Re: Pango, Cairo, Scale, and Ink Rectangles

[Yclept Nemo <orbisvicis gmail com>]

On Mon, Nov 24, 2014 at 5:12 PM, Behdad Esfahbod <behdad behdad org> wrote:

On 14-11-23 11:15 AM, Yclept Nemo wrote:
> This seems impossible if the glyph width/height ratios vary with scale/dpi.

Turn hinting off.  Like this:

  https://git.gnome.org/browse/pango/tree/examples/cairotwisted.c#n477

Thanks,

It is a necessary suggestion, but unfortunately the glyph width/height ratios continue to vary. I'm pretty sure I've followed the example correctly:

Using Pango resolution:
    cairo_fontoptions = cairo.FontOptions()
    cairo_fontoptions.set_hint_metrics(cairo.HINT_METRICS_OFF)
    cairo_fontoptions.set_hint_style(cairo.HINT_STYLE_NONE)
    ctx.set_font_options(cairo_fontoptions)
    ctx.identity_matrix()
    pango_context = PangoCairo.create_context(ctx)
    PangoCairo.context_set_resolution(pango_context, dpi)
    l1 = Pango.Layout(pango_context)
    l1.set_font_description(font_description)
    l1.set_text("8",1)
    e1 = l1.get_extents()[0]
    print(e1.x / Pango.SCALE, ...)

Using Cairo transformations:
    cairo_fontoptions = cairo.FontOptions()
    cairo_fontoptions.set_hint_metrics(cairo.HINT_METRICS_OFF)
    cairo_fontoptions.set_hint_style(cairo.HINT_STYLE_NONE)
    ctx.set_font_options(cairo_fontoptions)
    ctx.identity_matrix()
    ctx.scale(*(scale,)*2)
    layout = PangoCairo.create_layout(ctx)
    layout.set_font_description(font_description)
    layout.set_text("8",1)
    e1 = layout.get_extents()[0]
    print(e1.x / Pango.SCALE, ...)

Sincerely,