OCRAsyncCodeActivity Class

Definition

• Namespace: UiPath.OCR.Contracts.Activities
• Assembly: UiPath.OCR.Contracts

Description

An abstract class that must be implemented in order to construct an AsyncCodeActivity from the Workflow Foundation framework.

Members

Methods

• BeforeExecute(System.Activities.AsyncCodeActivityContext, System.AsyncCallback, object) System.Collections.Generic.Dictionary<string, object> - Overrides this method to compute and provide all the activity input arguments, other than the Image argument, and returns the activity input arguments as a dictionary where the key is the argument name and the value is the argument value.
  Note: At design time, when no contexts are available, the method's parameters are null. In this case, the activity arguments can't be read, so you may want to provide default values for them.
• BeginExecute(System.Activities.AsyncCodeActivityContext, System.AsyncCallback, object) System.IAsyncResult - This method can be overridden to implement the activity code. It is called by the workflow runtime to execute the activity asynchronously. It also provides access to tracking, variables, and arguments.
• EndExecute(System.Activities.AsyncCodeActivityContext, System.IAsyncResult) - System.Collections.Generic.IEnumerable<System.Collections.Generic.KeyValuePair<System.Drawing.Rectangle, string>> - This method can be overridden to notify the workflow runtime that the associated asynchronous activity operation has completed.
• OCRAsyncCodeActivity()
• OnSuccess(System.Activities.AsyncCodeActivityContext, UiPath.OCR.Contracts.DataContracts.OCRResult) void OnSuccess - This method is called after computing the OCR result. It can be used to set output arguments or any other final operations.
• PerformOCRAsync(System.Drawing.Image, System.Collections.Generic.Dictionary<string, object>, System.Threading.CancellationToken) System.Threading.Tasks.Task<UiPath.OCR.Contracts.DataContracts.OCRResult> - Processes an image and returns the extracted text information. The options parameter is a dictionary of activity arguments having as key the argument name and as value the argument value.

Properties

• ExtractWords - Gets or sets if the words should be extracted.
• Image System.Activities.InArgument<System.Drawing.Image> - Image to be processed.
• Language System.Activities.InArgument<string> - The language used by the OCR engine to extract the string from the UI element. For the Google OCR engine, this field needs to contain the language file prefix, such as “ron” for Romanian, “ita” for Italian, and “fra” for French. You can find the supported language prefixes on this page.
• Output System.Activities.OutArgument<UiPath.OCR.Contracts.OcrActivityResult> - The activity output. Legacy, obsolete argument.
• Text System.Activities.OutArgument<string> - The textual value of the word.

Code Sample

[DisplayName("Sample OCRAsyncCodeActivity")]
internal class SampleOCRAsyncCodeActivity : OCRAsyncCodeActivity
    {
        [Browsable(true)]
        public override InArgument<Image> Image { get; set; }

        public InArgument<string> CustomInput { get; set; }

        public OutArgument<string> CustomOutput { get; set; }

        public override Task<OCRResult> PerformOCRAsync(Image image, Dictionary<string, object> options, CancellationToken ct)
        {
            string customInput = options[nameof(CustomInput)] as string;
            string text = $"Text from {nameof(SampleOCRAsyncCodeActivity)} with custom input: {customInput}";
            return Task.FromResult(OCRResultHelper.FromText(text));
        }

        protected override void OnSuccess(AsyncCodeActivityContext context, OCRResult result)
        {
            CustomOutput.Set(context, $"Custom output: '{result.Text}' has {result.Words.Length} words.");
        }

        protected override Dictionary<string, object> BeforeExecute(AsyncCodeActivityContext context, AsyncCallback callback, object state)
        {
            return new Dictionary<string, object>
            {
                { nameof(CustomInput), CustomInput.Get(context) }
            };
        }
    }