Loadstar 128 #35/q35.d81/t.ps to font

Text File | 1992-01-01 | 15.2 KB | 376 lines

                1 2 8   P R I N T   S H O P   T O   F O N T

                      Program and Text by Bob Markland


    The primary reason for selecting a C-128 over a C-64, aside from the
extra memory, is the 80-column mode. And here at LOADSTAR 128 nearly every
program is in the 80-column mode.

    As you no doubt know, the C-128 uses the text-oriented 8563 Video
Display Controller chip (VDC) to display the 80-column screen. Besides
allowing longer screen lines, its advantages include vivid colors,
additional attributes, and the ability to display two fonts (512 different
characters) simultaneously. And, unlike the VIC chip which stores
characters in ROM, the VDC chip's character sets are addressable in place.

    But, alas, there is a down side -- the VDC chip is text-oriented. There
is a limited bit-map mode, but the 640 x 400 pixels eat up nearly all of
the 8563's available memory. Ordinarily only the background and one
foreground color is available --  you can cut the bit-map by 1/4 and regain
color control -- but in any event the character sets are gone.

    An experienced (or masochistic) M/L programmer can overcome these
problems, but few have even attempted it. And no adequate solution is
available from BASIC. So, many 80-column programs lack the visual
enhancements common to C-64 programs.

    How about a compromise? What if you could easily display a smaller
graphic anywhere on the screen?

    Print Shop Icons are an ideal source for small graphics. Existing
images are plentiful or you can use The Print Shop Companion to draw just
the graphic you want. LOADSTAR's COMPLEAT PRINT SHOP disks contain over
2600 Print Shop icons. You're sure to find an icon in this collection to
fit your needs.

    Armed with a good idea for a program and an icon library you're almost
ready to begin, except for two major impediments. Print Shop 3-block icons
are stored in a format totally unlike any Commodore screen or font storage.
And, on the 80-column screen, if icons were displayed at their normal 11
byte width, they would be "squashed" horizontally. So a utility is needed
to alter the format and double the width, and 128 PRINT SHOP TO FONT does
just that.


 USING PRINT SHOP TO FONT
 ------------------------

    128 PS TO FONT is a freestanding utility. You can write a program that
uses only the utility and icons. However, it is also compatible with
CONTROL80 and 128 RLE for more complex applications.

    First you must decide how you are going to make use of the PS icons. If
your program will use only a few icons, you can store them on disk
individually and BLOAD them as needed.

    When numerous icons are required you should bundle them into a single
file. There are several ways to accomplish this, but here is the method I
used for the demo:

  1) With no program in memory, enter the built-in MONITOR and fill an area
of memory with a known value, let's say, BB.

         F 02000 04000 BB

     then exit the monitor.

  2) BLOAD all of your icons into successive areas of memory, 3 pages apart
(768 bytes), from direct mode, as follows:

         BLOAD"Icon 1",B0,P8192
         BLOAD"Icon 2",B0,P8960
                 etc.

    There are two reasons for spacing the icons on page boundaries. First,
a PS icon is 11 characters wide and 6-1/2 characters high. 128 PS TO FONT
uses the 44 bytes beyond each icon as a work area to account for the stray
1/2 character. Second, it is easier to keep track of the indexing for
multiple icons.

    You could write a 3-line Q&D program to read the icon names from DATA
statements, increment the load address with a variable, and complete the
above process in one operation. But, unless you plan to make several icon
files, it may not be worth the bother.

  3) When all of your icons are in memory, enter the MONITOR again, and
scan memory with the "M" command to find the ending address of the last
icon plus one (+1). Note the address and exit the monitor.

  4) BSAVE the icons as a single file using the following syntax, where
"start" is the beginning address of the first icon and "end" is the address
of the end of the last icon:

 BSAVE"FILENAME,B0,Pstart TO Pend+1

 Or, if you're comfortable with the monitor, you could save the icons as a
single file inside the monitor, using hex numbers and the S (save)
command.

  5) If the icon file is relatively short you may wish to end the process
at this point. Otherwise, use 128 RLE (Run Length Encoding) Packer/Unpacker
to "PACK A FILE", thus creating a file which takes up less disk space and
loads more quickly. Then include 128 RLE in your program to unpack the
file.

    You are now ready to begin your program. There are six versions of 128
PS TO FONT on disk and their file names indicate the necessary load
address:

        128 PS-FONT 0C00
        128 PS-FONT 1300
        128 PS-FONT 1C00
        128 PS-FONT 2400
        128 PS-FONT 3500
        128 PS-FONT 3800

    If you absolutely need a version at a location not found above, you can
use Jeff Jones' ML MOVER from LS 64 #156 to create versions almost anywhere
you want.

    Use BLOAD to load 128 PS TO FONT into bank 0, where dv is the number of
the active device:

      BLOAD"128 PS-FONT xxxx",B0,U(dv)

    The choice of which version to use depends upon what else you have
going on. If 128 PS TO FONT is the only utility you will be using, $0C00 or
$1300 are perhaps the best choices. You will notice the accompanying demo
uses both CONTROL80 and 128-RLE so the $1C00 version is the one to use. The
remaining versions are intended to nestle among the various incarnations of
CONTROL80, custom fonts, etc. If you choose to move the start of BASIC to
$4000, any of the higher versions may be used, with or without other
utilities.

 FENDER'S NOTE: When I use CONTROL80, I invariably move the start of BASIC
up to $4000 with the GRAPHIC1,1:GRAPHIC0:GRAPHIC5 sequence. I've never
written a 128 mode BASIC program so large that I needed BASIC to start at
the normal $1300, or even $1C00. So why not move BASIC up to $4000 and use
that open area from the top of CONTROL80 to $4000 for buffers, ML routines,
etc.?

    128 PS TO FONT supports two different types of icon displays -- full-
size and cropped. Full-size icons require 154 characters (22 x 7). As a
result, only two different icons may be imbedded in the character sets. One
in the upper portion of font 0 and the other in the upper portion of font
1.

    This not only limits the number of possibilities, but the 22 x 7 size
doesn't space well on a 80 x 25 screen. Unless there is a critical need to
display the entire icon, cropping is preferable.

    128 PS TO FONT can automatically crop an icon for you. The utility
trims 2 rows of pixels from the top and bottom of the image and 4 pixels
from both the left and right sides. The resulting image is 20 x 6
characters in size. You may wish to take this into consideration when you
select your icons, and use Print Shop Companion to edit them beforehand.

    Sixteen cropped icons fit nicely on the screen and you can store three
different icons simultaneously, still leaving 128 character definitions for
text.

    Numerous arrangements are possible, depending upon the needs of your
program. Some of the possibilities include:

  1) Store one icon in the upper half of font 0 and another in the upper
half of font 1. This leaves both uppercase and lowercase text intact.

  2) Reverse the above process, leaving both reversed character sets
available.

  3) Store two icons in one font or the other. You then have one entire
character set for text/graphics characters.

  4) Store two icons in one or the other font and one in half of the
remaining font. 128 text characters remain available in either normal or
reverse.

  It is theoretically possible to store four icons at one time. However,
doing so will corrupt any text characters on the screen and prevent further
use of text until at least one font is restored with CONTROL80's FCOPY.

    While it is not necessary to include a custom font, if you plan to
write a program for LOADSTAR it is not likely to be accepted without one.
Include CONTROL80 in your program and FCOPY a custom font into place before
using 128 PS TO FONT.

    You should also be aware that alterations to the fonts can cause a
BASIC listing to look weird at best, unintelligible at worst. The trick is
to enter FINIT in the immediate mode to restore normal fonts. You may even
want to use a TRAP routine to automatically do a FINIT when you press STOP
to edit your program.

    How and where you load the icon images depends upon what other
utilities you may be using. If you are using single icons, use the same 3-
block area of Bank 0 and load to it repeatedly. When CONTROL80 is in use
memory becomes a little more scarce. Personally, I prefer to use Bank 1 for
storage. Bank 1 is the bank BASIC uses for variable storage. Numeric
variables and static strings are stored from $0400 upward and dynamic
strings are stored from $FF00 downward. Unless your program uses a huge
number of variables or you have somehow induced garbage collection problems
(by creating a bunch of concatenated strings), a large section of memory in
the middle of Bank 1 remains free.

    Once you have 128 PS TO FONT and at least one icon in place you are
ready to display it. Everything is handled with one simple SYS command:

        SYSADDR:B,IA,F,P,C

    Because of the way BASIC 7.0 handles the SYS command you MUST include
the colon (:) before the first parameter.

  SYSADDR - Is the starting ADDRess of the version of 128 PS TO FONT you
are using.

  B - Is the Bank where your icon images reside (0 or 1).

  IA - This is the address of the icon you wish to transfer to a font. Note
that this can be a variable or formula. When you have a series of icons in
a single file, stored as explained above, you can address them with:

     Icon Address+768*Location Number

  F - Selects the Font into which you wish to imbed the icon (0 or 1):

     Font 0 - Uppercase/Graphics
     Font 1 - Lowercase

  P - Determines the Position within the selected font (0 or 1):

     0 - Selects lower half - Normal
     1 - Selects upper half - Reverse

    Note: If you select Normal for the cropped option, 1 is the only
setting possible for Position, and the utility will force this condition if
necessary.

 C - This option tells the utility to transfer a normal or Cropped image:

     0 - Cropped
     1 - Normal

    Compiler and M/L uses are also supported. Because compilers choke on
the non-standard method used to get the parameters use this instead:

     POKEload address+551,BANK
     POKE176,low byte Icon Address
     POKE177,high byte Icon Address
     POKEload address+552,FONT
     POKEload address+553,POSITION
     POKEload address+554,CROP
     SYSADDR+3

    From a M/L program:
         lda bank
         sta load'addr+551
         lda <icon'address
         sta $b0
         lda >icon'address
         sta $b1
         lda font
         sta load'addr+552
         lda position
         sta load'addr+553
         lda crop
         sta load'addr+554
         jsr sys'addr+3


    You now have an icon in one of your fonts, but it is not yet displayed
on the screen. To do this you must define a string.

    Now is probably a good time to print a copy of this text and run the
PRINT SHOP TO FONT DEMO. After viewing the demo you can break out with
STOP/RESTORE and more easily follow the logic.


 DISPLAYING ICONS
 ----------------

    There are several ways to define your print string, but I prefer to
READ from DATA statements and concatenate one long string. All the
important sections of the demo are REMmed so you can easily incorporate
them into your own program.

    CR$ is for the display of cropped icons. It consists of the first 120
CHR$ values as a font is laid out. The string is the same for both normal
and reversed. The difference is accounted for when you print CR$.

  PRINTCHR$(146)CR$ - for an icon in position 0 (reverse off)

  PRINTCHR$(18)CR$ - for an icon in position 1 (reverse on)

    FL$ is for displaying FulL-size icons. It consists of the last 26
characters from the first half of the font, a CHR$(18), and the 128
characters from the second half of the font.

    You must also include CHR$(142) and CHR$(14) in the PRINT command
depending upon whether the icon is in font 0 or 1. For example:

    PRINTCHR$(142)CHR$(18)CR$ - for an icon in font 0, position 1.

    This may sound a bit confusing at first, but after you LIST and examine
the demo you will find it is quite easy.

    Another key element in displaying icons with a minimum of effort is the
WINDOW command. You will notice in the above text, there is no provision
for carriage returns (CHR$(13)) following each series of 20 or 22
characters. There is a very good reason for this.

    Use the following syntax to define a window and display an icon in it:

     WINDOW TC,TR,TC+19,TR+5,[1]:
     PRINTCHR$(27)"M":COLOR5,CO:
     PRINTCHR$(142)CHR$(18)CR$

  TC = Top left Column
  TR = Top left Row
  [1] - Is optional and clears the window before printing
  CHR$(27)"M" - prevents the window from scrolling
  CO - Determines the color of the icon to be displayed

    To display full-size icons, simply use TC+21, TR+6 and FL$ in the above
example.

    It is not necessary to use a window if you prefer not to. Instead, you
can imbed CHR$(13)s in the appropriate places within the string.

    You can also use an array:

     CR$(1)="@ABCDEFGHIJKLMNOPQRS"
     CR$(2)=  second line
     CR$(3)=  third line
                  etc.

    By calculating which characters make up the image you can also print
color change commands and selected characters to produce a multi-color icon
image.

    If you elect to use CONTROL80 in your program, in addition to custom
fonts, you can use POST and an array to display an entire icon. Or you can
use POST, BLOCK or FILL to achieve multi-color effects and flashing
characters.

    The demo also illustrates how you can quickly change an icon image
already on the screen. This is accomplished by simply transferring a
different icon to the same area of the appropriate font.

    To create even larger images you can use Print Shop Companion to draw
three icons which are a part of a larger graphic. Then link or stack the
icons on screen to form a single large mural. On the other hand, in a game
or puzzle, you could selectively display only a portion of an icon. For
that matter you could draw a custom icon which has a different image in
each quadrant. Then by displaying only a quarter of each icon with a PRINT
statement you could have 12 different smaller images on the screen at
once.

    With a little imagination and experimentation, there should be no limit
to the effects you can create. You will surely think of numerous
possibilities I haven't even considered.

 FT'S POSTMUMBLE: Is 128 PS TO FONT fast enough for animation? I remember
making a demo for the C-64 version of PS TO FONT years ago and it
"simulated" animation of Medusa, the snake-haired lady. I allowed the user
to set the speed and found that the animation looked best at a less than
maximum speed. So let us know, if you use this utility to attempt some
"small-screen" animation, how it goes. I see 128 PS TO FONT as a tool
begging for someone to use in a creative way. If you tackle animation,
you'll still have all the hard work of making multiple copies of some PS
icons, but at least the displaying will be painless, thanks to Bob
Markland.

                    \\\\\ R - Run   RETURN - Menu \\\\\