PPM format isn't consitent with tile's memory layout as a result ppm display isn't right.

[wellcomez]

I used example "minimal" but output is wrong.

[wellcomez]

export2file()
{
    jniTiledSurface* surface = this;
    uint16_t * data = surface->tile_buffer;
    
    
    struct rgba {
        uint16_t arr[4];
    };
    struct tiledata {
        struct rgba aaa[MYPAINT_TILE_SIZE][MYPAINT_TILE_SIZE];
    };
    struct rgba* begin = (struct rgba*)data;
    struct rgba* dest=  (struct rgba*)malloc(sizeof(struct tiledata)*surface->tiles_width*surface->height);

    struct tiledata* beginTile = (struct tiledata*)data;
    for (int i=0; i<surface->tiles_width*surface->tiles_height; i++) {
        struct rgba* r =(struct rgba*)(beginTile+i);
        int txOffset = i%surface->tiles_width*MYPAINT_TILE_SIZE;
        int tyOffset = i/surface->tiles_width*MYPAINT_TILE_SIZE;
        for (int y=0; y<MYPAINT_TILE_SIZE; y++) {
            for (int x=0; x<MYPAINT_TILE_SIZE; x++) {
                int xx = txOffset+x;
                int yy = tyOffset+y;
                struct rgba* e = r+y*MYPAINT_TILE_SIZE+x;
                dest[MYPAINT_TILE_SIZE*surface->tiles_width*yy+xx] = *e;
            }
        }
    }
    int h = surface->height;
    int w = surface->width;
    FILE * fp = fopen("output_raw.ppm", "w");
    if (!fp) {
        perror("fopen 'output_raw.ppm'");
        return;
    }
    fprintf(fp, "P3\n#Handwritten\n%d %d\n255\n", w, h);
    data = (uint16_t*)dest;
    for (int y=0; y<h; y++) {
        struct rgba* r = (struct rgba*)data+y*surface->tiles_width*MYPAINT_TILE_SIZE;
        for (int x=0; x<w; x++) {
            fprintf(fp, "%d ", r->arr[0]/256);
            fprintf(fp, "%d ", r->arr[1]/256);
            fprintf(fp, "%d ", r->arr[2]/256);
            r++;
        }
        fprintf(fp, "\n");
    }
    fclose(fp);
}

Above is my implementation.

[jplloyd]

The write_ppm function is now fixed. I only fixed the issues in the existing implementation, but thank you nonetheless for providing a reference implementation.