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| BGIFONT.INC v1.0 beta |
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| Written in pure assembler by Ivushkin Andrey aka Willow |
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| At present Menuet operation system has poor means to draw charaters. Its |
| distro contains 2 raster fonts (CHAR.MT & CHAR2.MT files). The kernel supports |
| them internally. That is Jarek Pelczar who makes certain efforts to develop |
| scalable TTF-like fonts but huge Menuet C Library does not become widespread |
| inside our assembly-written OS. Bulgarian MenuetOS team also tries to include |
| third scalable font into the kernel, though, as far as I know, its characters |
| are still under design and are incomplete. Therefore Bulgarian developing is |
| not valuable for ordinary users. It is obvious that scalable fonts will help |
| to develop such products as browsers and word processors where character |
| formatting is of great importance. |
| Let me introduce for public domain an include file BGIFONT.INC to process |
| vector fonts (*.CHR) worked out by famous Borland Corporation to use in Turbo |
| Pascal, Turbo C and Borland C++ compilers under MS-DOS. Sorry, I still fail to |
| add BGI font support into kernel - deeper knowledge on memory allocation and |
| system calls needed. I hope that Menuet system programmers will be glad to help |
| me. Module compiling within kernel is supposed using constant BGI_LEVEL equ |
| KERNEL. By means of conditional compiling it will be possible to use the module |
| at both kernel and application levels. Following is concerned using the include |
| file while programming an application. |
| |
| BGI fonts may reside in any folder on HD or RD. They are searched using value |
| of constant BGI_PATH. If constant BGI_WINDOW_CLIP is equal to 1, module routines |
| perform window bounds check to avoid artifacts while drawing. Use this if you |
| aren't sure that strings are fit in window. All BGIFONT.INC routines are |
| declared as macros, that is they are used without "call". To load 11 fonts into |
| application's memory a contiguous free space up to 120 kb is needed. When |
| loading, font data relocation is performed to save memory. Let us see a chart: |
| |
| | Font | | BGIrec | | Font | | BGIrec | | Font | | BGIrec | |
| | counter | | structure| | data | | structure| | data | | structure| ... |
| | (1 byte)| | | | | | |
| | ------------->------ -------------->----- ---------- |
| - referenced by [BGIfont_Ptr] |
| |
| BGIrec structure fields have following meaning: |
| |
| +00 dword .FontName font name (4 characters) |
| +04 byte .CharsCount amount of font characters |
| +05 byte .FirstChar code of the first character present |
| +06 byte .UpperMargin high bound of characters |
| +07 byte .LowerMargin low bound of characters |
| +08 dword .Widths offset to width array |
| +12 dword .FirstData offset to vector table |
| +16 dword .EOF pointer to the following BGIrec |
| +20 dword .font_data here font data begin |
| |
| Font loading and verification are carried out by BGIfont_Prepare procedure. |
| |
| BGIfont_Prepare |
| in: EDX - font name (4 characters) to be loaded. It must to be the same as |
| the font filename (without extension) |
| EDI - address to where font have to be loaded. Used only for the |
| first time. Then you may find this value in [BGIfont_Ptr] |
| out: EAX=0, if an error occured, otherwise EAX is identifier (ID) of the |
| loaded font. Later it is possible to get font ID with BGIfont_GetID |
| function. |
| |
| For the simultaneous loading of few fonts you may use BGIfont_Init routine. |
| |
| BGIfont_Init |
| in: ESI - pointer to array of font names (for example db 'TRIPSIMPEURO') |
| ECX is amount of fonts to load |
| EDI - see BGIfont_Prepare |
| out: nothing. |
| |
| To load 10 standard fonts the module defines an array BGIfont_names (see in |
| BGITEST for usage demonstration). |
| |
| For compatibility and subsequent kernel introduction, the module offers 2 |
| routines for drawing vector characters. One of them uses registers (like sysfunc |
| 4), another uses a structure. |
| |
| BGIfont_Outtext |
| in: EAX - "pivot point" of a string [x] shl 16+[y] |
| ECX - text color and font size 0xXYRRGGBB, |
| where X - vector font ID(4..F), |
| Y - size of caracters divided by 4, e.g. 0x1 - 1/4 of |
| ordinary size, 0xC - triple size. |
| EDX - pointer to the string |
| ESI - string length + formatting flags (see below). BGI_ITALIC and |
| BGI_NODRAW flags are ignored. |
| out: EAX - coords at the end of the string drawn [x] shl 16+[y]. |
| |
| As you can see, BGIfont_Outtext is similar to the 4th system function, |
| but provides an extended management of drawing symbols. |
| |
| The most complete use of vector fonts is provided by BGIfont_Freetext routine. |
| Parameters are passed in a BGIfree structure. |
| |
| BGIfree structure fields have following meaning: |
| |
| +00 dword font name (4 characters) |
| +04 dword "pivot point" of a string [x] shl 16+[y] |
| +08 dword turn angle (clockwise, 0 is horizontal) |
| +12 dword X scale (floating point value!) |
| +16 dword Y scale (floating point value!) |
| +20 dword pointer to the string |
| +24 dword string length WITHOUT formatting flags |
| +28 dword text color 0x00RRGGBB |
| +32 dword formatting flags |
| |
| The module defines following formatting flags: |
| BGI_NODRAW - do not draw |
| BGI_ITALIC - italic |
| BGI_BOLD - bold |
| BGI_HALEFT - left alignment |
| BGI_HARIGHT - right alignment |
| BGI_HACENTER - center alignment |
| BGI_VABOTTOM - bottom alignment |
| BGI_VATOP - top alignment |
| BGI_VACENTER - middle vertical alignment |
| |
| Combination of flags can be performed by addition or the OR operation. |
| |
| BGIfont_Freetext |
| in: EBX - pointer to BGIfree structure |
| out: EAX coords at the end of the string drawn [x] shl 16+[y]. |
| |
| BGIfont_GetID routine returns font ID by its name. |
| |
| BGIfont_GetID |
| in: EDX - font name (4 characters) |
| out: EAX - ID of the font |
| EDI - pointer on font's BGIrec structure. |
| |
| Using functions of BGIFONT.INC module is demonstrated by BGITEST app. |
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| Todo list: |
| 1. An insidious bug sometimes shows up while loading multiple fonts (as in |
| BGITEST), that corrupts some characters. It disappears when font loading |
| order is changed... :-( |
| 2. To correct a hardly reproduceable bug when moving along the font list. |
| 3. To perfect drawing of bold fonts. |
| 4. To add number drawing routines. |
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| Property changes: |
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| Added: svn:eol-style |
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| +native |
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| \ No newline at end of property |
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