Compiler Explorer

Source code

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>

#define HEADER_BYTES 18 // Ammount of bytes header should take up

typedef struct TGAImg_t{
    uint8_t idLength;           // Length of image ID field (0-255)
    uint8_t colorMapType;       // If a color map is present (1) or not (0)
    uint8_t imageType;          // Compression and color types (0-3 and 9-11)
    uint16_t colorMapOrigin;    // Index of first color map entry
    uint16_t colorMapLength;    // Count of color map entries
    uint8_t colorMapEntrySize;  // Number of bits in each color map entry. 16 for Targa 16, 24 for Targa 24...
    uint16_t xOrigin;           // X coord of the lower left corner of the image
    uint16_t yOrigin;           // Y coord of the lower left corner of the image
    uint16_t width;             // Width of the image in pixels
    uint16_t height;            // Height of the image in pixels
    uint8_t imagePixelSize;     // Number of bits in a stored pixel index
    uint8_t imageDescriptorByte;// Document says to just keep this byte as 0
    uint8_t imageDataField[0];  // Array of image pixels.
} TGAImg;

typedef struct RGB_t{
    uint8_t red;
    uint8_t green;
    uint8_t blue;
} RGB;

TGAImg* makeImage(uint8_t idLength, uint8_t colorMapType,
                        uint8_t imageType, uint16_t colorMapOrigin,
                        uint16_t colorMapLength, uint8_t colorMapEntrySize,
                        uint16_t xOrigin, uint16_t yOrigin,
                        uint16_t width, uint16_t height,
                        uint8_t imagePixelSize, uint8_t imageDescriptorByte){
    // Allocate memory for header + image pixels (using info from header params)
    uint32_t dataFieldBytes = width * height * (imagePixelSize / 8);
    TGAImg* img = calloc(HEADER_BYTES + dataFieldBytes, 1 );
    if (!img){
        printf("ERROR: calloc fail for img @ makeImg");
        exit(EXIT_FAILURE);
    }
    // Set header values
    img->idLength = idLength;
    img->colorMapType = colorMapType;
    img->imageType = imageType;
    img->colorMapOrigin = colorMapOrigin;
    img->colorMapLength = colorMapLength;
    img->colorMapEntrySize = colorMapEntrySize;
    img->xOrigin = xOrigin;
    img->yOrigin = yOrigin;
    img->width = width;
    img->height = height;
    img->imagePixelSize = imagePixelSize;
    img->imageDescriptorByte = imageDescriptorByte;
    return img;
}

// Writes contents of a TGAImg struct to a image of name imageName
void saveImage(char imageName[], TGAImg* img){
    FILE* imageFile = fopen(imageName, "wb");

fwrite(&img->idLength, sizeof(img->idLength), 1, imageFile);
    fwrite(&img->colorMapType, sizeof(img->colorMapType), 1, imageFile);
    fwrite(&img->imageType, sizeof(img->imageType), 1, imageFile);
    fwrite(&img->colorMapOrigin, sizeof(img->colorMapOrigin), 1, imageFile);
    fwrite(&img->colorMapLength, sizeof(img->colorMapLength), 1, imageFile);
    fwrite(&img->colorMapEntrySize, sizeof(img->colorMapEntrySize), 1, imageFile);
    fwrite(&img->xOrigin, sizeof(img->xOrigin), 1, imageFile);
    fwrite(&img->yOrigin, sizeof(img->yOrigin), 1, imageFile);
    fwrite(&img->width, sizeof(img->width), 1, imageFile);
    fwrite(&img->height, sizeof(img->height), 1, imageFile);
    fwrite(&img->imagePixelSize, sizeof(img->imagePixelSize), 1, imageFile);
    fwrite(&img->imageDescriptorByte, sizeof(img->imageDescriptorByte), 1, imageFile);
    fwrite(&img->imageDataField, img->width * img->height * (img->imagePixelSize / 8), 1, imageFile);

fclose(imageFile);
}

void setPixel(TGAImg* img, RGB color, int x, int y){
    uint32_t index = ((y * img->width) + x) * 3; // Convert x and y to index for array
    // Apply pixel change to all colors
    // mildly cursed 4-byte read from 3-byte struct, there is no CDQE *here* but it appears in the inlined version
    memcpy(&img->imageDataField[index], &color, 4);
    //img->imageDataField[index] = color.blue;
    //img->imageDataField[index+1] = color.green;
    //img->imageDataField[index+2] = color.red;
}

void test(TGAImg* img)
{
    RGB black = { .red = 0, .green = 0, .blue = 0 };
    for (int y = 0; y < 10; y++) {
        for (int x = 0; x < 10; x++) {
            setPixel(img, black, x, y);
        }
    }
}