69 lines
1.9 KiB
Plaintext
69 lines
1.9 KiB
Plaintext
|
# Deshab Bitmap Font (.dbf)
|
|||
|
|
|
|||
|
|
`CODE/font` 包含 Deshab 自研位图字体工具和规范。
|
|||
|
|
|
|||
|
|
## 文件格式
|
|||
|
|
|
|||
|
|
```text
|
|||
|
|
Offset Size Field
|
|||
|
|
0 4 magic "DBF\x10" (version 16)
|
|||
|
|
4 4 u32 glyph_count
|
|||
|
|
8 2 u16 default_width
|
|||
|
|
10 2 u16 default_height
|
|||
|
|
12 2 u16 bits_per_pixel (8=grayscale)
|
|||
|
|
14 N×12 index table (N entries)
|
|||
|
|
... ... glyph bitmap data
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
每条索引：
|
|||
|
|
```text
|
|||
|
|
[0..1] u16 codepoint (Unicode BMP)
|
|||
|
|
[2..3] u16 actual_width (pixels)
|
|||
|
|
[4..7] u32 data_offset
|
|||
|
|
[8..11] u32 data_size
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
索引按 codepoint 升序排列，可用二分查找。
|
|||
|
|
|
|||
|
|
## 字体文件
|
|||
|
|
|
|||
|
|
| 文件 | 大小 | 字形数 | 精度 |
|
|||
|
|
|------|------|--------|------|
|
|||
|
|
| [simhei_16.dbf](file:///d:/Code/Deshab/SYSTEM/system/font/simhei_16.dbf) | 1.8MB | 6858 | 16×16 8bpp |
|
|||
|
|
| [simhei_24.dbf](file:///d:/Code/Deshab/SYSTEM/system/font/simhei_24.dbf) | 3.9MB | 6858 | 24×24 8bpp |
|
|||
|
|
| [simhei_32.dbf](file:///d:/Code/Deshab/SYSTEM/system/font/simhei_32.dbf) | 6.9MB | 6858 | 32×32 8bpp |
|
|||
|
|
|
|||
|
|
字形覆盖：GB2312 全部 6763 个简体汉字 + ASCII 32–126 可打印字符。
|
|||
|
|
|
|||
|
|
## 生成工具
|
|||
|
|
|
|||
|
|
```bash
|
|||
|
|
python CODE/font/mkfont.py <ttf_path> <pixel_size> <output.dbf>
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
依赖：Python 3 + Pillow (`pip install Pillow`)
|
|||
|
|
|
|||
|
|
## C 头文件
|
|||
|
|
|
|||
|
|
[dbf.h](file:///d:/Code/Deshab/CODE/font/dbf.h) 定义数据结构和二分查找函数：
|
|||
|
|
|
|||
|
|
```c
|
|||
|
|
#include "dbf.h"
|
|||
|
|
const u8 *font = ...; // 加载 .dbf 到内存
|
|||
|
|
dbf_header *hdr = (dbf_header *)font;
|
|||
|
|
dbf_index_entry *idx = (dbf_index_entry *)(font + 14);
|
|||
|
|
int entry = dbf_lookup(idx, hdr->count, codepoint);
|
|||
|
|
if (entry >= 0) {
|
|||
|
|
u8 *glyph = font + idx[entry].offset;
|
|||
|
|
u16 w = idx[entry].width;
|
|||
|
|
u16 h = hdr->height;
|
|||
|
|
// 逐行渲染 8bpp 灰度位图
|
|||
|
|
}
|
|||
|
|
```
|
|||
|
|
|
|||
|
|
## 使用方式
|
|||
|
|
|
|||
|
|
1. 启动时将 `.dbf` 文件通过 boot module 或 FAT32 加载到内存
|
|||
|
|
2. GBK/GB2312 双字节序列转为 Unicode codepoint 后查表
|
|||
|
|
3. 8bpp 灰度可直接 alpha-blend 到 framebuffer
|