ArcGIS Engine Developer Guide

BUILDING APPLICATIONS WITH C++ AND CONTROL WIDGETS
d. Remember to clean up the global variables when the application closes.
// Function called when WM_DELETE_WINDOW protocol is passed
void CloseAppCallback(Widget w, XtPointer client_data, XtPointer
call_data)
{
…
delete g_tocEvents;
g_ipPopupMenu = 0;
g_ipFillSymbol = 0;
g_ipCurrentExtent = 0;
g_ipToolbarControl = 0;
3. To have the MapControl work as an overview window, it must display the full
extent of the data. Since this needs to be done every time there is a new map
document, the following code should be placed into the
PageLayoutControlEvents.cpp file’s OnPageLayoutReplaced event.
void PageLayoutControlEvents::OnPageLayoutReplaced(VARIANT newPageLayout)
{
// Load the same pre-authored map document into the MapControl
CComBSTR DocFileName;
IPageLayoutControl2Ptr ipPage2 = g_ipPageLayoutControl;
ipPage2->get_DocumentFilename(&DocFileName);
g_ipMapControl->LoadMxFile(DocFileName);
// Set the extent of the MapControl to be the full extent
IEnvelopePtr ipFullExtentEnv;
g_ipMapControl->get_FullExtent(&ipFullExtentEnv);
g_ipMapControl->put_Extent(ipFullExtentEnv);
}
4. The global variable g_ipCurrentExtent, which will be used to draw the overview
on the MapControl, needs to be updated with every new PageLayout. To
implement this, you will need access to the g_ipCurrentExtent global variable
from within the PageLayoutControlEvents class. Add the following into
PageLayoutControlEvents.h:
extern IToolbarMenuPtr g_ipPopupMenu;
extern IEnvelopePtr g_ipCurrentExtent;
5. To update the extent rectangle on the overview map to match the extent
shown in every new PageLayout, you need to set the current extent rectangle to
match the visible extent of the PageLayout’s map. Do this in the
OnPageLayoutReplaced event (in PageLayoutControlEvents.cpp).
void PageLayoutControlEvents::OnPageLayoutReplaced(VARIANT newPageLayout)
{
// Get the extent of the PageLayout's focus map
IActiveViewPtr ipActiveView;
g_ipPageLayoutControl->get_ActiveView(&ipActiveView);
IMapPtr ipFocusMap;
384 • ArcGIS Engine Developer Guide