Evas text object example

In this example, we illustrate how to use text objects in various manners.

We place, in the canvas, a text object along with a border image to delimit its geometry. After we instantiate the text object, we set lots of properties on it to the initial ones from a preset list, which has the following declaration:

   /* init values one is going to cycle through while running this
    * example */
   struct text_preset_data init_data =
   {
      .font = {"DejaVu", "Courier", "Utopia"},
      .text = {BLACK, WHITE, GREY, RED, GREEN, BLUE},
      .shadow = {WHITE, BLUE, GREEN, RED},
      .outline = {WHITE, RED, GREEN, BLUE},
      .glow = {WHITE, BLUE, GREEN, RED},
      .glow2 = {WHITE, RED, BLUE, GREEN}
   };

Then, we set the text string itself, on it, with evas_object_text_text_set(). We set an explicit size of 30 points for our font, as you could see, what we check back with the getter evas_object_text_font_get().

Look at how it translates to code:

   d.text = evas_object_text_add(d.evas);
   evas_object_text_style_set(d.text, EVAS_TEXT_STYLE_PLAIN);

   /* let the pre-set thingies be enforced */
   evas_object_color_set(
     d.text, d.t_data.text_ptr->r, d.t_data.text_ptr->g,
     d.t_data.text_ptr->b, d.t_data.text_ptr->a);

   evas_object_text_glow_color_set(
     d.text, d.t_data.glow_ptr->r, d.t_data.glow_ptr->g,
     d.t_data.glow_ptr->b, d.t_data.glow_ptr->a);

   evas_object_text_glow2_color_set(
     d.text, d.t_data.glow2_ptr->r, d.t_data.glow2_ptr->g,
     d.t_data.glow2_ptr->b, d.t_data.glow2_ptr->a);

   evas_object_text_outline_color_set(
     d.text, d.t_data.outline_ptr->r, d.t_data.outline_ptr->g,
     d.t_data.outline_ptr->b, d.t_data.outline_ptr->a);

   evas_object_text_shadow_color_set(
     d.text, d.t_data.shadow_ptr->r, d.t_data.shadow_ptr->g,
     d.t_data.shadow_ptr->b, d.t_data.shadow_ptr->a);

   evas_object_text_font_set(d.text, *d.t_data.font_ptr, 30);
   evas_object_text_text_set(d.text, "sample text");

   evas_object_resize(d.text, (3 * WIDTH) / 4, HEIGHT / 4);
   evas_object_move(d.text, WIDTH / 8, (3 * HEIGHT) / 8);
   evas_object_show(d.text);

   evas_object_text_font_get(d.text, &font, &size);
   fprintf(stdout, "Adding text object with font %s, size %d\n", font, size);

Like in other Evas examples, one interacts with it by means of key commands:

static const char *commands = \
  "commands are:\n"
  "\tt - change text's current style\n"
  "\tz - change text's font size\n"
  "\tf - change text's font family\n"
  "\tb - change text's base color\n"
  "\ts - change text's \'shadow\' color\n"
  "\to - change text's \'outline\' color\n"
  "\tw - change text's \'glow\' color\n"
  "\tg - change text's \'glow 2\' color\n"
  "\th - print help\n";

Use the 't' key to exercise the evas_object_text_style_set() function on the text -- it will cycle through all styles on Evas_Text_Style_Type (note we start on #EVAS_TEXT_STYLE_PLAIN, thus with no effects on it) and, with other keys, you'll be able to set properties applicable to individual styles on the text object.

The 'z' key will change the text's size, keeping the font family for it. Use 'f' to change the font, keeping the last size set. There are three font families the example will cycle through:

The 'b' command shows us that evas_object_color_set(), on a given text object, will change the text's base color. Experiment with it, which will cycle through the colors in the .text list in init_data.

The 's', 'o', 'w' and 'g' keys will make the text object to cycle to the preset values on colors for shadow, outline, glow and 'glow 2' effects, respectively. Naturally, they will only take effect on the text styles which resemble them.

The full example follows.

#ifdef HAVE_CONFIG_H
#include "config.h"
#else
#define PACKAGE_EXAMPLES_DIR "."
#endif

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

#define WIDTH  (320)
#define HEIGHT (240)

#define GREY {190, 190, 190, 255}
#define BLACK {0, 0, 0, 255}
#define WHITE {255, 255, 255, 255}
#define RED   {255, 0, 0, 255}
#define GREEN {0, 255, 0, 255}
#define BLUE  {0, 0, 255, 255}

#define POINTER_CYCLE(_ptr, _array)                             \
  do                                                            \
    {                                                           \
       if ((unsigned int)(((unsigned char *)(_ptr)) - ((unsigned char *)(_array))) >= \
           sizeof(_array))                                      \
         _ptr = _array;                                         \
    }                                                           \
  while(0)

static const char *commands = \
  "commands are:\n"
  "\tt - change text's current style\n"
  "\tz - change text's font size\n"
  "\tf - change text's font family\n"
  "\tb - change text's base color\n"
  "\ts - change text's \'shadow\' color\n"
  "\to - change text's \'outline\' color\n"
  "\tw - change text's \'glow\' color\n"
  "\tg - change text's \'glow 2\' color\n"
  "\th - print help\n";

static const char *border_img_path = PACKAGE_EXAMPLES_DIR "/red.png";

struct color_tuple
{
   int r, g, b, a;
};

struct text_preset_data
{
   const char        **font_ptr;
   const char         *font[3];

   struct color_tuple *text_ptr;
   struct color_tuple  text[6];

   struct color_tuple *shadow_ptr;
   struct color_tuple  shadow[4];

   struct color_tuple *outline_ptr;
   struct color_tuple  outline[4];

   struct color_tuple *glow_ptr;
   struct color_tuple  glow[4];

   struct color_tuple *glow2_ptr;
   struct color_tuple  glow2[4];
};

struct test_data
{
   Ecore_Evas             *ee;
   Evas                   *evas;
   struct text_preset_data t_data;
   Evas_Object            *text, *bg, *border;
};

static struct test_data d = {0};

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

/* here just to keep our example's window size and background image's
 * size in synchrony */
static void
_canvas_resize_cb(Ecore_Evas *ee)
{
   int w, h;

   ecore_evas_geometry_get(ee, NULL, NULL, &w, &h);
   evas_object_resize(d.bg, w, h);
}

static const char *
_text_style_type_to_str(Evas_Text_Style_Type mode)
{
   switch (mode)
     {
      case EVAS_TEXT_STYLE_PLAIN:
        return "plain";

      case EVAS_TEXT_STYLE_SHADOW:
        return "shadow";

      case EVAS_TEXT_STYLE_OUTLINE:
        return "outline";

      case EVAS_TEXT_STYLE_SOFT_OUTLINE:
        return "soft outline";

      case EVAS_TEXT_STYLE_GLOW:
        return "glow";

      case EVAS_TEXT_STYLE_OUTLINE_SHADOW:
        return "outline shadow";

      case EVAS_TEXT_STYLE_FAR_SHADOW:
        return "far shadow";

      case EVAS_TEXT_STYLE_OUTLINE_SOFT_SHADOW:
        return "outline soft shadow";

      case EVAS_TEXT_STYLE_SOFT_SHADOW:
        return "soft shadow";

      case EVAS_TEXT_STYLE_FAR_SOFT_SHADOW:
        return "far soft shadow";

      default:
        return "invalid";
     }
}

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, "t") == 0) /* change text's current style */
     {
        Evas_Text_Style_Type type = evas_object_text_style_get(d.text);

        type = (type + 1) % 10;

        evas_object_text_style_set(d.text, type);

        fprintf(stdout, "Changing text's style to \'%s\'\n",
                _text_style_type_to_str(type));

        return;
     }

   if (strcmp(ev->key, "f") == 0) /* change text's font */
     {
         int sz;

        (d.t_data.font_ptr)++;

        evas_object_text_font_get(d.text, NULL, &sz);

        POINTER_CYCLE(d.t_data.font_ptr, d.t_data.font);

        evas_object_text_font_set(d.text, *d.t_data.font_ptr, sz);

        fprintf(stdout, "Changing text's font to %s\n", *d.t_data.font_ptr);

        return;
     }

   if (strcmp(ev->key, "b") == 0) /* change text's base color */
     {
        (d.t_data.text_ptr)++;

        POINTER_CYCLE(d.t_data.text_ptr, d.t_data.text);

        evas_object_color_set(
          d.text, d.t_data.text_ptr->r, d.t_data.text_ptr->g,
          d.t_data.text_ptr->b, d.t_data.text_ptr->a);

        fprintf(stdout, "Changing base color for text to (%d, %d, %d, %d)\n",
                d.t_data.text_ptr->r, d.t_data.text_ptr->g,
                d.t_data.text_ptr->b, d.t_data.text_ptr->a);

        return;
     }

   if (strcmp(ev->key, "g") == 0) /* change text's glow 2 color */
     {
        (d.t_data.glow2_ptr)++;

        POINTER_CYCLE(d.t_data.glow2_ptr, d.t_data.glow2);

        evas_object_text_glow2_color_set(
          d.text, d.t_data.glow2_ptr->r, d.t_data.glow2_ptr->g,
          d.t_data.glow2_ptr->b, d.t_data.glow2_ptr->a);

        fprintf(stdout, "Changing glow 2 color for text to (%d, %d, %d, %d)\n",
                d.t_data.glow2_ptr->r, d.t_data.glow2_ptr->g,
                d.t_data.glow2_ptr->b, d.t_data.glow2_ptr->a);

        return;
     }

   if (strcmp(ev->key, "w") == 0) /* change text's glow color */
     {
        (d.t_data.glow_ptr)++;

        POINTER_CYCLE(d.t_data.glow_ptr, d.t_data.glow);

        evas_object_text_glow_color_set(
          d.text, d.t_data.glow_ptr->r, d.t_data.glow_ptr->g,
          d.t_data.glow_ptr->b, d.t_data.glow_ptr->a);

        fprintf(stdout, "Changing glow color for text to (%d, %d, %d, %d)\n",
                d.t_data.glow_ptr->r, d.t_data.glow_ptr->g,
                d.t_data.glow_ptr->b, d.t_data.glow_ptr->a);

        return;
     }

   if (strcmp(ev->key, "o") == 0) /* change text's outline color */
     {
        (d.t_data.outline_ptr)++;

        POINTER_CYCLE(d.t_data.outline_ptr, d.t_data.outline);

        evas_object_text_outline_color_set(
          d.text, d.t_data.outline_ptr->r, d.t_data.outline_ptr->g,
          d.t_data.outline_ptr->b, d.t_data.outline_ptr->a);

        fprintf(stdout, "Changing outline color for text to (%d, %d, %d, %d)\n",
                d.t_data.outline_ptr->r, d.t_data.outline_ptr->g,
                d.t_data.outline_ptr->b, d.t_data.outline_ptr->a);

        return;
     }

   if (strcmp(ev->key, "s") == 0) /* change text's shadow color */
     {
        (d.t_data.shadow_ptr)++;

        POINTER_CYCLE(d.t_data.shadow_ptr, d.t_data.shadow);

        evas_object_text_shadow_color_set(
          d.text, d.t_data.shadow_ptr->r, d.t_data.shadow_ptr->g,
          d.t_data.shadow_ptr->b, d.t_data.shadow_ptr->a);

        fprintf(stdout, "Changing shadow color for text to (%d, %d, %d, %d)\n",
                d.t_data.shadow_ptr->r, d.t_data.shadow_ptr->g,
                d.t_data.shadow_ptr->b, d.t_data.shadow_ptr->a);

        return;
     }

   if (strcmp(ev->key, "z") == 0) /* change text's font size */
     {
        const char *font;
        int size;

        evas_object_text_font_get(d.text, &font, &size);

        size = (size + 10) % 50;
        if (!size) size = 10;

        evas_object_text_font_set(d.text, font, size);

        fprintf(stdout, "Changing text's font size to %d\n", size);

        return;
     }
}

int
main(void)
{
   int size;
   const char *font;

   if (!ecore_evas_init())
     return EXIT_FAILURE;

   /* init values one is going to cycle through while running this
    * example */
   struct text_preset_data init_data =
   {
      .font = {"DejaVu", "Courier", "Utopia"},
      .text = {BLACK, WHITE, GREY, RED, GREEN, BLUE},
      .shadow = {WHITE, BLUE, GREEN, RED},
      .outline = {WHITE, RED, GREEN, BLUE},
      .glow = {WHITE, BLUE, GREEN, RED},
      .glow2 = {WHITE, RED, BLUE, GREEN}
   };

   d.t_data = init_data;
   d.t_data.font_ptr = d.t_data.font;
   d.t_data.text_ptr = d.t_data.text;
   d.t_data.glow_ptr = d.t_data.glow;
   d.t_data.glow2_ptr = d.t_data.glow2;
   d.t_data.outline_ptr = d.t_data.outline;
   d.t_data.shadow_ptr = d.t_data.shadow;

   /* this will give you a window with an Evas canvas under the first
    * engine available */
   d.ee = ecore_evas_new(NULL, 10, 10, WIDTH, HEIGHT, NULL);
   if (!d.ee)
     goto error;

   ecore_evas_callback_destroy_set(d.ee, _on_destroy);
   ecore_evas_callback_resize_set(d.ee, _canvas_resize_cb);
   ecore_evas_show(d.ee);

   /* the canvas pointer, de facto */
   d.evas = ecore_evas_get(d.ee);

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

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

   d.text = evas_object_text_add(d.evas);
   evas_object_text_style_set(d.text, EVAS_TEXT_STYLE_PLAIN);

   /* let the pre-set thingies be enforced */
   evas_object_color_set(
     d.text, d.t_data.text_ptr->r, d.t_data.text_ptr->g,
     d.t_data.text_ptr->b, d.t_data.text_ptr->a);

   evas_object_text_glow_color_set(
     d.text, d.t_data.glow_ptr->r, d.t_data.glow_ptr->g,
     d.t_data.glow_ptr->b, d.t_data.glow_ptr->a);

   evas_object_text_glow2_color_set(
     d.text, d.t_data.glow2_ptr->r, d.t_data.glow2_ptr->g,
     d.t_data.glow2_ptr->b, d.t_data.glow2_ptr->a);

   evas_object_text_outline_color_set(
     d.text, d.t_data.outline_ptr->r, d.t_data.outline_ptr->g,
     d.t_data.outline_ptr->b, d.t_data.outline_ptr->a);

   evas_object_text_shadow_color_set(
     d.text, d.t_data.shadow_ptr->r, d.t_data.shadow_ptr->g,
     d.t_data.shadow_ptr->b, d.t_data.shadow_ptr->a);

   evas_object_text_font_set(d.text, *d.t_data.font_ptr, 30);
   evas_object_text_text_set(d.text, "sample text");

   evas_object_resize(d.text, (3 * WIDTH) / 4, HEIGHT / 4);
   evas_object_move(d.text, WIDTH / 8, (3 * HEIGHT) / 8);
   evas_object_show(d.text);

   evas_object_text_font_get(d.text, &font, &size);
   fprintf(stdout, "Adding text object with font %s, size %d\n", font, size);

   /* this is a border around the text object above, here just to
    * emphasize its geometry */
   d.border = evas_object_image_filled_add(d.evas);
   evas_object_image_file_set(d.border, border_img_path, NULL);
   evas_object_image_border_set(d.border, 3, 3, 3, 3);
   evas_object_image_border_center_fill_set(d.border, EVAS_BORDER_FILL_NONE);

   evas_object_resize(d.border, ((3 * WIDTH) / 4) + 3, (HEIGHT / 4) + 3);
   evas_object_move(d.border, (WIDTH / 8) - 3, ((3 * HEIGHT) / 8) - 3);
   evas_object_show(d.border);

   fprintf(stdout, commands);
   ecore_main_loop_begin();

   ecore_evas_free(d.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;
}