmap/maybe-delayed! vregion #:only-the-overlay? #t)]))
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(super-new)
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(send (get-dc) set-smoothing 'aligned)))
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