[developer] Control fontsize of hex diff/dump display - #1681

Add user specification of the font size to use for the hex diff/dump
display, without affecting any other Chirp displays.
This is done with a new chirp.config integer property diff_fontsize
in a new [developer] section. The default is unchanged at 11.
Values between 4 and 144 are accepted; others result in the default.

Add a new file README.developers at the top level of the repository
to document chirp.config [developer] section properties.

#1681

README.developers

@@ -0,0 +1,31 @@
+This file describes some features in the Chirp Developer's Functions
+that allow some customization of their behavior, but are only
+accessible through editing the chirp.config file before starting
+Chirp, and are not accessible through the GUI.
+
+The Developer Functions are enabled in the GUI by checking the box
+in  the "Help" tab. They enable the Image Browser tab in the left
+sidebar, and several tools under the View -> Developer tab.
+
+These directives are similar to other chirp.config entries in syntax.
+They reside in the [developer] section in chirp.config.
+This section, and all the directives, are not required to be present;
+all the options have defaults.
+
+Here is an example [developer] section listing all the directives,
+followed by an explanation of each directive:
+
+===================================
+[developer]
+diff_fontsize = 16
+
+===================================
+
+diff_fontize = <integer>
+This specifies the fontsize used in the hex dump/diff display which is
+invoked by selecting View -> Developer -> Diff tabs, and then in the
+"Diff Radios" popup, selecting < 0 for either or both memory locations.
+
+The default size is 11. Values less than 4, greater than 144, or not
+recognized as an integer will result in a log message and the default 
+size will be used.

chirpui/common.py

@@ -23,7 +23,9 @@
 import traceback
 
 from chirp import errors
-from chirpui import reporting
+from chirpui import reporting, config
+
+CONF = config.get()
 
 class Editor(gobject.GObject):
     __gsignals__ = {
@@ -391,6 +393,14 @@ def show_diff_blob(title, result):
     tag.set_property("weight", pango.WEIGHT_BOLD)
     tags.add(tag)
 
+    try:
+        fontsize = CONF.get_int("diff_fontsize", "developer")
+    except Exception:
+        fontsize = 11
+    if fontsize < 4 or fontsize > 144:
+        print "Unsupported diff_fontsize %i. Using 11." % fontsize
+        fontsize = 11
+
     lines = result.split(os.linesep)
     for line in lines:
         if line.startswith("-"):
@@ -401,7 +411,7 @@ def show_diff_blob(title, result):
             tags = ()
         b.insert_with_tags_by_name(b.get_end_iter(), line + os.linesep, *tags)
     v = gtk.TextView(b)
-    fontdesc = pango.FontDescription("Courier 11")
+    fontdesc = pango.FontDescription("Courier %i" % fontsize)
     v.modify_font(fontdesc)
     v.set_editable(False)
     v.show()