Tizen Native API  4.0
Image Object Functions

Here are grouped together functions used to create and manipulate image objects. They are available to whichever occasion one needs complex imagery on a GUI that could not be achieved by the other Evas' primitive object types, or to make image manipulations.

Evas will support whichever image file types it was compiled with support to (its image loaders) -- check your software packager for that information and see evas_object_image_extension_can_load_get().

Image object basics

The most common use of image objects -- to display an image on the canvas -- is achieved by a common function triplet:

 img = evas_object_image_add(canvas);
 evas_object_image_file_set(img, "path/to/img", NULL);
 evas_object_image_fill_set(img, 0, 0, w, h);

The first function, naturally, is creating the image object. Then, one must set an source file on it, so that it knows where to fetch image data from. Next, one must set how to fill the image object's area with that given pixel data. One could use just a sub-region of the original image or even have it tiled repeatedly on the image object. For the common case of having the whole source image to be displayed on the image object, stretched to the destination's size, there's also a function helper, to be used instead of evas_object_image_fill_set():

 evas_object_image_filled_set(img, EINA_TRUE);

See those functions' documentation for more details.

Scale and resizing

Resizing of image objects will scale their respective source images to their areas, if they are set to "fill" the object's area (evas_object_image_filled_set()). If the user wants any control on the aspect ratio of an image for different sizes, he/she has to take care of that themselves. There are functions to make images to get loaded scaled (up or down) in memory, already, if the user is going to use them at pre-determined sizes and wants to save computations.

Evas has even a scale cache, which will take care of caching scaled versions of images with more often usage/hits. Finally, one can have images being rescaled smoothly by Evas (more computationally expensive) or not.

Performance hints

When dealing with image objects, there are some tricks to boost the performance of your application, if it does intense image loading and/or manipulations, as in animations on a UI.

Load hints

In image viewer applications, for example, the user will be looking at a given image, at full size, and will desire that the navigation to the adjacent images on his/her album be fluid and fast. Thus, while displaying a given image, the program can be on the background loading the next and previous images already, so that displaying them on the sequence is just a matter of repainting the screen (and not decoding image data).

Evas addresses this issue with image pre-loading. The code for the situation above would be something like the following:

If you're loading images which are too big, consider setting previously it's loading size to something smaller, in case you won't expose them in real size. It may speed up the loading considerably:

 //to load a scaled down version of the image in memory, if that's
 //the size you'll be displaying it anyway
 evas_object_image_load_scale_down_set(img, zoom);

 //optional: if you know you'll be showing a sub-set of the image's
 //pixels, you can avoid loading the complementary data
 evas_object_image_load_region_set(img, x, y, w, h);

Refer to Elementary's Photocam widget for a high level (smart) object which does lots of loading speed-ups for you.

Animation hints

If you want to animate image objects on a UI (what you'd get by concomitant usage of other libraries, like Ecore and Edje), there are also some tips on how to boost the performance of your application. If the animation involves resizing of an image (thus, re-scaling), you'd better turn off smooth scaling on it during the animation, turning it back on afterwards, for less computations. Also, in this case you'd better flag the image object in question not to cache scaled versions of it:

 evas_object_image_scale_hint_set(wd->img, EVAS_IMAGE_SCALE_HINT_DYNAMIC);

 // resizing takes place in between

 evas_object_image_scale_hint_set(wd->img, EVAS_IMAGE_SCALE_HINT_STATIC);

Finally, movement of opaque images through the canvas is less expensive than of translucid ones, because of blending computations.

Borders

Evas provides facilities for one to specify an image's region to be treated specially -- as "borders". This will make those regions be treated specially on resizing scales, by keeping their aspect. This makes setting frames around other objects on UIs easy. See the following figures for a visual explanation:

image-borders.png
border-effect.png

Manipulating pixels

Evas image objects can be used to manipulate raw pixels in many ways. The meaning of the data in the pixel arrays will depend on the image's color space, be warned (see next section). You can set your own data as an image's pixel data, fetch an image's pixel data for saving/altering, convert images between different color spaces and even advanced operations like setting a native surface as image objects' data.

Color spaces

Image objects may return or accept "image data" in multiple formats. This is based on the color space of an object. Here is a rundown on formats:

Warning:
We don't guarantee any proper results if you create a Image object without setting the evas engine.

Some examples on this group of functions can be found here.

Functions

Eina_Bool evas_object_image_extension_can_load_get (const char *file)
Eina_Bool evas_object_image_extension_can_load_fast_get (const char *file)

Typedefs

typedef void(* Evas_Object_Image_Pixels_Get_Cb )(void *data, Evas_Object *o)
typedef Emile_Colorspace Evas_Colorspace

Typedef Documentation

typedef Emile_Colorspace Evas_Colorspace

Colorspaces for pixel data supported by Evas Colorspaces for pixel data supported by Evas

typedef void(* Evas_Object_Image_Pixels_Get_Cb)(void *data, Evas_Object *o)

Function signature for the evas object pixels get callback function

See also:
evas_object_image_pixels_get()

By data it will be passed the private data. By o it will be passed the Evas_Object image on which the pixels are requested.


Function Documentation

Creates a new image object on the given Evas e canvas.

Parameters:
eThe given canvas.
Returns:
The created image object handle.
Note:
If you intend to display an image somehow in a GUI, besides binding it to a real image file/source (with evas_object_image_file_set(), for example), you'll have to tell this image object how to fill its space with the pixels it can get from the source. See evas_object_image_filled_add(), for a helper on the common case of scaling up an image source to the whole area of the image object.
See also:
evas_object_image_fill_set()

Example:

 img = evas_object_image_add(canvas);
 evas_object_image_file_set(img, "/path/to/img", NULL);
Since :
2.3
Examples:
evas-images.c, and evas-images2.c.

Enable an image to be used as an alpha mask.

This will set any flags, and discard any excess image data not used as an alpha mask.

Note there is little point in using a image as alpha mask unless it has an alpha channel.

Parameters:
objObject to use as an alpha mask.
ismaskUse image as alphamask, must be true.
Since :
2.3

Check if an image object can be animated (have multiple frames)

Returns:
whether obj support animation

This returns if the image file of an image object is capable of animation such as an animated gif file might. This is only useful to be called once the image object file has been set.

Example:

 extern Evas_Object *obj;

 if (evas_object_image_animated_get(obj))
 {
 int frame_count;
 int loop_count;
 Evas_Image_Animated_Loop_Hint loop_type;
 double duration;

 frame_count = evas_object_image_animated_frame_count_get(obj);
 printf("This image has %d frames\n",frame_count);

 duration = evas_object_image_animated_frame_duration_get(obj,1,0);
 printf("Frame 1's duration is %f. You had better set object's frame to 2 after this duration using timer\n");

 loop_count = evas_object_image_animated_loop_count_get(obj);
 printf("loop count is %d. You had better run loop %d times\n",loop_count,loop_count);

 loop_type = evas_object_image_animated_loop_type_get(obj);
 if (loop_type == EVAS_IMAGE_ANIMATED_HINT_LOOP)
 printf("You had better set frame like 1->2->3->1->2->3...\n");
 else if (loop_type == EVAS_IMAGE_ANIMATED_HINT_PINGPONG)
 printf("You had better set frame like 1->2->3->2->1->2...\n");
 else
 printf("Unknown loop type\n");

 evas_object_image_animated_frame_set(obj,1);
 printf("You set image object's frame to 1. You can see frame 1\n");
 }
See also:
evas_object_image_animated_get()
evas_object_image_animated_frame_count_get()
evas_object_image_animated_loop_type_get()
evas_object_image_animated_loop_count_get()
evas_object_image_animated_frame_duration_get()
evas_object_image_animated_frame_set()
Since (EFL) :
1.1
Since :
2.3
Deprecated:
evas_object_image_data_conver
Since :
2.3

Check if a file extension may be supported by Image Object Functions.

Parameters:
fileThe file to check, it should be an Eina_Stringshare.
Returns:
EINA_TRUE if we may be able to open it, EINA_FALSE if it's unlikely.
Since (EFL) :
1.1

This functions is threadsafe.

Since :
2.3

Check if a file extension may be supported by Image Object Functions.

Parameters:
fileThe file to check
Returns:
EINA_TRUE if we may be able to open it, EINA_FALSE if it's unlikely.
Since (EFL) :
1.1

If file is a Eina_Stringshare, use directly evas_object_image_extension_can_load_fast_get.

This functions is threadsafe.

Since :
2.3
void evas_object_image_file_get ( const Eo *  obj,
const char **  file,
const char **  key 
)

Retrieve the source file from where an image object is to fetch the real image data (it may be an Eet file, besides pure image ones).

You must not modify the strings on the returned pointers.

Note:
Use NULL pointers on the file components you're not interested in: they'll be ignored by the function.
Parameters:
[out]fileThe image file path.
[out]keyThe image key in file (if its an Eet one), or NULL, otherwise.
Since :
2.3
void evas_object_image_file_set ( Eo *  obj,
const char *  file,
const char *  key 
)

Set the source file from where an image object must fetch the real image data (it may be an Eet file, besides pure image ones).

If the file supports multiple data stored in it (as Eet files do), you can specify the key to be used as the index of the image in this file.

Example:

 img = evas_object_image_add(canvas);
 evas_object_image_file_set(img, "/path/to/img", NULL);
 err = evas_object_image_load_error_get(img);
 if (err != EVAS_LOAD_ERROR_NONE)
 {
 fprintf(stderr, "could not load image '%s'. error string is \"%s\"\n",
 valid_path, evas_load_error_str(err));
 }
 else
 {
 evas_object_image_fill_set(img, 0, 0, w, h);
 evas_object_resize(img, w, h);
 evas_object_show(img);
 }
Parameters:
[in]fileThe image file path.
[in]keyThe image key in file (if its an Eet one), or NULL, otherwise.
Since :
2.3
Examples:
ecore_evas_buffer_example_02.c, edje-basic.c, edje-signals-messages.c, evas-aspect-hints.c, evas-box.c, evas-events.c, evas-hints.c, evas-images.c, evas-images2.c, evas-map-utils.c, evas-object-manipulation.c, evas-smart-interface.c, evas-smart-object.c, and evas-text.c.
void evas_object_image_fill_get ( const Evas_Object obj,
Evas_Coord x,
Evas_Coord y,
Evas_Coord w,
Evas_Coord h 
)

Retrieve how an image object is to fill its drawing rectangle, given the (real) image bound to it.

Note:
Use NULL pointers on the fill components you're not interested in: they'll be ignored by the function.

See evas_object_image_fill_set() for more details.

Parameters:
[out]xThe x coordinate (from the top left corner of the bound image) to start drawing from.
[out]yThe y coordinate (from the top left corner of the bound image) to start drawing from.
[out]wThe width the bound image will be displayed at.
[out]hThe height the bound image will be displayed at.
Since :
2.3
Examples:
evas-images.c.

Set how to fill an image object's drawing rectangle given the (real) image bound to it.

Note that if w or h are smaller than the dimensions of obj, the displayed image will be tiled around the object's area. To have only one copy of the bound image drawn, x and y must be 0 and w and h need to be the exact width and height of the image object itself, respectively.

See the following image to better understand the effects of this call. On this diagram, both image object and original image source have a x a dimensions and the image itself is a circle, with empty space around it:

image-fill.png
Warning:
The default values for the fill parameters are x = 0, y = 0, w = 0 and h = 0. Thus, if you're not using the evas_object_image_filled_add() helper and want your image displayed, you'll have to set valid values with this function on your object.
Note:
evas_object_image_filled_set() is a helper function which will override the values set here automatically, for you, in a given way.
Parameters:
[in]xThe x coordinate (from the top left corner of the bound image) to start drawing from.
[in]yThe y coordinate (from the top left corner of the bound image) to start drawing from.
[in]wThe width the bound image will be displayed at.
[in]hThe height the bound image will be displayed at.
Since :
2.3
Examples:
evas-images.c.
Evas_Fill_Spread evas_object_image_fill_spread_get ( const Evas_Object obj)

Retrieves the spread (tiling mode) for the given image object's fill.

Returns:
The current spread mode of the image object.
Since :
2.3
void evas_object_image_fill_spread_set ( Evas_Object obj,
Evas_Fill_Spread  spread 
)

Sets the tiling mode for the given evas image object's fill. EVAS_TEXTURE_RESTRICT, or EVAS_TEXTURE_PAD.

Parameters:
[in]spreadOne of EVAS_TEXTURE_REFLECT, EVAS_TEXTURE_REPEAT,
Since :
2.3

Creates a new image object that automatically scales its bound image to the object's area, on both axis.

Parameters:
eThe given canvas.
Returns:
The created image object handle.

This is a helper function around evas_object_image_add() and evas_object_image_filled_set(). It has the same effect of applying those functions in sequence, which is a very common use case.

Note:
Whenever this object gets resized, the bound image will be rescaled, too.
See also:
evas_object_image_add()
evas_object_image_filled_set()
evas_object_image_fill_set()
Since :
2.3
Examples:
ecore_evas_buffer_example_02.c, edje-basic.c, edje-signals-messages.c, evas-aspect-hints.c, evas-box.c, evas-events.c, evas-hints.c, evas-images.c, evas-images2.c, evas-map-utils.c, evas-object-manipulation.c, evas-smart-interface.c, evas-smart-object.c, and evas-text.c.
void evas_object_image_load_size_get ( const Eo *  obj,
int *  w,
int *  h 
)

Get the load size of a given image object's source image.

This function gets the geometry size set manually for the given canvas image.

Note:
Use NULL pointers on the size components you're not interested in: they'll be ignored by the function.
w and h will be set with the image's loading size only if the image's load size is set manually: if evas_object_image_load_size_set() has not been called, w and h will be set with 0.
See also:
evas_object_image_load_size_set() for more details
Parameters:
[out]wThe new width of the image's load size.
[out]hThe new height of the image's load size.
Since :
2.3
void evas_object_image_load_size_set ( Eo *  obj,
int  w,
int  h 
)

Set the load size of a given image object's source image.

This function sets a new geometry size for the given canvas image. The image will be loaded into memory as if it was the set size instead of the original size.

Note:
The size of a given image object's source image will be less than or equal to the size of w and h.
See also:
evas_object_image_load_size_get()
Parameters:
[in]wThe new width of the image's load size.
[in]hThe new height of the image's load size.
Since :
2.3
void evas_object_image_memfile_set ( Evas_Object obj,
void *  data,
int  size,
char *  format,
char *  key 
)

Sets the data for an image from memory to be loaded

This is the same as evas_object_image_file_set() but the file to be loaded may exist at an address in memory (the data for the file, not the filename itself). The data at the address is copied and stored for future use, so no data needs to be kept after this call is made. It will be managed and freed for you when no longer needed. The size is limited to 2 gigabytes in size, and must be greater than 0. A NULL data pointer is also invalid. Set the filename to NULL to reset to empty state and have the image file data freed from memory using evas_object_image_file_set().

The format is optional (pass NULL if you don't need/use it). It is used to help Evas guess better which loader to use for the data. It may simply be the "extension" of the file as it would normally be on disk such as "jpg" or "png" or "gif" etc.

Parameters:
objThe given image object.
dataThe image file data address
sizeThe size of the image file data in bytes
formatThe format of the file (optional), or NULL if not needed
keyThe image key in file, or NULL.
Since :
2.3
void evas_object_image_mmap_get ( const Eo *  obj,
const Eina_File **  f,
const char **  key 
)

Get the source mmaped file from where an image object must fetch the real image data (it must be an Eina_File).

If the file supports multiple data stored in it (as Eet files do), you can get the key to be used as the index of the image in this file.

Since (EFL) :
1.10
Parameters:
[out]fThe mmaped file
[out]keyThe image key in file (if its an Eet one), or NULL, otherwise.
Since :
3.0
void evas_object_image_mmap_set ( Eo *  obj,
const Eina_File f,
const char *  key 
)

Set the source mmaped file from where an image object must fetch the real image data (it must be an Eina_File).

If the file supports multiple data stored in it (as Eet files do), you can specify the key to be used as the index of the image in this file.

Since (EFL) :
1.8
Parameters:
[in]fThe mmaped file
[in]keyThe image key in file (if its an Eet one), or NULL, otherwise.
Since :
3.0

Set the native surface of a given image of the canvas

Parameters:
objThe given canvas pointer.
surfThe new native surface.

This function sets a native surface of a given canvas image.

Since :
2.3
Eina_Bool evas_object_image_pixels_import ( Evas_Object obj,
Evas_Pixel_Import_Source *  pixels 
)
Deprecated:
evas_object_image_pixels_impor
Since :
2.3
void evas_object_image_preload ( Evas_Object obj,
Eina_Bool  cancel 
)

Preload an image object's image data in the background

Parameters:
objThe given image object.
cancelEINA_FALSE will add it the preloading work queue, EINA_TRUE will remove it (if it was issued before).

This function requests the preload of the data image in the background. The work is queued before being processed (because there might be other pending requests of this type).

Whenever the image data gets loaded, Evas will call EVAS_CALLBACK_IMAGE_PRELOADED registered callbacks on obj (what may be immediately, if the data was already preloaded before).

Use EINA_TRUE for cancel on scenarios where you don't need the image data preloaded anymore.

Note:
Any evas_object_show() call after evas_object_image_preload() will make the latter to be cancelled, with the loading process now taking place synchronously (and, thus, blocking the return of the former until the image is loaded). It is highly advisable, then, that the user preload an image with it being hidden, just to be shown on the EVAS_CALLBACK_IMAGE_PRELOADED event's callback.
Since :
2.3
Examples:
evas-images2.c.
Deprecated:
evas_object_image_reloa
Since :
2.3
Eina_Bool evas_object_image_save ( const Eo *  obj,
const char *  file,
const char *  key,
const char *  flags 
)

Save the given image object's contents to an (image) file.

The extension suffix on file will determine which saver module Evas is to use when saving, thus the final file's format. If the file supports multiple data stored in it (Eet ones), you can specify the key to be used as the index of the image in it.

You can specify some flags when saving the image. Currently acceptable flags are quality and compress. Eg.: "quality=100 compress=9"

Parameters:
[in]fileThe filename to be used to save the image (extension obligatory).
[in]keyThe image key in the file (if an Eet one), or NULL, otherwise.
[in]flagsString containing the flags to be used (NULL for none).
Since :
2.3
Examples:
evas-images2.c.
void evas_object_image_size_get ( const Evas_Object obj,
int *  w,
int *  h 
)

Retrieves the size of the given image object.

See evas_object_image_size_set() for more details.

Parameters:
[out]wThe new width of the image.
[out]hThe new height of the image.
Since :
2.3
Examples:
evas-map-utils.c.
void evas_object_image_size_set ( Evas_Object obj,
int  w,
int  h 
)

Sets the size of the given image object.

This function will scale down or crop the image so that it is treated as if it were at the given size. If the size given is smaller than the image, it will be cropped. If the size given is larger, then the image will be treated as if it were in the upper left hand corner of a larger image that is otherwise transparent.

Parameters:
[in]wThe new width of the image.
[in]hThe new height of the image.
Since :
2.3
Examples:
ecore_evas_buffer_example_02.c, and evas-images2.c.

Retrieves whether the given image object is using high-quality image scaling algorithm.

Returns:
Whether smooth scale is being used.

See evas_object_image_smooth_scale_set() for more details.

Since :
2.3
Examples:
evas-images.c.
void evas_object_image_smooth_scale_set ( Eo *  obj,
Eina_Bool  smooth_scale 
)

Sets whether to use high-quality image scaling algorithm on the given image object.

When enabled, a higher quality image scaling algorithm is used when scaling images to sizes other than the source image's original one. This gives better results but is more computationally expensive.

Note:
Image objects get created originally with smooth scaling on.
See also:
evas_object_image_smooth_scale_get()
Parameters:
[in]smooth_scaleWhether to use smooth scale or not.
Since :
2.3
Examples:
evas-images.c.

Clear the source object on a proxy image object.

Parameters:
objImage object to clear source of.
Returns:
EINA_TRUE on success, EINA_FALSE on error.

This is equivalent to calling evas_object_image_source_set() with a NULL source.

Since :
2.3