Each gtkfont back end now provides a routine that will return the name
of a similar font to the current one but one notch larger or smaller.
For Pango, this is just a matter of incrementing the font size field
in a standard way; for X11 server-side fonts, we have to go and do an
XListFonts query with a wildcard that requests fonts that vary only in
the size fields from the current one, and then iterate over the result
looking for the best one.
(I expect this will be more useful to Pango scalable-font users than
to X11 fonts, but it seemed a shame not to give the X11 side my best
shot while I was at it.)
Choice of hotkey: I know I'm being inconsistent with gnome-terminal's
use of Ctrl-plus and Ctrl-minus. I thought that was because I was
already using Ctrl-minus as a more convenient synonym for
Ctrl-underscore (which sends the actual control code 0x1F), but now I
actually try it, apparently I'm not. However, Ctrl-plus and Ctrl-minus
are quite horrible as a keystroke pair anyway (one has to be typed
with shift and one without!), and I feel as if the 'less' and
'greater' signs are more specific anyway, in that they specifically
indicate _size_ rather than just 'unspecified numerical value'.
The top-level loop in gtkwin.c which draws text was expecting that the
right way to draw a printing character plus combining characters was
to overprint them one by one on top of each other. This is an OK
assumption for X bitmap fonts, but in Pango, it works very badly -
most obviously because asking Pango to display a combining char on its
own causes it to print a dotted circle representing the base char, but
also because surely there will be character combinations where Pango
wants to do something more sophisticated than just printing them each
at a standard offset, and it would be a shame not to let it.
So I've moved the previous overprinting loop down into the x11font
subclass of the unifont mechanism. The top-level gtkwin.c drawing code
now calls a new method unifont_draw_combining, which in the X11 case
does the same loop as before, but in the Pango case, just passes a
whole base+combinings string to Pango in one go and lets it do the
best job it can.
We won't be able to use them in GTK3, or when compiling with GTK2 and
-DGDK_DISABLE_DEPRECATED.
This applies to the one we use for the main terminal window, and also
the small one we use for the preview pane in the unified font selector.
We're going to have to use Cairo in the GTK3 port, because that's all
GTK3 supports; but we still need old-style GDK for GTK1 support, and
also for performance reasons in GTK2 (see below). Hence, this change
completely restructures GTK PuTTY's drawing code so that there's a
central 'drawing context' structure which contains a type code
indicating GDK or Cairo, and then either some GDK gubbins or some
Cairo gubbins as appropriate; all actual drawing is abstracted through
a set of routines which test the type code in that structure and do
one thing or another. And because the type code is tested at run time,
both sets of drawing primitives can be compiled in at once, and where
possible, they will be.
X server-side bitmap fonts are still supported in the Cairo world, but
because Cairo drawing is entirely client-side, they have to work by
cheekily downloading each glyph bitmap from the server when it's first
needed, and building up a client-side cache of 'cairo_surface_t's
containing the bitmaps with which we then draw on the window. This
technique works, but it's rather slow; hence, even in GTK2, we keep
the GDK drawing back end compiled in, and switch over to it when the
main selected font is a bitmap one.
One visible effect of the new Cairo routines is in the double-width
and double-height text you can get by sending ESC # 3, ESC # 4 and
ESC # 6 escape sequences. In GDK, that's always been done by a really
horrible process of manually scaling the bitmap, server-side, column
by column and row by row, causing each pixel to be exactly doubled or
quadrupled. But in Cairo, we can just set a transformation matrix, and
then that takes effect _before_ the scalable fonts are rendered - so
the results are visibly nicer, and use all the available resolution.
(Sadly, if you're using a server-side bitmap font as your primary one,
then the GDK backend will be selected for all drawing in the terminal
as a whole - so in that situation, even fallback characters absent
from the primary font and rendered by Pango will get the old GDK
scaling treatment. It's only if your main font is scalable, so that
the Cairo backend is selected, that DW/DH characters will come out
looking nice.)
by introducing a wrapper around an individual unifont which falls back
to Pango (which already has built-in fallback) in the case where the
selected font doesn't support the glyph in question.
The wrapper itself is a (vestigial) subclass of unifont, to minimise
disturbance at the call sites.
[originally from svn r9293]
individual font implementation as wchar_t, rather than having to be
converted by the client into the appropriate MBCS/SBCS.
This also means I can remove 'real_charset' from the public-facing
contents of the unifont structure.
[originally from svn r9292]
sizable TODO at the top of gtkfont.c - but it's basically functional
enough to select fonts of both types, so I'm checking it in now
before I accidentally break it.
[originally from svn r7938]
explicitly deals with GdkFont out into a new module, behind a
polymorphic interface (done by ad-hoc explicit vtable management in
C). This should allow me to drop in a Pango font handling module in
parallel with the existing one, meaning that GTK2 PuTTY will be able
to seamlessly switch between X11 server-side fonts and Pango client-
side ones as the user chooses, or even use a mixture of the two
(e.g. an X11 font for narrow characters and a Pango one for wide
characters, or vice versa).
In the process, incidentally, I got to the bottom of the `weird bug'
mentioned in the old do_text_internal(). It's not a bug in
gdk_draw_text_wc() as I had thought: it's simply that GdkWChar is a
32-bit type rather than a 16-bit one, so no wonder you have to
specify twice the length to find all the characters in the string!
However, there _is_ a bug in GTK2's gdk_draw_text_wc(), which causes
it to strip off everything above the low byte of each GdkWChar,
sigh. Solution to both problems is to use an array of the underlying
Xlib type XChar2b instead, and pass it to gdk_draw_text() cast to
gchar *. Grotty, but it works. (And it'll become significantly less
grotty if and when we have to stop using the GDK font handling
wrappers in favour of going direct to Xlib.)
[originally from svn r7933]
