1 Jul 11:38
TIP #321: Add a tk::busy Command
From: Jos Decoster <jos.decoster@...>
Subject: TIP #321: Add a tk::busy Command
Newsgroups: gmane.comp.lang.tcl.core
Date: 2008-07-01 09:41:56 GMT
Subject: TIP #321: Add a tk::busy Command
Newsgroups: gmane.comp.lang.tcl.core
Date: 2008-07-01 09:41:56 GMT
TIP #321: ADD A TK::BUSY COMMAND ================================== Version: $Revision: 1.1 $ Author: Jos Decoster <jos.decoster_at_gmail.com> State: Draft Type: Project Tcl-Version: 8.6 Vote: Pending Created: Thursday, 26 June 2008 URL: http://purl.org/tcl/tip/321.html WebEdit: http://purl.org/tcl/tip/edit/321 Post-History: ------------------------------------------------------------------------- ABSTRACT ========== The *blt::busy* commands can be used to make Tk widget busy, with all user interaction blocked and the cursor can be changed to e.g. a clock. This TIP proposes to add this useful feature to Tk. RATIONALE =========== BLT has a lot of very useful commands: *bgexec*, *busy*, *vector*, *graph* widget, *barchart* widget, ... But getting BLT to work with the latest releases of Tcl and Tk becomes more and more difficult. Some of the problems I experienced are: * internal Tk structures are mirrored * interaction with xft fails, so Tk has to be build without xft support * the build process is different from the one used in Tcl and Tk Discussions on CLT and #tcl indicated that extracting functionality from BLT and add it to Tcl and Tk might be a good way to make the blt commands available for every Tcl programmer. This TIP proposes a way to add the blt::busy command to Tk, based on the code as found in BLT2.4z and the code as found in busy.kit. While adding the code to Tk, it was rewritten to use the Tcl_Obj interface and the new option interface. The name of this new Tk command as currently implemented is *tk::busy*. Adding it as an option to the *grab* command might cause confusion as the *tk::busy* command has the opposite functionality of the *grab* command. It blocks all user interaction rather than redirecting it to one widget. Another alternative is adding it to the ensemble of *tk* commands (*tk appname*, *tk scaling*, *tk inactive*, ...). SPECIFICATION =============== The *tk::busy* command is an ensemble with a special feature that any unrecognized subcommand that starts with a period is treated as an invokation of the *hold* subcommand upon the widget with that name. HOLD SUBCOMMAND ----------------- *tk::busy* /window/ ?/option value/? *tk::busy hold* /window/ ?/option value/? Makes the widget window (and its descendants in the Tk window hierarchy) busy. /Window/ must be a valid path name of a Tk widget. The busy window is mapped the next time idle tasks are processed, and the widget and its descendants will be blocked from user interactions. All events in the widget window and its descendants are ignored. Normally update should be called immediately afterward to insure that the hold operation is in effect before the application starts its processing. The following configuration options are valid: *-cursor* /cursorName/ Specifies the cursor to be displayed when the widget is made busy. CursorName can be in any form accepted by Tk_GetCursor. The default cursor is watch. FORGET SUBCOMMAND ------------------- *tk::busy forget* /window/ Releases resources allocated by the *tk::busy* command for /window/, including the busy window. User events will again be received again by window. Resources are also released when window is destroyed. /Window/ must be the name of a widget specified in the *hold* operation, otherwise an error is reported. RELEASE SUBCOMMAND -------------------- *tk::busy release* /window/ Restores user interactions to the widget /window/ again. This differs from the *forget* operation in that the busy window is not destroyed, but simply unmapped. /Window/ must be the name of a widget specified in a *hold* operation, otherwise an error is reported. ISBUSY SUBCOMMAND ------------------- *tk::busy isbusy* ?/pattern/? Returns the pathnames of all widgets that are currently busy. If a /pattern/ is given, the path names of busy widgets matching /pattern/ are returned. NAMES SUBCOMMAND ------------------ *tk::busy names* ?/pattern/? Returns the pathnames of all widgets that have previously been made busy (i.e. a busy window is allocated and associated with the widget). It makes no difference if the window is currently busy or not. If a /pattern/ is given, the path names of busy widgets matching /pattern/ are returned. STATUS SUBCOMMAND ------------------- *tk::busy status* /window/ Returns the busy status of a widget /window/. If /window/ presently can not receive user interactions, 1 is returned, otherwise 0. CONFIGURE SUBCOMMAND ---------------------- *tk::busy configure* /window/ ?/option/? ?/value .../? Queries or modifies the *tk::busy* command configuration options for /window/. /Window/ must be the path name of a widget previously made busy by the *hold* operation. If no options are specified, a list describing all of the available options for window (see Tk_ConfigureInfo for information on the format of this list) is returned. If /option/ is specified with no /value/, then the command returns a list describing the one named option (this list will be identical to the corresponding sublist of the value returned if no option is specified). If one or more /option-value/ pairs are specified, then the command modifies the given widget option(s) to have the given value(s); in this case the command returns the empty string. Option may have any of the values accepted by the hold operation. Please note that the option database is referenced through window. For example, if the widget .frame is to be made busy, the busy cursor can be specified for it by either option command: option add *frame.busyCursor gumby option add *Frame.BusyCursor gumby CGET SUBCOMMAND ----------------- *tk::busy cget* /window option/ Queries the *tk::busy* command configuration options for /window/. /Window/ must be the path name of a widget previously made busy by the *hold* operation. The command returns the present value of the specified /option/. /Option/ may have any of the values accepted by the *hold* operation. REFERENCE IMPLEMENTATION ========================== See SourceForge patch #1997907 [<URL:http://sf.net/tracker/?func=detail&aid=1997907&group_id=12997&atid=312997>]. COMPATIBILITY =============== Because the command as proposed above has the same interface and behavior as the *blt::busy* command, replacing *blt::busy* with *tk::busy* is all that's needed to switch to the Tk version of the busy command. ALTERNATIVES ============== The busy command is available as starkit from <URL:http://tcl.tk/starkits/busy.kit> COPYRIGHT =========== This document has been placed in the public domain. ------------------------------------------------------------------------- TIP AutoGenerator - written by Donal K. Fellows ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php
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