Fix missed grab state changes in SDL demos

Move grab handling out of `nk_sdl_handle_event` to `nk_sdl_handle_grab`,
which is now called outside of the event loop.
This change makes the logic similar to the GLFW demos and fixes issues
with missed grab state changes and mouse cursor disappearing.

demo/sdl_opengl2/main.c

@@ -139,6 +139,7 @@ main(int argc, char *argv[])
             if (evt.type == SDL_QUIT) goto cleanup;
             nk_sdl_handle_event(&evt);
         }
+        nk_sdl_handle_grab(); /* optional grabbing behavior */
         nk_input_end(ctx);
 
         /* GUI */

demo/sdl_opengl2/nuklear_sdl_gl2.h

@@ -233,22 +233,26 @@ nk_sdl_font_stash_end(void)
         nk_style_set_font(&sdl.ctx, &sdl.atlas.default_font->handle);
 }
 
+NK_API void
+nk_sdl_handle_grab(void)
+{
+    struct nk_context *ctx = &sdl.ctx;
+    if (ctx->input.mouse.grab) {
+        SDL_SetRelativeMouseMode(SDL_TRUE);
+    } else if (ctx->input.mouse.ungrab) {
+        SDL_WarpMouseInWindow(sdl.win, (int)ctx->input.mouse.prev.x, (int)ctx->input.mouse.prev.y);
+        SDL_SetRelativeMouseMode(SDL_FALSE);
+    } else if (ctx->input.mouse.grabbed) {
+        ctx->input.mouse.pos.x = ctx->input.mouse.prev.x;
+        ctx->input.mouse.pos.y = ctx->input.mouse.prev.y;
+    }
+}
+
 NK_API int
 nk_sdl_handle_event(SDL_Event *evt)
 {
     struct nk_context *ctx = &sdl.ctx;
 
-    /* optional grabbing behavior */
-    if (ctx->input.mouse.grab) {
-        SDL_SetRelativeMouseMode(SDL_TRUE);
-        ctx->input.mouse.grab = 0;
-    } else if (ctx->input.mouse.ungrab) {
-        int x = (int)ctx->input.mouse.prev.x, y = (int)ctx->input.mouse.prev.y;
-        SDL_SetRelativeMouseMode(SDL_FALSE);
-        SDL_WarpMouseInWindow(sdl.win, x, y);
-        ctx->input.mouse.ungrab = 0;
-    }
-
     switch(evt->type)
     {
         case SDL_KEYUP: /* KEYUP & KEYDOWN share same routine */

demo/sdl_opengl3/main.c

@@ -149,7 +149,9 @@ int main(int argc, char *argv[])
         while (SDL_PollEvent(&evt)) {
             if (evt.type == SDL_QUIT) goto cleanup;
             nk_sdl_handle_event(&evt);
-        } nk_input_end(ctx);
+        }
+        nk_sdl_handle_grab(); /* optional grabbing behavior */
+        nk_input_end(ctx);
 
         /* GUI */
         if (nk_begin(ctx, "Demo", nk_rect(50, 50, 230, 250),

demo/sdl_opengl3/nuklear_sdl_gl3.h

@@ -342,22 +342,26 @@ nk_sdl_font_stash_end(void)
 
 }
 
+NK_API void
+nk_sdl_handle_grab(void)
+{
+    struct nk_context *ctx = &sdl.ctx;
+    if (ctx->input.mouse.grab) {
+        SDL_SetRelativeMouseMode(SDL_TRUE);
+    } else if (ctx->input.mouse.ungrab) {
+        SDL_WarpMouseInWindow(sdl.win, (int)ctx->input.mouse.prev.x, (int)ctx->input.mouse.prev.y);
+        SDL_SetRelativeMouseMode(SDL_FALSE);
+    } else if (ctx->input.mouse.grabbed) {
+        ctx->input.mouse.pos.x = ctx->input.mouse.prev.x;
+        ctx->input.mouse.pos.y = ctx->input.mouse.prev.y;
+    }
+}
+
 NK_API int
 nk_sdl_handle_event(SDL_Event *evt)
 {
     struct nk_context *ctx = &sdl.ctx;
 
-    /* optional grabbing behavior */
-    if (ctx->input.mouse.grab) {
-        SDL_SetRelativeMouseMode(SDL_TRUE);
-        ctx->input.mouse.grab = 0;
-    } else if (ctx->input.mouse.ungrab) {
-        int x = (int)ctx->input.mouse.prev.x, y = (int)ctx->input.mouse.prev.y;
-        SDL_SetRelativeMouseMode(SDL_FALSE);
-        SDL_WarpMouseInWindow(sdl.win, x, y);
-        ctx->input.mouse.ungrab = 0;
-    }
-
     switch(evt->type)
     {
         case SDL_KEYUP: /* KEYUP & KEYDOWN share same routine */

demo/sdl_opengles2/main.c

@@ -92,6 +92,7 @@ MainLoop(void* loopArg){
         if (evt.type == SDL_QUIT) running = nk_false;
         nk_sdl_handle_event(&evt);
     }
+    nk_sdl_handle_grab(); /* optional grabbing behavior */
     nk_input_end(ctx);
 
 

demo/sdl_opengles2/nuklear_sdl_gles2.h

@@ -342,22 +342,26 @@ nk_sdl_font_stash_end(void)
 
 }
 
+NK_API void
+nk_sdl_handle_grab(void)
+{
+    struct nk_context *ctx = &sdl.ctx;
+    if (ctx->input.mouse.grab) {
+        SDL_SetRelativeMouseMode(SDL_TRUE);
+    } else if (ctx->input.mouse.ungrab) {
+        SDL_WarpMouseInWindow(sdl.win, (int)ctx->input.mouse.prev.x, (int)ctx->input.mouse.prev.y);
+        SDL_SetRelativeMouseMode(SDL_FALSE);
+    } else if (ctx->input.mouse.grabbed) {
+        ctx->input.mouse.pos.x = ctx->input.mouse.prev.x;
+        ctx->input.mouse.pos.y = ctx->input.mouse.prev.y;
+    }
+}
+
 NK_API int
 nk_sdl_handle_event(SDL_Event *evt)
 {
     struct nk_context *ctx = &sdl.ctx;
 
-    /* optional grabbing behavior */
-    if (ctx->input.mouse.grab) {
-        SDL_SetRelativeMouseMode(SDL_TRUE);
-        ctx->input.mouse.grab = 0;
-    } else if (ctx->input.mouse.ungrab) {
-        int x = (int)ctx->input.mouse.prev.x, y = (int)ctx->input.mouse.prev.y;
-        SDL_SetRelativeMouseMode(SDL_FALSE);
-        SDL_WarpMouseInWindow(sdl.win, x, y);
-        ctx->input.mouse.ungrab = 0;
-    }
-
     switch(evt->type)
     {
         case SDL_KEYUP: /* KEYUP & KEYDOWN share same routine */

demo/sdl_renderer/main.c

@@ -177,6 +177,7 @@ main(int argc, char *argv[])
             if (evt.type == SDL_QUIT) goto cleanup;
             nk_sdl_handle_event(&evt);
         }
+        nk_sdl_handle_grab(); /* optional grabbing behavior */
         nk_input_end(ctx);
 
         /* GUI */

demo/sdl_renderer/nuklear_sdl_renderer.h

@@ -264,22 +264,26 @@ nk_sdl_font_stash_end(void)
         nk_style_set_font(&sdl.ctx, &sdl.atlas.default_font->handle);
 }
 
+NK_API void
+nk_sdl_handle_grab(void)
+{
+    struct nk_context *ctx = &sdl.ctx;
+    if (ctx->input.mouse.grab) {
+        SDL_SetRelativeMouseMode(SDL_TRUE);
+    } else if (ctx->input.mouse.ungrab) {
+        SDL_WarpMouseInWindow(sdl.win, (int)ctx->input.mouse.prev.x, (int)ctx->input.mouse.prev.y);
+        SDL_SetRelativeMouseMode(SDL_FALSE);
+    } else if (ctx->input.mouse.grabbed) {
+        ctx->input.mouse.pos.x = ctx->input.mouse.prev.x;
+        ctx->input.mouse.pos.y = ctx->input.mouse.prev.y;
+    }
+}
+
 NK_API int
 nk_sdl_handle_event(SDL_Event *evt)
 {
     struct nk_context *ctx = &sdl.ctx;
 
-    /* optional grabbing behavior */
-    if (ctx->input.mouse.grab) {
-        SDL_SetRelativeMouseMode(SDL_TRUE);
-        ctx->input.mouse.grab = 0;
-    } else if (ctx->input.mouse.ungrab) {
-        int x = (int)ctx->input.mouse.prev.x, y = (int)ctx->input.mouse.prev.y;
-        SDL_SetRelativeMouseMode(SDL_FALSE);
-        SDL_WarpMouseInWindow(sdl.win, x, y);
-        ctx->input.mouse.ungrab = 0;
-    }
-
     switch(evt->type)
     {
         case SDL_KEYUP: /* KEYUP & KEYDOWN share same routine */