Background

The background UI component is used to set a solid background decoration to a window or a container object. It works like an image, but has some background-specific properties. It can be set to a tiled, centered, scaled, or stretched mode. The background is the most simple UI component in that it emits no signals. For more information, see the Background API.

This feature is supported in wearable applications only.

Basic Usage

To use a background component in your application:

Add a background with the elm_bg_add() function:

Evas_Object *bg;

bg = elm_bg_add(parent);

Set the appearance of the background:
- Set a color to the background using the elm_bg_color_set() function:
```
elm_bg_color_set(bg, 64, 127, 256);
```
- Set an Edje group as a background using the elm_bg_file_set() function:
```
elm_bg_file_set(bg, "/path/to/the/edje", "group name");
```
- Set an image file as a background using the elm_bg_file_set() function.
  
  For an image background, you can set additional options.
```
elm_bg_file_set(bg, "/path/to/the/image", NULL);
```

Set a swallow part:

/* Load content at the topmost layer of the background */
elm_object_content_set(bg, evas_object);

The following example shows a simple use case of the background component.

Example: Background use case

Background

Evas_Object *bg;
Evas_Object *box;
Evas_Object *label;
Evas_Object *nfl;

/* Starting right after the basic EFL UI layout code */
/* (win - conformant - naviframe) */

/* Add a background object */
bg = elm_bg_add(nf);

/* Set a color (R:64, G:127, B:256) */
elm_bg_color_set(bg, 64, 127, 256);

/* Add a box and set it as the background content */
box = elm_box_add(bg);
elm_object_content_set(bg, box);

label = elm_label_add(box);
elm_object_text_set(label, "overlay swallow part");
evas_object_show(label);
elm_box_pack_end(box, label);

elm_naviframe_item_push(nf, "Background", NULL, NULL, bg, "empty");

Options

When you set an image, you can set a few background options using the elm_bg_option_set() function.

The following modes are available:

ELM_BG_OPTION_CENTER: Centers the background image.
ELM_BG_OPTION_SCALE: Scales the background image, retaining the aspect ratio.
ELM_BG_OPTION_STRETCH: Stretches the background image to fill the UI component’s area.
ELM_BG_OPTION_TILE: Tiles the background image at its original size.

Table: Background options