Write TGA file in C with zero dependencies (apart stdio)

write_tga.h

/**
 * writetga: A zero dependencies writer for the TGA file format.
 *
 * Copyright 2020 Marco Mastropaolo <[email protected]>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#ifndef __WRITE_TGA_H__
#define __WRITE_TGA_H__

#include <stdio.h>

typedef enum _TgaPixelFormat {
    TGAPIXELFMT_BGR,
    TGAPIXELFMT_BGRA,
    TGAPIXELFMT_ABGR,
    TGAPIXELFMT_BGRX,
    TGAPIXELFMT_XBGR,
    TGAPIXELFMT_RGB,
    TGAPIXELFMT_RGBA,
    TGAPIXELFMT_ARGB,
    TGAPIXELFMT_RGBX,
    TGAPIXELFMT_XRGB,
} TgaPixelFormat;


static void write_tga_ftpr(const char *data, int width, int height, TgaPixelFormat format, FILE *fptr)
{
    char TGA_HEADER_PREFIX[12] = { 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0 };

    fwrite(TGA_HEADER_PREFIX, sizeof(TGA_HEADER_PREFIX), 1, fptr);
    
    putc(width & 0xFF, fptr);
    putc(width >> 8, fptr);
    putc(height & 0xFF, fptr);
    putc(height >> 8, fptr);

    switch(format) {
    case TGAPIXELFMT_BGR:
    case TGAPIXELFMT_RGB:
    case TGAPIXELFMT_BGRX:
    case TGAPIXELFMT_XBGR:
    case TGAPIXELFMT_RGBX:
    case TGAPIXELFMT_XRGB:
        putc(24, fptr);
        break;
    case TGAPIXELFMT_BGRA:
    case TGAPIXELFMT_ABGR:
    case TGAPIXELFMT_RGBA:
    case TGAPIXELFMT_ARGB:
        putc(32, fptr);
        break;
    }

    putc(0x20, fptr); /* flip vertical */

    switch(format) {
    case TGAPIXELFMT_BGR:
        fwrite(data, width * height, 3, fptr);
        break;
    case TGAPIXELFMT_BGRA:
        fwrite(data, width * height, 4, fptr);
        break;
    case TGAPIXELFMT_BGRX:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 0], fptr);
            putc(data[i + 1], fptr);
            putc(data[i + 2], fptr);
        }    
        break;
    case TGAPIXELFMT_ABGR:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 1], fptr);
            putc(data[i + 2], fptr);
            putc(data[i + 3], fptr);
            putc(data[i + 0], fptr);
        }    
        break;
    case TGAPIXELFMT_XBGR:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 1], fptr);
            putc(data[i + 2], fptr);
            putc(data[i + 3], fptr);
        }    
        break;
    case TGAPIXELFMT_RGB:
        for (int i = 0, len = width * height * 3; i < len; i += 3) {
            putc(data[i + 2], fptr);
            putc(data[i + 1], fptr);
            putc(data[i + 0], fptr);
        }    
        break;
    case TGAPIXELFMT_ARGB:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 3], fptr);
            putc(data[i + 2], fptr);
            putc(data[i + 1], fptr);
            putc(data[i + 0], fptr);
        }    
        break;
    case TGAPIXELFMT_XRGB:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 3], fptr);
            putc(data[i + 2], fptr);
            putc(data[i + 1], fptr);
        }    
        break;
    case TGAPIXELFMT_RGBA:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 2], fptr);
            putc(data[i + 1], fptr);
            putc(data[i + 0], fptr);
            putc(data[i + 3], fptr);
        }    
        break;
    case TGAPIXELFMT_RGBX:
        for (int i = 0, len = width * height * 4; i < len; i += 4) {
            putc(data[i + 2], fptr);
            putc(data[i + 1], fptr);
            putc(data[i + 0], fptr);
        }    
        break;
    }
}


static int write_tga(const void *framebuffer, int width, int height, TgaPixelFormat format, const char* filename)
{
    FILE *fptr = fopen(filename, "wb");

    if (!fptr) {
        return 0;
    }

    write_tga_ftpr((const char *)framebuffer, width, height, format, fptr);

    fclose(fptr);
    return 1;
}

#endif