Driving win32 GUIs with Python, part 3

Some things you can do with a control once you have it.

See Driving win32 GUIs with Python, part 1 and Driving win32 GUIs with Python, part 2.

There are, of course, loads of things you can do with a control. Anything that you can do with a mouse or a keyboard can be automated. I'll just give a few simple examples, from which you should be able to extrapolate most things that you might need to do.

A great many of these actions are class specific - you can select one or many of a combo box's items, for example, but a button doesn't have items to select.

OK A nice simple one first. Let's click a button:

def click(hwnd):

    win32gui.SendMessage(hwnd, win32con.WM_LBUTTONDOWN, 0, 0)

    win32gui.SendMessage(hwnd, win32con.WM_LBUTTONUP, 0, 0)

We can use this function like so:

optDialog = findTopWindow(wantedText="Options")

def findAButtonCalledOK(hwnd, windowText, windowClass): # Define a function to find our button

    return windowClass == "Button" and windowText == "OK"

okButton = findControl(optDialog, findAButtonCalledOK)

click(okButton)

You could do this more tersely with a lambda, by the way:

optDialog = findTopWindow(wantedText="Options")

okButton = findControl(optDialog, lambda hwnd, windowText, windowClass : windowClass == "Button" and windowText == "OK") 

click(okButton)

I prefer the first form, but that's purely subjective.

And now, for my next trick, let's get the text from an Edit control. "But wait", you'll say, "can't you use the win32gui.GetWindowText() function"? No, actually, you can't. The thing is, this works for some classes of window - you can use win32gui.GetWindowText() to get the text of a button or a label, for example. But other classes don't have the kind of text that win32gui.GetWindowText() sets. An edit control is one of these - it has lines of text rather than just text. Here's a function which will get it for you:

def getEditText(hwnd):

    result = []

    bufferlength = struct.pack('i', 255)

    linecount = win32gui.SendMessage(hwnd, win32con.EM_GETLINECOUNT, 0, 0)

    for line in range(linecount):

        linetext = bufferlength + "".ljust(253)

        linelength = win32gui.SendMessage(hwnd, win32con.EM_GETLINE, line, linetext)

        result.append(linetext[:linelength])

    return result

The only complicated bit here is the struct stuff. When sending the win32con.EM_GETLINE, you need to pass a string, into which the line of text will be inserted. The first byte of this string must contain the total length of the string. struct to the rescue! It would be nice to wrap this up into a class, implementing a file-like interface, at some point. Or perhaps it should be a generator? Anyway, as it stands, you can use it like so:

genTop = findTopWindow(wantedText="Generating the Runtime")

def editFinder(hwnd, windowText, windowClass): return windowClass == "Edit"

genEdit = findControl(genTop, editFinder)

print getEditText(genEdit)

Now, combo-boxes. (These are the ones with a little down-arrow button to the right hand side, allowing you to select one (or perhaps more) from several options.) Here is the code to get a list of the values from a combo box:

def getComboboxItems(hwnd):

    result = []

    bufferlength = struct.pack('i', 255)

    itemCount = win32gui.SendMessage(hwnd, win32con.CB_GETCOUNT, 0, 0)

    for itemIndex in range(itemCount):

        linetext = bufferlength + "".ljust(253)

        linelength = win32gui.SendMessage(hwnd, win32con.CB_GETLBTEXT, itemIndex, linetext)

        result.append(linetext[:linelength])

    return result

Looks a bit like getEditText, doesn't it? I thought so - refactored version below:

def getMultipleWindowValues(hwnd, getCountMessage, getValueMessage):

    result = []

    bufferlength = struct.pack('i', 255)

    count = win32gui.SendMessage(hwnd, getCountMessage, 0, 0)

    for itemIndex in range(count):

        value = bufferlength + "".ljust(253)

        valueLength = win32gui.SendMessage(hwnd, getValueMessage, itemIndex, value)

        result.append(value[:valueLength])

    return result 


def getComboboxItems(hwnd): return getMultipleWindowValues(hwnd, getCountMessage=win32con.CB_GETCOUNT, getValueMessage=win32con.CB_GETLBTEXT)

def getEditText(hwnd): return getMultipleWindowValues(hwnd, getCountMessage=win32con.EM_GETLINECOUNT, getValueMessage=win32con.EM_GETLINE)

Last thing today - selection a combo-box item.

def selectComboboxItem(hwnd, item):

    win32gui.SendMessage(hwnd, win32con.CB_SETCURSEL, item, 0)

    click(hwnd)

    keystroke(hwnd, win32con.VK_RETURN)

    

def keystroke(hwnd, key):

    win32gui.SendMessage(hwnd, win32con.WM_KEYDOWN, key, 0)

    win32gui.SendMessage(hwnd, win32con.WM_KEYUP, key, 0)

I had hoped that the first of these messages would be enough. Unfortunately, it was not to be - while the selected item did change in the GUI, the application that I was automating didn't respond to the change without the click, and the drop-down list didn't disappear without the keystroke. If anyone can suggest a more elegant way of doing this, I'd be pleased to hear of it.

Here I put it all together

# Find the ACE window library selection combo

def findAceLibrarySelectionFunction(hwnd, windowText, windowClass): return windowClass == "ComboBox" and ("EVO1" in getComboboxItems(hwnd))    

libCombo = findControl(findTopWindow(wantedText="ACE"), findAceLibrarySelectionFunction)


# Get a list of the combo items

items = getComboboxItems(libCombo)

print "Items: " + str(items)

import random

# Pick one at random, and select it    

selectItemIndex = random.randrange(len(items))

print "Selecting: " + items[selectItemIndex]

selectComboboxItem(libCombo, selectItemIndex)

Well, that's just about it from me on this, really, though if anything else occurs to me, you'll be sure to know. ;-)

Update: See the whole series: Driving win32 GUIs with Python, part 1, Driving win32 GUIs with Python, part 2, Driving win32 GUIs with Python, part 3, Driving win32 GUIs with Python, part 4 and 7 hours, one line of code.

Posted to Python by Simon Brunning at March 21, 2003 04:59 PM