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Dito Desktop Release picture
15B06 — Dito Desktop Release

Dito is an image dithering editor.

Dito is a tool to convert bmp images to the .chr format, designed to be used with Nasu for the creation of Famicom projects.

The application works by defining a range of 4 colors, each pixel of the original image will snap to the nearest color selected by one of the four color pickers.

dito.c

To learn more, see the complete manual in the repository.

cc dito.c -std=c89 -Os -DNDEBUG -g0 -s -Wall -L/usr/local/lib -lSDL2 -o dito

The following code is a single-file implementation written ANSI C with SDL2 as its only dependecy.

#include <SDL2/SDL.h>
#include <stdio.h>

/* 
Copyright (c) 2020 Devine Lu Linvega

Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE.
*/

#define HOR 32
#define VER 16
#define PAD 2
#define SZ (HOR * VER * 16)

typedef unsigned char Uint8;

typedef struct {
	int unsaved;
	char name[256];
	Uint8 data[SZ];
} Document;

typedef struct {
	int w, h;
} Size2d;

typedef struct {
	int x, y;
} Point2d;

int WIDTH = 8 * HOR + 8 * PAD * 2;
int HEIGHT = 8 * (VER + 2) + 8 * PAD * 2;
int FPS = 30, GUIDES = 1, DOWN = 0, ZOOM = 2, COLORS = 1;

Document doc;
Size2d size;

Point2d pickers[4];
Point2d *selected;

Uint32 theme[] = {
	0x000000,
	0xFFFFFF,
	0x72DEC2,
	0x666666,
	0x222222};

Uint8 icons[][8] = {
	{0x38, 0x7c, 0xfe, 0xfe, 0xfe, 0x7c, 0x38, 0x00}, /* color:full */
	{0x00, 0x38, 0x7c, 0x7c, 0x7c, 0x38, 0x00, 0x00}, /* color:blank */
	{0xfe, 0x82, 0x82, 0xfe, 0x82, 0x82, 0xfe, 0x00}, /* brush:colors2 */
	{0xfe, 0x92, 0x92, 0xfe, 0x92, 0x92, 0xfe, 0x00}, /* brush:colors4 */
	{0x18, 0x38, 0x18, 0x18, 0x18, 0x18, 0x7e, 0x00}, /* picker:1 */
	{0x7c, 0xc6, 0x0e, 0x3c, 0x78, 0xe0, 0xfe, 0x00}, /* picker:2 */
	{0x7e, 0x0c, 0x18, 0x3c, 0x06, 0xc6, 0x7c, 0x00}, /* picker:3 */
	{0x1c, 0x3c, 0x6c, 0xcc, 0xfe, 0x0c, 0x0c, 0x00}, /* picker:4 */
	{0xee, 0x92, 0x82, 0x54, 0x82, 0x92, 0xee, 0x00}, /* view:bigpixels */
	{0x00, 0x00, 0x00, 0x82, 0x44, 0x38, 0x00, 0x00}, /* eye open */
	{0x00, 0x38, 0x44, 0x92, 0x28, 0x10, 0x00, 0x00}, /* eye closed */
	{0x10, 0x54, 0x28, 0xc6, 0x28, 0x54, 0x10, 0x00}  /* unsaved */
};

SDL_Window *gWindow;
SDL_Renderer *gRenderer;
SDL_Texture *gTexture;
Uint32 *pixels;
SDL_Surface *image;

#pragma mark - HELPERS

int
clamp(int val, int min, int max)
{
	return (val >= min) ? (val <= max) ? val : max : min;
}

int
distance(int ax, int ay, int bx, int by)
{
	return (bx - ax) * (bx - ax) + (by - ay) * (by - ay);
}

int
coloroffset(Uint32 a, Uint32 b)
{
	Uint8 r0 = (a >> 16) & 0xFF, g0 = (a >> 8) & 0xFF, b0 = a & 0xFF;
	Uint8 r1 = (b >> 16) & 0xFF, g1 = (b >> 8) & 0xFF, b1 = b & 0xFF;
	return abs(r0 - r1) + abs(g0 - g1) + abs(b0 - b1);
}

char *
scpy(char *src, char *dst, int len)
{
	int i = 0;
	while((dst[i] = src[i]) && i < len - 2)
		i++;
	dst[i + 1] = '\0';
	return dst;
}

#pragma mark - CHR HANDLERS

int
rowchr(int x, int y)
{
	return (y % 8) + ((x / 8 + y / 8 * HOR) * 16);
}

int
getchr(int x, int y)
{
	int ch1, ch2, r = rowchr(x, y);
	if(r < 0 || r > SZ - 8)
		return 0;
	ch1 = (doc.data[r] >> (7 - x % 8)) & 1;
	ch2 = (doc.data[r + 8] >> (7 - x % 8)) & 1;
	if(ch1 && !ch2)
		return 1;
	if(!ch1 && ch2)
		return 2;
	if(ch1 && ch2)
		return 3;
	return 0;
}

void
putchr(int x, int y, int color)
{
	int row = rowchr(x, y), col = x % 8;
	if(x < 0 || x >= HOR * 8 || y < 0 || y >= VER * 8)
		return;
	if(color == 0 || color == 2)
		doc.data[row] &= ~(1UL << (7 - col));
	else
		doc.data[row] |= 1UL << (7 - col);
	if(color == 0 || color == 1)
		doc.data[row + 8] &= ~(1UL << (7 - col));
	else
		doc.data[row + 8] |= 1UL << (7 - col);
	doc.unsaved = 1;
}

#pragma mark - DRAW

void
clear(Uint32 *dst)
{
	int v, h;
	for(v = 0; v < HEIGHT; v++)
		for(h = 0; h < WIDTH; h++)
			dst[v * WIDTH + h] = theme[0];
}

void
putpixel(Uint32 *dst, int x, int y, int color)
{
	if(x >= 0 && x < WIDTH - 8 && y >= 0 && y < HEIGHT - 8)
		dst[(y + PAD * 8) * WIDTH + (x + PAD * 8)] = theme[color];
}

void
drawchr(Uint32 *dst, int x, int y, Uint8 *sprite)
{
	int v, h;
	for(v = 0; v < 8; v++)
		for(h = 0; h < 8; h++) {
			int ch1 = ((sprite[v] >> h) & 0x1);
			int ch2 = (((sprite[v + 8] >> h) & 0x1) << 1);
			putpixel(dst, x + 7 - h, y + v, ch1 + ch2);
		}
}

void
drawicn(Uint32 *dst, int x, int y, Uint8 *sprite, int fg, int bg)
{
	int v, h;
	for(v = 0; v < 8; v++)
		for(h = 0; h < 8; h++) {
			int ch1 = (sprite[v] >> (7 - h)) & 0x1;
			putpixel(dst, x + h, y + v, ch1 ? fg : bg);
		}
}

void
drawicna(Uint32 *dst, int x, int y, Uint8 *icon, int fg)
{
	int v, h;
	for(v = 0; v < 8; v++)
		for(h = 0; h < 8; h++)
			if((icon[v] >> (7 - h)) & 0x1)
				putpixel(dst, x + h, y + v, fg);
}

void
drawui(Uint32 *dst)
{
	int bottom = VER * 8 + 8;
	drawicn(dst, 0, bottom, icons[COLORS ? 3 : 2], 1, 0);
	drawicn(dst, 2 * 8, bottom, icons[GUIDES ? 10 : 9], GUIDES ? 1 : 2, 0);
	drawicn(dst, (HOR - 1) * 8, bottom, icons[11], doc.unsaved ? 2 : 3, 0); /* save state */
}

Uint32
getpixel(SDL_Surface *surface, int x, int y)
{
	int bpp = surface->format->BytesPerPixel;
	Uint8 *p = (Uint8 *)surface->pixels + y * surface->pitch + x * bpp;
	switch(bpp) {
	case 1: return *p;
	case 2: return *(Uint16 *)p;
	case 3:
		if(SDL_BYTEORDER == SDL_BIG_ENDIAN)
			return p[0] << 16 | p[1] << 8 | p[2];
		else
			return p[0] | p[1] << 8 | p[2] << 16;
	case 4: return *(Uint32 *)p;
	}
	return 0;
}

Uint32
getcolor(int x, int y)
{
	SDL_Color rgb;
	SDL_GetRGB(getpixel(image, x, y), image->format, &rgb.r, &rgb.g, &rgb.b);
	return ((rgb.r & 0xFF) << 16) + ((rgb.g & 0xFF) << 8) + (rgb.b & 0xFF);
}

int
getpattern(int palette, int x, int y)
{
	if(palette == 3)
		return 3;
	if(palette == 2)
		return ((x + y) % 2) == 0 && ((y - x) % 2) == 0 ? 3 : 0;
	if(palette == 1)
		return ((x + y) % 4) == 0 && ((y - x) % 4) == 0 ? 3 : 0;
	return 0;
}

int
getpalette(Uint32 clr, int x, int y)
{
	Uint32 res = 0, dis = 999999;
	int i;
	for(i = 0; i < 4; ++i) {
		Uint32 d = coloroffset(clr, theme[i]);
		if(d < dis) {
			dis = d;
			res = i;
		}
	}
	return res;
}

void
drawpicker(Uint32 *dst, int id)
{
	drawicna(dst, pickers[id].x - 3, pickers[id].y - 3, icons[0], 4);
	drawicna(dst, pickers[id].x + 6, pickers[id].y - 3, icons[4 + id], 4);
	drawicna(dst, pickers[id].x - 3, pickers[id].y - 3, icons[1], id);
}

void
redraw(Uint32 *dst)
{
	int x, y;
	/* Update palette */
	theme[0] = getcolor(pickers[0].x, pickers[0].y);
	theme[1] = getcolor(pickers[1].x, pickers[1].y);
	theme[2] = getcolor(pickers[2].x, pickers[2].y);
	theme[3] = getcolor(pickers[3].x, pickers[3].y);
	/* Draw */
	clear(dst);
	drawui(dst);
	/* Draw images */
	SDL_LockSurface(image);
	for(y = 0; y < image->h; ++y) {
		for(x = 0; x < image->w; ++x) {
			int palette = getpalette(getcolor(x, y), x, y);
			putchr(x, y, COLORS ? palette : getpattern(palette, x, y));
		}
	}
	SDL_UnlockSurface(image);
	for(y = 0; y < VER; ++y)
		for(x = 0; x < HOR; ++x)
			drawchr(dst, x * 8, y * 8, &doc.data[(x + y * HOR) * 16]);
	if(GUIDES) { /* draw pickers */
		drawpicker(dst, 0);
		drawpicker(dst, 1);
		drawpicker(dst, 2);
		drawpicker(dst, 3);
	}
	SDL_UpdateTexture(gTexture, NULL, dst, WIDTH * sizeof(Uint32));
	SDL_RenderClear(gRenderer);
	SDL_RenderCopy(gRenderer, gTexture, NULL, NULL);
	SDL_RenderPresent(gRenderer);
}

#pragma mark - OPTIONS

int
error(char *msg, const char *err)
{
	printf("Error %s: %s\n", msg, err);
	return 0;
}

void
savemode(int *i, int v)
{
	*i = v;
	redraw(pixels);
}

void
makedoc(Document *d, char *name)
{
	int i;
	for(i = 0; i < SZ; ++i)
		d->data[i] = 0x00;
	d->unsaved = 0;
	scpy(name, d->name, 256);
	printf("Made: %s\n", d->name);
	redraw(pixels);
}

int
savedoc(Document *d, char *name)
{
	FILE *f = fopen(name, "w");
	if(!fwrite(d->data, sizeof(d->data), 1, f))
		return error("Save", "Failure");
	d->unsaved = 0;
	scpy(name, d->name, 256);
	fclose(f);
	printf("0x%x 0x%x 0x%x 0x%x\n", theme[0], theme[1], theme[2], theme[3]);
	printf("Saved: %s\n", d->name);
	redraw(pixels);
	return 1;
}

int
saveicn(Document *d, char *name)
{
	int i;
	FILE *f = fopen(name, "w");
	Uint8 data[SZ / 2];
	for(i = 0; i < SZ / 2; ++i)
		data[i] = d->data[(i / 4) * 8 + (i % 8)];
	if(!fwrite(data, sizeof(data), 1, f))
		return error("Save", "Failure");
	d->unsaved = 0;
	scpy(name, d->name, 256);
	fclose(f);
	printf("Saved(icn): %s\n", d->name);
	redraw(pixels);
	return 1;
}

void
setpicker(Point2d *picker, int x, int y)
{
	picker->x = clamp(x, 0, HOR * 8);
	picker->y = clamp(y, 0, VER * 8);
	redraw(pixels);
}

Point2d *
selectpicker(int x, int y)
{
	int i;
	for(i = 0; i < 4; ++i)
		if(distance(x, y, pickers[i].x, pickers[i].y) < 20)
			return &pickers[i];
	return NULL;
}

int
savebmp(void)
{
	SDL_Surface *surface = SDL_GetWindowSurface(gWindow);
	SDL_RenderReadPixels(gRenderer,
		NULL,
		SDL_PIXELFORMAT_ARGB8888,
		surface->pixels,
		surface->pitch);
	if(SDL_SaveBMP(surface, "dito-render.bmp"))
		return error("Render", "Failed");
	puts("Render: dito-render.bmp");
	SDL_FreeSurface(surface);
	return 1;
}

void
selectoption(int option)
{
	switch(option) {
	case 0: savemode(&COLORS, !COLORS); break;
	case 2: savemode(&GUIDES, !GUIDES); break;
	case HOR - 1: savedoc(&doc, doc.name); break;
	}
}

void
quit(void)
{
	free(pixels);
	SDL_DestroyTexture(gTexture);
	gTexture = NULL;
	SDL_DestroyRenderer(gRenderer);
	gRenderer = NULL;
	SDL_DestroyWindow(gWindow);
	gWindow = NULL;
	SDL_Quit();
	exit(0);
}

#pragma mark - TRIGGERS

void
domouse(SDL_Event *event)
{
	switch(event->type) {
	case SDL_MOUSEBUTTONUP:
		DOWN = 0;
		selected = NULL;
		break;
	case SDL_MOUSEBUTTONDOWN:
		if(event->motion.y / ZOOM / 8 - PAD == VER + 1) {
			selectoption(event->motion.x / ZOOM / 8 - PAD);
			return;
		}
		selected = selectpicker(event->motion.x / ZOOM - PAD * 8, event->motion.y / ZOOM - PAD * 8);
		DOWN = 1;
		break;
	case SDL_MOUSEMOTION:
		if(DOWN && selected)
			setpicker(selected, event->motion.x / ZOOM - PAD * 8, event->motion.y / ZOOM - PAD * 8);
		break;
	}
}

void
dokey(SDL_Event *event)
{
	int shift = SDL_GetModState() & KMOD_LSHIFT || SDL_GetModState() & KMOD_RSHIFT;
	int ctrl = SDL_GetModState() & KMOD_LCTRL || SDL_GetModState() & KMOD_RCTRL;
	if(ctrl) {
		switch(event->key.keysym.sym) {
		/* Generic */
		case SDLK_s: shift ? saveicn(&doc, doc.name) : savedoc(&doc, doc.name); break;
		case SDLK_h: savemode(&GUIDES, !GUIDES); break;
		}
	} else {
		switch(event->key.keysym.sym) {
		case SDLK_SPACE: savemode(&COLORS, !COLORS); break;
		}
	}
}

int
init(void)
{
	if(SDL_Init(SDL_INIT_VIDEO) < 0)
		return error("Init", SDL_GetError());
	gWindow = SDL_CreateWindow("Dito",
		SDL_WINDOWPOS_UNDEFINED,
		SDL_WINDOWPOS_UNDEFINED,
		WIDTH * ZOOM,
		HEIGHT * ZOOM,
		SDL_WINDOW_SHOWN);
	if(gWindow == NULL)
		return error("Window", SDL_GetError());
	gRenderer = SDL_CreateRenderer(gWindow, -1, 0);
	if(gRenderer == NULL)
		return error("Renderer", SDL_GetError());
	gTexture = SDL_CreateTexture(gRenderer,
		SDL_PIXELFORMAT_ARGB8888,
		SDL_TEXTUREACCESS_STATIC,
		WIDTH,
		HEIGHT);
	if(gTexture == NULL)
		return error("Texture", SDL_GetError());
	pixels = (Uint32 *)malloc(WIDTH * HEIGHT * sizeof(Uint32));
	if(pixels == NULL)
		return error("Pixels", "Failed to allocate memory");
	clear(pixels);
	return 1;
}

int
main(int argc, char **argv)
{
	int ticknext = 0;
	if(argc < 2)
		return error("Load", "Missing bmp image.");
	if(!init())
		return error("Init", "Failure");
	image = SDL_LoadBMP(argv[1]);
	if(!image)
		return error("Load", "Invalid bmp image.");
	setpicker(&pickers[0], 66, 16);
	setpicker(&pickers[1], 46, 49);
	setpicker(&pickers[2], 140, 10);
	setpicker(&pickers[3], 120, 40);
	makedoc(&doc, "untitled.chr");
	while(1) {
		int tick = SDL_GetTicks();
		SDL_Event event;
		if(tick < ticknext)
			SDL_Delay(ticknext - tick);
		ticknext = tick + (1000 / FPS);
		while(SDL_PollEvent(&event) != 0) {
			switch(event.type) {
			case SDL_QUIT: quit(); break;
			case SDL_MOUSEBUTTONUP:
			case SDL_MOUSEBUTTONDOWN:
			case SDL_MOUSEMOTION: domouse(&event); break;
			case SDL_KEYDOWN: dokey(&event); break;
			case SDL_WINDOWEVENT:
				if(event.window.event == SDL_WINDOWEVENT_EXPOSED)
					redraw(pixels);
				break;
			}
		}
	}
	quit();
	return 0;
}
— Submit an edit to dito.c.txt(535 lines)

incoming(2): nasu chr format

Last update on 15B07, edited 2 times. +9/14fh -----|