From: "John M. Aldrich" Newsgroups: comp.os.msdos.djgpp Subject: Re: why can't printf text in graphics mode Date: Mon, 23 Dec 1996 19:17:41 -0800 Organization: Two pounds of chaos and a pinch of salt Lines: 33 Message-ID: <32BF4B55.3D73@cs.com> References: <59djoa$3al AT owani8 DOT cc DOT hirosaki-u DOT ac DOT jp> <32bef179 DOT 9420621 AT ursa DOT smsu DOT edu> Reply-To: fighteer AT cs DOT com NNTP-Posting-Host: ppp108.cs.com Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit CC: zhang AT cc DOT hirosaki-u DOT ac DOT jp To: djgpp AT delorie DOT com DJ-Gateway: from newsgroup comp.os.msdos.djgpp Tony O'Bryan wrote: > > > Now I want to printf text in the graphics mode, but it does not work, why? > > Maybe djgpp's printf() writes directly to text screen memory, which is > at a different address than graphics memory. printf() does not write to any kind of memory; it simply writes to the stdout file descriptor. DOS then determines where that file descriptor goes. Normally, it goes to the CON: device, which results in the text being sent to the BIOS for display on the console screen. Since neither DOS nor the BIOS know or care what video mode you are in, this will not work in graphics modes. You may say, "But this works in Pascal!" That's because Pascal is designed as a beginner's programming language, and thus has lots of little gimmicks to help you out. Normally, the video screen and the text screen reside in totally separate and independent areas of memory. Each graphics package has its own functions to display text on the graphics screen. You will have to look up the docs for that package to see how to do it. BTW, the functions won't work either; all they do is bypass DOS and write to video memory directly. -- --------------------------------------------------------------------- | John M. Aldrich, aka Fighteer I | mailto:fighteer AT cs DOT com | | God's final message to His Creation: | http://www.cs.com/fighteer | | "We apologize for the inconvenience."| Fight against proprietary | | - Douglas Adams | software - support the FSF!| ---------------------------------------------------------------------