Yoctopuce Yocto-Display, User Manual

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Then add in the same manner the
yapi.dll
DLL, located in the
Sources/dll
directory
4
. Then,
from the Solution Explorer window, right click on the DLL, select Properties and in the Properties
panel, set the Copy to output folder to always . You are now ready to use your Yoctopuce modules
from Visual Studio.
In order to keep them simple, all the examples provided in this documentation are console
applications. Naturally, the libraries function in a strictly identical manner if you integrate them in an
application with a graphical interface.
13.3. Control of the Display function
A few lines of code are enough to use a Yocto-Display. Here is the skeleton of a Visual Basic code
snipplet to use the Display function.
[...]
Dim
errmsg As String errmsg
Dim display As YDisplay
REM Get access to your device, connected locally on USB for instance
yRegisterHub ( "usb" , errmsg )
display = yFindDisplay ( "YD128X32-123456.display" )
REM Hot - plug is easy: just check that the device is online
If ( display . isOnline ()) Then
REM Use display . get_displayLayer () , ...
End If
Let's look at these lines in more details.
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.
display = yFindDisplay ( "YD128X32-123456.display" )
display = yFindDisplay ( "YD128X32-123456.MyFunction" )
display = yFindDisplay ( "MyModule.display" )
display = yFindDisplay ( "MyModule.MyFunction" )
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.
4
Remember to change the filter of the selection window, otherwise the DLL will not show.
13. Using Yocto-Display with Visual Basic .NET
72 www.yoctopuce.com