[racket-dev] draw-text always pixel aligned?

Yes, it's the same on Mac and Windows.

At Mon, 16 Dec 2013 14:12:18 -0500, David Vanderson wrote:
> Thanks for looking into it. Can you confirm if you see similar output on 
> a different platform (Mac or Win)?
> 
> On 12/16/2013 12:26 PM, Matthew Flatt wrote:
> > I'm not sure about that part. I've confirmed that the cairo_move_to()
> > call just before pango_cairo_show_layout_line() varies the "y" argument
> > by 0.1, and I don't see any options that would affect vertical
> > alignment.
> >
> > At Mon, 16 Dec 2013 10:37:39 -0500, David Vanderson wrote:
> >> That makes sense, but the picture with 'unaligned seems strange
> >> (attached). It looks like each individual character is being pixel
> >> aligned, and also the vertical pixel drop doesn't happen until it's 0.7
> >> pixels down. Does this make sense?
> >>
> >> On 12/16/2013 08:15 AM, Matthew Flatt wrote:
> >>> Did you mean to pass 'unaligned instead of 'aligned as the last
> >>> argument to `find-or-create-font`? That should disable pixel alignment.
> >>>
> >>> At Mon, 16 Dec 2013 01:28:23 -0500, David Vanderson wrote:
> >>>> Hello,
> >>>>
> >>>> It seems that draw-text always pixel-aligns its text. In the example
> >>>> below, I draw a black "hello" on top of a red one, with a pixel offset
> >>>> of 0, 0.1, 0.2, . . . 0.9. At least for me, I see no change until 0.5,
> >>>> where the black text jumps a whole pixel (see attached image).
> >>>>
> >>>> Am I missing something? Do others see this behavior?  (I'm on Linux)
> >>>>
> >>>> Thanks,
> >>>> Dave
> >>>>
> >>>>
> >>>> #lang racket/gui
> >>>>
> >>>> (define (draw-text dc offset)
> >>>>      (send dc set-text-foreground "red")
> >>>>      (send dc draw-text "hello" 0 0 #t)
> >>>>      (send dc set-text-foreground "black")
> >>>>      (send dc draw-text "hello" offset offset #t))
> >>>>
> >>>> (define (draw-screen canvas dc)
> >>>>      (send dc set-smoothing 'smoothed)
> >>>>      (send dc set-font
> >>>>            (send the-font-list find-or-create-font
> >>>>                  12 'default 'normal 'normal #f 'smoothed #f 'aligned))
> >>>>      (send dc set-initial-matrix (vector 1 0 0 1 0 0))
> >>>>      (for ((i 10))
> >>>>        (draw-text dc (/ i 10.0))
> >>>>        (send dc translate 50 0)))
> >>>>
> >>>> (define frame (new frame% (label "Test draw-text")))
> >>>>
> >>>> (define canvas
> >>>>      (new canvas%
> >>>>           (parent frame)
> >>>>           (min-width 500)
> >>>>           (min-height 100)
> >>>>           (paint-callback draw-screen)))
> >>>>
> >>>> (send frame show #t)
> >>
> >> 
> ------------------------------------------------------------------------------
> >> [image/png "draw-text2-unaligned.png"] [~/Desktop & open] [~/Temp & open]
> >> .