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] > . _________________________ Racket Developers list: http://lists.racket-lang.org/dev
