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generateCode

Class: matlab.task.LiveTask
Package: matlab.task

Generate code for instance of Live Editor task subclass

Syntax

[code,taskoutputs] = generateCode(obj)

Description

[code,taskoutputs] = generateCode(obj) generates the MATLAB® commands and output for the task. This method executes when the state of the task changes. The generated code displays in the code section of the task. When the live script section containing the task runs, the Live Editor uses the generated code to run the task. Define this method in a method block with no arguments, along with the get.Summary, get.State, set.State, and reset methods.

Input Arguments

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Object of the class that inherits from the matlab.task.LiveTask base class.

Output Arguments

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Generated code for the task, returned as a string array or character array.

Output variables generated by the task, returned as a cell array. If the task does not generate output, return taskoutputs as an empty cell array.

Attributes

Abstracttrue

To learn about attributes of methods, see Method Attributes.

Examples

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Define a class called DisplayImage that creates a custom Live Editor task for displaying an image.

To define the class, create a file called DisplayImage.m that contains the following class definition with these features:

  • State and Summary public properties that store the current state of the task and a dynamic summary of what the task does.

  • Private properties that store the edit field and button for selecting an image.

  • A setup method that initializes the task.

  • A generateCode method that updates the generated code for the task when the selected image changes.

  • get.Summary, get.State, and set.State methods for getting and setting the summary and state of the task.

  • A getImageFile method that prompts the user to select an image to display.

  • A reset method that resets the state of the task.

classdef DisplayImage < matlab.task.LiveTask
    properties(Access = private,Transient)
        FileNameEditField           matlab.ui.control.EditField
        BrowseButton                matlab.ui.control.Button
    end

    properties(Dependent)
        State
        Summary
    end

    methods(Access = protected)
        function setup(task)
            createComponents(task);
            setComponentsToDefault(task);
        end
    end

    methods
        function [code,outputs] = generateCode(task)
            if isempty(task.FileNameEditField.Value)
                % Not have enough information to generate code,
                % return empty values
                code = "";
                outputs = {};
                return
            end
            
            outputs = {"im"};
            code = "% Get Image";
            code = code + newline + outputs{1} + " = imread('" ...
                + task.FileNameEditField.Value + "');";
            code = code + newline + newline + "% Visualize results" + ...
                newline + "figure" + newline;          
            code = code + "imshow(" + outputs{1} + ");";
        end
        
        function summary = get.Summary(task)
            if isempty(task.FileNameEditField.Value)
                summary = "Display selected image";
            else
                [~,name,~] = fileparts(task.FileNameEditField.Value);
                summary = "Display image '" + name + "'";
            end
        end

        function state = get.State(task)
            state = struct;
            state.FileNameEditFieldValue = task.FileNameEditField.Value;
        end

        function set.State(task,state)
            task.FileNameEditField.Value = state.FileNameEditFieldValue;            
            inputImageFile(task);
        end
        
        function reset(task)
            setComponentsToDefault(task);
            inputImageFile(task);
        end
    end

    methods(Access = private)
        function createComponents(task)
            task.LayoutManager.RowHeight = ["fit" "fit" "fit" "fit"]; 
            task.LayoutManager.ColumnWidth = "fit";

            % Row 1: Select image section label
            uilabel(g,"Text","Select image","FontWeight","bold");

            % Row 2: Select data section components
            inputgrid = uigridlayout(g,"RowHeight","fit","ColumnWidth", ...
                {"fit",200,"fit"},"Padding",0);
            uilabel(inputgrid,"Text","Input image");
            task.FileNameEditField = uieditfield("Parent",inputgrid, ...
                "Editable",false);            
            task.BrowseButton = uibutton("Parent",inputgrid,"Text","Browse", ...
               "ButtonPushedFcn",@task.inputImageFile);
            
            % Row 3: Display results section label
            uilabel(g,"Text","Display results","FontWeight","bold");
        end

        function setComponentsToDefault(task)
            task.FileNameEditField.Value = "";    
        end

        function inputImageFile(task,~,~)
            % Display uigetfile dialog box
            filterspec = ["*.jpg;*.tif;*.png;*.gif","All Image Files"];
            [f,p] = uigetfile(filterspec);
            
            % Make sure user did not cancel uigetfile dialog box
            if (ischar(p))
               fileName = [p f];
               task.FileNameEditField.Value = fileName;
            end
            
            notify(task,"StateChanged");
        end
    end
end

Next, configure the task metadata by calling the matlab.task.configureMetadata function and selecting the DisplayImage.m file. The Task Metadata dialog box opens with all of the required task metadata details prepopulated.

Select OK to use the prepopulated metadata details. MATLAB creates a folder named resources inside the folder containing your task class definition file. Inside the resources folder, MATLAB generates a file named liveTasks.json. Add the folder containing the task class definition file to the MATLAB path by calling the addpath function or using the Add Folder button in the Set Path dialog box. To make your task available in the Live Editor in future MATLAB sessions, save the path by calling the savepath function or using the Save button in the Set Path dialog box.

Add the task to a live script. On a code line, type display. MATLAB shows a list of suggested matches.

Select Display Image from the list. MATLAB adds the Display Image task to the live script.

Version History

Introduced in R2022a