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Fontproblems with PyGUI and gtk 2.4.10

P: n/a
Hi!

After some installation problems related to PyGUI (well, indirectly -- I
had to install new versions of: freetype, fontconfig, xft2 (from
fcpackage.2_1.tar.gz, because the latest xft2 won't compile with X4.2.0)
(which needed a patch to Xft.h because apparently the #include-style of
freetype did change), GLib, Pango, ATK, GTK+ and pygtk) I ran the
scripts from Tests and there were problems that text was cut off or
textfields were not tall enough (e.g. 09-textfield.py). I did some
digging and found the cause. The problem is in the line

gdk_font = gdk.font_from_description(self._pango_description)

in Fonts.Font._get_gdk_font(). In gtk 2.4.10 gdk_font_from_description
calls gdk_font_from_description_for_display in gdkfont-x11.c, which
contains the line

return gdk_font_load_for_display (display, "fixed");

So regardless what font is wanted, the fixed font gets loaded. The big
problem here is that some widgets use a different font but use
Font.width(), get_height() etc. for layout. Of course this give wrong
values (e.g. get_height() always returns 13, width(s) always 6*len(s)).

It looks as if Fonts.py has to be ported to fully use pango. For
get_ascent, get_descent (btw. the gdk_font based version returns ascent)
and get_height there is code which seems to work, it is just commented
and some small changes must made. But rewriting width() and x_to_pos() to
use pango seems to be not easy. At least I see no obvious way to do it.
But this change really should be made because all the GdkFont functions
are declared obsolete in the gtk+ documentation.

I've attached a patch for two small typos in Fonts.py

--- Fonts.py.orig Tue Sep 21 23:08:28 2004
+++ Fonts.py Tue Sep 21 23:12:43 2004
@@ -45,7 +45,7 @@
return self._pango_description.get_family()

def get_size(self):
- return self.self._pango_description.get_size()
+ return self._pango_description.get_size()

def get_style(self):
style = []
@@ -60,7 +60,7 @@
return self._get_gdk_font().ascent

def get_descent(self):
- return self._get_gdk_font().ascent
+ return self._get_gdk_font().descent

def get_height(self):
gdk_font = self._get_gdk_font()

and here one to change get_ascent, get_descent and get_height to pango

--- Fonts.py.orig Tue Sep 21 23:18:54 2004
+++ Fonts.py Tue Sep 21 23:15:09 2004
@@ -10,6 +10,7 @@
class Font(GFont):

_gdk_font = None
+ _pango_metrics = None

# def _from_gdk_font(cls, gdk_font):
# font = cls.__new__(cls)
@@ -56,15 +57,15 @@
style.append('italic')
return style

- def get_ascent(self):
- return self._get_gdk_font().ascent
-
- def get_descent(self):
- return self._get_gdk_font().descent
-
- def get_height(self):
- gdk_font = self._get_gdk_font()
- return gdk_font.ascent + gdk_font.descent
+# def get_ascent(self):
+# return self._get_gdk_font().ascent
+#
+# def get_descent(self):
+# return self._get_gdk_font().descent
+#
+# def get_height(self):
+# gdk_font = self._get_gdk_font()
+# return gdk_font.ascent + gdk_font.descent

def _get_gdk_font(self):
gdk_font = self._gdk_font
@@ -73,26 +74,26 @@
self._gdk_font = gdk_font
return gdk_font

-# def get_ascent(self):
-# pfm = self._get_pango_metrics()
-# return pfm.ascent
-#
-# def get_descent(self):
-# self._get_pango_metrics()
-# return self._descent
-#
-# def get_height(self):
-# self._get_pango_metrics()
-# return self._ascent + self._descent
-#
-# def _get_pango_metrics(self):
-# pfm = self._pango_metrics
-# if not pfm:
-# pfm = _pango_context.get_metrics(self._pango_description )
-# self._pango_metrics = pfm
-# self._ascent = pfm.ascent / pango.SCALE
-# self._descent = pfm.descent / pango.SCALE
-# return pfm
+ def get_ascent(self):
+ self._get_pango_metrics()
+ return self._ascent
+
+ def get_descent(self):
+ self._get_pango_metrics()
+ return self._descent
+
+ def get_height(self):
+ self._get_pango_metrics()
+ return self._ascent + self._descent
+
+ def _get_pango_metrics(self):
+ pfm = self._pango_metrics
+ if not pfm:
+ pfm = _pango_context.get_metrics(self._pango_description )
+ self._pango_metrics = pfm
+ self._ascent = pfm.get_ascent() / pango.SCALE
+ self._descent = pfm.get_descent() / pango.SCALE
+ return pfm

def width(self, s, start = 0, end = sys.maxint):
gdk_width = self._get_gdk_font().width
Jul 18 '05 #1
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