ArcGIS Engine Developer Guide

BUILDING APPLICATIONS WITH C++ AND CONTROL WIDGETS
}
The ICommand_OnCreate event is passed a
handle or hook to the application that the
command will work with. In this case it can be a
MapControl, PageLayoutControl, or
ToolbarControl. Rather than adding code to
the OnCreate event to determine the type of
hook that is being passed to the command, you
will use the HookHelper to handle this. A
command or tool needs to know how to handle
the hook it gets passed, so a check is needed to
determine the type of ArcGIS control that has
been passed. The HookHelper is used to hold the
hook and return the ActiveView regardless of the
type of hook (in this case a MapControl,
PageLayoutControl, or ToolbarControl).
// Create the command and set who it will work with
HRESULT AddDateTool::OnCreate(IDispatch* hook)
{
if (!hook)
return E_POINTER;
m_ipHookHelper->putref_Hook(hook);
return S_OK;
}
HRESULT AddDateTool::OnClick()
{
return S_OK;
}
e. Write a function that will format the date for display on the
PageLayoutControl.
i. Before the class in AddDate.h, include the following header files:
#include
#include
#include
ii. Add a private function to the AddDate class in AddDate.h to take care
of the formatting.
OLE_HANDLE m_hCursor;
char* FormatDate();
iii. Implement the function at the bottom of AddDate.cpp.
char* AddDateTool::FormatDate()
{
time_t dateInfo = time(NULL);
tm* todaysDate = localtime(&dateInfo);
int month = todaysDate->tm_mon + 1;
int day = todaysDate->tm_mday;
int year = todaysDate->tm_year + 1900;
char* dateDisplay = new char[12];
sprintf(dateDisplay, "%d/%d/%d\n", month, day, year);
return dateDisplay;
}
f. Continue implementing your custom tool by stubbing out all the properties
and events of the ITool interface before the FormatDate function in
AddDate.cpp. Pay attention to the implementation of the OnMouseDown
method, as it creates the date text element and adds it to the graphics
container of the application.
HRESULT AddDateTool::OnClick()
{
return S_OK;
}
Chapter 6 • Developer scenarios • 397