• On Windows, there are no other modules to install.

• On OS X, run sudo pip3 install pyobjc-framework-Quartz, sudo pip3 install pyobjc-core, and then sudo pip3 install pyobjc.

• On Linux, run sudo pip3 install python3-xlib, sudo apt-get install scrot, sudo apt-get install python3-tk, and sudo apt-get install python3-dev. (Scrot is a screenshot program that PyAutoGUI uses.)

Perhaps the simplest way to stop an out-of-control GUI automation program is to log out, which will shut down all running programs. On Windows and Linux, the logout hotkey is CTRL-ALT-DEL. On OS X, it is -SHIFT-OPTION-Q. By logging out, you’ll lose any unsaved work, but at least you won’t have to wait for a full reboot of the computer.

You can tell your script to wait after every function call, giving you a short window to take control of the mouse and keyboard if something goes wrong. To do this, set the pyautogui.PAUSE variable to the number of seconds you want it to pause. For example, after setting pyautogui.PAUSE = 1.5, every PyAutoGUI function call will wait one and a half seconds after performing its action. Non-PyAutoGUI instructions will not have this pause.

PyAutoGUI also has a fail-safe feature. Moving the mouse cursor to the upper-left corner of the screen will cause PyAutoGUI to raise the pyautogui.FailSafeException exception. Your program can either handle this exception with try and except statements or let the exception crash your program. Either way, the fail-safe feature will stop the program if you quickly move the mouse as far up and left as you can. You can disable this feature by setting pyautogui.FAILSAFE = False. Enter the following into the interactive shell:

>>> import pyautogui
>>> pyautogui.PAUSE = 1
>>> pyautogui.FAILSAFE = True

Here we import pyautogui and set pyautogui.PAUSE to 1 for a one-second pause after each function call. We set pyautogui.FAILSAFE to True to enable the fail-safe feature.

Now that you understand screen coordinates, let’s move the mouse. The pyautogui.moveTo() function will instantly move the mouse cursor to a specified position on the screen. Integer values for the x- and y-coordinates make up the function’s first and second arguments, respectively. An optional duration integer or float keyword argument specifies the number of seconds it should take to move the mouse to the destination. If you leave it out, the default is 0 for instantaneous movement. (All of the duration keyword arguments in PyAutoGUI functions are optional.) Enter the following into the interactive shell:

>>> import pyautogui
>>> for i in range(10):
      pyautogui.moveTo(100, 100, duration=0.25)
      pyautogui.moveTo(200, 100, duration=0.25)
      pyautogui.moveTo(200, 200, duration=0.25)
      pyautogui.moveTo(100, 200, duration=0.25)

This example moves the mouse cursor clockwise in a square pattern among the four coordinates provided a total of ten times. Each movement takes a quarter of a second, as specified by the duration=0.25 keyword argument. If you hadn’t passed a third argument to any of the pyautogui.moveTo() calls, the mouse cursor would have instantly teleported from point to point.

The pyautogui.moveRel() function moves the mouse cursor relative to its current position. The following example moves the mouse in the same square pattern, except it begins the square from wherever the mouse happens to be on the screen when the code starts running:

>>> import pyautogui
>>> for i in range(10):
      pyautogui.moveRel(100, 0, duration=0.25)
      pyautogui.moveRel(0, 100, duration=0.25)
      pyautogui.moveRel(-100, 0, duration=0.25)
      pyautogui.moveRel(0, -100, duration=0.25)

pyautogui.moveRel() also takes three arguments: how many pixels to move horizontally to the right, how many pixels to move vertically downward, and (optionally) how long it should take to complete the movement. A negative integer for the first or second argument will cause the mouse to move left or upward, respectively.

You can determine the mouse’s current position by calling the pyautogui.position() function, which will return a tuple of the mouse cursor’s x and y positions at the time of the function call. Enter the following into the interactive shell, moving the mouse around after each call:

>>> pyautogui.position()
(311, 622)
>>> pyautogui.position()
(377, 481)
>>> pyautogui.position()
(1536, 637)

Of course, your return values will vary depending on where your mouse cursor is.

• Display the current x- and y-coordinates of the mouse cursor.

• Update these coordinates as the mouse moves around the screen.

• Call the position() function to fetch the current coordinates.

• Erase the previously printed coordinates by printing \b backspace characters to the screen.

• Handle the KeyboardInterrupt exception so the user can press CTRL-C to quit.

Start your program with the following:

#! python3
# mouseNow.py - Displays the mouse cursor's current position.
import pyautogui
print('Press Ctrl-C to quit.')
#TODO: Get and print the mouse coordinates.

The beginning of the program imports the pyautogui module and prints a reminder to the user that they have to press CTRL-C to quit.

You can use an infinite while loop to constantly print the current mouse coordinates from mouse.position(). As for the code that quits the program, you’ll need to catch the KeyboardInterrupt exception, which is raised whenever the user presses CTRL-C. If you don’t handle this exception, it will display an ugly traceback and error message to the user. Add the following to your program:

   #! python3
   # mouseNow.py - Displays the mouse cursor's current position.
   import pyautogui
   print('Press Ctrl-C to quit.')
   try:
       while True:
           # TODO: Get and print the mouse coordinates.
❶ except KeyboardInterrupt:
❷     print('\nDone.')

To handle the exception, enclose the infinite while loop in a try statement. When the user presses CTRL-C, the program execution will move to the except clause ❶ and Done. will be printed in a new line ❷.

The code inside the while loop should get the current mouse coordinates, format them to look nice, and print them. Add the following code to the inside of the while loop:

#! python3
# mouseNow.py - Displays the mouse cursor's current position.
import pyautogui
print('Press Ctrl-C to quit.')
--snip--
        # Get and print the mouse coordinates.
        x, y = pyautogui.position()
        positionStr = 'X: ' + str(x).rjust(4) + ' Y: ' + str(y).rjust(4)
--snip--

Using the multiple assignment trick, the x and y variables are given the values of the two integers returned in the tuple from pyautogui.position(). By passing x and y to the str() function, you can get string forms of the integer coordinates. The rjust() string method will right-justify them so that they take up the same amount of space, whether the coordinate has one, two, three, or four digits. Concatenating the right-justified string coordinates with 'X: ' and ' Y: ' labels gives us a neatly formatted string, which will be stored in positionStr.

At the end of your program, add the following code:

   #! python3
   # mouseNow.py - Displays the mouse cursor's current position.
   --snip--
           print(positionStr, end='')
❶         print('\b' * len(positionStr), end='', flush=True)

This actually prints positionStr to the screen. The end='' keyword argument to print() prevents the default newline character from being added to the end of the printed line. It’s possible to erase text you’ve already printed to the screen—but only for the most recent line of text. Once you print a newline character, you can’t erase anything printed before it.

To erase text, print the \b backspace escape character. This special character erases a character at the end of the current line on the screen. The line at ❶ uses string replication to produce a string with as many \b characters as the length of the string stored in positionStr, which has the effect of erasing the positionStr string that was last printed.

For a technical reason beyond the scope of this book, always pass flush=True to print() calls that print \b backspace characters. Otherwise, the screen might not update the text as desired.

Since the while loop repeats so quickly, the user won’t actually notice that you’re deleting and reprinting the whole number on the screen. For example, if the x-coordinate is 563 and the mouse moves one pixel to the right, it will look like only the 3 in 563 is changed to a 4.

When you run the program, there will be only two lines printed. They should look like something like this:

Press Ctrl-C to quit.
X: 290 Y: 424

The first line displays the instruction to press CTRL-C to quit. The second line with the mouse coordinates will change as you move the mouse around the screen. Using this program, you’ll be able to figure out the mouse coordinates for your GUI automation scripts.

To send a virtual mouse click to your computer, call the pyautogui.click() method. By default, this click uses the left mouse button and takes place wherever the mouse cursor is currently located. You can pass x- and y-coordinates of the click as optional first and second arguments if you want it to take place somewhere other than the mouse’s current position.

If you want to specify which mouse button to use, include the button keyword argument, with a value of 'left', 'middle', or 'right'. For example, pyautogui.click(100, 150, button='left') will click the left mouse button at the coordinates (100, 150), while pyautogui.click(200, 250, button='right') will perform a right-click at (200, 250).

Enter the following into the interactive shell:

>>> import pyautogui
>>> pyautogui.click(10, 5)

You should see the mouse pointer move to near the top-left corner of your screen and click once. A full “click” is defined as pushing a mouse button down and then releasing it back up without moving the cursor. You can also perform a click by calling pyautogui.mouseDown(), which only pushes the mouse button down, and pyautogui.mouseUp(), which only releases the button. These functions have the same arguments as click(), and in fact, the click() function is just a convenient wrapper around these two function calls.

As a further convenience, the pyautogui.doubleClick() function will perform two clicks with the left mouse button, while the pyautogui.rightClick() and pyautogui.middleClick() functions will perform a click with the right and middle mouse buttons, respectively.

Dragging means moving the mouse while holding down one of the mouse buttons. For example, you can move files between folders by dragging the folder icons, or you can move appointments around in a calendar app.

PyAutoGUI provides the pyautogui.dragTo() and pyautogui.dragRel() functions to drag the mouse cursor to a new location or a location relative to its current one. The arguments for dragTo() and dragRel() are the same as moveTo() and moveRel(): the x-coordinate/horizontal movement, the y-coordinate/vertical movement, and an optional duration of time. (OS X does not drag correctly when the mouse moves too quickly, so passing a duration keyword argument is recommended.)

To try these functions, open a graphics-drawing application such as Paint on Windows, Paintbrush on OS X, or GNU Paint on Linux. (If you don’t have a drawing application, you can use the online one at http://sumopaint.com/.) I will use PyAutoGUI to draw in these applications.

With the mouse cursor over the drawing application’s canvas and the Pencil or Brush tool selected, enter the following into a new file editor window and save it as spiralDraw.py:

   import pyautogui, time
❶ time.sleep(5)
❷ pyautogui.click()    # click to put drawing program in focus
   distance = 200
   while distance > 0:
❸     pyautogui.dragRel(distance, 0, duration=0.2)   # move right
❹     distance = distance - 5
❺     pyautogui.dragRel(0, distance, duration=0.2)   # move down
❻     pyautogui.dragRel(-distance, 0, duration=0.2)  # move left
       distance = distance - 5
       pyautogui.dragRel(0, -distance, duration=0.2)  # move up

When you run this program, there will be a five-second delay ❶ for you to move the mouse cursor over the drawing program’s window with the Pencil or Brush tool selected. Then spiralDraw.py will take control of the mouse and click to put the drawing program in focus ❷. A window is in focus when it has an active blinking cursor, and the actions you take—like typing or, in this case, dragging the mouse—will affect that window. Once the drawing program is in focus, spiralDraw.py draws a square spiral pattern like the one in Figure 18-2.

Figure 18-2. The results from the pyautogui.dragRel() example

The distance variable starts at 200, so on the first iteration of the while loop, the first dragRel() call drags the cursor 200 pixels to the right, taking 0.2 seconds ❸. distance is then decreased to 195 ❹, and the second dragRel() call drags the cursor 195 pixels down ❺. The third dragRel() call drags the cursor –195 horizontally (195 to the left) ❻, distance is decreased to 190, and the last dragRel() call drags the cursor 190 pixels up. On each iteration, the mouse is dragged right, down, left, and up, and distance is slightly smaller than it was in the previous iteration. By looping over this code, you can move the mouse cursor to draw a square spiral.

You could draw this spiral by hand (or rather, by mouse), but you’d have to work slowly to be so precise. PyAutoGUI can do it in a few seconds!

The final PyAutoGUI mouse function is scroll(), which you pass an integer argument for how many units you want to scroll the mouse up or down. The size of a unit varies for each operating system and application, so you’ll have to experiment to see exactly how far it scrolls in your particular situation. The scrolling takes place at the mouse cursor’s current position. Passing a positive integer scrolls up, and passing a negative integer scrolls down. Run the following in IDLE’s interactive shell while the mouse cursor is over the IDLE window:

>>> pyautogui.scroll(200)

You’ll see IDLE briefly scroll upward—and then go back down. The downward scrolling happens because IDLE automatically scrolls down to the bottom after executing an instruction. Enter this code instead:

>>> import pyperclip
>>> numbers = ''
>>> for i in range(200):
      numbers = numbers + str(i) + '\n'

>>> pyperclip.copy(numbers)

This imports pyperclip and sets up an empty string, numbers. The code then loops through 200 numbers and adds each number to numbers, along with a newline. After pyperclip.copy(numbers), the clipboard will be loaded with 200 lines of numbers. Open a new file editor window and paste the text into it. This will give you a large text window to try scrolling in. Enter the following code into the interactive shell:

>>> import time, pyautogui
>>> time.sleep(5); pyautogui.scroll(100)

On the second line, you enter two commands separated by a semicolon, which tells Python to run the commands as if they were on separate lines. The only difference is that the interactive shell won’t prompt you for input between the two instructions. This is important for this example because we want to the call to pyautogui.scroll() to happen automatically after the wait. (Note that while putting two commands on one line can be useful in the interactive shell, you should still have each instruction on a separate line in your programs.)

After pressing ENTER to run the code, you will have five seconds to click the file editor window to put it in focus. Once the pause is over, the pyautogui.scroll() call will cause the file editor window to scroll up after the five-second delay.

To take screenshots in Python, call the pyautogui.screenshot() function. Enter the following into the interactive shell:

>>> import pyautogui
>>> im = pyautogui.screenshot()

The im variable will contain the Image object of the screenshot. You can now call methods on the Image object in the im variable, just like any other Image object. Enter the following into the interactive shell:

>>> im.getpixel((0, 0))
(176, 176, 175)
>>> im.getpixel((50, 200))
(130, 135, 144)

Pass getpixel() a tuple of coordinates, like (0, 0) or (50, 200), and it’ll tell you the color of the pixel at those coordinates in your image. The return value from getpixel() is an RGB tuple of three integers for the amount of red, green, and blue in the pixel. (There is no fourth value for alpha, because screenshot images are fully opaque.) This is how your programs can “see” what is currently on the screen.

Say that one of the steps in your GUI automation program is to click a gray button. Before calling the click() method, you could take a screenshot and look at the pixel where the script is about to click. If it’s not the same gray as the gray button, then your program knows something is wrong. Maybe the window moved unexpectedly, or maybe a pop-up dialog has blocked the button. At this point, instead of continuing—and possibly wreaking havoc by clicking the wrong thing—your program can “see” that it isn’t clicking on the right thing and stop itself.

PyAutoGUI’s pixelMatchesColor() function will return True if the pixel at the given x- and y-coordinates on the screen matches the given color. The first and second arguments are integers for the x- and y-coordinates, and the third argument is a tuple of three integers for the RGB color the screen pixel must match. Enter the following into the interactive shell:

   >>> import pyautogui
   >>> im = pyautogui.screenshot()
❶ >>> im.getpixel((50, 200))
   (130, 135, 144)
❷ >>> pyautogui.pixelMatchesColor(50, 200, (130, 135, 144))
   True
❸ >>> pyautogui.pixelMatchesColor(50, 200, (255, 135, 144))
   False

After taking a screenshot and using getpixel() to get an RGB tuple for the color of a pixel at specific coordinates ❶, pass the same coordinates and RGB tuple to pixelMatchesColor() ❷, which should return True. Then change a value in the RGB tuple and call pixelMatchesColor() again for the same coordinates ❸. This should return false. This method can be useful to call whenever your GUI automation programs are about to call click(). Note that the color at the given coordinates must exactly match. If it is even slightly different—for example, (255, 255, 254) instead of (255, 255, 255)—then pixelMatchesColor() will return False.

The pyautogui.typewrite() function sends virtual keypresses to the computer. What these keypresses do depends on what window and text field have focus. You may want to first send a mouse click to the text field you want in order to ensure that it has focus.

As a simple example, let’s use Python to automatically type the words Hello world! into a file editor window. First, open a new file editor window and position it in the upper-left corner of your screen so that PyAutoGUI will click in the right place to bring it into focus. Next, enter the following into the interactive shell:

>>> pyautogui.click(100, 100); pyautogui.typewrite('Hello world!')

Notice how placing two commands on the same line, separated by a semicolon, keeps the interactive shell from prompting you for input between running the two instructions. This prevents you from accidentally bringing a new window into focus between the click() and typewrite() calls, which would mess up the example.

Python will first send a virtual mouse click to the coordinates (100, 100), which should click the file editor window and put it in focus. The typewrite() call will send the text Hello world! to the window, making it look like Figure 18-3. You now have code that can type for you!

Figure 18-3. Using PyAutogGUI to click the file editor window and type Hello world! into it

By default, the typewrite() function will type the full string instantly. However, you can pass an optional second argument to add a short pause between each character. This second argument is an integer or float value of the number of seconds to pause. For example, pyautogui.typewrite('Hello world!', 0.25) will wait a quarter-second after typing H, another quarter-second after e, and so on. This gradual typewriter effect may be useful for slower applications that can’t process keystrokes fast enough to keep up with PyAutoGUI.

For characters such as A or !, PyAutoGUI will automatically simulate holding down the SHIFT key as well.

Not all keys are easy to represent with single text characters. For example, how do you represent SHIFT or the left arrow key as a single character? In PyAutoGUI, these keyboard keys are represented by short string values instead: 'esc' for the ESC key or 'enter' for the ENTER key.

Instead of a single string argument, a list of these keyboard key strings can be passed to typewrite(). For example, the following call presses the A key, then the B key, then the left arrow key twice, and finally the X and Y keys:

>>> pyautogui.typewrite(['a', 'b', 'left', 'left', 'X', 'Y'])

Because pressing the left arrow key moves the keyboard cursor, this will output XYab. Table 18-1 lists the PyAutoGUI keyboard key strings that you can pass to typewrite() to simulate pressing any combination of keys.

You can also examine the pyautogui.KEYBOARD_KEYS list to see all possible keyboard key strings that PyAutoGUI will accept. The 'shift' string refers to the left SHIFT key and is equivalent to 'shiftleft'. The same applies for 'ctrl', 'alt', and 'win' strings; they all refer to the left-side key.

Much like the mouseDown() and mouseUp() functions, pyautogui.keyDown() and pyautogui.keyUp() will send virtual keypresses and releases to the computer. They are passed a keyboard key string (see Table 18-1) for their argument. For convenience, PyAutoGUI provides the pyautogui.press() function, which calls both of these functions to simulate a complete keypress.

Run the following code, which will type a dollar sign character (obtained by holding the SHIFT key and pressing 4):

>>> pyautogui.keyDown('shift'); pyautogui.press('4'); pyautogui.keyUp('shift')

This line presses down SHIFT, presses (and releases) 4, and then releases SHIFT. If you need to type a string into a text field, the typewrite() function is more suitable. But for applications that take single-key commands, the press() function is the simpler approach.

A hotkey or shortcut is a combination of keypresses to invoke some application function. The common hotkey for copying a selection is CTRL-C (on Windows and Linux) or ⌘-C (on OS X). The user presses and holds the CTRL key, then presses the C key, and then releases the C and CTRL keys. To do this with PyAutoGUI’s keyDown() and keyUp() functions, you would have to enter the following:

pyautogui.keyDown('ctrl')
pyautogui.keyDown('c')
pyautogui.keyUp('c')
pyautogui.keyUp('ctrl')

This is rather complicated. Instead, use the pyautogui.hotkey() function, which takes multiple keyboard key string arguments, presses them in order, and releases them in the reverse order. For the CTRL-C example, the code would simply be as follows:

pyautogui.hotkey('ctrl', 'c')

This function is especially useful for larger hotkey combinations. In Word, the CTRL-ALT-SHIFT-S hotkey combination displays the Style pane. Instead of making eight different function calls (four keyDown() calls and four keyUp() calls), you can just call hotkey('ctrl', 'alt', 'shift', 's').

With a new IDLE file editor window in the upper-left corner of your screen, enter the following into the interactive shell (in OS X, replace 'alt' with 'ctrl'):

   >>> import pyautogui, time
   >>> def commentAfterDelay():
❶       pyautogui.click(100, 100)
❷       pyautogui.typewrite('In IDLE, Alt-3 comments out a line.')
         time.sleep(2)
❸       pyautogui.hotkey('alt', '3')

   >>> commentAfterDelay()

This defines a function commentAfterDelay() that, when called, will click the file editor window to bring it into focus ❶, type In IDLE, Atl-3 comments out a line ❷, pause for 2 seconds, and then simulate pressing the ALT-3 hotkey (or CTRL-3 on OS X) ❸. This keyboard shortcut adds two # characters to the current line, commenting it out. (This is a useful trick to know when writing your own code in IDLE.)

• moveTo(x, y). Moves the mouse cursor to the given x and y coordinates.

• moveRel(xOffset, yOffset). Moves the mouse cursor relative to its current position.

• dragTo(x, y). Moves the mouse cursor while the left button is held down.

• dragRel(xOffset, yOffset). Moves the mouse cursor relative to its current position while the left button is held down.

• click(x, y, button). Simulates a click (left button by default).

• rightClick(). Simulates a right-button click.

• middleClick(). Simulates a middle-button click.

• doubleClick(). Simulates a double left-button click.

• mouseDown(x, y, button). Simulates pressing down the given button at the position x, y.

• mouseUp(x, y, button). Simulates releasing the given button at the position x, y.

• scroll(units). Simulates the scroll wheel. A positive argument scrolls up; a negative argument scrolls down.

• typewrite(message). Types the characters in the given message string.

• typewrite([key1, key2, key3]). Types the given keyboard key strings.

• press(key). Presses the given keyboard key string.

• keyDown(key). Simulates pressing down the given keyboard key.

• keyUp(key). Simulates releasing the given keyboard key.

• hotkey([key1, key2, key3]). Simulates pressing the given keyboard key strings down in order and then releasing them in reverse order.

• screenshot(). Returns a screenshot as an Image object. (See Chapter 17 for information on Image objects.)