[racket-dev] draw-text sensitive to scale when first called

From: David Vanderson (david.vanderson at gmail.com)
Date: Thu Dec 5 16:08:45 EST 2013


I'm seeing that if the first draw-text on a canvas is at a small scale 
(0.1), then later draw-text calls at larger scales (1) show strange 
character spacing (see attached image).

This can be worked around by passing #t as the combine? argument to 
draw-text, but it seems some state is being shared between draw-text calls.

Does this happen for others? (I'm on Linux)


#lang racket/gui

(define (draw-screen canvas dc)

   (define t (send dc get-transformation))
   (send dc scale 0.1 0.1)

   (send dc draw-text "small" 1000 1000)

   (send dc set-transformation t)

   (define t2 (send dc get-transformation))
   (send dc translate (+ (/ 500 2)) (/ 500 2))
   (send dc scale 1 1)
   (send dc draw-text "" 0 0 #f)  ; change #f to #t to fix
   (send dc set-transformation t2))

(define frame (new (class frame% (super-new))
                    (label "Test draw-text when scaled")))

(define canvas
   (new canvas%
        (parent frame)
        (min-width 500)
        (min-height 500)
        (paint-callback draw-screen)
        (style '(no-autoclear))))

(send frame show #t)

;(send (send canvas get-dc) draw-text "" 0 0)  ; or uncomment to fix
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