Question

My first question ever, so I’ll try to be as descriptive as possible.

I have a TFT display that I have connected to an embedded processor’s bus (64kb RAM, no OS obviously). I wrote a C++ class to set pixels on the display. My goal is to print letters. Each pixel of the letter only needs to be described by 1 bit: on or off. I imagined making a header file of the following format:

#ifndef ABC_H
#define ABC_H

namespace ABC{
    const unsigned int a[]={0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
}

#endif

The character above, which I have called “ABC::a”, represents a thin white box with a black box on top and bottom. I have a program that turns bmp files into a header file above. The array is 32 ints long, and each int is 32 bits (I will probably use uint32_t in the final draft, so don’t worry!). This effectively means that I’ve described one ASCII character as a 32×32 bmp. To print it at a specified (X,Y) coordinate, I would just need to do this:

void PrintChar(const int* c,X,Y){
    for(unsigned int y=0; y<32; y++)
        for(unsigned int x=0; x<32; x++)
            if(c[y] & 1<<x)
                SetPixel(x+X,y+Y); //SetPixel(x,y) lights up a pixel at coordinates (x,y) on the display
}

Question: What would be a good way to generate 32×32 bmps of ASCII characters, preferably not tediously by hand with paint.exe. Alternatively once, does someone have a better means to the end that I want (like skipping the middleman program somehow)? Alternatively twice, am I just being dumb and there’s a much better way to describe ASCII characters for my purposes?

Note: I realize using C++ for an embedded processor is a questionable practice (at least I think so) but that’s what I was instructed to do. /shrug

edit: Ignore the compression part! I’ll handle that on my own (unless you really want to share some ideas, then fire away!).

Answer 1

You can use any graphics library to draw characters to a buffer, and then construct your character data from the buffer.

On Windows, the most obvious way would be to use GDI+ and ClearType, or you could take a look at Cairo. If you want full control over character rendering, I suggest using Freetype.

Once you have a buffer containing the character, you might need to test individual pixesl whether they should be black or white (because graphics libraries might apply anti-alias). Alternatively, depending on how you draw the text and which font you use, it might not use anti-alias at all.