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91 lines
2.3 KiB
Markdown
91 lines
2.3 KiB
Markdown
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[← Home](../README.md) · [Graphics](README.md)
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# Text and Fonts — TextFont, TextAttr, OpenFont, Text
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## Overview
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AmigaOS uses bitmap fonts rendered through `graphics.library`. Fonts are described by `TextAttr` (request) and `TextFont` (loaded instance). Disk fonts require `diskfont.library`.
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---
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## Key Structures
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```c
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/* graphics/text.h — NDK39 */
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struct TextAttr {
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STRPTR ta_Name; /* font name, e.g. "topaz.font" */
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UWORD ta_YSize; /* desired height in pixels */
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UBYTE ta_Style; /* FSF_BOLD, FSF_ITALIC, FSF_UNDERLINED */
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UBYTE ta_Flags; /* FPF_ROMFONT, FPF_DISKFONT, etc. */
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};
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struct TextFont {
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struct Message tf_Message;
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UWORD tf_YSize; /* font height */
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UBYTE tf_Style;
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UBYTE tf_Flags;
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UWORD tf_XSize; /* nominal width */
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UWORD tf_Baseline; /* baseline from top */
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UWORD tf_BoldSmear; /* bold smear width */
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UWORD tf_Accessors; /* open count */
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UBYTE tf_LoChar; /* first character code */
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UBYTE tf_HiChar; /* last character code */
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APTR tf_CharData; /* bitmap data */
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UWORD tf_Modulo; /* bytes per row of font bitmap */
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APTR tf_CharLoc; /* character location table */
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APTR tf_CharSpace; /* proportional spacing table */
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APTR tf_CharKern; /* kerning table */
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};
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```
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---
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## Opening Fonts
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```c
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/* ROM font (topaz, always available): */
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struct TextAttr ta = {"topaz.font", 8, 0, FPF_ROMFONT};
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struct TextFont *font = OpenFont(&ta);
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/* Disk font (requires diskfont.library): */
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struct TextAttr ta2 = {"helvetica.font", 24, 0, FPF_DISKFONT};
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struct TextFont *font2 = OpenDiskFont(&ta2);
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/* Set in RastPort: */
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SetFont(rp, font);
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```
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---
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## Rendering Text
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```c
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Move(rp, 10, 20); /* position cursor */
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Text(rp, "Hello Amiga", 11); /* render 11 characters */
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/* Get pixel width of a string: */
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UWORD width = TextLength(rp, "Hello", 5);
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```
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---
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## Style Flags
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```c
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#define FSF_UNDERLINED 0x01
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#define FSF_BOLD 0x02
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#define FSF_ITALIC 0x04
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#define FSF_EXTENDED 0x08
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/* Set algorithmic style: */
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SetSoftStyle(rp, FSF_BOLD | FSF_ITALIC,
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AskSoftStyle(rp)); /* ask which styles the font supports */
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```
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---
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## References
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- NDK39: `graphics/text.h`
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- ADCD 2.1: `OpenFont`, `OpenDiskFont`, `SetFont`, `Text`, `TextLength`
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