On 04/26/2009 09:09 PM, Ian Puleston wrote:
I may well be wrong, but it seems to me that in this case it should not matter. Should
10-point courier font not be the same size no matter what it is printed on since a point
is fixed at 1/72 inch? The "device unit" of a Pango layout is a point so it
would seem logical that the text width being a certain number of points is the always
going to be the same size. What am I missing here?
Font hinting. The same font can have different widths when hinted vs not
hinted.
To put it another way, the font metrics from the Pango context can tell me the
width of the characters (see below) so Pango should be able to tell me the
width of the string.
The character widths change depending on the hinting setting.
I can't use pango_cairo_create_layout() at this point because I don't yet know
what print device it will be printed on.
Then at least 1) make sure your context is set to 72 dpi, and 2) set font
options to disable metrics hinting.
behdad
Note that the following code gets the width of a character from the
font and
reports it as 6074. Converting that from Pango units to points and
then to
inches works out at 0.988" for the above 12-digit strings, which
looks
exactly right. So why would this yield the correct width when
pango_layout_get_size apparently does not?
ctx = pango_layout_get_context(layout);
g_assert(ctx);
fontDesc = pango_context_get_font_description(ctx);
g_assert(fontDesc);
lang = pango_context_get_language(ctx);
g_assert(lang);
metrics = pango_context_get_metrics(ctx, fontDesc, lang);
g_assert(metrics);
g_print("char width %d\n",
pango_font_metrics_get_approximate_char_width(metrics));
Ian
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