wct@po.CWRU.Edu (William C. Thompson) (04/22/91)
I did some more work on saving dynamically sized structures
to disk. I have almost perfected it, but it's a bit slow.
It works beautifully, though...
type
buffer=array[1..64000] of byte;
procedure saveimage(x1,y1,x2,y2:word; fn:string; var size:word);
{ This procedure captures an image from the screen and writes
it to the specified file and returns the size. There is no error
checking as to how much memory is available. The size of an image
is the number of pixels divided by two plus 6 (VGA mode) }
var
f: file of byte;
p: ^buffer;
i: word;
begin
size:=imagesize(x1,y1,x2,y2);
getmem(p,size); { allocate space }
getimage(x1,y1,x2,y2,p^); { capture the image from screen }
assign(f,fn);
rewrite(f);
for i:=1 to size do write(f,p^[i]); { write image to disk }
freemem(p,size); { return memory }
close(f);
end;
procedure recallimage(x1,y1:word; fn: string; size:word; wput:byte);
{ This procedure reads in an image from the specified file
and puts the image on the screen }
var
f: file of byte;
p: ^buffer;
i: word;
begin
getmem(p,size); { allocate space }
assign(f,fn); { prepare file }
reset(f);
for i:=1 to size do read(f,p^[i]); { read in the image }
close(f);
putimage(x1,y1,p^,wput); { put image on screen }
freemem(p,size); { return memory }
end;
The only drawback at all is that the part where I read from and
write to a file is slow. I tried BlockWrite and BlockRead,
but those made my files WAY too big. The file sizes didn't
match the number of bytes I told it to write. Here is the code
I used ---
BlockRead(f,p^,size,n) & BlockWrite(f,p^,size,n)
Where f: FILE and n: WORD
Anyone see any problems with this code? I'm not quite sure what
that 4th parameter is for, either. I think it's for confirmation
of how got written to disk, but I'm not sure. There was a buffer
I used that should have been around 7.5K, but the file size was
40K! That seems like a huge gap to me. Anyone with advice or
experience in these matters please E-mail me so I can wrap this
business up.
Thanx in advance
--
Ticking away, the moments that make up a dull day. | William C. Thompson
You fritter and waste the hours in an offhand way. | Michelson 620D (wct)
Kicking around on a piece of ground in your hometown,| a.k.a. Master of Time,
waiting for someone or something to show you the way.| Space, and Dimensionwct@po.CWRU.Edu (William C. Thompson) (04/22/91)
In a previous article, wct@po.CWRU.Edu (William C. Thompson) says: I managed to fix my own problem... Here is the solution, though. >type > buffer=array[1..64000] of byte; > >procedure saveimage(x1,y1,x2,y2:word; fn:string; var size:word); >{ This procedure captures an image from the screen and writes > it to the specified file and returns the size. There is no error > checking as to how much memory is available. The size of an image > is the number of pixels divided by two plus 6 (VGA mode) } >var > f: file of byte; ^^^^^^^^^^^^ Change this to just plain FILE > p: ^buffer; > i: word; >begin > size:=imagesize(x1,y1,x2,y2); > getmem(p,size); { allocate space } > getimage(x1,y1,x2,y2,p^); { capture the image from screen } > assign(f,fn); > rewrite(f); > for i:=1 to size do write(f,p^[i]); { write image to disk } Replace these lines with rewrite(f,1) { tells compiler file's object size is 1 } blockwrite(f,p^,size,dummy) > freemem(p,size); { return memory } > close(f); >end; > >procedure recallimage(x1,y1:word; fn: string; size:word; wput:byte); >{ This procedure reads in an image from the specified file > and puts the image on the screen } >var > f: file of byte; ^^^^^^^^^^^^ Same here... > p: ^buffer; > i: word; >begin > getmem(p,size); { allocate space } > assign(f,fn); { prepare file } > reset(f); > for i:=1 to size do read(f,p^[i]); { read in the image } Replace these two lines by reset(f,1); blockread(f,p^,size,dummy) > close(f); > putimage(x1,y1,p^,wput); { put image on screen } > freemem(p,size); { return memory } >end; >The only drawback at all is that the part where I read from and >write to a file is slow. I tried BlockWrite and BlockRead, >but those made my files WAY too big. The file sizes didn't >match the number of bytes I told it to write. Here is the code >I used --- > >BlockRead(f,p^,size,n) & BlockWrite(f,p^,size,n) I think the main problem was that I didn't tell the compiler how big the file's objects were. Once I made that change, everything fell into place. -- Ticking away, the moments that make up a dull day. | William C. Thompson You fritter and waste the hours in an offhand way. | Michelson 620D (wct) Kicking around on a piece of ground in your hometown,| a.k.a. Master of Time, waiting for someone or something to show you the way.| Space, and Dimension
Harold.Ruby@f1999.n106.z1.fidonet.org (Harold Ruby) (04/24/91)
Try this: procedure savescreen; var image:file; begin assign (image,'FILENAME.EXT'); rewrite (image,1); blockwrite (image,mem[$A000,0],$FA00); end; procedure restorescreen; var image:file; begin assign (image,'FILENAME.EXT'); reset (image,1); blockread (image,mem[$A000,0],$FA00); end; Note - I've left out error correction / file exist checking / etc.. Harold