On this example, we show you how to deal with Ecore_Evas window size hints, which are implemented per Evas engine.

We start by defining an initial size for our window and, after creating it, adding a background white rectangle and a text object to it, to be used to display the current window's sizes, at any given time:

#define WIDTH  (300)
#define HEIGHT (300)

   if (!ecore_evas_init())
     return EXIT_FAILURE;

   /* this will give you a window with an Evas canvas under the first
    * engine available */
   ee = ecore_evas_new(NULL, 0, 0, WIDTH, HEIGHT, NULL);
   if (!ee) goto error;

   ecore_evas_callback_delete_request_set(ee, _on_destroy);
   ecore_evas_title_set(ee, "Ecore_Evas window sizes example");
   ecore_evas_callback_resize_set(ee, _canvas_resize_cb);
   ecore_evas_show(ee);

   evas = ecore_evas_get(ee);

   bg = evas_object_rectangle_add(evas);
   evas_object_color_set(bg, 255, 255, 255, 255);  /* white bg */
   evas_object_move(bg, 0, 0);  /* at canvas' origin */
   evas_object_resize(bg, WIDTH, HEIGHT);  /* covers full canvas */
   evas_object_show(bg);

   text = evas_object_text_add(evas);
   evas_object_color_set(text, 0, 0, 0, 255);
   evas_object_resize(text, 150, 50);
   evas_object_text_font_set(text, "Sans", 20);
   evas_object_show(text);

   _canvas_resize_cb(ee);
   fprintf(stdout, commands);
   ecore_main_loop_begin();

/* to inform current window's size */
static void
_canvas_resize_cb(Ecore_Evas *ee_)
{
   int w, h;
   char buf[1024];

   ecore_evas_geometry_get(ee_, NULL, NULL, &w, &h);
   snprintf(buf, sizeof(buf), "%d x %d", w, h);
   evas_object_text_text_set(text, buf);
   evas_object_move(text, (w - 150) / 2, (h - 50) / 2);

   evas_object_resize(bg, w, h);
}

The program has a command line interface, responding to the following keys:

static const char commands[] = \
  "commands are:\n"
  "\tm - impose a minumum size to the window\n"
  "\tx - impose a maximum size to the window\n"
  "\tb - impose a base size to the window\n"
  "\ts - impose a step size (different than 1 px) to the window\n"
  "\tg - get the screen geometry\n"
  "\th - print help\n";

Use the 'm' key to impose a minimum size of half the initial ones on our window. Test it by trying to resize it to smaller sizes than that:

   if (strcmp(ev->key, "m") == 0) /* impose a minimum size on the window */
     {
        min_set = !min_set;

        if (min_set)
          {
             ecore_evas_size_min_set(ee, WIDTH / 2, HEIGHT / 2);
             fprintf(stdout, "Imposing a minimum size of %d x %d\n",
                     WIDTH / 2, HEIGHT / 2);
          }
        else
          {
             ecore_evas_size_min_set(ee, 0, 0);
             fprintf(stdout, "Taking off minimum size restriction from the"
                             " window\n");
          }
        return;
     }

The 'x' key will, in turn, set a maximum size on our window -- to two times our initial size. Test it by trying to resize the window to bigger sizes than that:

   if (strcmp(ev->key, "x") == 0) /* impose a maximum size on the window */
     {
        max_set = !max_set;

        if (max_set)
          {
             ecore_evas_size_max_set(ee, WIDTH * 2, HEIGHT * 2);
             fprintf(stdout, "Imposing a maximum size of %d x %d\n",
                     WIDTH * 2, HEIGHT * 2);
          }
        else
          {
             ecore_evas_size_max_set(ee, 0, 0);
             fprintf(stdout, "Taking off maximum size restriction from the"
                             " window\n");
          }
        return;
     }

Window base sizes will override any minimum sizes set, so try it with the 'b' key. It will set a base size of two times the initial one:

   if (strcmp(ev->key, "b") == 0) /* impose a base size on the window */
     {
        base_set = !base_set;

        if (base_set)
          {
             ecore_evas_size_base_set(ee, WIDTH * 2, HEIGHT * 2);
             fprintf(stdout, "Imposing a base size of %d x %d\n",
                     WIDTH * 2, HEIGHT * 2);
          }
        else
          {
             ecore_evas_size_base_set(ee, 0, 0);
             fprintf(stdout, "Taking off base size restriction from the"
                             " window\n");
          }
        return;
     }

Finally, there's a key to impose a "step size" on our window, of 40 pixels. With than on ('s' key), you'll see the window will always be bound to multiples of that size, for dimensions on both axis:

   if (strcmp(ev->key, "s") == 0) /* impose a step size on the window */
     {
        step_set = !step_set;

        if (step_set)
          {
             ecore_evas_size_step_set(ee, 40, 40);
             fprintf(stdout, "Imposing a step size of %d x %d\n", 40, 40);
          }
        else
          {
             ecore_evas_size_step_set(ee, 0, 0);
             fprintf(stdout, "Taking off step size restriction from the"
                             " window\n");
          }
        return;
     }

The full example follows.

#ifdef HAVE_CONFIG_H

#include "config.h"
#else
#define EINA_UNUSED
#endif

#include <Ecore.h>
#include <Ecore_Evas.h>

#define WIDTH  (300)
#define HEIGHT (300)

static Ecore_Evas *ee;
static Evas_Object *text, *bg;
static Eina_Bool min_set = EINA_FALSE;
static Eina_Bool max_set = EINA_FALSE;
static Eina_Bool base_set = EINA_FALSE;
static Eina_Bool step_set = EINA_FALSE;

static const char commands[] = \
  "commands are:\n"
  "\tm - impose a minumum size to the window\n"
  "\tx - impose a maximum size to the window\n"
  "\tb - impose a base size to the window\n"
  "\ts - impose a step size (different than 1 px) to the window\n"
  "\tg - get the screen geometry\n"
  "\th - print help\n";

/* to inform current window's size */
static void
_canvas_resize_cb(Ecore_Evas *ee_)
{
   int w, h;
   char buf[1024];

   ecore_evas_geometry_get(ee_, NULL, NULL, &w, &h);
   snprintf(buf, sizeof(buf), "%d x %d", w, h);
   evas_object_text_text_set(text, buf);
   evas_object_move(text, (w - 150) / 2, (h - 50) / 2);

   evas_object_resize(bg, w, h);
}

static void
_on_destroy(Ecore_Evas *ee_ EINA_UNUSED)
{
   ecore_main_loop_quit();
}

static void
_on_keydown(void *data EINA_UNUSED,
            Evas *evas EINA_UNUSED,
            Evas_Object *o EINA_UNUSED,
            void *einfo)
{
   Evas_Event_Key_Down *ev = einfo;

   if (strcmp(ev->key, "h") == 0) /* print help */
     {
        fprintf(stdout, commands);
        return;
     }

   if (strcmp(ev->key, "m") == 0) /* impose a minimum size on the window */
     {
        min_set = !min_set;

        if (min_set)
          {
             ecore_evas_size_min_set(ee, WIDTH / 2, HEIGHT / 2);
             fprintf(stdout, "Imposing a minimum size of %d x %d\n",
                     WIDTH / 2, HEIGHT / 2);
          }
        else
          {
             ecore_evas_size_min_set(ee, 0, 0);
             fprintf(stdout, "Taking off minimum size restriction from the"
                             " window\n");
          }
        return;
     }

   if (strcmp(ev->key, "x") == 0) /* impose a maximum size on the window */
     {
        max_set = !max_set;

        if (max_set)
          {
             ecore_evas_size_max_set(ee, WIDTH * 2, HEIGHT * 2);
             fprintf(stdout, "Imposing a maximum size of %d x %d\n",
                     WIDTH * 2, HEIGHT * 2);
          }
        else
          {
             ecore_evas_size_max_set(ee, 0, 0);
             fprintf(stdout, "Taking off maximum size restriction from the"
                             " window\n");
          }
        return;
     }

   if (strcmp(ev->key, "b") == 0) /* impose a base size on the window */
     {
        base_set = !base_set;

        if (base_set)
          {
             ecore_evas_size_base_set(ee, WIDTH * 2, HEIGHT * 2);
             fprintf(stdout, "Imposing a base size of %d x %d\n",
                     WIDTH * 2, HEIGHT * 2);
          }
        else
          {
             ecore_evas_size_base_set(ee, 0, 0);
             fprintf(stdout, "Taking off base size restriction from the"
                             " window\n");
          }
        return;
     }

   if (strcmp(ev->key, "s") == 0) /* impose a step size on the window */
     {
        step_set = !step_set;

        if (step_set)
          {
             ecore_evas_size_step_set(ee, 40, 40);
             fprintf(stdout, "Imposing a step size of %d x %d\n", 40, 40);
          }
        else
          {
             ecore_evas_size_step_set(ee, 0, 0);
             fprintf(stdout, "Taking off step size restriction from the"
                             " window\n");
          }
        return;
     }

   if (strcmp(ev->key, "g") == 0) /* get screen geometry */
     {
        int x, y, w, h;
        ecore_evas_screen_geometry_get(ee, &x, &y, &w, &h);
        fprintf(stdout, "screen geometry: %d,%d, %dx%d\n", x, y, w, h);
        return;
     }
}

int
main(void)
{
   Evas *evas;

   if (!ecore_evas_init())
     return EXIT_FAILURE;

   /* this will give you a window with an Evas canvas under the first
    * engine available */
   ee = ecore_evas_new(NULL, 0, 0, WIDTH, HEIGHT, NULL);
   if (!ee) goto error;

   ecore_evas_callback_delete_request_set(ee, _on_destroy);
   ecore_evas_title_set(ee, "Ecore_Evas window sizes example");
   ecore_evas_callback_resize_set(ee, _canvas_resize_cb);
   ecore_evas_show(ee);

   evas = ecore_evas_get(ee);

   bg = evas_object_rectangle_add(evas);
   evas_object_color_set(bg, 255, 255, 255, 255);  /* white bg */
   evas_object_move(bg, 0, 0);  /* at canvas' origin */
   evas_object_resize(bg, WIDTH, HEIGHT);  /* covers full canvas */
   evas_object_show(bg);

   evas_object_focus_set(bg, EINA_TRUE);
   evas_object_event_callback_add(
     bg, EVAS_CALLBACK_KEY_DOWN, _on_keydown, NULL);

   text = evas_object_text_add(evas);
   evas_object_color_set(text, 0, 0, 0, 255);
   evas_object_resize(text, 150, 50);
   evas_object_text_font_set(text, "Sans", 20);
   evas_object_show(text);

   _canvas_resize_cb(ee);
   fprintf(stdout, commands);
   ecore_main_loop_begin();

   ecore_evas_free(ee);
   ecore_evas_shutdown();

   return 0;

error:
   fprintf(stderr, "You got to have at least one Evas engine built"
                   " and linked up to ecore-evas for this example to run"
                   " properly.\n");
   ecore_evas_shutdown();
   return -1;
}