spectrum graphics - OpenLibra

ORG EMC
C5 T_ LOCATE R)SH BC
reec CP SO
>004 JR HC,T_L0CJ June ir A contains either • grarhle
symbol or a VDG.
tl«BJ«5C ID PC,(CHARS) point BC to Pixel*-Layout table In
SOU, less OlOCb.
ieoe JR 1JQCJ
D6?0 T_ _LDC_1 SUB 90
jeoo JR C,T_L0C_) • wp If A contains a graphic code.
EWB7B5C LD PC.IUW) Point BC to Pixel-Layouts for Uper
Defined Graphics. (Note; Range of
A is now 00 to ?9h).
T _wcJ LO L,A
?too LO H,00 HLI» character code.
ADD HL.HL
ADD HL,KL
2$ ADD HL.HL
09 ADC HL,BC HL: paints to pixel layout of
required character.
Ct POP BC
C9 RET
47 T LD B,A Lev nibble of B Indicates which
graphic synbnl Is required.
CDJSOB CALL OB58,PO_3R_1 Construct graphic synbV; in "WBCT.
J1925C LD HL.MEXBOT Point HL to this newly created
pixel layout.
CI FOP BC
09 RI7
again to get back to normal. In
this manner, the keys 1 to 8 will
produce block graphics, which
may be inversed by the additional
use of SHIFT. The letter
keys will produce the User
Defined Graphics. In this pro
gram, five extra UOG's are
allowed on keys V, W. Y and
Z, To use them it is necessary toallow
an extra forty bytes in the
UDG are of RAM, and graphics
V. W, X, Y and Z may be defined
in this area.
To break with tradition,
SPACE will print a space it will
not escape from Text Mode.
There are two ways to exit Texi
Mode. One is lo press SPACE
with CAPS SHIFT, and the other
is to press ENTER
Characters
It's worth pointing out at this
stage that the characters are no!
necessarily printed on whole
character squares. Depending
upon the position of the cursor a
character may overlap two or
more character squares. You
see when you hit TEXT MODE
ORG EJ71
F5 FR_XZ_DE PUSH A F Stack the zero flag.
}EP0 LD A,"space*
U1 RST 10 Print a space.
n POP AP Restore the tero flag.
2CC1 JR NZ,PR_SZ_1
JCC LD A,*space"
DT HST 10 Print a second spac*.
JBO LD A,"space"
07 RST 10 Print a third space.
C9 R£T
TA LD A,D
07 RST 10 Print CHRS(D);
7B LC A,E
Vt RST 10 Print CHRt(E)[
C9 RET
CH0 KJM
CJ T_00LCUR PUSH BC
D5 FJSH DK
e, PUSH HL Stack register*.
CD0B0B CALL OBDe,PO_ATTR Colour appropriate attribute byte.
It POP HL
D1 POP DE
CI POP BC Restore registers.
?J OC HI KLt points to next byte In screen.
jsoa LD A,oe A:» munter of pixels In this byte.
C? RXT
ZX COMPUTING DECEMBER/JANUARY 1985
ZX CRAPHICS
and you change from crosswire
cursor to text cursor, the text
cursor is printed as an outline,
whose top left hand corner ex
actly coincides wilh the position
of the crosswire cursor to the
exact pixel'
You can print text with this
facility in many different ways
We've already seen the effect of
CAPS LOCK and GRAPHICS,
but what about the rest of the
control keys ?
TRUE VIDEO will switch between
7 pixel wide, and 8 pixel
ing 7 pixel wide bold characters
if vou want to.
You can also print characters in
italics. SYMBOL SHIFT W will
switch to half-slope italics (slop
incj two pixels down for every
one pixel across); SYMBOL
SHIFT E will switch to full slope
itttlies (sloping at forty-five
degrees); and SYMBOL
SHIFT Q will switch to fully
upright characters (italics offl.
Finally, you can change the
size of characters. You are not
restricted to printing characters
the size of a standard character
OflO E591
JEM 7I_PRUT' LD A,CM"
38 TIL00P_t U AF.AP' A" := Dumber If rows in pixel layout.
JAOlEJ U> A,(HEIGHT)
J2675C 10 (B_REQ),A (B REG) t- Ktimher of tixwa each row
mat be duplicated.
5A40DB TXL00P_? 14) A,(JJTJ10S)
IETO XCR 10
J24OD0 LD (J_fLAGS),A Coiaplenent CrS/EVBI RO* flag.
05 P'St! BC &t*ck cursor coordinates.
D5 FUSH DE Stack pixel layout pointer.
E5 PUSH HL Stack add re- s of screen-byte
containing cursor.
19 IH A,C A:» oolurai mirther of cursor (in pixels).
E607 AND 07
4F LD C,A Cir position within acrcen-byt*
of cursor.
1A LD A,(Mi)
57 LD D.A Di< current, row fron pixel layout.
BOCBOOiE SIT 5,U_FUGS)
?80J JR Z,TXF_1 Juicp -jnless usln)' BOLD tyrvrae*.
87 ADD A,A »ift lert one bit. Hit 0 reset.
re OR D Use r»ch hit twice, if set.
57 LD D,A D: now ^lenended tnr BOLD typ»*.
JA0JI5 TXP_1 LD A,(WIDTH)
n LD B,A H:= niwber of ti»s eneh rl*«l
eiust be duplicated.
JEM LD A.08 A:- nunber of pixels in screeiwbyte.
5P LD F.,A E:> nwiber or blti in pix»' layout row.
OC ac c
180J JH TIALUO©
JO TOLircm DEC A A;n nunber of remaining pixels in (HL),
C906 RLC (HL) More next pixel fro* screen Into bit 7,
00 TXALLK*? DEC C
?0FA JR KZ.TXAl L!»1 Pixel at cursor rosition w
In bit 7 of (HL).
C5 TIL0CP_J PUSH BC Stack character width. (8),
F5 tVSH AF Stack screeo-byte pixel counter.
CHOP KLC D Haee next pixel frnai pixel-layout
into bit 0 of D.
wide characters. 7-pixel wide
characters are obtained by over
printing the 8th column of pix
els, which leaves less space between
two consecutive
characters. This will give you
thirty six characters across the
screen instead of thirty two. I
personally think that this makes
text look much better.
INVERSE VIDEO will switch between
standard and bold
typeface. Bold type is produced
by printing each INKEd pixel
twice instead of once. Bold type
looks very nice, and of course
there's nothing to stop you us
square — you can have double
width, double-height, triple
height, and so on. To achieve
this press both shifts together
(or the Extended Mode key on
the Spectrum Plus). You can
then alter the size of the cursor
by pressing the cursor keys:
RIGHT to increase ihe width,
and LEFT to decrease the width;
DOWN to increase the height,
and UP to decrease the height.
Spae will allow you to ESCAPE
from Extended Mode and return
the cursor keys to their normal
functions. Any other key will be
acted upon as normal, as well as
escaping from E Mode.
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