hwUnlitShader/NodeMonitor.cpp

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// NodeMonitor.cpp

// DESCRIPTION: This class monitors a given node. 
//
// TODO: Take care of renamed nodes.
//
// AUTHOR: Christian Laforte
//

#include <assert.h>
#include "NodeMonitor.h"

MObject getObjFromName(MString name, MStatus& stat)
{
    MObject obj;
    
    MSelectionList list;
    
    // Attempt to add the given name to the selection list,
    // then get the corresponding dependency node handle.
    if (!list.add(name) ||
        !list.getDependNode(0, obj))
    {
        // Failed.
        stat = MStatus::kInvalidParameter;
        return obj;
    }

    // Successful.
    stat = MStatus::kSuccess;
    return obj;
}

// If a problem occurs, this function returns an empty string.
MString getNameFromObj(MObject obj)
{
    MString nodeName;

    // If this object is a MFnDagNode, we should store the dag name.
    // Otherwise, use the MFnDependencyNode name.
    if (obj.hasFn(MFn::kDagNode))
    {
        MFnDagNode dagNode(obj);
        nodeName = dagNode.fullPathName();
    }
    else if (obj.hasFn(MFn::kDependencyNode))
    {
        MFnDependencyNode node(obj);
        nodeName = node.name();
    }

    return nodeName;
}


//-----------------------------------------------------------
// Public interface:
//-----------------------------------------------------------

NodeMonitor::NodeMonitor(NodeMonitorManager* manager /* = NULL */)
{
    fNodeName = "";
    fIsDirty = false;
    
    fRenamedCallbackId = 0;
    fDirtyCallbackId = 0;

    fManager = manager;
}

NodeMonitor::~NodeMonitor()
{
    stopWatching();
}

bool NodeMonitor::watch(MString nodeName)
{
    // if already watching another object, release the callbacks.
    stopWatching();

    fNodeName = nodeName;
    return attachCallbacks();
}

bool NodeMonitor::watch(MObject nodeObj)
{
    MString newNodeName = getNameFromObj(nodeObj);

    // If already watching another object, release the callbacks.
    stopWatching();

    // Get the name of the given object... since an MObject is not
    // persistent. We'll use the name of the object to attach/re-attach
    // callbacks when necessary.
    if (newNodeName == "")
    {
        // This is bad. We've been given an invalid node object.
        // return false to indicate that an error occured.

        return false;
    }

    fNodeName = newNodeName;
    return attachCallbacks();   
}

void NodeMonitor::stopWatching()
{
    if (fNodeName != "")
    {
        // Clean up the callbacks
        detachCallbacks();

        fNodeName = "";
        fIsDirty = false;
    }
}

bool NodeMonitor::dirty()
{
    return fIsDirty;
}

void NodeMonitor::cleanIt()
{
    if (dirty())
    {
        // We have to re-attach the callback.
        attachCallbacks();
    }

    fIsDirty = false;
}


//----------------------------------------------------------------
// Private interface:
//----------------------------------------------------------------

bool NodeMonitor::attachCallbacks()
{
    // Make sure that there are no callbacks currently enabled.
    detachCallbacks();

    MStatus stat;
    MObject node = getObjFromName(fNodeName, stat);
    if (!stat)
    {
        detachCallbacks();
        return false;
    }

    fIsDirty = false;

    fDirtyCallbackId = MNodeMessage::addNodeDirtyCallback(node, watchedObjectDirtyCallback, this, &stat );
    if (stat)
    {
        fRenamedCallbackId = MNodeMessage::addNameChangedCallback (node, watchedObjectRenamedCallback, this, &stat); 
    }

    // If an error occured, detach any valid callback.
    if (!stat)
    {
        detachCallbacks();
        return false;
    }

    return true;
}

void NodeMonitor::detachCallbacks()
{
    MStatus stat;

    if (fDirtyCallbackId)
    {
        stat = MMessage::removeCallback(fDirtyCallbackId);
        assert(stat);
    }

    if (fRenamedCallbackId)
    {
        stat = MMessage::removeCallback(fRenamedCallbackId);
        assert(stat);
    }

    fRenamedCallbackId = 0;
    fDirtyCallbackId = 0;
}

void NodeMonitor::callbackOccured()
{
    fIsDirty = true;

    // Detach the callback so that we don't get called needlessly. We'll
    // re-attach when the dirty bit is read back.
    detachCallbacks();
}

// Callback functions. Those are called, respectively, when a node is dirty (has changed substantially),
// or when a node is renamed.

/*static*/ void NodeMonitor::watchedObjectDirtyCallback(void* clientData)
{
    NodeMonitor* pMon = (NodeMonitor*) clientData;

    pMon->callbackOccured();
}

/*static*/ void NodeMonitor::watchedObjectRenamedCallback(MObject & node, void* clientData)
{
    NodeMonitor* pMon = (NodeMonitor*) clientData;

    // Get the new name of the node, and use it from now on.
    MString oldName = pMon->fNodeName;
    pMon->fNodeName = getNameFromObj(node);
    
    // Call the manager, if there's one.
    if (pMon->fManager != NULL)
        pMon->fManager->onNodeRenamed(node, oldName, pMon->fNodeName);

    pMon->callbackOccured();
}