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- .so man.macros
- .HS blt_intro cmds BLT Commands
- .BS
- '\" Note: do not modify the .SH NAME line immediately below!
- .SH NAME
- blt_intro \- Introduction to the BLT library
- .BE
- .SH DESCRIPTION
- BLT is a library of extensions to the Tk library. It adds new
- commands and variables (all prefixed by "blt_") to the application's
- interpreter.
- .LP
- .SH COMMANDS
- The following commands are added to the interpreter from the BLT library:
- .TP 15
- \fBblt_drag&drop\fR
- Provides a drag-and-drop facility for Tk. Information (represented
- by a token window) can be dragged to and from any Tk window, including
- those of another Tk application. \fBblt_drag&drop\fR acts as a
- coordinator, directing Tk \fBsend\fR commands between (or within) TCL/Tk
- applications.
- .TP 15
- \fBblt_htext\fR
- A simple hypertext widget. Combines text and Tk widgets into a single
- scroll-able window. Tcl commands can be embedded into text, which are
- invoked as the text is parsed. In addition, Tk widgets can be appended
- to the window at the current point in the text. \fBblt_htext\fR can
- be also used to create scrolled windows of Tk widgets.
- .TP 15
- \fBblt_graph\fR
- A 2D plotting widget. Plots two variable data in a window with an optional
- legend and annotations. It has of several components; coordinate axes,
- crosshairs, a legend, and a collection of elements and tags.
- .TP 15
- \fBblt_barchart\fR
- A barchart widget. Plots two-variable data as rectangular bars in a
- window. The x-coordinate values designate the position of the bar along
- the x-axis, while the y-coordinate values designate the magnitude.
- The \fBblt_barchart\fR widget has of several components; coordinate axes,
- crosshairs, a legend, and a collection of elements and tags.
- .TP 15
- \fBblt_table\fR
- A table geometry manager for Tk. You specify window placements as table
- row,column positions and windows can also span multiple rows or columns.
- It also has many options for setting and/or bounding window sizes.
- .TP 15
- \fBblt_bitmap\fR
- Reads and writes bitmaps from Tcl. New X bitmaps can be defined
- on-the-fly from Tcl, obviating the need to copy around bitmap files.
- Other options query loaded X bitmap's dimensions and data.
- .TP 15
- \fBblt_bgexec\fR
- Like Tcl's \fBexec\fR command, \fBblt_bgexec\fR runs a pipeline of Unix
- commands in the background. Unlike \fBexec\fR, the output of the last
- process is collected and a global Tcl variable is set upon its completion.
- \fBblt_bgexec\fR can be used with \fBtkwait\fR to wait for Unix commands
- to finish while still handling expose events. Intermediate output is
- also available while the pipeline is active.
- .TP 15
- \fBblt_busy\fR
- Creates a "busy window" which prevents user-interaction when an
- application is busy. The busy window also provides an easy way
- to have temporary busy cursors (such as a watch or hourglass).
- .TP 15
- \fBblt_win\fR
- Raise, lower, map, or, unmap any window. The raise and lower functions
- are useful for stacking windows above or below "busy windows".
- .TP 15
- \fBblt_watch\fR
- Arranges for Tcl procedures to be called before and/or after the execution
- of every Tcl command. This command
- may be used in the logging, profiling, or tracing of Tcl code.
- .TP 15
- \fBblt_debug\fR
- A simple Tcl command tracing facility useful for debugging Tcl code.
- Displays each Tcl command before and after substitution along its level
- in the interpreter on standard error.
- .TP 15
- \fBblt_bell\fR
- Rings the keyboard bell. This is useful when the application can't
- write to a tty.
- .TP 15
- \fBblt_cutbuffer\fR
- Manipulates X cutbuffer properties. This is useful for communicating with
- other X applications that don't properly use X selections.
- .SH VARIABLES
- .PP
- The following Tcl variables are either set or used by BLT at various times
- in its execution:
- .TP 15
- \fBblt_library\fR
- This variable contains the name of a directory containing a library
- of Tcl scripts and other files related to BLT. Currently, this
- directory contains the \fBblt_drag&drop\fR protocol scripts and the
- PostScript prolog
- used by \fBblt_graph\fR and \fBblt_barchart\fR.
- The value of this variable is taken from the BLT_LIBRARY environment
- variable, if one exists, or else from a default value compiled into
- the \fBBLT\fR library.
- .TP 15
- \fBblt_versions\fR
- This variable is set in the interpreter for each application. It is an
- array of the current version numbers for each
- of the BLT commands in the form \fImajor\fR.\fIminor\fR. \fIMajor\fR and
- \fIminor\fR are integers. The major version number increases in
- any command that includes changes that are not backward compatible
- (i.e. whenever existing applications and scripts may have to change to
- work with the new release). The minor version number increases with
- each new release of a command, except that it resets to zero whenever the
- major version number changes. The array is indexed by the individual
- command name.
- .SH ADDING BLT TO YOUR APPLICATIONS
- It's easy to add BLT to an existing Tk application. BLT requires no
- patches or edits to the Tcl or Tk libraries. To add BLT, simply add the
- following code snippet to your application's tkAppInit.c file.
- .DS
- \fCif (Blt_Init(interp) != TCL_OK) {
- return TCL_ERROR;
- }\fR
- .DE
- Recompile and link with the BLT library (libBLT.a) and that's it.
- .SH BUGS
- Send bug reports, correspondence, etc. to george.howlett@att.com
- .SH KEYWORDS
- BLT
-