forked from enlightenment/efl
[evas] More love to a given example's text.
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@ -169,74 +169,114 @@
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* @page Example_Evas_Events Evas events (canvas and object ones) and some canvas operations example
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* @dontinclude evas-events.c
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*
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* In this example we illustrate how to interact with canvas' (and
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* its objects') events and other canvas operations.
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* In this example we illustrate how to interact with canvas' (and its
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* objects') events, including the key input ones. We also demonstrate
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* precise point collision on objects and canvas "obscured regions",
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* here.
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*
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* After we grab our canvas pointer, we registrate two event callbacks on it:
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* The example application consists of a window with a white
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* background and an image -- the Enlightenment logo. The application
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* begins with this image switching back and forth into two sizes: the
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* exact canvas' size and one quarter of it (when it's placed on the
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* top left quadrant). Thus, we'll have an @b animation going on,
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* with image states set to change each 2 elapsed seconds.
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*
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* There's a global variable to aid accessing our desired context
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* variables from anywhere in the code:
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* @dontinclude evas-events.c
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* @skip test_data
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* @until {0}
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*
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* What interests us there are the @c canvas pointer, our image handle
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* -- @c img -- and the background one, @c bg.
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*
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* The first interesting thing on the example is the registration of a
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* callback on each canvas resizing event, where we put our canvas'
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* size and the background rectangle's one in synchrony, so that we
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* don't get bogus content on rendering with canvas resizes:
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* @dontinclude evas-events.c
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* @skip resize_set
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* @until resize_set
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* @dontinclude evas-events.c
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* @skip here to keep
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* @until }
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*
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* Than, after grabbing our canvas pointer from the Ecore Evas helper
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* infrastructure, we registrate an event callbacks on it:
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* @skip evas_event_callback_add(d.canvas, EVAS_CALLBACK_RENDER_FLUSH_PRE,
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* @until two canvas event callbacks
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* The first of them, which has the following code,
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* @dontinclude evas-events.c
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* @skip render flush callback
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* @until }
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* will be called whenever our canvas has to flush its rendering pipeline.
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* In this example, two ways of observing that message which is printed in
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* the cited callback are:
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* It will be called whenever our canvas has to flush its rendering
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* pipeline. In this example, two ways of observing that message
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* which is printed in the cited callback are:
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* - to resize the example's window (thus resizing the canvas' viewport)
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* - let the animation run
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*
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* When one resizes the canvas, there's at least one operation it has
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* to do which will require new calculation for rendering: the
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* resizing of the background rectangle:
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* resizing of the background rectangle, in a callback we already
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* shown you.
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*
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* The creation of our background rectangle is so that we give it a @b name,
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* via evas_object_name_set() and we give it the canvas @b focus:
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* @dontinclude evas-events.c
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* @skip here just to keep
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* @skip bg = evas_object_rectangle_add
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* @until focus_set
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*
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* Still exempliflying events and callbacks, we register a callback on
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* the canvas event of an object being focused:
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* @dontinclude evas-events.c
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* @skip add(d.canvas, EVAS_CALLBACK_CANVAS_OBJECT_FOCUS
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* @until }
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* The animation we talked about comes from a timer we register just before
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* we start the example's main loop:
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* @dontinclude evas-events.c
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* @skip called when
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* @until }
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*
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* In that call, @c event_info is going to be the focused object's
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* handle, in this case our background rectangle. We print its name,
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* so you can check it's the same. We check that pointer is the same
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* reported by Evas' API with regard to the newest focused
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* object. Finally, we check whether that object is really flagged as
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* focused, now using an Evas object API function.
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*
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* The animation we talked about comes from a timer we register just
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* before we start the example's main loop. As we said, the resizing
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* of the image will also force the canvas to repaint itself, thus
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* flushing the rendering pipeline whenever the timer ticks:
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* @dontinclude evas-events.c
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* @skip d.resize_timer = ecore
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* @until d.resize_timer = ecore
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* being the timer's callback what follows:
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* @dontinclude evas-events.c
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* @skip put some action
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* @until }
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* As you see, the resizing of the image will also force the canvas to
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* repaint itself, thus flushing the rendering pipeline whenever the
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* timer ticks. When you start this example, this animation will be
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* When you start this example, this animation will be
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* running, by default. To interact with the program, there's a
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* command line interface. A help string can be asked for with the
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* 'h' key:
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* @dontinclude evas-events.c
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* @skip if (strcmp(ev->keyname, "h") == 0)
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* @until }
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* @skip static const char *commands
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* @until ;
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* These are the commands the example will accept at any time, except
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* when one triggers the 'f' one:
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* when one triggers the 'f' one. This command will exemplify
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* evas_event_freeze(), which interrupts @b all input events
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* processing for the canvas (in the example, just for 3 seconds). Try
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* to issue events for it during that freeze time:
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* @dontinclude evas-events.c
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* @skip if (strcmp(ev->keyname, "f") == 0)
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* @until }
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* This command will exemplify evas_event_freeze(), which interrupts
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* @b all input events processing for the canvas (in the example, just
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* for 3 seconds). Try to issue events for it during that freeze time.
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* The 'd' command will unregister those two canvas callbacks for you,
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* so you won't see the messages about the focused object and the
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* rendering process anymore:
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* @dontinclude evas-events.c
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* @skip if (strcmp(ev->keyname, "d") == 0)
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* @until }
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* The second of those callbacks has the following code:
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* @dontinclude evas-events.c
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* @skip called when our rectangle gets focus
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* In this example, we start using a focused object to handle the input
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* events -- the background rectangle. We register a callback on an key input
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* event occurring on it, so that we can act on each key stroke:
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* @skip object_event_callback_add
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* @until }
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* It will take place whenever an object in the canvas receives
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* focus. In this example, we use the focus to handle the input
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* events:
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* @skip so we get input events
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* @until }
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* The background rectangle is the chosen object to receive the
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* focus. This also illustrates the use of
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* evas_object_event_callback_add(), which registers an event callback
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* on an Evas @b object (in this case, the event of a key being
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* pressed down). On this callback, we examine each key pressed and,
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* if they match one between the expected, we take some actions:
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* @dontinclude evas-events.c
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* @skip examine the keys pressed
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* @until key grab
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@ -246,7 +286,7 @@
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* example -- evas_object_key_grab(). The 'c' command will, when
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* firstly used, @b unfocus the background rectangle. Unfocused
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* objects on an Evas canvas will @b never receive key events. We
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* grab, then, the keys we're interested at, to the object forcefully:
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* grab, then, the keys we're interested at to the object forcefully:
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* @skip if (d.focus)
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* @until got here by key grabs
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* This shows how one can handle input not depending on focus issues
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@ -254,10 +294,10 @@
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* forced key grabbing with the 'c' key, and observe the messages
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* printed about the focused object. Observe, also, that we register
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* two more @b object callbacks, this time on the image object
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* (Enlightenment logo):
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* (Enlightenment logo), where we just print messages telling the mouse
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* pointer has entered or exited it area:
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* @skip evas_object_show(d.img);
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* @until mouse_out, NULL
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* The code code blocks for those callbacks are
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* @dontinclude evas-events.c
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* @skip mouse enters the object's area
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* @until mouse exits the object's area
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@ -266,25 +306,25 @@
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* experience). When you start the example, Evas will consider this
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* area by being the whole boundary rectangle around the picture. If
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* you issue the 'p' command, though, you get a demonstration of Evas'
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* precise point collision detection on objects:
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* precise point collision detection on objects. With
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* evas_object_precise_is_inside_get(), one can make Evas consider the
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* transparent areas of an object (the middle of the logo's E letter,
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* in the case) as not belonging to it when calculating mouse
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* in/out/up/down events:
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* @dontinclude evas-events.c
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* @skip if (strcmp(ev->keyname, "p") == 0)
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* @until }
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* With evas_object_precise_is_inside_get(), one can make Evas
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* consider the transparent areas of an object (the middle of the
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* logo's E letter, in the case) as not belonging to it when
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* calculating mouse in/out/up/down events. To finish the example, try
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* the command bound to Cotrol + 'o':
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* @skip mods = evas_key_modifier_get(evas);
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* @until end of obscured region command
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* It exemplifies Evas' <b>obscured regions</b>. When firstly pressed,
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* you'll get the same contents, in a region in the middle of the
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* canvas, at the time the key was pressed, until you toggle the
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* To finish the example, try the command bound to Control + 'o',
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* which exemplifies Evas' <b>obscured regions</b>. When firstly
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* pressed, you'll get the same contents, in a region in the middle of
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* the canvas, at the time the key was pressed, until you toggle the
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* effect off again (make sure the animation is running on to get the
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* idea better). When you toggle this effect off, we also demonstrate
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* the use of evas_render_updates(), which will force immediate
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* updates on the canvas rendering, bringing back the obscured
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* region's contents to normal.
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* @skip mods = evas_key_modifier_get(evas);
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* @until end of obscured region command
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*
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* What follows is the complete code for this example.
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*
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@ -31,6 +31,16 @@
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static const char *img_path = PACKAGE_EXAMPLES_DIR "/enlightenment.png";
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static const char *commands = \
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"commands are:\n"
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"\ta - toggle animation timer\n"
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"\tc - cycle between focus and key grabs for key input\n"
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"\td - delete canvas callbacks\n"
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"\tf - freeze input for 3 seconds\n"
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"\tp - toggle precise point collision detection on image\n"
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"\tControl + o - add an obscured rectangle\n"
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"\th - print help\n";
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struct test_data
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{
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Ecore_Evas *ee;
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static struct test_data d = {0};
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/* here just to keep our example's window size and background image's
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/* here to keep our example's window size and background image's
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* size in synchrony */
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static void
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_canvas_resize_cb(Ecore_Evas *ee)
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"OK!" : "Oops, something is bad.");
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}
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static void /* render flush callback */
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/* render flush callback */
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static void
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_render_flush_cb(void *data __UNUSED__,
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Evas *e __UNUSED__,
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void *event_info __UNUSED__)
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return EINA_TRUE; /* re-issue the timer */
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}
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static Eina_Bool
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/* let's have our events back */
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static Eina_Bool
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_thaw_cb(void *data __UNUSED__)
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{
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fprintf(stdout, "Canvas was frozen %d times, now thawing.\n",
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return EINA_FALSE; /* do not re-issue the timer */
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}
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static void /* mouse enters the object's area */
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/* mouse enters the object's area */
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static void
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_on_mouse_in(void *data __UNUSED__,
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Evas *evas __UNUSED__,
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Evas_Object *o __UNUSED__,
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if (strcmp(ev->keyname, "h") == 0) /* print help */
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{
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fprintf(stdout,
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"commands are:\n"
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"\ta - toggle animation timer\n"
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"\tc - cycle between focus and key grabs for key input\n"
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"\td - delete canvas callbacks\n"
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"\tf - freeze input for 3 seconds\n"
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"\tp - toggle precise point collision detection on image\n"
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"\tControl + o - add an obscured rectangle\n\n"
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"\th - print help\n");
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fprintf(stdout, commands);
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return;
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}
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@ -393,6 +397,7 @@ main(void)
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d.resize_timer = ecore_timer_add(2, _resize_cb, NULL);
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fprintf(stdout, commands);
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ecore_main_loop_begin();
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ecore_evas_free(d.ee);
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