Locating and targeting user interface elements in Robocorp Lab

Your robot needs to locate user interface elements, such as buttons. For web-based applications, when the HTML markup provides identifiers for the elements, locating them is straightforward. With desktop applications, locating and targeting the elements might be more difficult. The following examples demonstrate locator auto-completion in different types of applications.

Important: The locator auto-completion works only in the Notebook mode.

Locator auto-completion (Calculator, Windows 10)

Automated Windows Calculator

This example demonstrates the interactive element locator using the Calculator application in Windows 10. The robot:

  • opens the Calculator application
  • adds two numbers together, using the user interface buttons
  • logs the result
*** Settings ***
Library           RPA.Desktop.Windows
Library           String

*** Keywords ***
Open the Calculator
    Open Executable    calc.exe    Calculator

*** Keywords ***
Add two numbers
    [Arguments]    ${first}    ${second}
    Mouse Click    id:clearEntryButton
    Mouse Click    id:num${first}Button
    Mouse Click    # Need to find the plus button locator
    Mouse Click    id:num${second}Button
    Mouse Click    id:equalButton

*** Keywords ***
Read the result
    ${result}=    Get Element Rich Text    id:CalculatorResults
    ${_}    ${result}=    Split String From Right    ${result}    max_split=1
    [Return]    ${result}

*** Tasks ***
Calculate and log the result
    Open the Calculator
    Add two numbers    5    7
    ${result}=    Read the result
    Log    ${result}

We are missing a locator for the plus button in the script:

Mouse Click    # Need to find the plus button locator

In Robocorp Lab, with the Calculator application visible so that you can click on it, type in the locator prefix uia:. This prefix is used to trigger the locator auto-completion:

Mouse Click    uia:

With the cursor placed after the prefix (uia:), press Ctrl+Space on your keyboard. The mouse cursor changes into a crosshair. With the crosshair, click on the plus button on the Calculator user interface. You will see a list of available locators for that element:

Robocorp Lab: Element locator auto-completion

Click on the automation_id:plusButton locator to insert it into the script.

Image template matching (Paint, Windows 10)

Automated Windows Paint

Some applications do not expose their internals in a way that can be targeted using textual locators. In these situations, you can try image template matching. This example demonstrates the use of image templates with the Paint application in Windows 10.

The RPA.Desktop library is a cross-platform solution for navigating and interacting with desktop environments (Windows, Linux, macOS!). It can be used to automate applications through the same interfaces that are available to human users.

Add the rpaframework-recognition package as a dependency in the conda.yaml file to enable image template matching:

channels:
  - conda-forge
dependencies:
  - python=3.7.5
  - pip=20.1
  - pip:
      - rpaframework==9.3.0
      - rpaframework-recognition==0.7.0

The robot:

  • opens the Paint application
  • selects the Text tool
  • uses the Text tool to type on the canvas
*** Settings ***
Library           RPA.Desktop

*** Keywords ***
Open Paint
    Open Application    mspaint.exe

*** Keywords ***
Write on canvas
    Wait For Element    # Insert UI locator alias
    Click    # Insert UI locator alias
    Move Mouse    # Insert UI locator alias
    Click    offset:0,100
    Type Text    Paint
    Type Text    ${SPACE}
    Type Text    >
    Type Text    ${SPACE}
    Type Text    insert-your-favorite-image-editing-software-here

*** Tasks ***
Do a paint operation
    Open Paint
    Write on canvas

We are missing the UI locator aliases for the Text tool and the canvas in the script:

Wait For Element    # Insert UI locator alias
Click    # Insert UI locator alias
Move Mouse    # Insert UI locator alias
Click    offset:0,100

Open the UI locator interface

Press Ctrl+Shift+U (Windows / Linux) or Shift-Command-U (macOS) to open the UI locators interface.

Add a new locator

Press the + button to add a new locator:

Add a new UI locator

Select Image Based and click Pick UI Area:

Robocorp Lab: UI locators: Image Based: Pick UI Area

macOS: Robocorp Lab will ask for permissions. Go to System Preferences -> Security & Privacy and check Robocorp Lab in the Accessibility and Screen Recording sections.

The mouse cursor changes into a crosshair. With the crosshair, drag a rectangle around the Text button on the Paint user interface. Select only the element that you are targeting:

Robocorp Lab: Image locator selector tool

When running the robot, the mouse click will target the center of the selected image.

Robocorp Lab saves a screenshot of the selection. Provide a name for the locator (Paint.TextTool). Click Add:

Robocorp Lab: UI locators: Name

The locators are stored in the locators.json file at the root of your robot. The images are stored in the .images directory. The files can be shared with other developers. This way, you can build locator libraries for your applications and reuse them over and over again!

Copy the UI locator alias to the clipboard using the copy button:

Robocorp Lab: UI locators: Copy alias

Paste the UI locator alias into the robot script:

Wait For Element    alias:Paint.TextTool
Click    alias:Paint.TextTool

Now that we have the Text tool located, the remaining locator should help the robot to find the canvas to type on. Repeat the above steps, this time selecting the Tools text:

Robocorp Lab: Image locator selector tool

Store the locator using Paint.ToolsLabel as the name. Copy the locator alias and paste it into the robot script:

Move Mouse    alias:Paint.ToolsLabel
Click    offset:0, 100

Why did we select that particular element? One option for finding the canvas is to use a reference point on the user interface and then click somewhere under that point. In this case, we decided the Tools text is pretty stable (it will stay there even if the window size is bigger than expected). Using the reference point, we can instruct the robot to find that point and then click 100 pixels under that point (offset:0, 100).

The finalized Write on canvas keyword implementation looks like this:

*** Keywords ***
Write on canvas
    Wait For Element    alias:Paint.TextTool
    Click    alias:Paint.TextTool
    Move Mouse    alias:Paint.ToolsLabel
    Click    offset:0, 100
    Type Text    Paint
    Type Text    space
    Type Text    >
    Type Text    space
    Type Text    insert-your-favorite-image-editing-software-here

Performance considerations

The image template matching takes a screenshot of the entire screen for every match operation. This can add a 500-1500ms delay depending on the operating system, screen resolution, CPU, and other factors.

Locator auto-completion for browsers

Robocorp Lab: Browser locator selector tool

Robocorp Lab assists in selecting elements when using a web browser.

Important: The locator auto-completion works only when the robot script is executed in the Notebook mode.

Run the following Robot script once in Robocorp Lab to open a browser. The Lab keeps track of the opened browser so that you can interact with it using locators. The script will complain about invalid selectors. No worries, you are going to complete the selectors soon!

Note that Robocorp Lab can communicate only with browsers that it has opened itself (for example, using the Open Available Browser keyword from the RPA.Browser.Selenium library). You will not be able to interact with a browser that you opened manually.

*** Settings ***
Library           RPA.Browser.Selenium

*** Tasks ***
Click on elements on a website
    Open Available Browser    https://google.com/
    Click Element    css:
    Click Element    id:

The CSS locator

Let's locate the Google Search button at https://google.com/. Here is the HTML markup for the button:

<input
  class="gNO89b"
  value="Google Search"
  aria-label="Google Search"
  name="btnK"
  type="submit"
  data-ved="0ahUKEwiD_ta6lL3rAhWF_KQKHXkXB70Q4dUDCAs"
/>

With the cursor placed after the CSS locator prefix (css:), press Ctrl+Space on your keyboard. In the browser, click on the Google Search button. You will see a list of locators. Click on the name:btnK locator to insert it into the script:

Robocorp Lab: CSS element locator auto-completion

The ID locator

With the cursor placed after the ID locator prefix (id:), press Ctrl+Space on your keyboard. You will see a list of HTML id attribute locators:

Robocorp Lab: ID element locator auto-completion

Other locators

Use the link: prefix to locate links and the name: prefix to locate elements having a name attribute.

UI locators

UI locators enable you to create and store user interface locators so that they can be shared and reused. Let's create a named locator for the search field on google.com.

Open the UI locator interface

Press Ctrl+Shift+U (Windows) or Shift-Command-U (macOS) to open the UI locators interface.

Add a new locator

Press the + button to add a new locator:

Add a new UI locator

The locator requires a name. The suggested format is Website.ElementName. In our case, let's use Google.SearchField, where Google is the group name and SearchField is the element name (you could later add Google.SearchButton, Google.LoginLink, etc.).:

Naming the UI locator

Locate the element

Press Start to launch a new browser. Navigate to google.com. Press Locate and click on the search field. The locator is detected. The strategy, value, and the source of the locator are displayed:

UI locator auto-detection

Store the locator

Click Add to store the locator. You will see useful information, such as the name, type, and even a screenshot of the locator:

Stored UI locator

Use the stored locator

To use the stored locator in your robot, copy the locator alias:

Copy the UI locator

Paste the UI locator alias:

*** Settings ***
Documentation     Locator UI demonstration.
Library           RPA.Browser.Selenium

*** Tasks ***
Search for "dinosaur" on google.com
    Open Available Browser    https://www.google.com/
    Input Text When Element Is Visible    alias:Google.SearchField    dinosaur

The UI locators feature is still very new. Please try it out and give feedback!

Conclusion

Robocorp Lab assists you with finding the user interface elements for your robot.

Learn more about the libraries mentioned on this page: