83Plus:Hooks:9B9C - Revision history

Eeems: Clarify zero is the zero flag

2023-09-05T18:12:00Z

Clarify zero is the zero flag

FloppusMaximus: clarified width condition, added fracdrawlfont condition, updated example code; note that B is not always equal to the character!

2005-09-21T18:23:37Z

clarified width condition, added fracdrawlfont condition, updated example code; note that B is not always equal to the character!

Aquanight: Fixed flag link.

2005-07-19T00:31:25Z

Fixed flag link.

84plusfreak: /* Using the Hook */

2005-04-13T18:52:36Z

‎Using the Hook

83.118.75.45: /* Using the Hook */

2005-04-06T15:07:42Z

‎Using the Hook

JasonM at 02:18, 2 April 2005

2005-04-02T02:18:29Z

JasonM: All the bullets scared me.

2005-04-02T02:16:30Z

All the bullets scared me.

FloppusMaximus at 05:13, 30 March 2005

2005-03-30T05:13:24Z

FloppusMaximus: categorized

2005-03-28T16:58:28Z

categorized

FloppusMaximus: /* Synopsis */

2005-03-28T10:23:05Z

‎Synopsis

@@ Line 21: / Line 21: @@
 * '''A = 2''': The width of a small font character is requested.
 * '''A = 3''': A large font bitmap is requested for variable-width display.  The bitmap provided will be shifted left by 1 bit and copied to [[83Plus:RAM:845A|lFont_record]] ''plus 1'', so that (lFont_record) can be set to 6.
-HL contains the font table offset, equal to the character multiplied by 8.  In modes 1 and 3, B also contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL and B '''must''' be left intact.  Otherwise, your outputs depend on the mode.
+HL contains the font table offset, equal to the character multiplied by 8.  In modes 1 and 3, B also contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with the zero flag reset. If you do this, HL and B '''must''' be left intact.  Otherwise, your outputs depend on the mode.
 * In modes 0 and 1, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] or [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
 * In mode 2, set B to the width of the character.

@@ Line 16: / Line 16: @@
 == Using the Hook ==
-This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font, 2 for small font width and 3 for something unknown. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] and [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
+This hook is called to request information about a particular character.  The accumulator indicates the type of information:
-* In small font:
+=== Character bitmap formats ===
   <nowiki>(HL) = width of character
 (HL+1) = first (accent) row, right aligned (the last pixel usually clear)
@@ Line 25: / Line 34: @@
 (HL+6) = sixth row</nowiki>
   (HL+7) = seventh row (only displayed with bit [[83Plus:Flags:05#Bit_1|textEraseBelow, (iy+textFlags)]] set)
-* In large font:
   <nowiki>(HL) = first row, right aligned
 ...
@@ Line 38: / Line 48: @@
 The following code displays the letter A in boldface:
-  <nowiki>FontHook:
+  FontHook:
          .db 83h             ; Required for all hooks
-         or a                ; is it small or large font?
+         ld c,a
-        jr z,SmallFont
+         ld a,h              ; what character is to be displayed?
-         ld a,b              ; what character is to be displayed?
+        or l
          cp 'A'
          ret nz
          ld hl,BigA          ; get our replacement bitmap
-         ld de,lFont_record
+         ld de,[[83Plus:RAM:845A|lFont_record]]+1
          ld bc,7             ; copy it into RAM
          ldir
-         ld hl,lFont_record
+         ld hl,[[83Plus:RAM:845A|lFont_record]]+1
          cp a
          ret
-SmallFont:
+ SmallFontMode:
-        ld a,b              ; what character is to be displayed?
-        cp 'A'
-        ret nz
          ld hl,SmallA        ; get our replacement bitmap
-         ld de,sFont_record
+         ld de,[[83Plus:RAM:8462|sFont_record]]
          ld bc,8             ; copy it into RAM
          ldir
-         ld hl,sFont_record
+         ld hl,[[83Plus:RAM:8462|sFont_record]]
          cp a
          ret
-BigA:
+ WidthMode:
          .db 00001110b
          .db 00010011b
@@ Line 71: / Line 90: @@
          .db 00010011b
          .db 00010011b
-SmallA:
+ SmallA:
          .db 5
          .db 00000000b
@@ Line 79: / Line 98: @@
          .db 00010110b
          .db 00010110b
-         .db 00000000b</nowiki>
+         .db 00000000b

@@ Line 24: / Line 24: @@
 ...
 (HL+6) = sixth row</nowiki>
-  (HL+7) = seventh row (only displayed with bit [[83Plus:Flags:5#Bit_1|textEraseBelow, (iy+textFlags)]] set)
+  (HL+7) = seventh row (only displayed with bit [[83Plus:Flags:05#Bit_1|textEraseBelow, (iy+textFlags)]] set)
 * In large font:
   <nowiki>(HL) = first row, right aligned

@@ Line 16: / Line 16: @@
 == Using the Hook ==
-This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font, 2 for small font width. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] and [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
+This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font, 2 for small font width and 3 for something unknown. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] and [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
 * In small font:

@@ Line 16: / Line 16: @@
 == Using the Hook ==
-This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] and [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
+This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font, 2 for small font width. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM. If you want to, you can copy data to [[83Plus:RAM:8462|sFont_record]] and [[83Plus:RAM:845A|lFont_record]], and then point HL to this location. Of course, you can use any location you want.
 * In small font:

@@ Line 16: / Line 16: @@
 == Using the Hook ==
-* A = 0 for small font, 1 for large font
+This hook is called when a character is about to be displayed. A = 0 for small font, 1 for large font. B contains the character. If you want to use the default characters (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]]), return with zero reset. If you do this, HL '''must''' be left intact. Otherwise, set HL pointing to the font data, which must be in RAM:
-* B = character
-* NZ to use the default bitmaps (or rather, the bitmaps provided by the [[83Plus:Hooks:9BCC|localize hook]])
+* In small font:
-* Otherwise, set HL pointing to the font data, which must be in RAM:
+ <nowiki>(HL) = width of character
-** In small font:
+(HL+1) = first (accent) row, right aligned (the last pixel usually clear)
-*** (HL) = width of character
+(HL+2) = second row
-*** (HL+1) = first (accent) row, right aligned (with the last pixel usually clear)
+...
-*** (HL+2) = second row
+(HL+6) = sixth row</nowiki>
-*** ...
+ (HL+7) = seventh row (only displayed with bit  [[83Plus:Flags:5#Bit_1|textEraseBelow, (iy+textFlags)]] set)
-*** (HL+6) = sixth row
+* In large font:
-*** (HL+7) = seventh row (only displayed with bit [[83Plus:Flags:5#Bit_1|textEraseBelow, (iy+textFlags)]] set)
+ <nowiki>(HL) = first row, right aligned
-** In large font:
+...
-*** (HL) = first row, right aligned
+(HL+6) = seventh row</nowiki>
-*** ...
-*** (HL+6) = seventh row
+See the example code for actual formatted data.
 == Comments ==

@@ Line 1: / Line 1: @@
-[[Category:83Plus:Hooks:By_Name|Font Hook]]
+[[Category:83Plus:Hooks:By_Name|Font Hook]] [[Category:83Plus:Hooks:By_Address|9B9C - Font Hook]]
 [[Category:83Plus:Hooks:By_Address|9B9C - Font Hook]]
 == Synopsis ==
 '''Name:''' Font Hook

← Older revision		Revision as of 16:58, 28 March 2005
Line 1:		Line 1:
		+	[[Category:83Plus:Hooks:By_Name\|Font Hook]]
		+	[[Category:83Plus:Hooks:By_Address\|9B9C - Font Hook]]
	== Synopsis ==		== Synopsis ==
	'''Name:''' Font Hook		'''Name:''' Font Hook

@@ Line 10: / Line 10: @@
 '''Hook Call BCALL:''' [[83Plus:BCALLs:4003|4003]]
-'''Hook Active Flag:''' [[83Plus:BCALLs:35#Bit_5|5, (iy + 35h)]]
+'''Hook Active Flag:''' [[83Plus:Flags:35#Bit_5|5, (iy + 35h)]]
 This hook allows you to change the font bitmaps; for example, it is used for [http://www.detachedsolutions.com/omnicalc/ Omnicalc]'s custom fonts.