STM32-LCD_Font_Generator

Generate C source text fonts for STM32Cube Fonts Utilities Driver.

For use with the BSP LCD driver for STM32xx-EVAL boards.

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Examples of generating fonts

Refer to this project: TFT-CustomFonts

Monospace fonts

cd example
python3 ../stm32-font.py --font Menlo.ttc --size 32

Proportional font

Proportional fonts will have monospace-style spacing

cd example
python3 ../stm32-font.py --font 'Avenir Next.ttc' --size 20

Other charsets

Example shown is having chinese charsets

cd example-chinese
python3 ../stm32-font.py -f 'STHeiti Medium.ttc' -s 24 -c chinese-hello-world.txt 
python3 ../stm32-font.py -f 'STHeiti Medium.ttc' -s 32 -c chinese-hello-world.txt 

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Adding fonts into project

Fixing the BSP library (Part 1)

The main code for drawing chars on the LCD is inside stm32l073z_eval_lcd.c via the LCD_DrawChar function. In the function, the font bytes are converted into a bitmap. However, the bitmap has a max size.

#define MAX_HEIGHT_FONT         17
#define MAX_WIDTH_FONT          24

/* Max size of bitmap will based on a font24 (17x24) */
static uint8_t bitmap[MAX_HEIGHT_FONT*MAX_WIDTH_FONT*2+OFFSET_BITMAP] = {0};

This means that that beyond 408 bytes (17x24), the fonts are not displayed at all. For a simple fix, we can add the bitmap array locally in the function which has a dynamic size.

static void LCD_DrawChar(uint16_t Xpos, uint16_t Ypos, const uint8_t *pChar)
{
  // ADDED
  uint8_t *bitmap = calloc(DrawProp.pFont->Height * DrawProp.pFont->Width*2 + OFFSET_BITMAP, sizeof(uint8_t));

  /* Original Code */

  // ADDED
  free(bitmap);
}

Fixing the BSP library (Part 2)

Another issue is that when generated font uses more than 3 bytes per row, the fonts will not display at all again.

if(((width + 7)/8) == 3)
{
  line =  (pchar[0]<< 16) | (pchar[1]<< 8) | pchar[2];
}

if(((width + 7)/8) == 2)
{
  line =  (pchar[0]<< 8) | pchar[1];
}

if(((width + 7)/8) == 1)
{
  line =  pchar[0];
}   

This is because it is hardcoded for 1 to 3 bytes.

line is little-endian swapped order of pchar Replace it with this which works for any number of bytes

int bytes = ((width + 7)/8);
line = 0;
for (int i = 0; i < bytes; i++) {
    line <<= 8;
    line |= pchar[i];
}

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The changes are done accordingly in stm32l073z_eval_lcd_new.h. Copy it into the project

Additional Unsolved Bugs

1. if the width of the character exceeds 32 pixels or 32 bits, the font will be cut off to the left.