|Microsoft DirectX 9.0|
After adding individual filters to the filter graph, you can establish connections between the filters by explicitly connecting each pin, or by automatically generating all connections that are needed downstream from a specific pin.
In both cases, you must traverse the hierarchy of Microsoft® DirectShow® objects to obtain the IPinInfo object that represents a pin of the filter object. This involves finding the desired filter in the filter collection of the filter graph object, then finding the desired pin in the pin collection of the filter object.
This section contains the following topics.
All filters in the filter graph are available in a collection that you can access using the FilgraphManager.FilterCollection property.
' refresh a list box that contains the current filters in the graph listFilters.Clear For Each objFI In g_objMC.FilterCollection listFilters.AddItem objFI.Name ' add to list box Next objFI
You can access the pins defined for a filter object through the IFilterInfo.Pins property. The Pins property is a collection of individual IPinInfo objects.
After you obtain an individual IPinInfo object from the collection, you can access its properties and call its methods, as shown in the following code fragment.
For Each objPin In g_objSelFilter.Pins If objPin.Name = listPins.Text Then ' selected pin? Set g_objSelPin = objPin ' yes, update information ' ... perform operations using that pin End If Next objPin
After you have obtained the pin object, you can explicitly connect to one other pin or automatically generate all subsequent pin connections needed to render the pin.
The IPinInfo object provides three methods to connect pins: Connect, ConnectDirect, and ConnectWithType. Connect adds other transform filters as needed, ConnectDirect does not add transform filters, and ConnectWithType performs the connection only if the specified pin matches the specified media type.
frmSelectPin.OtherDir = g_objSelPin.Direction Set frmSelectPin.Graph = g_objMC ' give that form a copy of the graph Set frmSelectPin.SelFilter = g_objSelFilter ' and the current filter frmSelectPin.RefreshFilters ' display available filters to connect frmSelectPin.Show 1 ' display the form If frmSelectPin.bOK Then ' user has selected one--used OK button Dim objPI As IPinInfo Set objPI = frmSelectPin.SelPin ' get the new pin from the form g_objSelPin.Connect objPI ' connect the two pins RefreshFilters ' display the latest pin information End If
Call the IPinInfo.Render method to automatically generate all portions of the filter graph that are needed downstream from that pin.
The term downstream refers to all connections needed to construct a complete path from that pin to a renderer filter. For example, consider the representation of the filter graph by the GraphEdit utility, which shows connections as moving from the source filter at the left to the renderer filter at the right. The Render method adds all required filters and connections to the right of the specified pin.
' call IPinInfo.Render ' complete the graph downstream from this pin ' g_objSelPin refers to the pin selected in the list box labeled 'Pins' g_objSelPin.Render