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The Virtual Device Interface: Escapes

The following functions ("escapes") are all accessed through VDI function 5. The function number is given in the special member of the CONTRL array.

1. void vq_chcells(WORD handle, WORD *rows, WORD *columns);

Get text screen size in characters. The first two words of INTOUT will hold the height and the width respectively, and this will therefore return #intout=2. If the device doesn't have a text screen (such as a printer) then this will return (-1, -1).

2. void v_exit_cur(WORD handle)

Exit text mode (and enter graphics mode).

3. void v_enter_cur(WORD handle)

Enter text mode.

Functions 4-19 (which deal with control of the text screen) aren't implemented in Intel GEM drivers. But they are:

4. void v_curup(WORD handle)

Text cursor up.

5. void v_curdown(WORD handle)

Text cursor down.

6. void v_curright(WORD handle)

Text cursor right.

7. void v_curleft(WORD handle)

Text cursor left.

8. void v_curhome(WORD handle)

Clear text screen, home cursor.

9. void v_eeos(WORD handle)

Clear from text cursor to end of screen.

10. void v_eeol(WORD handle)

Clear from text cursor to end of line.

11. void vs_curaddress(WORD handle, WORD row, WORD column)

Move text cursor to coordinates given in INTIN. Therefore this should be entered with #intin=2.

12. void v_curtext(WORD handle, BYTE *string)

Print (to the text screen) a string whose characters are stored in INTIN (one character to each word). #intin = length of string.

13. void v_rvon(WORD handle)

Select reverse video.

14. void v_rvoff(WORD handle)

Cancel reverse video.

15. void vq_curaddress(WORD handle, WORD *row, WORD *column );

Return the coordinates of the text cursor in the first two words of INTOUT.

16. WORD vq_tabstatus(WORD handle)

Is a tablet (or mouse etc.) available? Returns the first word of INTOUT as 0 if no, 1 if yes.

17. void v_hardcopy(WORD handle)

Dump the current screen to the printer.

18. void v_dspcur(WORD handle, WORD x, WORD y)

Place a graphic cursor (a mouse pointer or similar). Its coordinates are given in PTSIN, so enter with #ptsin=1.

19. void v_rmcur(WORD handle)

Remove the graphic cursor.

20. void v_form_adv(WORD handle)

Form advance - throw a page on a printer device.

21. void v_output_window (WORD handle, WORD xy[])

As v_updwk() - Print the page, but clipped within the rectangle given by the two points xy[]. Used on printers and other devices where drawing isn't immediate.

22. void v_clear_disp_list(WORD handle)

For a printer - discard any output for this page that has not been printed (ie, any output received since the last v_updwk() or v_output_window() ).

23. void v_bit_image(WORD handle, BYTE *filename, WORD aspect, WORD x_scale, WORD y_scale, WORD h_align, WORD v_align, WORD xy[])

Draw an image from a disc file onto the current device. Passed #ptsin=2, #intin=5 + length of filename. INTIN holds:

24. void vq_scan( WORD handle, WORD *g_height, WORD *g_slice, WORD *a_height, WORD *a_slice, WORD *factor )

Return printer "scan heights". Returns 5 values in INTOUT: 

	DEFW	g_height	;Height of a graphics slice
	DEFW	g_slice		;No. of graphics slices per page
	DEFW	a_height	;Height of a text slice
	DEFW	a_slice		;No. of text slices per page
	DEFW	factor		;?

25. void v_alpha_text( WORD handle, BYTE *string )

Output printer alphanumeric text. Entered with #intin = no. of characters; string in INTIN, one character per word.

27. void v_orient(WORD handle, WORD orientation)

[!] (GEM/3 and later) Set page orientation. Passed #intin = 1; INTIN[0] is 0 for portrait, 1 for landscape.

28. void v_copies(WORD handle, WORD count)

[!] (GEM/3 and later) Set number of copies to print. Passed #intin = 1; INTIN[0] is number of copies.

29. void v_tray(WORD handle, WORD tray)

[!] (GEM/3 and later) Set paper tray to use. Passed #intin = 1; INTIN[0] is the tray number.

60. WORD vs_palette( WORD handle, WORD palette )

Select a predefined palette. Passed #intin = 1, INTIN[0] holds the palette number. Returns the previous palette number in INTOUT[0].

61. void v_sound(WORD handle, WORD frequency, WORD duration)

Play a sound on the beeper. Passed #intin = 2; INTIN holds the frequency and duration in that order.

62. WORD vs_mute(WORD handle, WORD action)

Enable / disable sound. Entered with #intin = 1, INTIN[0] holds -1, 0 or 1. If INTIN[0] is:

-1
Returns the current status in INTOUT[0].
0
Sound is enabled.
1
Sound is disabled

81. void vt_resolution(WORD handle, WORD xres, WORD yres, WORD *xset, WORD *yset)

? Passed two words in INTIN (xres and yres); returns xset and yset in INTOUT.

82. void vt_axis(WORD handle, WORD xres, WORD yres, WORD *xset, WORD *yset)

? Passed two words in INTIN (xres and yres); returns xset and yset in INTOUT.

83. void vt_origin(WORD handle, WORD x, WORD y)

? Passed two words in INTIN (x and y).

84. void vq_tdimensions(WORD handle, WORD *xdim, WORD *ydim)

? Get two dimensions in INTOUT (x and y).

85. void vt_alignment( WORD handle, WORD dx, WORD dy )

? Set two words in INTIN (dx and dy).

91.void vsp_film( WORD handle, WORD index, WORD lightness )

? Set the film parameters for a camera. The two words go to INTIN[0] and INTIN[1] respectively, so this is called with #intin = 2.

92. BOOLEAN vqp_filmname( WORD handle, WORD index, BYTE *name )

? Get the name of film number "index". Passed one word in INTIN; returns #intout is the length of the name, which is stored in INTOUT (one character per word). If #intout is 0, then the C binding returns FALSE; else TRUE.

93. void vsc_expose( WORD handle, WORD state )

? Passed one word in INTIN, but for some reason the standard binding sets #intin to 2. This may be a bug.

98. void v_meta_extents( WORD handle, WORD min_x, WORD min_y, WORD max_x, WORD max_y )

Set the size of the drawing area when writing a metafile. The parameters are passed as the first two points in PTSIN (min then max), so the call is made with #ptsin equal to 2.

99. Metafile functions

Escape 99 is used to perform functions that only have effect in a metafile. INTIN[0] holds the "sub-opcode" number. Sub-opcode numbers 0-100 are reserved for the GEM system; other sub-opcodes can be used by users.

99. void v_write_meta( WORD handle, WORD num_ints, WORD *ints, WORD num_pts, WORD pts )

Write out a "user-defined" metafile record. The INTIN and PTSIN arrays can be any size (though the INTIN array must contain at least one element - the sub-opcode).

The subfunctions 99/0 and 99/1 do not actually add records to the metafile; rather, they set values in the metafile header.

99/0. void vm_pagesize(WORD handle, WORD width, WORD height)

Set the size of the page used by the metafile being written, in tenths of millimetres:

99/1. void vm_coords(WORD handle, WORD llx, WORD lly, WORD urx, WORD ury)

Set the lower left and upper right corners of the coordinate system used by the metafile being written.

99/32. WORD v_bez_qual( WORD handle, WORD prcnt)

Set Bezier curve quality.

100. void vm_filename(WORD handle, BYTE *filename)

? Set the metafile filename. The filename is passed in INTIN, one character per word, with #intin being its length.

101. void v_xbit_image(WORD handle, BYTE *filename, WORD aspect, WORD x_scale, WORD y_scale, WORD h_align, WORD v_align, WORD rotation, WORD foreground, WORD background, WORD xy[])

[!] (GEM/3 and later) Draw an image from a disc file onto the current device - with rotation and colouring. Passed #ptsin=2, #intin=8 + length of filename. INTIN holds:

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