Provided by: tk9.0-doc_9.0.1-1_all 
NAME
geometry, tk_library, tk_patchLevel, tk::scalingPct, tk_strictMotif, tk::svgFmt, tk_version - Variables
used or set by Tk
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DESCRIPTION
The following Tcl variables are either set or used by Tk at various times in its execution:
tk_library This variable holds the file name for a directory containing a library of Tcl scripts
related to Tk. These scripts include an initialization file that is normally processed
whenever a Tk application starts up, plus other files containing procedures that implement
default behaviors for widgets.
The initial value of tk_library is set when Tk is added to an interpreter; this is done
by searching several different directories until one is found that contains an appropriate
Tk startup script. If the TK_LIBRARY environment variable exists, then the directory it
names is checked first. If TK_LIBRARY is not set or does not refer to an appropriate
directory, then Tk checks several other directories based on a compiled-in default
location, the location of the Tcl library directory, the location of the binary containing
the application, and the current working directory.
The variable can be modified by an application to switch to a different library.
tk_patchLevel Contains a dot-separated sequence of decimal integers giving the current patch level for
Tk. The patch level is incremented for each new release or patch, and it uniquely
identifies an official version of Tk.
This value is normally the same as the result of “package require tk”.
tk::scalingPct Tk sets this variable at initialization time to the scaling percentage corresponding to
the display's DPI scaling level. This value is at least 100 and is restricted to
multiples of 25 (100, 125, 150, 175, 200, 225, ...). The sizes and various attributes of
the Tk core and Ttk widgets and their components, as well as the sizes of the images used
by Tk are chosen according to the scaling percentage, and this is recommended for
applications and library packages, too.
Note that any access to this variable is supposed to be strictly read-only! Note also
that whenever the scaling factor used to convert between physical units and pixels is
changed via tk scaling, the value of the variable tk::scalingPct is automatically updated.
On the windowing systems win32 and aqua the scaling percentage is computed by rounding [tk
scaling] * 75 to the nearest multiple of 25 that is at least 100. (On aqua the result is
always 100, and the desktop engine automatically scales everything as needed.) On x11,
deriving the scaling percentage from [tk scaling] is done as fallback method only, because
the implementation of display scaling is highly dependent on the desktop environment and
it mostly manipulates system resources that are resident outside of Xlib, which Tk is
based on. Moreover, for technical reasons, the value assigned to the variable
tk::scalingPct can be different from the one selected in the system settings (e.g., 200
rather than 125, 150, or 175 when running GNOME on Xorg or the Cinnamon desktop). On x11
the scaling percentage is computed mostly (but not exclusively) from the value of the X
resource Xft.dpi, and, as an additional step, Tk synchronizes the scaling factor used to
convert between physical units and pixels with the scaling percentage, with the aid of the
tk scaling command.
tk_strictMotif This variable is set to zero by default. If an application sets it to one, then Tk
attempts to adhere as closely as possible to Motif look-and-feel standards. For example,
active elements such as buttons and scrollbar sliders will not change color when the
pointer passes over them. Modern applications should not normally set this variable.
tk::svgFmt This variable is set at Tk initialization time to
[list svg -scale [expr {$tk::scalingPct / 100.0}]]
Typical values are {svg -scale 1.0}, {svg -scale 1.25}, {svg -scale 2.0}, etc. It is
recommended to pass the value of this variable to the commands image create photo,
imageName configure, imageName put, and imageName read as the value of their -format
option when creating or manipulating SVG images, to make sure that their sizes will
correspond to the display's DPI scaling level.
Note that any access to this variable is supposed to be strictly read-only! Note also
that whenever the scaling factor used to convert between physical units and pixels is
changed via tk scaling, the value of the variable tk::svgFmt is automatically updated.
tk_version Tk sets this variable in the interpreter for each application. The variable holds the
current version number of the Tk library in the form major.minor. Major and minor are
integers. The major version number increases in any Tk release that includes changes that
are not backward compatible (i.e. whenever existing Tk applications and scripts may have
to change to work with the new release). The minor version number increases with each new
release of Tk, except that it resets to zero whenever the major version number changes.
INTERNAL AND DEBUGGING VARIABLES
These variables should not normally be set by user code.
tk::Priv
This variable is an array containing several pieces of information that are private to Tk. The
elements of tk::Priv are used by Tk library procedures and default bindings. They should not be
accessed by any code outside Tk.
tk_textRedraw
tk_textRelayout
These variables are set by text widgets when they have debugging turned on. The values written to
these variables can be used to test or debug text widget operations. These variables are mostly
used by Tk's test suite.
OTHER GLOBAL VARIABLES
The following variables are only guaranteed to exist in wish executables; the Tk library does not define
them itself but many Tk environments do.
geometry
If set, contains the user-supplied geometry specification to use for the main Tk window.
SEE ALSO
package(3tcl), tclvars(3tcl), wish(1)
KEYWORDS
environment, text, variables, version
Tk 4.1 tkvars(3tk)