Tcl/Tk - Drawing on Canvases

Drawing on Canvases - Tcl/Tk module T219

Tcl/Tk GUIs consist largely of components such as buttons, labels entry boxes and sliders. Sometimes you'll need something that's much more graphic and for this you'll use a canvas widget. You can write to a canvas down to individual pixel level, and you can also draw lines, ovals, rectangles, text and polygons. This module studies the options for drawing to and manipulating a canvas, and introduces computer graphic techniques such as world to pixel co-ordinate transformations and display list manipulation.

This topic is presented on public course Tcl/Tk

Examples from our training material

can1	drawing on a canvas
can2	Drawing shapes on a canvas and dragging them with the mouse
can3	demo of different graphic objects
can4	Line styles on a Tk canvas
histo	Histogram drawn on a canvas - generalised code
imgoncanvas.tk	Placing a GIF on a canvas
tktext	text options in Tk - colour, font, size, centering

Opentalk forum discussions related to this topic

how to use scrollbars for canvas
binding rectangles in tk canvas
Moving object

Pictures

Using a Tcl/Tk canvas

Background information

Some modules are available for download as a sample of our material or under an Open Training Notes License for free download from http://www.training-notes.co.uk.

Topics covered in this module

Canvas basics.
Canvas and Canvas objects.
Interacting with drawing objects.
Canvas objects.
The rectangle (rect) object.
The oval object.
The polygon object.
The arc object.
The line object.
The text object.
Computer graphics - techniques.
Coordinate systems.
Clipping.
Display lists.
Hidden line and surface.
Further issues.

Complete learning

If you are looking for a complete course and not just a information on a single subject, visit our Listing and schedule page.

Well House Consultants specialise in training courses in Tcl/Tk, Expect,Python, Perl, PHP, and MySQL. We run Private Courses throughout the UK (and beyond for longer courses), and Public Courses at our training centre in Melksham, Wiltshire, England. It's surprisingly cost effective to come on our public courses - even if you live in a different country or continent to us.

We have a technical library of over 600 books on the subjects on which we teach. These books are available for reference at our training centre. Also available is the Opentalk Forum for discussion of technical questions.