stone@cunixb.cc.columbia.edu (Glenn Stone) (06/14/91)
There must an easy way to do this but I seem to have a mental block.
I'm writing a graphics mode equivalent of READLN(StringVariable) in
TP 5.5. This loop reads characters and tacks them onto a string
called T. The problem is in dealing with the backspace; I want the
pointer to back up and erase the last character, but the ' ' in
graphics mode doesn't do this. I need the equivalent of ClrEol.
How do you do it? Thanks in advance...
done := false;
t := '';
repeat
c := ReadKey;
case c of
#13 : done := true; { CR }
#8 : begin { backspace }
OutTextXY(GetX-TextWidth(t[length(t)]),GetY,' ');
delete(t,length(t),1); ^----here
end;
else begin { append char }
t := t + c;
MoveTo(x,y);
OutText(t);
end;
end;
until done;
-------------------------------------------------------------------------
Glenn Stone BITNET: stone@cunixc
Columbia University INTERNET: stone@cunixb.cc.columbia.edu
-------------------------------------------------------------------------tswingle@oucsace.cs.OHIOU.EDU (Tom Swingle) (06/18/91)
In article <1991Jun14.150309.5126@cunixf.cc.columbia.edu> stone@cunixb.cc.columbia.edu (Glenn Stone) writes: >There must an easy way to do this but I seem to have a mental block. >I'm writing a graphics mode equivalent of READLN(StringVariable) in >TP 5.5. This loop reads characters and tacks them onto a string >called T. The problem is in dealing with the backspace; I want the >pointer to back up and erase the last character, but the ' ' in >graphics mode doesn't do this. I need the equivalent of ClrEol. >How do you do it? Thanks in advance... > > done := false; > t := ''; > repeat > c := ReadKey; > case c of > #13 : done := true; { CR } > #8 : begin { backspace } > OutTextXY(GetX-TextWidth(t[length(t)]),GetY,' '); ^ ^ |--- Replace this line as described below ---| > delete(t,length(t),1); > end; > else begin { append char } > t := t + c; > MoveTo(x,y); > OutText(t); > end; > end; > until done; How about, before each character is added to the string and printed on the screen, using GetImage to save a piece of screen of width TextWidth(c) and height TextHeight(c) right under where the character is to go. Then, rather than an OutTextXY call to delete a character, use a call to PutImage to put back the area that was saved. What you will probably need is an array of tiny buffers large enough to hold a screen image the size of the largest character that could be printed. Then, as you read characters, store the characters in the string, and at the same time, store the corresponding screen images in the array of buffers. The array of buffers would need to contain the same number of buffers as the maximum length of the string to be read. Of course, if you know that the screen under the character to be printed will be blank, all you need is a call to Bar with the drawing color set to the current background color. The width of the bar should be TextWidth(c), and the height should be TextHeight(c). If you're not familiar with these procedures, mail me and I will provide more details. It's too late at night right now to come up with good explanations of the procedures, but I assume you would be familiar with them since you are creating a graphics application. I hope I have been clear enough with this explanation. It's late and I really should be in bed. -- "The problem you are experiencing is | "To be sure of hitting the target, not with the network nor with the | shoot first and, whatever you hit, station. Please adjust your set." | call it the target."
campbell@cutmcvax.cs.curtin.edu.au (Trevor George Campbell CC361) (06/19/91)
stone@cunixb.cc.columbia.edu (Glenn Stone) writes: >There must an easy way to do this but I seem to have a mental block. >I'm writing a graphics mode equivalent of READLN(StringVariable) in >TP 5.5. This loop reads characters and tacks them onto a string >called T. The problem is in dealing with the backspace; I want the >pointer to back up and erase the last character, but the ' ' in >graphics mode doesn't do this. I need the equivalent of ClrEol. >How do you do it? Thanks in advance... > #8 : begin { backspace } > OutTextXY(GetX-TextWidth(t[length(t)]),GetY,' '); > delete(t,length(t),1); ^----here > end; I had a similar problem, the only way that i could think to solve it was to rewrite the character in the background colour. Unfortunately this wont work if you don't know the background colour, or the colour varies from the start to end of the input string. The only other possability that i can think of is if you can XOR the original character onto the screen, and then XOR the character again to remove it from the screen. One further point that may speed up the program (a minute amount) would be to replace the delete(t,...) above with: t[0] := CHR(ORD(t[0]) - 1) as turbo just stores the length of a STRING in position 0. This is a useful hint if you need to use the LENGTH of a string a lot (just look at position 0 of the String) BUT unfortunately this is only in a character form (not a byte or integer) -- Trevor alias <**<TOMCAT>**> tuo em tel esaelP ,lanimret siht edisni kcuts m`I pleH ( for all of you out there who can't read backwards..... Help i'm stuck inside this terminal, Please let me out )
J_SCHULL@acc.haverford.edu (Jonathan Schull) (06/20/91)
How to erase characters when backspaced?
I wrote a Clear routine which erases a particular area of the screen
(The Bar command can be used for this purpose). So the backspace
tells you to rease from CursorPos to CursorPos-TextWidth('o');
.ts@uwasa.fi (Timo Salmi) (06/20/91)
In article <1991Jun14.150309.5126@cunixf.cc.columbia.edu> stone@cunixb.cc.columbia.edu (Glenn Stone) writes: >There must an easy way to do this but I seem to have a mental block. >I'm writing a graphics mode equivalent of READLN(StringVariable) in : This is only a partial help since the source code is not available, but it sometimes helps to take a look at a program that has had the same problem solved. I have a turbdemo.exe in /pc/ts/tsdemo14.arc which demonstrates various texthandling tricks in Turbo Pascal graphics mode. "The wares are available by anonymous ftp from garbo.uwasa.fi, Vaasa, Finland, 128.214.12.37, or by using our mail server (use the latter if, and only if you don't have anonymous ftp). If you are not familiar with anonymous ftp or mail servers, I am prepared to send prerecorded instructions on request. (If you don't get the instructions from me within a few days, it will mean that your email address cannot be reached by a simple email reply. It that case, contact your system manager for devicing a proper mail path for you, because unless you do, you wouldn't be able to utilize the mail server anyway. If you are in North America first consider using an ftp site near you to spare the overseas load.)" ................................................................... Prof. Timo Salmi Moderating at garbo.uwasa.fi anonymous ftp archives 128.214.12.37 School of Business Studies, University of Vaasa, SF-65101, Finland Internet: ts@chyde.uwasa.fi Funet: gado::salmi Bitnet: salmi@finfun