Amindu Viduranga (AndrewViduranga)
Virtusa | Polaris pvt Ltd.
Associate Consultant - Technology
Virtusa | Polaris pvt Ltd.
AndrewViduranga Member since 2012 2 posts
Virtusa | Polaris pvt Ltd.
Posted: December 5, 2018
Last activity: May 19, 2019
Posted: 5 Dec 2018 10:23 EST
Last activity: 19 May 2019 6:05 EDT

Pega-Robotics: Capturing the screen from a Pega Robotic Automation

Pega robotic automation allows to access the user's screen in order to capture a screenshot. This is represented by a static object called 'PrimaryScreen' which resides in the namespace 'System.Windows.Forms' . Here is the link for the documentation.


Note that the Assembly name is System.Windows.Forms.dill

Lets add this static property in to the toolbox. In the Pega Robotic studio, Go to 'Tools' -> 'Choose Toolbox Items...' -> 'Pega Robotics Static Members' -> 'From Global Assembly Cache'

Now from the 'Assembly' drop down, select the above mentioned assembly. Note that I have selected System.Windows.Forms, Version= as below.

Also note that when expanding the tree option 'Screen', you can see the 'PrimaryScreen' static property as above. check it and click Ok. The 'PrimaryScreen' static object will then be in your tool box under 'All Windows Forms' as below.

Now lets start to write the automation. I'm using the automation's 'Started' event to trigger the logic.

I have added a label called 'Capture Screen' and whenever the automation started the execution will direct to this label. Here's how the automation looks like.

As the fist step, extract a proxy from 'PrimaryScreen' that we just added into the tool box. This will provide a proxy of type 'System.Windows.Form.Screen'. Using the properties window, rename it as 'Screen'.

At this point the automation looks like below.

Same way, access the properties of the proxy 'Screen' using the object explorer window and extract a proxy of 'Bounds' object. This will provide a proxy of type System.Drawing.Rectangle. Rename it as 'Rectanlge'.

At this point, the automation looks like below.

Now we are going to create a Bitmap object. For this we need to access 'Add Constructor for Type' icon in the toolbar.

Click that Icon and click back again in the automation area. Type 'System Drawing Bitmap'. When typing, the options will be narrow down to the exact match. Press enter when you find the exact match.

When enter is pressed, we might need to select the exact constructor.

As highlighted above, select the constructor which accepts two Int32 variable called width and height and a PixelFormat object called 'format' and click ok. The bitmap object we just created will then be available in somewhere in the automation area as below.

Rename this object as 'BitMapImage'. Access the properties 'Height' and 'Width' of the the proxy 'Rectangle' and pass the same appropriately into the object 'BitMapImage'. Also select the pixel format as 'Format32bppRgb'. Now your automation looks like below.

Now that we have successfully created the Bitmap. Its the time to form an image from it. Again there is a static method called 'FormImage' in the 'Graphics' class. Here is the documentation.


According to the documentation, this time I'm going to select the assembly 'System.Drawing, Version='. Once the tree option 'Graphics' is expanded, I can find the 'FormImage' method as below.

Once added, I can find the method in the toolbox under 'All Windows Forms' as below.

Now I'm going to add another label called 'Get screen' in my automation. when the bit map was created, I'll be jumping into the new label and then continue the rest from there. First thing I'm going to do in the newly added label is capture the graphics. For that, I am passing the 'BitMapImage' in to the newly added static method 'FormImage'. When we extract a proxy from the results, it will give me the graphics that I needed. Following is how the automation looks like when complete these steps.

Rename the newly extracted proxy of type 'System.Drawing.Graphics' as 'BitMapGraphics'.

Now we are going to fill all the graphics. For that, we need to access following properties of the 'Rectangle' proxy.

1.) Left

2.) Top

3.) X

4.) Y

5.) Size

In order to understand why we need these properties, lets run the automation by adding a break point where we extract the 'Rectangle' proxy.

Add a break point as above an run the automation. Once the execution stops at the break point go to 'Debug' -> 'Windows' -> 'Automation Locals' . In the top most entry, you can see the string representation of the 'PrimaryScreen' object.

Note that as per the automation, we created the 'Rectangle' object from 'PrimaryScreen' through 'Bounds' object through proxies. Therefore the relevant properties in the rectangle is successfully initiated as below.

Imagine when you use snipping tool to capture the whole screen. Then you would start placing the pointer from the top left corner of the screen and drag it up to bottom right corner to capture the entire screen. This dragging will be form a rectangle by adjusting the area we need to capture.

Same way, we need a rectangle which's top left corner to be placed in the screen's top left corner and then resize it's size to the screen's resolution.

The screen's top left corner is considered as (0,0). We need the same coordinates to place our rectangle start point. Then the X and Y values should be initialized into zeros. As we see in the automation local values the TOP, LEFT, X and Y are initialized as appropriately as we need. The SIZE has two values, which is 1366 and 768 in above example. This is the current screen's resolution. This is the exact reason the we used the 'PrimaryScreen'. It is the exact size we need to capture the entire screen. Therefore, even if the screen resolution changes, we do not need to worry at all. This is the reason to use above property values in our next step.

As the next step, I'll be using the above values to capture the graphics for entire screen. I'm using the method 'CopyFromScreen' method of 'BitMapGraphics' proxy that we extracted earlier. Following is how the automation looks like when completing these steps.

Most of the time, we might need to send this captured image into an integrated application with this robotic automation, (E.g. Pega) and not saving it locally. We can use base 64 encoded strings to represent this image. Let's look in to that also.

I'm going to add a new label in to my automation called 'Get Base64'. The first thing I'm going to do is creating a memory stream object. As we did earlier, use 'Add Constructor for Type' option. This time type 'System.IO.MemoryStream'. Also choose the default constructor as below.

Rename the object as 'ImageMemoryStream'. Now I'm going to invoke the 'Save' method of 'BitMapImage' object that we created earlier by passing this memory stream object that we just crated and set the image format as PNG (This image format can be selected from a drop down in that method. Also note that we need to use the save method which accepts a memory stream. There might be overloaded methods). After that I'm going to invoke the 'ImageMemoryStream' object's 'ToArray' to get the byte array representation of the image.

Finally add the ToBase64String method by using the same way we added the other static methods and properties into the toolbox. This time I'll be using the assembly 'mscorlib, Version=' depicted in the below figure.

Also expand the tree option 'Convert' and choose the correct overloaded method of 'ToBase64String'. Here, since my memory stream object's 'ToArray' method returning byte array for me, I'll use the highlighted overloaded method of 'ToBase64String'. After completing these steps my automation's 'Get Base64' label will looks like below.

Note that I have used a String variable called 'Base64String' to store what is returned from 'ToBase64String' method. Let's see how the whole automation is now look like.

Now it is the time to test our work. Add a break point at the last process link in the automation and debug. The execution should stop as depicted below.

Lets check the value of what is returned from the method 'ToBase64String' in the automation locals window as discussed earlier.

We can copy the value to the notepad file as above, but do not forget to delete following highlighted tags at the beginning and the end which are additionally copied from the automation locals window.

Now you can use any online tool available to convert this as an image. Remember, when we save the memory stream, we gave the format as PNG? So do not remember to goole something like 'convert base 64 to PNG' got it? Here's how I converted it and verified.


***Edited by Moderator Marissa to change content type from Question to Discussion***

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