c - 用C在屏幕上绘制字体

Question

我使用 SDL 库模拟了一个屏幕。我想在这个屏幕上绘制字体，只需使用我已经制作的“draw_pixel”函数即可。

网上查了很多资料。 我找到了这个网站http://jared.geek.nz/2014/jan/custom-fonts-for-microcontrollers并且代码运行良好。但是它不支持可变宽度字符

我只想使用源代码。

您能告诉我是否有源代码或光源库可以从像素绘制字体吗？

编辑:这是我从 M Oehm 答案更改的代码。

int DrawChar(char c, uint8_t x, uint8_t y, int r, int g, int b, SDL_Surface *rectangle, SDL_Surface *ecran, SDL_Rect position)
{
uint8_t i,j;

// Convert the character to an index
c = c & 0x7F;
if (c < ' ') {
    c = 0;
} else {
    c -= ' ';
}

const uint8_t* chr = font[c];
int w = chr[0];

chr++;

for (j = 0; j < w; j++) {
    for (i = 0; i < CHAR_HEIGHT; i++) {

        if (chr[j] & (1 << i)) {
            draw_pixel(x+j, y+i, r, g, b, rectangle, ecran, position);
        }
    }
}

return w + CHAR_GAP;
}

void DrawString(const char* str, uint8_t x, uint8_t y, int r, int g, int b, SDL_Surface *rectangle, SDL_Surface *ecran, SDL_Rect position)
{
while (*str) {
    x += DrawChar(*str++, x, y, r, g, b, rectangle, ecran, position);
}
}

<小时/>

const unsigned char font[96][6] = {
{3, 0x00, 0x00, 0x00},          //
{3, 0x00, 0x2f, 0x00},          // !
{4, 0x03, 0x00, 0x00, 0x03},    // "

结果如下:字符仍然具有相同的大小。 http://hpics.li/d54f000

编辑: 解决方案在这里http://www.riuson.com/lcd-image-converter 您必须对代码进行一些更改，因为它们存在一些错误，但它可以工作。

Answer 1

您可以轻松地将给定代码扩展到可变宽度字符。更改字体的定义:

const unsigned char font[96][10] = {
    {3, 0x00, 0x00, 0x00},          //  
    {3, 0x00, 0x2f, 0x00},          // !
    {4, 0x03, 0x00, 0x00, 0x03},    // "
    ...
};

第一个条目是字符的宽度。必须选择第二个维度来容纳最宽的字符。在本例中，它的宽度可以是 9 像素。

然后扩展DrawChar函数，使用给定的宽度并返回绘制位置应前进的宽度，即字符的宽度加上一定的间隙。 (您可以将间隙设置为参数，以便打印双倍行距文本。)

然后，DrawString 函数使用返回的宽度:

int DrawChar(char c, uint8 x, uint8 y, uint8 brightness)
{
    uint8 i, j;

    // Convert the character to an index
    c = c & 0x7F;
    if (c < ' ') {
        c = 0;
    } else {
        c -= ' ';
    }

    const uint8* chr = font[c];
    int w = chr[0];

    chr++;

    for (j = 0; j < w; j++) {
        for (i = 0; i < CHAR_HEIGHT; i++) {

            if (chr[j] & (1 << i)) {
                DrawPixel(x + j, y + i, brightness);
            }
        }
    }

    return w + CHAR_GAP;
}

void DrawString(const char* str, uint8 x, uint8 y, uint8 brightness)
{
    while (*str) {
        x += DrawChar(*str++, x, y, brightness);
    }
}

编辑:这是一个更完整的示例，仅定义了一些字母:

#include <stdlib.h>
#include <stdio.h>
#include <string.h>

typedef unsigned char uint8;

char screen[25][80];

#define CHAR_HEIGHT 8
#define CHAR_GAP 2

const unsigned char font[96][10] = {
    [' ' - 32] = {1, 0x00},
    ['A' - 32] = {5, 0x3e, 0x09, 0x09, 0x09, 0x3e},
    ['B' - 32] = {5, 0x3f, 0x25, 0x25, 0x25, 0x19},
    ['D' - 32] = {5, 0x3f, 0x21, 0x21, 0x21, 0x1e},
    ['E' - 32] = {5, 0x3f, 0x25, 0x25, 0x25, 0x21},
    ['H' - 32] = {5, 0x3f, 0x04, 0x04, 0x04, 0x3f},
    ['I' - 32] = {1, 0x3f},
    ['L' - 32] = {4, 0x3f, 0x20, 0x20, 0x20},
    ['M' - 32] = {7, 0x3f, 0x02, 0x04, 0x18, 0x04, 0x02, 0x3f},
    ['O' - 32] = {5, 0x1e, 0x21, 0x21, 0x21, 0x1e},
    ['P' - 32] = {5, 0x3f, 0x09, 0x09, 0x09, 0x06},
    ['R' - 32] = {5, 0x3f, 0x09, 0x19, 0x19, 0x26},
    ['S' - 32] = {5, 0x22, 0x25, 0x25, 0x25, 0x19},
    ['W' - 32] = {7, 0x07, 0x38, 0x0c, 0x03, 0x0c, 0x38, 0x07},
};

void DrawPixel(int x, int y, uint8 c)
{
    screen[y][x] = c;
}

int DrawChar(char c, uint8 x, uint8 y, uint8 brightness)
{
    uint8 i, j;

    // Convert the character to an index
    c = c & 0x7F;
    if (c < ' ') {
        c = 0;
    } else {
        c -= ' ';
    }

    const uint8* chr = font[c];
    int w = chr[0];

    chr++;

    for (j = 0; j < w; j++) {
        for (i = 0; i < CHAR_HEIGHT; i++) {

            if (chr[j] & (1 << i)) {
                DrawPixel(x + j, y + i, brightness);
            }
        }
    }

    return w + CHAR_GAP;
}

void DrawString(const char* str, uint8 x, uint8 y, uint8 brightness)
{
    while (*str) {
        x += DrawChar(*str++, x, y, brightness);
    }
}

int main()
{
    int i;

    memset(screen, '.', sizeof(screen));

    DrawString("HELLO WORLD", 2, 2, 'O');
    DrawString("MISSISSIPPI", 8, 10, '#');

    for (i = 0; i < 25; i++) printf("%.80s\n", screen[i]);

    return 0;
}