// Hot-plug is easy: just check that the device is online
if(
display
->
isOnline
())
{
// Use display->get_displayLayer(), ...
}
Let's look at these lines in more details.
yocto_api.h et yocto_display.h
These two include files provide access to the functions allowing you to manage Yoctopuce modules.
yocto_api.h
must always be used,
yocto_display.h
is necessary to manage modules
containing a display, such as Yocto-Display.
yRegisterHub
The
yRegisterHub
function initializes the Yoctopuce API and indicates where the modules should
be looked for. When used with the parameter
"usb"
, it will use the modules locally connected to the
computer running the library. If the initialization does not succeed, this function returns a value
different from
YAPI_SUCCESS
and
errmsg
contains the error message.
yFindDisplay
The
yFindDisplay
function allows you to find a display from the serial number of the module on
which it resides and from its function name. You can use logical names as well, as long as you have
initialized them. Let us imagine a Yocto-Display module with serial number
YD128X32-123456
which
you have named "
MyModule
", and for which you have given the
display
function the name
"
MyFunction
". The following five calls are strictly equivalent, as long as "
MyFunction
" is defined only
once.
YDisplay
*
display
=
yFindDisplay
(
"YD128X32-123456.display"
);
YDisplay
*
display
=
yFindDisplay
(
"YD128X32-123456.MyFunction"
);
YDisplay
*
display
=
yFindDisplay
(
"MyModule.display"
);
YDisplay
*
display
=
yFindDisplay
(
"MyModule.MyFunction"
);
YDisplay
*
display
=
yFindDisplay
(
"MyFunction"
);
yFindDisplay
returns an object which you can then use at will to control the display.
isOnline
The
isOnline()
method of the object returned by
yFindDisplay
allows you to know if the
corresponding module is present and in working order.
get_displayLayer
The
get_diplayLayer()
method of the object returned by
YFindDisplay
allows you to
retrieve the object corresponding to one of the screen layers. This object implements all the graphical
routines.
A real example
Launch your C++ environment and open the corresponding sample project provided in the directory
Examples/Doc-GettingStarted-Yocto-Display
of the Yoctopuce library. If you prefer to work with
your favorite text editor, open the file
main.cpp
, and type
make
to build the example when you are
done.
In this example, you will recognize the functions explained above, but this time used with all side
materials needed to make it work nicely as a small demo.
#include "yocto_api.h"
#include "yocto_display.h"
#include <iostream>
#include <stdio.h>
#include <stdlib.h>
using
namespace
std
;
11. Using Yocto-Display with C++
58
www.yoctopuce.com
Содержание Yocto-Display
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Страница 158: ...22 High level API Reference 152 www yoctopuce com On failure throws an exception or returns a negative error code...
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Страница 424: ...24 Characteristics 418 www yoctopuce com...