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authorBryce Harrington <bryce@osg.samsung.com>2017-07-11 11:29:07 +0900
committerJean-Philippe Andre <jp.andre@samsung.com>2017-07-11 11:29:07 +0900
commit0e19bde33c902c0765edb38090b383619f00882c (patch)
tree242c7c8a4320517cddc64cbf002dafee4be42569
parentecore_evas_drm: Refuse to start a ticker for a manually rendered canvas (diff)
downloadefl-0e19bde33c902c0765edb38090b383619f00882c.tar.gz
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
-rw-r--r--src/examples/evas/README4
-rw-r--r--src/examples/evas/evas-object-manipulation.c28
-rw-r--r--src/examples/evas/evas-transparent.c77
3 files changed, 80 insertions, 29 deletions
diff --git a/src/examples/evas/README b/src/examples/evas/README
index 8bd00468ae..e32ad1ecd3 100644
--- a/src/examples/evas/README
+++ b/src/examples/evas/README
@@ -10,9 +10,9 @@ points to start from in learning more advanced topics.
== Basic Evas ==
evas-init-shutdown.c - Introduction to Evas
-evas-buffer-simple.c - Using the buffer engine
+evas-buffer-simple.c - Using the Evas buffer engine
+evas-transparent.c - Introduction to Ecore-Evas
evas-object-manipulation.c - Introduction to object manipulation
-evas-transparent.c - Setting alpha transparency on objects
== Event Handling ==
diff --git a/src/examples/evas/evas-object-manipulation.c b/src/examples/evas/evas-object-manipulation.c
index c1735ba941..e5be8c0aaf 100644
--- a/src/examples/evas/evas-object-manipulation.c
+++ b/src/examples/evas/evas-object-manipulation.c
@@ -1,11 +1,8 @@
/**
* Example of basic object manipulation in Evas.
*
- * The evas-buffer-simple.c example shows how to manually create and
- * manage buffers, but mentioned that real code would use higher level
- * functionality from Ecore's Ecore-Evas submodule. This example
- * shows the use of that submodule to create an Evas canvas and
- * manipulate the objects within it.
+ * This example shows how to manipulate objects within an Ecore-Evas
+ * canvas.
*
* Please note that this example uses Evas' legacy API. Compare this
* implementation with evas-object-manipulation-eo.c to learn how the
@@ -28,6 +25,7 @@
#include <Ecore.h>
#include <Ecore_Evas.h>
+
#include <stdio.h>
#include <errno.h>
#include "evas-common.h"
@@ -167,32 +165,16 @@ main(void)
{
int err;
- /* In other examples, evas_init() has been used to turn Evas on. In this
- * example we're using Ecore-Evas' init routine, which takes care of
- * bringing up Evas.
- */
if (!ecore_evas_init())
return EXIT_FAILURE;
- /* In the evas-buffer-simple.c example, we coded our own
- * create_canvas() routine. Here we make use of Ecore-Evas's
- * ecore_evas_new() routine to do it. The first argument of this
- * function is used to specify the name of an engine we wish to use;
- * by passing NULL instead, we are requesting a window with an Evas
- * canvas using the first engine available.
- */
d.ee = ecore_evas_new(NULL, 10, 10, WIDTH, HEIGHT, NULL);
if (!d.ee)
goto error;
- /* Like other windowing systems, Ecore-Evas provides hooks for a
- * number of different events. We can register our own functions to
- * be called when the events occur in our window.
- */
ecore_evas_callback_resize_set(d.ee, _canvas_resize_cb);
ecore_evas_show(d.ee);
- /* Retrieve a pointer to the canvas we created. */
d.canvas = ecore_evas_get(d.ee);
/* Create background. As mentioned earlier, the evas_object_*
@@ -206,10 +188,6 @@ main(void)
evas_object_resize(d.bg, WIDTH, HEIGHT); /* covers full canvas */
evas_object_show(d.bg);
- /* Callbacks can also be set on Evas objects. We'll add a keyboard
- * handler routine to the background rectangle, for processing user
- * key hits.
- */
evas_object_focus_set(d.bg, EINA_TRUE);
evas_object_event_callback_add(
d.bg, EVAS_CALLBACK_KEY_DOWN, _on_keydown, NULL);
diff --git a/src/examples/evas/evas-transparent.c b/src/examples/evas/evas-transparent.c
index 4ea74866cf..1d4d67d210 100644
--- a/src/examples/evas/evas-transparent.c
+++ b/src/examples/evas/evas-transparent.c
@@ -1,5 +1,23 @@
/**
- * Example of transparent windows in Evas.
+ * Example of basic usage of Ecore-Evas and transparent windows.
+ *
+ * The evas-buffer-simple.c example shows how to manually create and
+ * manage buffers, but mentioned that real code would use higher level
+ * functionality from Ecore's Ecore-Evas submodule. This example
+ * shows the use of that submodule to create a simple Evas canvas.
+ *
+ * This example also demonstrates how to create transparent windows with
+ * Evas. Like in most other graphics software, transparency and
+ * translucency is calculated using an integer parameter called an
+ * 'alpha channel'. Support for alpha transparency is platform
+ * dependent, and even where it is supported it may not be needed,
+ * so Ecore-Evas provides a simple API to turn it on and off, which
+ * this example will demonstrate by allowing it to be toggled via
+ * the 'n' and 'm' keys on the keyboard.
+ *
+ * The keyboard input will introduce 'event handling' in Ecore-Evas, but
+ * only briefly - we'll be exploring event handling in later examples
+ * more deeply.
*
* @verbatim
* gcc -o evas-transparent evas-transparent.c `pkg-config --libs --cflags evas ecore ecore-evas eina`
@@ -37,6 +55,9 @@ struct exemple_data
static struct exemple_data d;
+/* Keyboard event callback routine, to enable toggling transparency on
+ * and off.
+ */
static void
_on_keydown(void *data EINA_UNUSED,
Evas *evas EINA_UNUSED,
@@ -45,14 +66,16 @@ _on_keydown(void *data EINA_UNUSED,
{
Evas_Event_Key_Down *ev = einfo;
- if (strcmp(ev->key, "h") == 0) /* print help */
+ if (strcmp(ev->key, "h") == 0)
{
+ /* h - print help */
printf("%s", commands);
return;
}
if (strcmp(ev->key, "n") == 0)
{
+ /* n - turn alpha transparency on */
ecore_evas_alpha_set(d.ee, EINA_TRUE);
printf("turn on alpha\n");
@@ -61,6 +84,7 @@ _on_keydown(void *data EINA_UNUSED,
if (strcmp(ev->key, "m") == 0)
{
+ /* m - turn alpha transparency off */
ecore_evas_alpha_set(d.ee, EINA_FALSE);
printf("turn off alpha\n");
@@ -71,32 +95,81 @@ _on_keydown(void *data EINA_UNUSED,
static void
_on_delete(Ecore_Evas *ee EINA_UNUSED)
{
+ /* Communicate to ecore that the application is finished. Calling
+ * this routine allows any pending events to get processed and allow
+ * the main loop to finish the current iteration.
+ */
ecore_main_loop_quit();
}
int
main(void)
{
+ /* In other examples, evas_init() has been used to turn Evas on. In this
+ * example we're using Ecore-Evas' init routine, which takes care of
+ * bringing up Evas.
+ */
if (!ecore_evas_init())
return EXIT_FAILURE;
+ /* In the evas-buffer-simple.c example, we coded our own
+ * create_canvas() routine. Here we make use of Ecore-Evas's
+ * ecore_evas_new() routine to do it. The first argument of this
+ * function is used to specify the name of an engine we wish to use;
+ * by passing NULL instead, we are requesting a window with an Evas
+ * canvas using the first engine available.
+ *
+ * The next arguments set the canvas's position to 0,0 and its
+ * height and width to our desired size.
+ *
+ * The last parameter for ecore_evas_new() allows setting extra
+ * options, but for this example we don't need anything special
+ * so just pass NULL.
+ */
d.ee = ecore_evas_new(NULL, 0, 0, WIDTH, HEIGHT, NULL);
if (!d.ee)
goto panic;
+ /* Like other windowing systems, Ecore-Evas provides hooks for a
+ * number of different events. We can register our own functions to
+ * be called when the events occur in our window. Here we'll register
+ * a callback to be triggered when the window is closed.
+ */
ecore_evas_callback_delete_request_set(d.ee, _on_delete);
+
+ /* As in evas-buffer-simple.c, we need to explicitly 'unhide' our
+ * Evas objects. But here we'll use the Ecore-Evas API to do this,
+ * as it also manages some of the underlying device state.
+ */
ecore_evas_show(d.ee);
+ /* Retrieve a pointer to the canvas we created. */
d.evas = ecore_evas_get(d.ee);
+ /* Add a black background rectangle */
d.bg = evas_object_rectangle_add(d.evas);
evas_object_color_set(d.bg, 0, 0, 0, 0);
evas_object_show(d.bg);
+ /* Callbacks can also be set on Evas objects. We'll add a keyboard
+ * handler routine to the background rectangle, for processing user
+ * key hits.
+ */
evas_object_focus_set(d.bg, EINA_TRUE);
evas_object_event_callback_add(d.bg, EVAS_CALLBACK_KEY_DOWN,
_on_keydown, NULL);
+
+ /* Run the application until ecore_main_loop_quit() gets called by
+ * our _on_delete() handler. While this function is active, it will
+ * repeatedly call ecore_main_loop_iterate() to iterate through
+ * various internal processes, checking for keyboard input, updating
+ * the screen as needed, and so forth.
+ */
ecore_main_loop_begin();
+
+ /* With the application finished, we now direct the Ecore and Evas
+ * libraries to perform final cleanup and terminate the system.
+ */
ecore_evas_shutdown();
return 0;