gnocl::cairo instropection

The gnocl::cairo command is not intended to be some form of canvas object, but a means of drawing onto images for display on screen used perhaps in the creation of widgets or images. Bearing in mind the relatively small number of actions required for this task, it's reasonable to assume that the overhead of making multiple calls to the gnocl::cairo command is a worthwhile compromise.

In response to the problem of how to get the extents of rendered text back from Cairo I came up with the solution highlighted in the following code:

set pb(1) [gnocl::pixBuf new -width 256 -height 256]
set myString "Peter Piper picked a peck of pickled peppers."
set actions "
    select_font_face {Sans normal bold}
    set_font_size 15.0
    text_extents $myString"
array set extents [gnocl::cairo $pb(1) -actions $actions]

In the example above, the following values were obtained.

extents(height)    = 14.0
extents(width)     = 320.0
extents(x_advance) = 322.0
extents(x_bearing) = 1.0
extents(y_advance) = 0.0
extents(y_bearing) = -11.0

Comments

gnocl::calendar

Given this module some attention today. Added some of the more package wide options to the module and created customised handler for setting the month. (For some odd reason months are are counted 0-11 whereas days are 1-31.) There's still a little more to do to this one including the addition of code to store diary details. Here's the working test script to show the range of options at work. The percentage substitution string item %e explores something that I've been toying with, the name of the signal/event that initiated the call. Ok, a script can keep its own internal trace but who knows, it might prove useful. #--------------- # calendarTest.tcl #--------------- # Author: William J Giddings # Date: 07/05/09 #--------------- #!/bin/sh # the next line restarts using tclsh \ exec tclsh "$0" "$@" #--------------- package require Gnocl set cal [gnocl::calendar] $cal configure -day 8 -month 7 -year 1956 $cal configure -rowHeight 1 -colWidth 1 $ca

Gnocl Dashboard

Over the past few programming sessions I've been working on producing a central point, a dashboard, around which it's possible to see the various Gnocl widgets and commands in operation. In many ways like the demo script which shipped with the earlier releases of Gnocl but offers much more. The introspection functionality provides details of the various options and sub-commands of each Gnocl procedure which are displayed under the associated tab. Sample scripts are included for each item which offers newcomers a clearer insight into how make the most of what's on offer.

Creating a button box with right aligned widgets

The dialog widget has its own internal functionaluty to create and position buttons at the bottom right corner of the window container. When creating these for ourselves it must be born in mind that default settings for fill and expand are both 0.5. Failing to set these will always place the child objects in the centre, regardless of alignment. For most cases these defaults are acceptable but, to create that dialog-button arrangement, use the following snippet as a model! # to right align completely, set expand and fill to 0 set hbox [gnocl::hBox] set b1 [gnocl::button -text Select \ -data $lst -onClicked { puts DO-SOMETHING-WITH-%d} ] set b2 [gnocl::button -text Cancel -onClicked { puts DONE! } ] $vbox add $hbox -expand 0 -fill 0 -align right $hbox add $b1 $hbox add $b2

Gnocl -the Tcl/Gtk Bindings

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