Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

screen(3alleg4)


NAME

   screen  -  Global  pointer to the screen hardware video memory. Allegro
   game programming library.

SYNOPSIS

   #include <allegro.h>

   extern BITMAP *screen;

DESCRIPTION

   Global pointer to a  bitmap,  sized  VIRTUAL_W  x  VIRTUAL_H.  This  is
   created  by  set_gfx_mode(),  and represents the hardware video memory.
   Only a part of this bitmap will actually be visible, sized  SCREEN_W  x
   SCREEN_H.   Normally  this is the top left corner of the larger virtual
   screen, so you can ignore the  extra  invisible  virtual  size  of  the
   bitmap if you aren't interested in hardware scrolling or page flipping.
   To move the visible window to other parts of the  screen  bitmap,  call
   scroll_screen().   Initially  the clipping rectangle will be limited to
   the physical screen size, so if you want to draw onto a larger  virtual
   screen  space  outside  this  rectangle,  you  will  need to adjust the
   clipping.

   For example, to draw a pixel onto the screen you would write:

      putpixel(screen, x, y, color);

   Or to implement a double-buffered system:

      /* Make a bitmap in RAM. */
      BITMAP *bmp = create_bitmap(320, 200);
      /* Clean the memory bitmap. */
      clear_bitmap(bmp);
      /* Draw onto the memory bitmap. */
      putpixel(bmp, x, y, color);
      /* Copy it to the screen. */
      blit(bmp, screen, 0, 0, 0, 0, 320, 200);

   Warning: be very careful when using this pointer at the  same  time  as
   any  bitmaps  created  by  the  create_video_bitmap() function (see the
   description of this function for more detailed information). And  never
   try to destroy it with destroy_bitmap().

SEE ALSO

   set_gfx_mode(3alleg4),                       is_screen_bitmap(3alleg4),
   create_video_bitmap(3alleg4), scroll_screen(3alleg4)



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