[framework/uifw/evas.git] / doc / examples.dox

/**
 * @page Examples Examples
 *
 * Here is a page with examples.
 *
 * @ref Example_Evas_Buffer_Simple
 *
 * @ref Example_Evas_Init_Shutdown
 *
 * @ref Example_Evas_Images
 *
 * @ref Example_Evas_Images_2
 *
 * @ref Example_Evas_Events
 *
 * @ref Example_Evas_Object_Manipulation
 *
 * @ref Example_Evas_Aspect_Hints
 *
 * @ref Example_Evas_Size_Hints
 *
 * @ref Example_Evas_Stacking
 *
 * @ref Example_Evas_Smart_Objects
 */

/**
 * @page Example_Evas_Buffer_Simple Simple Evas canvas example
 *
 * The canvas will here use the buffer engine.
 *
 * @include evas-buffer-simple.c
 * @example evas-buffer-simple.c
 */

/**
 * @page Example_Evas_Init_Shutdown Evas' init/shutdown routines example
 *
 * @include evas-init-shutdown.c
 * @example evas-init-shutdown.c
 */

/**
 * @page Example_Evas_Images Some image object functions examples
 * @dontinclude evas-images.c
 *
 * In this example, we add two images to a canvas, each one having a
 * quarter of the canvas' size, positioned on the top left and bottom
 * right corners, respectively:
 * @skip img1 = evas_object_image_add(d.evas);
 * @until ecore_main_loop_begin
 * See there is a border image around the top left one, <b>which is
 * the one that should be displayed</b>. The other one will (on
 * purpose) fail to load, because we set a wrong file path as image
 * source on it:
 * @dontinclude evas-images.c
 * @skip valid_path
 * @until bogus_path
 * This is how one is supposed to test for success when binding source
 * images to image objects: evas_object_image_load_error_get(),
 * followed by evas_load_error_str(), if one wants to pretty print/log
 * the error. We'll talk about the border image further.
 *
 * To interact with the program, there's a command line interface,
 * whose help string can be asked for with the 'h' key:
 * @dontinclude evas-images.c
 * @skip commands
 * @until ;
 * The first four commands will change the top left images's @b fill property
 * values, which dictate how the source image (Enlightenment's logo)
 * is to be displayed through the image object's area. Experiment with
 * those switches until you get the idea of evas_object_fill_set().
 *
 * The 'f' command will toggle that image's "filled" property, which
 * is wheter it should track its size and set the fill one to fit the
 * object's boundaries perfectly (stretching). Note that this command
 * and the four above it will conflict: in real usage one would use
 * one or other ways of setting an image object's viewport with regard
 * to its image source.
 *
 * There are four commands which deal with the border image. This red
 * frame is there to illustrate <b>image borders</b>. The image source
 * for the border is a solid red rectangle, with a transparent @b
 * rectangular area in its middle. See how we use it to get a 3 pixel
 * wide frame with <code>evas_object_image_border_set(d.border, 3, 3,
 * 3, 3)</code>. To finish the effect of showing it as a border, we
 * issue <code>evas_object_image_border_center_fill_set(d.border,
 * EVAS_BORDER_FILL_NONE)</code>.
 *
 * Use 't' to change the border's thickness. 'b' will change the
 * border image's center region rendering schema: either a hole (no
 * rendering), blending (see the original transparent area, in this
 * case) or solid (the transparent area gets filled). Finally, 'c'
 * will change the border's scaling factor.
 *
 * While you have the border in 'blending mode', test the command 'm':
 * it will set whether to use or not smooth scaling on the border's
 * source image. Since the image is small originallly (30 x 30), we're
 * obviously up-scaling it (except the border pixels, do you
 * remember?). With this last switch, you'll either see the
 * transparent shape in the middle flat (no smoothing) or blurry
 * (smoothed).
 *
 * The full example follows.
 *
 * @include evas-images.c
 * @example evas-images.c
 */

/**
 * @page Example_Evas_Images_2 Some more image object functions examples (2nd block)
 * @dontinclude evas-images2.c
 *
 * In this example, we have three images on the canvas, but one of
 * them is special -- we're using it as a <b>proxy image
 * object</b>. It will mirror the contents of the other two images
 * (which are the ones on the top of the canvas), one at a time:
 * @skip d.proxy_img = evas_object_image_filled_add(d.evas);
 * @until evas_object_show(d.proxy_img);
 * As in other examples, we have a command line interface on it.
 * @dontinclude evas-images2.c
 * @skip commands
 * @until ;
 * The 'p' one will change the source of the proxy image to one of the
 * other two, as seem above.
 * @skip if (strcmp(ev->keyname, "p") == 0)
 * @until }
 * Note the top right image, the smaller one:
 * @dontinclude evas-images2.c
 * @skip noise_img =
 * @until show
 * Since we are creating the data for its pixel buffer ourselves, we
 * have to set its size with evas_object_image_size_set(), first. We
 * set our data with the function evas_object_image_data_set(),
 * whose second argument is a buffer with random data. There's a last
 * command to print it's @b stride value. Since its created with one
 * quarter of the canvas's original width
 * @dontinclude evas-images2.c
 * @skip define WIDTH
 * @until define HEIGHT
 * you can check this value.
 *
 * The image on the top left also has a subtlety: it is @b pre-loaded
 * on this example.
 * @dontinclude evas-images2.c
 * @skip d.logo =
 * @until show
 * On real use cases we wouldn't be just printing something like this
 * @dontinclude evas-images2.c
 * @skip static void
 * @until }
 * naturally.
 *
 * The 's' command will save one of the images on the disk, in the png
 * format:
 * @dontinclude evas-images2.c
 * @skip if (strcmp(ev->keyname, "a") == 0)
 * @until }
 *
 * The full example follows.
 *
 * @include evas-images2.c
 * @example evas-images2.c
 */

/**
 * @page Example_Evas_Events Evas events (canvas and object ones) and some canvas operations example
 * @dontinclude evas-events.c
 *
 * In this example we illustrate how to interact with canvas' (and
 * its objects') events and other canvas operations.
 *
 * After we grab our canvas pointer, we registrate two event callbacks on it:
 * @skip evas_event_callback_add(d.canvas, EVAS_CALLBACK_RENDER_FLUSH_PRE,
 * @until two canvas event callbacks
 * The first of them, whose code is
 * @dontinclude evas-events.c
 * @skip render flush callback
 * @until }
 * will be called whenever our canvas has to flush its rendering pipeline.
 * In this example, two ways of observing that message which is printed in
 * the cited callback are:
 * - to resize the example's window (thus resizing the canvas' viewport)
 * - let the animation run
 *
 * When one resizes the canvas, there's at least one operation it has
 * to do which will require new calculation for rendering: the
 * resizing of the background rectangle:
 * @dontinclude evas-events.c
 * @skip here just to keep
 * @until }
 * The animation we talked about comes from a timer we register just before
 * we start the example's main loop:
 * @dontinclude evas-events.c
 * @skip d.resize_timer = ecore
 * @until d.resize_timer = ecore
 * being the timer's callback what follows:
 * @dontinclude evas-events.c
 * @skip put some action
 * @until }
 * As you see, the resizing of the image will also force the canvas to
 * repaint itself, thus flushing the rendering pipeline whenever the
 * timer ticks. When you start this example, this animation will be
 * running, by default. To interact with the program, there's a
 * command line interface, whose help string can be asked for with the
 * 'h' key:
 * @dontinclude evas-events.c
 * @skip if (strcmp(ev->keyname, "h") == 0)
 * @until }
 * These are the commands the example will accept at any time, except
 * when one triggers the 'f' one:
 * @skip if (strcmp(ev->keyname, "f") == 0)
 * @until }
 * This command will exemplify evas_event_freeze(), which interrupts
 * @b all input events processing for the canvas (in the example, just
 * for 3 seconds). Try to issue events for it during that freeze time.
 * The 'd' command will unregister those two canvas callbacks for you,
 * so you won't see the messages about the focused object and the
 * rendering process anymore:
 * @dontinclude evas-events.c
 * @skip if (strcmp(ev->keyname, "d") == 0)
 * @until }
 * The second of those callbacks has the following code:
 * @dontinclude evas-events.c
 * @skip called when our rectangle gets focus
 * @until }
 * It will take place whenever an object in the canvas receives
 * focus. In this example, we use the focus to handle the input
 * events:
 * @skip so we get input events
 * @until }
 * The background rectangle is the chosen object to receive the
 * focus. This also illustrates the use of
 * evas_object_event_callback_add(), which registers an event callback
 * on an Evas @b object (in this case, the event of a key being
 * pressed down). On this callback, we examine each key pressed and,
 * if they match one between the expected, we take some actions:
 * @dontinclude evas-events.c
 * @skip examine the keys pressed
 * @until key grab
 * We do so by examining the @c ev->keyname string (remember the event
 * information struct for key down events is the #Evas_Event_Key_Down
 * one).  There's one more trick for grabbing input events on this
 * example -- evas_object_key_grab(). The 'c' command will, when
 * firstly used, @b unfocus the background rectangle. Unfocused
 * objects on an Evas canvas will @b never receive key events. We
 * grab, then, the keys we're interested at, to the object forcefully:
 * @skip if (d.focus)
 * @until got here by key grabs
 * This shows how one can handle input not depending on focus issues
 * -- you can grab them globally. Switch back and forth focus and
 * forced key grabbing with the 'c' key, and observe the messages
 * printed about the focused object.  Observe, also, that we register
 * two more @b object callbacks, this time on the image object
 * (Enlightenment logo):
 * @skip evas_object_show(d.img);
 * @until mouse_out, NULL
 * whose code blocks are
 * @dontinclude evas-events.c
 * @skip mouse enters the object's area
 * @until mouse exits the object's area
 * Experiment with moving the mouse pointer over the image, letting it
 * enter and exit its area (stop the animation with 'a', for a better
 * experience). When you start the example, Evas will consider this
 * area by being the whole boundary rectangle around the picture. If
 * you issue the 'p' command, though, you get a demonstration of Evas'
 * precise point collision detection on objects:
 * @dontinclude evas-events.c
 * @skip if (strcmp(ev->keyname, "p") == 0)
 * @until }
 * With evas_object_precise_is_inside_get(), one can make Evas
 * consider the transparent areas of an object (the middle of the
 * logo's E letter, in the case) as not belonging to it when
 * calculating mouse in/out/up/down events. To finish the example, try
 * the command bound to Cotrol + 'o':
 * @skip mods = evas_key_modifier_get(evas);
 * @until end of obscured region command
 * It exemplifies Evas' <b>obscured regions</b>. When firstly pressed,
 * you'll get the same contents, in a region in the middle of the
 * canvas, at the time the key was pressed, until you toggle the
 * effect off again (make sure the animation is running on to get the
 * idea better). When you toggle this effect off, we also demonstrate
 * the use of evas_render_updates(), which will force immediate
 * updates on the canvas rendering, bringing back the obscured
 * region's contents to normal.
 *
 * What follows is the complete code for this example.
 *
 * @include evas-events.c
 * @example evas-events.c
 */

/**
 * @page Example_Evas_Object_Manipulation Evas objects basic manipulation example
 *
 * @include evas-object-manipulation.c
 * @example evas-object-manipulation.c
 */

/**
 * @page Example_Evas_Aspect_Hints Evas aspect hints example
 *
 * @include evas-aspect-hints.c
 * @example evas-aspect-hints.c
 */

/**
 * @page Example_Evas_Size_Hints Evas alignment, minimum size, maximum size, padding and weight hints example
 *
 * @include evas-hints.c
 * @example evas-hints.c
 */

/**
 * @page Example_Evas_Stacking Evas object stacking functions (and some event handling)
 * @dontinclude evas-stacking.c
 *
 * In this example, we illustrate how to stack objects in a custom
 * manner and how to deal with layers.
 *
 * We have three objects of interest in it -- white background, red
 * rectangle, green rectangle and blue rectangle.
 * @skip d.bg = evas_object_rectangle_add(d.canvas);
 * @until evas_object_resize(d.bg, WIDTH, HEIGHT);
 * @skip d.rects[2] = evas_object_rectangle_add(d.canvas);
 * @until evas_object_show(d.rects[0]);
 * @dontinclude evas-stacking.c
 * Like in other Evas examples, one interacts with it be means of key commands:
 * @skip "commands are:\n"
 * @until "\th - print help\n");
 * At any given point, like seem above, you'll be operating one rectangle only.
 * Try stacking it below an adjacent object with "b":
 * @skip evas_object_stack_below(d.rects[d.cur_rect], neighbour);
 * @until evas_object_stack_below(d.rects[d.cur_rect], neighbour);
 * @dontinclude evas-stacking.c
 * "a" will do the opposite:
 * @skip evas_object_stack_above(d.rects[d.cur_rect], neighbour);
 * @until evas_object_stack_above(d.rects[d.cur_rect], neighbour);
 * To bring it directly to the top/bottom, use "t"/"m", respectively:
 * @dontinclude evas-stacking.c
 * @skip evas_object_raise(d.rects[d.cur_rect]);
 * @until evas_object_raise(d.rects[d.cur_rect]);
 * @skip evas_object_lower(d.rects[d.cur_rect]);
 * @until evas_object_lower(d.rects[d.cur_rect]);
 * At any time, use the "s" command to see the status of the
 * ordering. It will show the background's ordering too. Note that it
 * also shows the @b layer for this object. It starts at a @b
 * different layer than the others. Use "l" to change its layer
 * (higher layer numbers mean higher layers). If the background is on
 * the same layer as the others (0), you'll see it interact with them
 * on the ordering. If it's in the layer above, no matter what you do,
 * you'll see nothing but the white rectangle: it covers the other
 * layers. For the initial layer (-1), it will never mess nor occlude
 * the others.
 *
 * The last two commands available are "p" and "r", which will make
 * the target rectangle to @b pass (ignore) and @b repeat the mouse
 * events occurring on it (the commands will cycle through on and off
 * states). This is demonstrated with the following
 * #EVAS_CALLBACK_MOUSE_DOWN callback, registered on each of the
 * colored rectangles:
 * @dontinclude evas-stacking.c
 * @skip static void
 * @until }
 * Try to change these properties on the three rectangles while
 * experimenting with mouse clicks on their intersection region.
 *
 * The full example follows.
 *
 * @include evas-stacking.c
 * @example evas-stacking.c
 */

/**
 * @page Example_Evas_Map_Overview Evas Map - Overview
 * @dontinclude evas-map-utils.c
 *
 * Down to the very bottom, Map is simple: it takes an object and transforms
 * the way it will be shown on screen. But using it properly can be a bit
 * troublesome.
 *
 * For the most common operations there are utility functions that help in
 * setting up the map to achieve the desired effects. Now we'll go through
 * an overview of the map API and some of the things that can be done with
 * it.
 *
 * The full code can be found @ref evas-map-utils.c "here".
 *
 * To show how some funtions work, this example listens to keys pressed to
 * toggle several options.
 * @skip typedef
 * @until App_Data
 * @until ;
 *
 * In this program, we divide the window in four quadrants, each holding an
 * object that will have different map configurations applied to them in each
 * call to an animator function.
 * @skip static Eina_Bool
 * @until evas_output_size_get
 *
 * Let's first create a map and set some of our options to it. Only four
 * points maps are supported, so we'll stick to that magic number. We can
 * set a color for each vertex or apply one for all of them at once
 * @until evas_map_util_points_color_set
 *
 * For the first object, we'll have a plain rectangle. At its cration, this
 * rectangle was set to be semi-transparent, but whether its own alpha is
 * used will be defined by the map's alpha setting. If the map's alpha is
 * disabled, then the object will be completely opaque. The map's own color,
 * however, will use any alpha set to it.
 *
 * So we get our object, initialize our map geometry to match the rectangle
 * and make it rotate around its own center, then apply the map to the
 * object so it takes effect.
 * @until evas_object_map_enable_set
 *
 * The second object is an image. Here we don't have any color set for the
 * object, but the image itself contains an alpha channel that will not be
 * affected by the map settings, so even with alpha set to be off, the image
 * will still be transparent. Color applied to the map will tint it though.
 * Since setting a map copies it into the object, we can reuse the same one
 * we created before. We initialize it to the new object while all other
 * options are kept the same. Notice that no rotation will be done here, as
 * that's just an utility function that takes the coordinates set for each
 * point of the map and transforms it accordingly.
 * @until evas_map_util_points_populate_from_object_full
 *
 * This time the object is a bit farther into the screen, by using a @c z
 * value higher than 0 to init the map. We also need to map the image used
 * by the object, so Evas knows how to transform it properly. For this we
 * use the evas_map_point_image_uv_set() to tell the map what coordinate
 * within the image corresponds to each point of the map.
 * @until evas_map_point_image_uv_set(m, 3
 *
 * This object will also be rotated, but in all three axis and around some
 * other point, not its center, chosen mostly at random. If enabled, lighting
 * will be applied to, from a light source at the center of the window.
 * @until evas_object_map_enable_set
 *
 * For the third object we are doing, once more, a 3D rotation, but this time
 * perspective will be applied to our map to make it look more realistic.
 * The lighting source also follows the mouse cursor and it's possible to
 * toggle backface culling, so that the object is hidden whenever we are
 * not seeing its front face.
 * @until evas_object_map_enable_set
 *
 * And we free this map, since since we messed too much with it and for the
 * last object we want something cleaner.
 * @until evas_map_free
 *
 * The last object is actually two. One image, with an image set to it, and
 * one image proxying the first one with evas_object_image_source_set(). This
 * way, the second object will show whatever content its source has.
 * This time we'll be using a map more manually to simulate a simple reflection
 * of the original image.
 *
 * We know that the reflection object is placed just like the original, so
 * we take a shortcut by just getting the geometry of our to-be-mapped object.
 * We also need to get the image size of the source.
 * @until evas_object_image_size_get
 *
 * For this we'll create a map shaped so that it begins at the base of our
 * image and it expands horizontally as it grows (downwards) in height.
 * @until evas_map_point_coord_set(m, 3
 *
 * Since the reflection should show the image inverted, we need to map it
 * this way. The first point of the map (top-left) will be mapped to the
 * mapped to the first pixel of the last row. There's no horizontal reflection
 * and we want the full width of the image, but as we map its upper side ww
 * will only take two thirds of the image.
 * @until evas_map_point_image_uv_set(m, 3
 *
 * Finally, to fade out our reflection we set the colors for each point in
 * the map. The two at the top need to be visible, but we'll tone them down
 * a bit and make them a bit translucent. The other two will go straight to
 * full transparency. Evas interpolates the colors from one point to the next,
 * so this will make them fade out.
 * @until evas_object_map_enable_set
 *
 * Close up by freeing the map and do some other things needed to keep stuff
 * moving in our animations and we are done.
 * @until }
 *
 * The rest of the program is setup and listening to key events. Nothing that
 * matters within the scope of this example, so we are going to skip it.
 * Refer to it @ref evas-map-utils.c "here" however to see how everything
 * fits together.
 *
 * @example evas-map-utils.c
 */

/**
 * @page Example_Evas_Smart_Objects Evas object smart objects
 * @dontinclude evas-smart-object.c
 *
 * In this example, we illustrate how to create and handle Evas smart objects.
 *
 * A smart object is one that provides custom functions to handle
 * clipping, hiding, moving, resizing, color setting and more on @b
 * child elements, automatically, for the smart object's user. They
 * could be as simple as a group of objects that move together (see
 * @ref Evas_Smart_Object_Clipped) or implementations of whole complex
 * UI widgets, providing some intelligence (thus the name) and
 * extension to simple Evas objects.
 *
 * Here, we create one as an example. What it does is to control (at
 * maximum) 2 child objects, with regard to their geometries and
 * colors. There can be a "left" child and a "right" one. The former
 * will always occupy the top left quadrant of the smart object's
 * area, while the latter will occupy the bottom right. The smart
 * object will also contain an @b internal decorative border object,
 * which will also be controlled by it, naturally.
 *
 * Here is where we add it to the canvas:
 * @skip d.smt = evas_smart_example_add(d.evas);
 * @until show
 *
 * The magic starts to happen in the @c evas_smart_example_add()
 * function, which is one in the example smart object's defined @b
 * interface. These should be the functions you would export to the
 * users of your smart object. We made three for this one:
 * - @c evas_smart_example_add(): add a new instance of the example
 *   smart object to a canvas
 * - @c evas_smart_example_remove(): remove a given child of the smart
 *   object from it
 * - @c evas_smart_example_set_left(): set the left child of the smart
 *   object
 * - @c evas_smart_example_set_right(): set the right child of the
 *   smart object
 *
 * The object's creation takes place as:
 * @dontinclude evas-smart-object.c
 * @skip add a new example smart object to a canvas
 * @until }
 *
 * Smart objects are define by <b>smart classes</b>, which are structs
 * defining their interfaces, or <b>smart functions</b> (see
 * #Evas_Smart_Class, the base class for any smart object).  As you
 * see, one has to use the evas_object_smart_add() function to
 * instantiate smart objects. Its second parameter is what matters --
 * an #Evas_Smart struct, which contains all the smart class
 * definitions (smart functions, smart callbacks, and the like). Note,
 * however, that @c _evas_smart_example_smart_class_new() seems not to
 * be defined in our example's code. That's because it came from a very
 * handy <b>helper macro</b>:
 * @dontinclude evas-smart-object.c
 * @skip EVAS_SMART_SUBCLASS_NEW
 * @until _signals
 * What it does is to @b subclass a given existing smart class, thus
 * specializing it. This is very common and useful in Evas. There is a
 * built-in smart object, the "clipped smart object", whose behavior is
 * mostly desired by many other smart object implementors: it will clip
 * its children to its area and move them along with it, on
 * evas_object_resize() calls. Then, our example smart object will get
 * that behavior for free.
 *
 * The first argument to the macro,
 * @dontinclude evas-smart-object.c
 * @skip _evas_smart_example_type
 * @until _evas_smart_example_type
 * will define the new smart class' name. The second tells the macro
 * what is the @b prefix of the function it will be declaring with a @c
 * _smart_set_user() suffix. On this function, we may override/extend
 * any desired method from our parent smart class:
 * @dontinclude evas-smart-object.c
 * @skip setting our smart interface
 * @until }
 *
 * The first function pointer's code will take place at an example
 * smart object's @b creation time:
 * @dontinclude evas-smart-object.c
 * @skip create and setup
 * @until }
 *
 * The #EVAS_SMART_DATA_ALLOC macro will take care of allocating our
 * smart object data, which will be available on other contexts for us
 * (mainly in our interface functions):
 * @dontinclude evas-smart-object.c
 * @skip typedef struct _Evas_Smart_Example_Data
 * @until };
 *
 * See that, as we're inheriting from the clipped smart object's
 * class, we @b must have their data struct as our first member. Other
 * data of interest for us is a child members array and the border
 * object's handle. The latter is what is created in the last
 * mentioned function. Note how to tell Evas the border will be
 * managed by our smart object from that time on:
 * <code>evas_object_smart_member_add(priv->border, o);</code>.
 * The counterpart of this function is exemplifyed on the smart
 * object's interface function to remove children:
 * @skip remove a child element
 * @until set to
 *
 * At the end of that function we make use of an constant defined by
 * the #EVAS_SMART_SUBCLASS_NEW: @c _evas_smart_example_parent_sc. It
 * has the same prefix we passed to the macro, as you can see, and it
 * holds a pointer to our @b parent smart class. Then, we can call the
 * specialized method, itself, after our code. The @c del, @c hide, @c
 * show and @c resize specializations are straightforward, we let the
 * reader take a look at them below to check their behavior. What's
 * interesting is the @c calculate one:
 * @dontinclude evas-smart-object.c
 * @skip act on child objects' properties
 * @until setting
 *
 * This code will take place whenever the smart object itself is
 * flagged "dirty", i.e., must be recalculated for rendering (that
 * could come from changes on its clipper, resizing, moving,
 * etc). There, we make sure the decorative border lies on the edges of
 * the smart object and the children, if any, lie on their respective
 * quadrants.
 *
 * After instantiating our smart object, we do some checks to exemplify
 * some of the API on smart objects:
 * @dontinclude evas-smart-object.c
 * @skip ret = evas_object_smart_type_check
 * @until "no"
 * The evas_object_smart_type_check() one will assure we have the
 * string naming our smart class really set to the live object. The
 * evas_object_smart_clipped_clipper_get() exemplifyes usage of
 * "static clippers" -- clipped smart objects have their global
 * clippers flagged static.
 *
 * As in other examples, to interact with this one there's a command
 * line interface, whose help string can be asked for with the 'h' key:
 *
 * @dontinclude evas-smart-object.c
 * @skip static const char *commands =
 * @until ;
 * Use 'l' and 'r' keys, to create new rectangles and place them on the
 * left (@c evas_smart_example_set_left()) or right
 * (@c evas_smart_example_set_right()) spots of our smart object,
 * respectively. The keyboard arrows will move the smart object along
 * the canvas. See how it takes any child objects with it during its
 * movement. The 'd' and 'i' keys will increase or decrease the smart
 * object's size -- see how it affects the children's sizes,
 * too. Finally, 'c' will change the color of the smart object's
 * clipper (which is the exact internal clipper coming from a clipped
 * smart object):
 * @dontinclude evas-smart-object.c
 * @skip d.clipper =
 * @until .a);
 *
 * "Real life" examples of smart objects are Edje and Emotion objects:
 * they both have independent libraries implementing their
 * behavior. The full example follows.
 *
 * @include evas-smart-object.c
 * @example evas-smart-object.c
 */