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# adskHttpSchemeResolver.py

    """
    Custom file resolver derived from MPxFileResolver that handles
    the URI 'htpp' scheme.
    When this resolver is active, URI file paths using the 'http://<domain>/'
    scheme will be processed using methods on this class.
    Refer to MPxFileResolver for more information about custom file resolvers.

    To use, make sure that adskHttpSchemeResolver.py is in
    your MAYA_PLUG_IN_PATH then do the following:

    # Load the plug-in
    import maya.cmds
    maya.cmds.loadPlugin("adskHttpSchemeResolver.py")
    # Once loaded, Maya will call the resolver methods in this plug-in when
    # a URI file path is encountered during file resolution processing
    # (file open, setAttr, etc.)
    # Unload the plug-in
    maya.cmds.unloadPlugin("adskHttpSchemeResolver")
    # Maya will no longer have access to this file
    # resolver to handle URI file paths using the 'http:///' scheme

    """

    import sys
    import maya.OpenMaya as OpenMaya
    import maya.OpenMayaMPx as OpenMayaMPx
    import maya.cmds as cmds
    import urllib
    import os.path

    #Specify the location for downloaded file
    kTempDir = cmds.internalVar(userTmpDir=True)

    # Set status messages on or off
    kWantStatusOutput = True;

    def downloadProgress(data, dataSize, fileSize):
        """ Display download progress - callback invoked by urllib.urlretrieve """
        percent = 100.0*data*dataSize/fileSize
        if percent > 100:
            percent = 100
        printStatus('Download progress: %.2f%%' % (percent))

    def printStatus(msg):
        """ Print status output for diagnostic purposes (when enabled) """
        if (kWantStatusOutput):
            sys.stderr.write('%s: %s\n' % (adskHttpSchemeResolver.className(), msg) )

    def printWarning(msg):
        """ Print warning messages """
        sys.stderr.write('Warning %s: %s\n' % (adskHttpSchemeResolver.className(), msg) )

    # 'http' scheme resolver
    class adskHttpSchemeResolver(OpenMayaMPx.MPxFileResolver):
        """
        This custom plug-in resolver handles the 'http' uri scheme.
        This resolver will copy the file from its 'http' location
        using standard url library to a temporary location. This temporary location
        of the file is the fully qualified resolved path.
        It also implements a crude caching system.
        """

        kPluginURIScheme = "http"
        kPluginResolverName = "adskHttpSchemeResolver"

        def __init__(self):
            OpenMayaMPx.MPxFileResolver.__init__(self)

        def uriScheme(self):
            return(self.kPluginURIScheme)

        def resolveURI(self,URI,mode):
            # Determine temporary location that will be used for this file
            uri = URI.asString()
            tempFile = kTempDir + URI.getFileName()
            result = u''

            # Check resolver mode, since not all modes require the file
            # to be downloaded.

            # When mode is kNone, simply return the resolved path
            if mode & OpenMayaMPx.MPxFileResolver.kNone:
                result = tempFile;

            # When mode is kInput, Maya is expecting to use this
            # file for input. Download the file to the temporary storage
            # area if it hasn't already been done.
            elif mode & OpenMayaMPx.MPxFileResolver.kInput:
                if not os.path.exists(tempFile):
                    # If the file does not exist in the cache then go and
                    # download it. At this point we assume we have a well
                    # formed URI and that it exists on the web somewhere
                    # Any error here and the resolved file is simply not
                    # found. Would need to code for all the errors that
                    # could go wrong here in a production case (lost
                    # connections, server down, etc.)
                    printStatus('Downloading URI: %s to location: %s' % (uri, tempFile))

                    data = urllib.urlretrieve(uri, tempFile, downloadProgress)
                    if os.path.exists(tempFile):
                        printStatus('Download complete')
                    else:
                        printWarning('Download failed for URI: %s to location: %s'
                                 % (uri, tempFile))
                    result = tempFile
                else:
                    printStatus('Download skipped, using cached version of URI: %s at location: %s'
                            % (uri, tempFile))
                    result = tempFile

            # Unexpected mode - simply return the resolved path
            else:
                printWarning('Unexpected resolve mode encountered: %s' % str(mode))
                result = tempFile

            # Return the resolved path
            return result

        def performAfterSaveURI(self,URI,resolvedFullPath):
            uri = URI.asString()
            printStatus('Uploading local file %s to URI location %s'
                            % (resolvedFullPath, uri))

        @staticmethod
        # Creator for the proxy instance
        def theCreator():
            return OpenMayaMPx.asMPxPtr( adskHttpSchemeResolver() )

        @staticmethod
        def className():
            return 'adskHttpSchemeResolver'

    # Initialize the script plug-in
    def initializePlugin(plugin):
        pluginFn = OpenMayaMPx.MFnPlugin(plugin)
        try:
            pluginFn.registerURIFileResolver( adskHttpSchemeResolver.kPluginResolverName,
                              adskHttpSchemeResolver.kPluginURIScheme,
                              adskHttpSchemeResolver.theCreator )
        except:
            sys.stderr.write( "Failed to register custom resolver: %s for scheme: %s\n" %
                      (adskHttpSchemeResolver.kPluginResolverName,
                       adskHttpSchemeResolver.kPluginURIScheme ))
            raise

    # Uninitialize the script plug-in
    def uninitializePlugin(plugin):
        pluginFn = OpenMayaMPx.MFnPlugin(plugin)
        try:
            pluginFn.deregisterURIFileResolver(adskHttpSchemeResolver.kPluginResolverName)
        except:
            sys.stderr.write(
                "Failed to deregister custom file resolver: %s\n" %
                adskHttpSchemeResolver.kPluginResolverName)
            raise

    #-
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