forked from enlightenment/efl
examples: Move introduction to Ecore-Evas to evas-transparent.c
Summary: The evas-transparent.c example is quite short, and so will allow for more detailed explanation of setting up Ecore-Evas. Then evas-object-manipulation.c can focus more on the explanation of objects in Ecore-Evas. Reviewers: cedric Subscribers: jpeg Differential Revision: https://phab.enlightenment.org/D5011
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@ -10,9 +10,9 @@ points to start from in learning more advanced topics.
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== Basic Evas ==
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evas-init-shutdown.c - Introduction to Evas
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evas-buffer-simple.c - Using the buffer engine
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evas-buffer-simple.c - Using the Evas buffer engine
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evas-transparent.c - Introduction to Ecore-Evas
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evas-object-manipulation.c - Introduction to object manipulation
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evas-transparent.c - Setting alpha transparency on objects
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== Event Handling ==
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@ -1,11 +1,8 @@
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/**
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* Example of basic object manipulation in Evas.
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*
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* The evas-buffer-simple.c example shows how to manually create and
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* manage buffers, but mentioned that real code would use higher level
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* functionality from Ecore's Ecore-Evas submodule. This example
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* shows the use of that submodule to create an Evas canvas and
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* manipulate the objects within it.
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* This example shows how to manipulate objects within an Ecore-Evas
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* canvas.
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*
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* Please note that this example uses Evas' legacy API. Compare this
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* implementation with evas-object-manipulation-eo.c to learn how the
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@ -28,6 +25,7 @@
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#include <Ecore.h>
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#include <Ecore_Evas.h>
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#include <stdio.h>
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#include <errno.h>
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#include "evas-common.h"
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@ -167,32 +165,16 @@ main(void)
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{
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int err;
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/* In other examples, evas_init() has been used to turn Evas on. In this
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* example we're using Ecore-Evas' init routine, which takes care of
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* bringing up Evas.
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*/
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if (!ecore_evas_init())
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return EXIT_FAILURE;
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/* In the evas-buffer-simple.c example, we coded our own
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* create_canvas() routine. Here we make use of Ecore-Evas's
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* ecore_evas_new() routine to do it. The first argument of this
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* function is used to specify the name of an engine we wish to use;
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* by passing NULL instead, we are requesting a window with an Evas
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* canvas using the first engine available.
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*/
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d.ee = ecore_evas_new(NULL, 10, 10, WIDTH, HEIGHT, NULL);
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if (!d.ee)
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goto error;
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/* Like other windowing systems, Ecore-Evas provides hooks for a
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* number of different events. We can register our own functions to
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* be called when the events occur in our window.
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*/
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ecore_evas_callback_resize_set(d.ee, _canvas_resize_cb);
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ecore_evas_show(d.ee);
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/* Retrieve a pointer to the canvas we created. */
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d.canvas = ecore_evas_get(d.ee);
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/* Create background. As mentioned earlier, the evas_object_*
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@ -206,10 +188,6 @@ main(void)
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evas_object_resize(d.bg, WIDTH, HEIGHT); /* covers full canvas */
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evas_object_show(d.bg);
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/* Callbacks can also be set on Evas objects. We'll add a keyboard
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* handler routine to the background rectangle, for processing user
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* key hits.
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*/
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evas_object_focus_set(d.bg, EINA_TRUE);
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evas_object_event_callback_add(
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d.bg, EVAS_CALLBACK_KEY_DOWN, _on_keydown, NULL);
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@ -1,5 +1,23 @@
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/**
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* Example of transparent windows in Evas.
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* Example of basic usage of Ecore-Evas and transparent windows.
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*
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* The evas-buffer-simple.c example shows how to manually create and
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* manage buffers, but mentioned that real code would use higher level
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* functionality from Ecore's Ecore-Evas submodule. This example
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* shows the use of that submodule to create a simple Evas canvas.
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*
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* This example also demonstrates how to create transparent windows with
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* Evas. Like in most other graphics software, transparency and
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* translucency is calculated using an integer parameter called an
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* 'alpha channel'. Support for alpha transparency is platform
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* dependent, and even where it is supported it may not be needed,
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* so Ecore-Evas provides a simple API to turn it on and off, which
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* this example will demonstrate by allowing it to be toggled via
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* the 'n' and 'm' keys on the keyboard.
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*
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* The keyboard input will introduce 'event handling' in Ecore-Evas, but
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* only briefly - we'll be exploring event handling in later examples
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* more deeply.
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*
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* @verbatim
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* gcc -o evas-transparent evas-transparent.c `pkg-config --libs --cflags evas ecore ecore-evas eina`
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@ -37,6 +55,9 @@ struct exemple_data
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static struct exemple_data d;
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/* Keyboard event callback routine, to enable toggling transparency on
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* and off.
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*/
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static void
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_on_keydown(void *data EINA_UNUSED,
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Evas *evas EINA_UNUSED,
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{
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Evas_Event_Key_Down *ev = einfo;
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if (strcmp(ev->key, "h") == 0) /* print help */
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if (strcmp(ev->key, "h") == 0)
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{
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/* h - print help */
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printf("%s", commands);
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return;
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}
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if (strcmp(ev->key, "n") == 0)
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{
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/* n - turn alpha transparency on */
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ecore_evas_alpha_set(d.ee, EINA_TRUE);
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printf("turn on alpha\n");
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@ -61,6 +84,7 @@ _on_keydown(void *data EINA_UNUSED,
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if (strcmp(ev->key, "m") == 0)
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{
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/* m - turn alpha transparency off */
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ecore_evas_alpha_set(d.ee, EINA_FALSE);
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printf("turn off alpha\n");
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@ -71,32 +95,81 @@ _on_keydown(void *data EINA_UNUSED,
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static void
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_on_delete(Ecore_Evas *ee EINA_UNUSED)
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{
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/* Communicate to ecore that the application is finished. Calling
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* this routine allows any pending events to get processed and allow
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* the main loop to finish the current iteration.
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*/
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ecore_main_loop_quit();
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}
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int
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main(void)
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{
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/* In other examples, evas_init() has been used to turn Evas on. In this
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* example we're using Ecore-Evas' init routine, which takes care of
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* bringing up Evas.
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*/
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if (!ecore_evas_init())
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return EXIT_FAILURE;
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/* In the evas-buffer-simple.c example, we coded our own
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* create_canvas() routine. Here we make use of Ecore-Evas's
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* ecore_evas_new() routine to do it. The first argument of this
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* function is used to specify the name of an engine we wish to use;
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* by passing NULL instead, we are requesting a window with an Evas
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* canvas using the first engine available.
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*
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* The next arguments set the canvas's position to 0,0 and its
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* height and width to our desired size.
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*
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* The last parameter for ecore_evas_new() allows setting extra
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* options, but for this example we don't need anything special
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* so just pass NULL.
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*/
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d.ee = ecore_evas_new(NULL, 0, 0, WIDTH, HEIGHT, NULL);
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if (!d.ee)
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goto panic;
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/* Like other windowing systems, Ecore-Evas provides hooks for a
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* number of different events. We can register our own functions to
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* be called when the events occur in our window. Here we'll register
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* a callback to be triggered when the window is closed.
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*/
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ecore_evas_callback_delete_request_set(d.ee, _on_delete);
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/* As in evas-buffer-simple.c, we need to explicitly 'unhide' our
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* Evas objects. But here we'll use the Ecore-Evas API to do this,
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* as it also manages some of the underlying device state.
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*/
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ecore_evas_show(d.ee);
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/* Retrieve a pointer to the canvas we created. */
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d.evas = ecore_evas_get(d.ee);
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/* Add a black background rectangle */
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d.bg = evas_object_rectangle_add(d.evas);
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evas_object_color_set(d.bg, 0, 0, 0, 0);
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evas_object_show(d.bg);
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/* Callbacks can also be set on Evas objects. We'll add a keyboard
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* handler routine to the background rectangle, for processing user
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* key hits.
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*/
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evas_object_focus_set(d.bg, EINA_TRUE);
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evas_object_event_callback_add(d.bg, EVAS_CALLBACK_KEY_DOWN,
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_on_keydown, NULL);
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/* Run the application until ecore_main_loop_quit() gets called by
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* our _on_delete() handler. While this function is active, it will
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* repeatedly call ecore_main_loop_iterate() to iterate through
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* various internal processes, checking for keyboard input, updating
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* the screen as needed, and so forth.
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*/
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ecore_main_loop_begin();
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/* With the application finished, we now direct the Ecore and Evas
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* libraries to perform final cleanup and terminate the system.
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*/
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ecore_evas_shutdown();
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return 0;
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