ExportPNG.FCMacro

import os
from datetime import datetime

def exportViewToPNG():
    '''Exports the current view to a PNG suitable for printing on A4 or Letter.
       The filename will be e.g. MyProject-view.png in the project directory.'''
    # Reference: http://www.freecadweb.org/wiki/index.php?title=Std_ViewScreenShot

    # Create an image which fits on an A4 or Letter page at 300dpi, landscape
    width = 11 * 300    # inside letter
    height = int(8.26 * 300) # inside A4

    doc = FreeCAD.ActiveDocument

    if not doc.FileName:
        FreeCAD.Console.PrintError('Must save project first\n')
        return

    docDir, docFilename = os.path.split(doc.FileName)

    filePrefix = os.path.splitext(docFilename)[0]
    dt=datetime.now().strftime("%Y-%m-%d-%H-%M-%S")

    filename = filePrefix + '-' + dt + '.png'
    filePath = os.path.join(docDir, 'img/', filename)

    FreeCAD.Console.PrintMessage("Saving view to %s\n" % filePath)
    FreeCADGui.ActiveDocument.ActiveView.saveImage(filePath.encode("utf-8"), width, height, 'White')

exportViewToPNG()