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

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]
>> .