Unable to drawString characters as (char) above 127

[Shdwdrgn]

While attempting to display a sample of a font on the screen I discovered you cannot directly show characters above 127 with the drawString command. For example:

display.setTextAlignment(TEXT_ALIGN_CENTER);
uint8_t c;
for(int i=0; i<6; i++) {
  for(int j=0; j<16; j++) {
    c = 128 + (16*i) + j;
    display.drawString(j*8+3, i*10, String((char)c));
  }
}

A couple of characters are shown here (I believe these are 0xC2 and 0xC3 which are specifically managed in DefaultFontTableLookup), but the rest are blank. However if I copy/paste text into my code they seem to show up correctly. This is likely due to differences between ASCII and UTF-8 management, but I don't know enough about how UTF-8 characters work to reliably determine the difference in what the user is requesting.

My solution to this problem was to add a new function to OLEDDisplay.cpp to display specific chars.

void OLEDDisplay::drawChar(int16_t xMove, int16_t yMove, char ch) {
  uint16_t lineHeight = pgm_read_byte(fontData + HEIGHT_POS);

  char* text = &ch;
  drawStringInternal(xMove, yMove, text, 1, getStringWidth(text, 1));
}

To OLEDDisplay.h I added this line:

void drawChar(int16_t x, int16_t y, char ch);

Now in the example above you can replace the drawString line with: display.drawChar(j*8+3, i*10, (char)c); and all of the upper characters from 128-255 can be displayed individually on the screen.

Maybe someone with more knowledge of the subject will be able to find a better solution, but this should work without breaking any existing functionality.

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