Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

Perspective(3I)

NAME

   Perspective - visible portion of an interactor

SYNOPSIS

   #include <InterViews/perspective.h>

DESCRIPTION

   A  perspective  object  describes  which  part of an interactor's total
   display area is visible in the interactor's canvas.  The  main  use  of
   perspectives  is  for scrolling, panning, and zooming interactors.  The
   member variables (x0, y0) define the origin of the interactor's display
   area; width and height define the total height of the area.  The member
   variables (curx, cury) define the lower-left corner of the interactor's
   canvas  relative  to  the total area; curwidth and curheight define how
   much of the total area is displayed in the canvas.

   The member variables sx,  sy,  lx,  and  ly  specify  small  and  large
   increments  in each dimension.  These increments are used by a scroller
   to implement line and page scrolling.

PUBLIC OPERATIONS

   Perspective()
          Define a new perspective with all member  variables  initialized
          to zero.

   void Attach(Interactor*)
          Add to the list of interactors that are interested in updates to
          the perspective.   These  interactors  reflect  the  perspective
          visually; examples include scrollers and sliders.

   void Detach(Interactor*)
          Remove  an  interactor  from  the  list  of  those interested in
          updates.  This operation should be called from the  interactor's
          destructor.

   void Init(Coord x0, Coord y0, Coord width, Coord height)
          Initialize the perspective display area.

   void Update()
          Notify all the interactors interested in the perspective that it
          has changed.  The perspective's interactor  should  call  Update
          after modifying its perspective.

SEE ALSO

   Adjuster(3I), Interactor(3I), Panner(3I), Scroller(3I)



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.


Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.


Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.


Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner