Problem with displaying Vietnamese font

[tanmanh0707]

Hi Bodmer,

First of all I would like to say thanks to all of your hard word on this library.
I got problem when trying to display Vietnamese font. I used your tool Create_font.pde to create font header file.
However, the unicode character is broken on the screen.
Could you please help to check if I missed something?

Here is my code and font file, the string is "Việt Nam" and the unicode character is U1EC7:

https://github.com/humacompany/tft_espi_vietnamese_font

Thank you and best regards,
Manh

[tanmanh0707]

Updated:

So I managed to draw Vietnamese characters on the screen. However, there are some curious points that I want to share with you guys and hopely I can understand them deeply.

1. Previously, I wrongly generated *.vlw file using Processing project. I didnot specify unicode blocks area. So I tried to find what unicode block that Vietnamese font is. According to this link, it turns out that the font is listed in several noncontiguous Unicode ranges.
   Then I found an online tool to analyze font file Font Drop. The tool shows that the font is listed in 2 parts, basic latin from 0x20 to 0x7E, and Unicode characters from 0xA0 to 0xFE
   After that, I specified the Unicode blocks in Processing project in Custom range area. Finally, the *.vlw file is generated properly.

My question is, Is there a more convenient way to identify the unicode block from the font either than using above online tool?

2. However, I cannot draw the text that is defined directly in Arduino IDE 1.8.19 using this:

String vietnamese_str = "Việt Nam";
tft.drawString(vietnamese_str, 0); //Not work - broken character

The problem is, my font file is encoded to Latin-1 and the library only support Unicode (correct me if I'm wrong)

My question is, is there a way to change decoding method to other than Unicode?

3. Ok, so my solution is to use drawGlyph instead and it's working very very well except one thing. That is, I have to define the string as a char array instead of a string, and draw the characters one by one in a loop like this:

const char text[] = {'V', 'i', 0xD6, 't', ' ', 'N', 'a', 'm', 0x00}; //Annoying
const char *ptr = str;

while (*ptr) {
  tft.drawGlyph(*ptr);
  ptr++;
}

Also, due to draw character one by one, I need to calculate the text width manually to draw in a center alignment. I used tft.textWidth(text); but it returns incorrect width. The returned value is less than the actual printing.

Is there a way to calculate exact text width with smooth font?