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# Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
include <gio.h>
# GTEXT -- Draw text. All textual output via GIO is via this primitive. Unlike
# polyline, polymarker, fill area, and cell array output, textual output is not
# subjected to clipping by GIO. Clipping may be performed at the kernel level
# if a workstation viewport is defined. Our task here is principally to parse
# the format string and set up the text attributes, then insert the text drawing
# instruction into the GKI instruction stream. The real work of text generation
# is very device dependent and is therefore left to the kernel.
procedure gtext (gp, x, y, text, format)
pointer gp # graphics descriptor
real x, y # position at which text is to be drawn
char text[ARB] # text to be drawn
char format[ARB] # text drawing parameters
int ip, i
real mx, my
pointer sp, ap, tx
bool text_attributes_modified
begin
call smark (sp)
call salloc (ap, LEN_TX, TY_STRUCT)
# Set up pointers to text attribute packets and initialize the
# new packet to the default values. Two text attribute packets
# are maintained in GP: TXAP, the default packet, and TXAPCUR,
# the packet last sent to the device. In what follows, AP is
# the new packet and TX is the packet last sent to the device.
# We start by initializing the new packet at AP to the default
# text drawing parameters.
call amovi (Memi[GP_TXAP(gp)], Memi[ap], LEN_TX)
tx = GP_TXAPCUR(gp)
# Parse the format string and set the text attributes. The code is
# more general than need be, i.e., the entire attribute name string
# is extracted but only the first character is used. Whitespace is
# permitted and ignored.
ip = 1
call gtxset (ap, format, ip)
# If the old text attribute packet was never fixed always fix the
# new packet, otherwise determine whether or not any text attributes
# were actually modified and only fix the new packet if it is
# different.
text_attributes_modified = false
for (i=2; i <= LEN_TX; i=i+1)
if (Memi[ap+i-1] != Memi[tx+i-1]) {
text_attributes_modified = true
break
}
# Flush any buffered polyline output, and transform the text coordinates
# to GKI device coordinates.
call gpl_flush()
call gpl_wcstogki (gp, x, y, mx, my)
# Update text attributes if necessary.
if (text_attributes_modified || TX_STATE(tx) != FIXED) {
call amovi (Memi[ap], Memi[tx], LEN_TX)
call gki_txset (GP_FD(gp), tx)
TX_STATE(tx) = FIXED
}
# Output text drawing instruction.
call gki_text (GP_FD(gp), nint(mx), nint(my), text)
call sfree (sp)
end
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