With the release of SDL3, I was wondering if it could help me out in building cross platform GUI applications in C. My goal is to simplify my programming environment as much as I can, especially for my own projects, to enjoy programming more. I ended up writing this super simple microui renderer using the SDL3 rendering functions, that should work on all platforms and is super simple to build just by running the following command once you have SDL3 installed.
gcc *.c -lSDL3
I think the best part is that this compiles on mac and linux with this simple command and works well. I plan to test this by building a simple cross platform application.
I'll write more about that process once I have it further along.
#include "microui.h"
#include <SDL3/SDL_events.h>
#include <SDL3/SDL_init.h>
#include <SDL3/SDL_oldnames.h>
#include <SDL3/SDL_render.h>
#include <SDL3/SDL_surface.h>
#include <stdlib.h>
#include <SDL3/SDL.h>
#include <SDL3/SDL_main.h>
#include "atlas.inl"
static SDL_Window *window = NULL;
static SDL_Renderer *renderer = NULL;
static SDL_FPoint points[500];
int text_width(mu_Font font, const char *text, int len) {
int res = 0;
for (const char *p = text; *p && len--; p++) {
if ((*p & 0xc0) == 0x80) { continue; }
int chr = mu_min((unsigned char) *p, 127);
res += atlas[ATLAS_FONT + chr].w;
}
return res;
}
int text_height(mu_Font font) {
return 18;
}
int min(int a, int b) {
return a < b ? a : b;
}
static const char button_map[256] = {
[ SDL_BUTTON_LEFT & 0xff ] = MU_MOUSE_LEFT,
[ SDL_BUTTON_RIGHT & 0xff ] = MU_MOUSE_RIGHT,
[ SDL_BUTTON_MIDDLE & 0xff ] = MU_MOUSE_MIDDLE,
};
static const char key_map[256] = {
[ SDLK_LSHIFT & 0xff ] = MU_KEY_SHIFT,
[ SDLK_RSHIFT & 0xff ] = MU_KEY_SHIFT,
[ SDLK_LCTRL & 0xff ] = MU_KEY_CTRL,
[ SDLK_RCTRL & 0xff ] = MU_KEY_CTRL,
[ SDLK_LALT & 0xff ] = MU_KEY_ALT,
[ SDLK_RALT & 0xff ] = MU_KEY_ALT,
[ SDLK_RETURN & 0xff ] = MU_KEY_RETURN,
[ SDLK_BACKSPACE & 0xff ] = MU_KEY_BACKSPACE,
};
int main(void) {
mu_Context *ctx = malloc(sizeof(mu_Context));
mu_init(ctx);
SDL_SetAppMetadata("Corolla", "0.0.0", "com.ktjst.corolla");
if(!SDL_Init(SDL_INIT_VIDEO)) {
SDL_Log("Init failed");
return 1;
}
if(!SDL_CreateWindowAndRenderer("Corolla", 1500, 1000, 0, &window, &renderer)) {
SDL_Log("Window init failed");
return 1;
}
ctx->text_height = text_height;
ctx->text_width = text_width;
unsigned char pixels[128*128*4];
int c = 0;
for(int i = 0; i < 128 * 128; i++) {
pixels[c] = atlas_texture[i];
pixels[c+1] = atlas_texture[i];
pixels[c+2] = atlas_texture[i];
pixels[c+3] = 255;
c+=4;
}
SDL_Surface *sur = SDL_CreateSurfaceFrom(128, 128, SDL_PIXELFORMAT_XRGB8888, pixels, 4 * 128);
SDL_Texture *tex = SDL_CreateTextureFromSurface(renderer, sur);
bool running = true;
while(running) {
SDL_Event e;
while (SDL_PollEvent(&e)) {
switch (e.type) {
case SDL_EVENT_QUIT: exit(EXIT_SUCCESS); break;
case SDL_EVENT_MOUSE_MOTION: mu_input_mousemove(ctx, e.motion.x, e.motion.y); break;
case SDL_EVENT_MOUSE_WHEEL: mu_input_scroll(ctx, 0, e.wheel.y * -30); break;
case SDL_EVENT_TEXT_INPUT: mu_input_text(ctx, e.text.text); break;
case SDL_EVENT_MOUSE_BUTTON_DOWN:
case SDL_EVENT_MOUSE_BUTTON_UP: {
int b = button_map[e.button.button & 0xff];
if (b && e.type == SDL_EVENT_MOUSE_BUTTON_DOWN) { mu_input_mousedown(ctx, e.button.x, e.button.y, b); }
if (b && e.type == SDL_EVENT_MOUSE_BUTTON_UP) { mu_input_mouseup(ctx, e.button.x, e.button.y, b); }
break;
}
case SDL_EVENT_KEY_DOWN:
case SDL_EVENT_KEY_UP: {
int c = key_map[e.key.key & 0xff];
if (c && e.type == SDL_EVENT_KEY_DOWN) { mu_input_keydown(ctx, c); }
if (c && e.type == SDL_EVENT_KEY_UP) { mu_input_keyup(ctx, c); }
break;
}
}
}
SDL_FRect rect;
mu_begin(ctx);
if(mu_begin_window(ctx, "Test", mu_rect(10, 10, 100, 100))) {
mu_end_window(ctx);
}
mu_end(ctx);
// UI drawing
mu_Command *cmd = NULL;
SDL_FRect full;
full.x = 0;
full.y = 0;
full.w = 128;
full.h = 128;
SDL_FRect full2;
full2.x = 0;
full2.y = 0;
full2.w = 256;
full2.h = 256;
SDL_SetRenderDrawColor(renderer, 0, 255, 255, 255);
SDL_RenderClear(renderer);
// SDL_RenderTexture(renderer, tex, &full, &full2);
while(mu_next_command(ctx, &cmd)) {
if(cmd->type == MU_COMMAND_TEXT) {
SDL_FRect dest;
dest.x = cmd->text.pos.x;
dest.y = cmd->text.pos.y;
for(const char *p = cmd->text.str; *p; p++) {
if((*p & 0xc0) == 0x80) { continue; }
int chr = min((unsigned char) *p, 127);
mu_Rect src = atlas[ATLAS_FONT + chr];
dest.w = src.w;
dest.h = src.h;
SDL_FRect srcSDL;
srcSDL.h = src.h;
srcSDL.w = src.w;
srcSDL.x = src.x;
srcSDL.y = src.y;
SDL_RenderTexture(renderer, tex, &srcSDL, &dest);
dest.x += dest.w;
}
}
if(cmd->type == MU_COMMAND_RECT) {
SDL_FRect rect;
rect.h = cmd->rect.rect.h;
rect.w = cmd->rect.rect.w;
rect.x = cmd->rect.rect.x;
rect.y = cmd->rect.rect.y;
SDL_SetRenderDrawColor(renderer, cmd->rect.color.r, cmd->rect.color.g, cmd->rect.color.b, cmd->rect.color.a);
SDL_RenderFillRect(renderer, &rect);
}
if(cmd->type == MU_COMMAND_ICON) {
SDL_FRect rect;
rect.h = cmd->icon.rect.h;
rect.w = cmd->icon.rect.w;
rect.x = cmd->icon.rect.x;
rect.y = cmd->icon.rect.y;
mu_Rect r = atlas[cmd->icon.id];
SDL_FRect srect;
srect.h = r.h;
srect.w = r.w;
srect.x = r.x;
srect.y = r.y;
SDL_RenderTexture(renderer, tex, &srect, &rect);
}
if(cmd->type == MU_COMMAND_CLIP) {
SDL_Rect clip = {
cmd->clip.rect.x,
cmd->clip.rect.y,
cmd->clip.rect.w,
cmd->clip.rect.h
};
if (cmd->clip.rect.w > 0) {
SDL_SetRenderClipRect(renderer, &clip);
} else {
SDL_SetRenderClipRect(renderer, NULL);
}
}
}
SDL_RenderPresent(renderer);
}
}