ASC字库文件驱动分享

发布于 2013-01-21 16:41:16 浏览：4697 订阅该版

如果系统中使用了多套较大的asc字库，放在内部flash中明显不是一种很好的方法，所以还是仿照汉字字库的方式，可以读取SD字库，也算是GUI字库的一种完善吧。
新建并添加font_asc_file.c:
```
/*
 * Cached asc font engine
 */
#include <rtgui/dc.h>
#include <rtgui/font.h>
#include <rtgui/tree.h>
#include <rtgui/rtgui_system.h>

#define RTGUI_USING_ASC_FILE
#ifdef RTGUI_USING_ASC_FILE
#ifdef _WIN32_NATIVE
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <io.h>
#define open    _open
#define close   _close
#define read    _read
#define write   _write
#define unlink  _unlink
#else
#include <dfs_posix.h>
#endif

#define ASC_CACHE_MAX    2

static int _font_cache_compare(struct asc_cache *node1, struct asc_cache *node2);

static void rtgui_asc_file_font_load(struct rtgui_font *font);
static void rtgui_asc_file_font_draw_text(struct rtgui_font *font, struct rtgui_dc *dc, const char *text, rt_ubase_t len, struct rtgui_rect *rect);
static void rtgui_asc_file_font_get_metrics(struct rtgui_font *font, const char *text, rtgui_rect_t *rect);
const struct rtgui_font_engine rtgui_asc_file_font_engine =
{
    RT_NULL,
    rtgui_asc_file_font_load,
    rtgui_asc_file_font_draw_text,
    rtgui_asc_file_font_get_metrics
};

SPLAY_PROTOTYPE(asc_cache_tree, asc_cache, asc_node, _font_cache_compare);
SPLAY_GENERATE(asc_cache_tree, asc_cache, asc_node, _font_cache_compare);

static int _font_cache_compare(struct asc_cache *cache_1, struct asc_cache *cache_2)
{
    if (cache_1->asc_id > cache_2->asc_id) return 1;
    if (cache_1->asc_id < cache_2->asc_id) return -1;

return 0;
}

static rt_uint8_t *_font_cache_get(struct rtgui_asc_file_font *font, rt_uint8_t asc_id)
{
    rt_uint32_t seek;
    struct asc_cache *cache, search;

search.asc_id = asc_id;

/* enter critical */
    rtgui_enter_critical();

cache = SPLAY_FIND(asc_cache_tree, &(font->cache_root), &search);
    if (cache != RT_NULL)
    {
        /* exit critical */
        rtgui_exit_critical();

/* found it */
        return (rt_uint8_t *)(cache + 1);
    }

/* exit critical */
    rtgui_exit_critical();

/* can not find it, load to cache */
    cache = (struct asc_cache *) rtgui_malloc(sizeof(struct asc_cache) + font->font_data_size);
    if (cache == RT_NULL)
        return RT_NULL; /* no memory yet */

cache->asc_id = asc_id;
    seek =asc_id;
    seek *= font->font_data_size;

/* read asc font data */
    if ((lseek(font->fd, seek, SEEK_SET) < 0) ||
            read(font->fd, (char *)(cache + 1), font->font_data_size) !=
            font->font_data_size)
    {
        rtgui_free(cache);
        return RT_NULL;
    }

/* enter critical */
    rtgui_enter_critical();

if (font->cache_size >= ASC_CACHE_MAX)
    {
        /* remove a cache */
        struct asc_cache *left;
        left = font->cache_root.sph_root;
        while (SPLAY_LEFT(left, asc_node) != RT_NULL) left = SPLAY_LEFT(left, asc_node);

/* remove the left node */
        SPLAY_REMOVE(asc_cache_tree, &(font->cache_root), left);
        rtgui_free(left);
        font->cache_size --;
    }

/* insert to cache */
    SPLAY_INSERT(asc_cache_tree, &(font->cache_root), cache);
    font->cache_size ++;

/* exit critical */
    rtgui_exit_critical();

return (rt_uint8_t *)(cache + 1);
}

static void rtgui_asc_file_font_load(struct rtgui_font *font)
{
    struct rtgui_asc_file_font *asc_file_font = (struct rtgui_asc_file_font *)font->data;
    RT_ASSERT(asc_file_font != RT_NULL);

asc_file_font->fd = open(asc_file_font->font_fn, O_RDONLY, 0);
}

static void _rtgui_asc_file_font_draw_text(struct rtgui_asc_file_font *asc_file_font, struct rtgui_dc *dc, const char *text, rt_ubase_t len, struct rtgui_rect *rect)
{
    rt_uint8_t *str;
    rtgui_color_t bc;
    rt_uint16_t style;
    register rt_base_t h, word_bytes;

/* get text style */
    style = rtgui_dc_get_gc(dc)->textstyle;
    bc = rtgui_dc_get_gc(dc)->background;

/* drawing height */
    h = (asc_file_font->font_size + rect->y1 > rect->y2) ?
        rect->y2 - rect->y1 : asc_file_font->font_size;
    word_bytes = (asc_file_font->font_size + 15) / 16;

str = (rt_uint8_t *)text;

while (len > 0 && rect->x1 < rect->x2)
    {
        const rt_uint8_t *font_ptr;
        register rt_base_t i, j, k;

/* get font pixel data */
        font_ptr = _font_cache_get(asc_file_font, *str);

/* draw word */
        for (i = 0; i < h; i ++)
        {
            for (j = 0; j < word_bytes; j++)
                for (k = 0; k < 8; k++)
                {
                    if (((font_ptr[i * word_bytes + j] >> (7 - k)) & 0x01) != 0 &&
                            (rect->x1 + 8 * j + k < rect->x2))
                    {
                        rtgui_dc_draw_point(dc, rect->x1 + 8 * j + k, rect->y1 + i);
                    }
                    else if (style & RTGUI_TEXTSTYLE_DRAW_BACKGROUND)
                    {
                        rtgui_dc_draw_color_point(dc, rect->x1 + 8 * j + k, rect->y1 + i, bc);
                    }
                }
        }

/* move x to next character */
        rect->x1 += asc_file_font->font_size /2;
        str += 1;
        len -= 1;
    }
}

static void rtgui_asc_file_font_draw_text(struct rtgui_font *font, struct rtgui_dc *dc, const char *text, rt_ubase_t length, struct rtgui_rect *rect)
{
    rt_uint32_t len;
    struct rtgui_font *cfont;
    struct rtgui_asc_file_font *asc_file_font = (struct rtgui_asc_file_font *)font->data;

RT_ASSERT(dc != RT_NULL);
    RT_ASSERT(asc_file_font != RT_NULL);

cfont = rtgui_font_refer("asc", font->height);
    if (cfont == RT_NULL) cfont = rtgui_font_default(); /* use system default font */

while (length > 0)
    {
        len = 0;
        while (((rt_uint8_t) * (text + len)) >= 0x80 && len < length) len ++;
        /* draw text with Chinese font */
        if (len > 0)
        {
            rtgui_font_draw(cfont, dc, text, len, rect);

text += len;
            length -= len;
        }

len = 0;
        while (((rt_uint8_t) * (text + len)) < 0x80 && *(text + len) && len < length) len ++;
        if (len > 0)
        {
            _rtgui_asc_file_font_draw_text(asc_file_font, dc, text, len, rect);

text += len;
            length -= len;
        }
    }
    rtgui_font_derefer(cfont);
}

static void rtgui_asc_file_font_get_metrics(struct rtgui_font *font, const char *text, rtgui_rect_t *rect)
{
    struct rtgui_asc_file_font *asc_file_font = (struct rtgui_asc_file_font *)font->data;
    RT_ASSERT(asc_file_font != RT_NULL);

/* set metrics rect */
    rect->x1 = rect->y1 = 0;
    rect->x2 = (rt_int16_t)(asc_file_font->font_size / 2 * rt_strlen((const char *)text));
    rect->y2 = asc_file_font->font_size;
}
#endif
```
在font.h里添加定义:
```
struct asc_cache
{
    SPLAY_ENTRY(asc_cache) asc_node;

rt_uint8_t asc_id;
};
struct rtgui_asc_file_font
{
    struct asc_cache_tree cache_root;
    rt_uint16_t cache_size;

/* font size */
    rt_uint16_t font_size;
    rt_uint16_t font_data_size;

/* file descriptor */
    int fd;

/* font file name */
    const char *font_fn;
};
extern const struct rtgui_font_engine rtgui_asc_file_font_engine;
```
这样系统就支持SD卡的asc字库了。
使用时仿照汉字字库的使用方法哈
例如 高度为24号的asc字符定义:
```
struct rtgui_asc_file_font ascii24 =
{
    {RT_NULL},              /* cache root       */
    0,                      /* cache size       */
    24,                     /* font size        */
    48,                     /* font data size   */
    -1,                     /* fd               */
    "/resource/ascii24.fnt"   /* font_fn          */
};

struct rtgui_font rtgui_font_ascii24 =
{
    "asc",                   								/* family */
    24,                     								/* height */
    1,                      								/* refer count */
    &rtgui_asc_file_font_engine,							/* font engine */
    (void *) &ascii24,         /* font private data */
};
```
添加字体字库
```
rtgui_font_system_add_font(&rtgui_font_ascii24);
```
这样只需要是24高度的ASC，就会用它显示了。
关于字库的制作参照
[http://www.rt-thread.org/phpBB3/viewtopic.php?f=3&t=1095](http://www.rt-thread.org/phpBB3/viewtopic.php?f=3&t=1095)
在最后生成的时候选择生成二进制字库文件即可，后缀是没有任何影响的。