Tk Source Code

The current Scale widget isn't able to display a range starting with 1 and having a resolution of 2. Instead the "-from" value is rounded to be a multiple of the "-resolution".

Example:
pack [scale .s -orient hor -from 1 -to 9 -resolution 2 -tickinterval 1] -fill x

The attached diffs contain all changes necessary to fix this odd behaviour. It's a diff for Tk 8.5.8, tkScale.c and tkScale.h.
The "TkRoundToResolution" function has to be updated and "TkRoundTickToResolution" is introduced. The first one now refers to the "-from" value, too, and the latter is needed to round the "-tickinterval" without any reference to this value.

Merged to core-8-6-branch and trunk.

Better fix committed [83c7e670]. All tests now pass in the bugfix branch.

Should probably study [5e295d879b98ead5] (the changes in scale.c)

Test scale-14.13 that I have just added reveals that the proposed fix unfortunately resurrects [220665ffff], and duplicates [220265ffff] and [779559ffff].

This needs further work.

The completed scale.test passes 100% OK on Linux Debian 8 and macOS 10.14.2 Mojave as well as on Windows Vista.

I have committed a fix in a bugfix branch that is largely inspired by your proposal, and I have added two new tests.

This all passes scale.test 100% OK (tested on Windows).

Because I couldn't find a way to upload a second file, here's the diff-content for the header file.

--- tkScale.h2005-11-26 20:36:14.000000000 +0100
+++ tkScale.h2010-05-18 15:40:33.281250000 +0200
@@ -233,6 +233,7 @@
 
 MODULE_SCOPE voidTkEventuallyRedrawScale(TkScale *scalePtr, int what);
 MODULE_SCOPE doubleTkRoundToResolution(TkScale *scalePtr, double value);
+MODULE_SCOPE doubleTkRoundTickToResolution(TkScale *scalePtr, double value);
 MODULE_SCOPE TkScale *TkpCreateScale(Tk_Window tkwin);
 MODULE_SCOPE voidTkpDestroyScale(TkScale *scalePtr);
 MODULE_SCOPE voidTkpDisplayScale(ClientData clientData);

File Added - 374397: tkScale.c.diff