Finding width of a piece of text

["Ian Puleston" <ian underpressuredivers com>]

Hi,

I'm having (yet another) problem with Pango. I have a need to find the width
that a piece of text will be displayed. I thought this piece of code would
do it, but the result is not quite right. The Pango attributes have been set
for "Courier" font and point size 10:

    lbl = gtk_label_new(pText);
    gtk_label_set_attributes(GTK_LABEL(lbl), attrList);
    layout = gtk_label_get_layout(GTK_LABEL(lbl));
    g_assert(layout);
    pango_layout_get_size(layout, &width, &height);

    gdouble wid = (gdouble)width / (72 * PANGO_SCALE);
    g_print("'%s' width %d units (%.2g\")\n", pText, width, wid);

An example of what it prints is:

'Ken Hanlon' width 81920 units (1.1")
'Ian Puleston' width 98304 units (1.3")

But those don't match the widths it prints on paper with the same font and
point size - these names are both about 1" wide.

I also tried getting the PangoLayoutLine from the layout and using
pango_layout_line_get_extents but got the same result.

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