matlab.ui.componentcontainer.ComponentContainer.update - Update instance of UI component container subclass after setting

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Class: matlab.ui.componentcontainer.ComponentContainer
Namespace: matlab.ui.componentcontainer

Update instance of UI component container subclass after setting properties

Since R2020b

Description

update([obj](#mw%5Fd4b27eb4-4d8f-4e99-8abb-cfd8cd07a756%5Fsep%5Fmw%5Fe72055e4-681f-4c08-a285-ed570d7c1140)) updates the contents of the UI component after one or more property values change. Define this method to update the underlying graphics objects in the UI component using the new property values. This method executes during the next drawnow execution after the user changes one or more property values on the UI component.

Input Arguments

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Object of the class that inherits from thematlab.ui.componentcontainer.ComponentContainer base class.

Attributes

To learn about attributes of methods, seeMethod Attributes.

Examples

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Define a class named IPAddressComponent that creates a custom component for inputting four values to form an IP address.

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

• A Value public property that stores the IP address.
• NumericField and GridLayout private properties that place four numeric edit fields in a horizontal row.
• A setup method that initializes NumericField and GridLayout.
• An update method that updates the NumericField values when the IP address changes.
• A handleNewValue method that sets the Value property based on the values of the 4 numeric edit fields.

classdef IPAddressComponent < matlab.ui.componentcontainer.ComponentContainer % IPAddressComponent a set of 4 edit fields for IP Address input properties Value (1,4) {mustBeNonnegative, mustBeInteger, mustBeLessThanOrEqual(Value, 255)} = [192 168 1 2]; end

events (HasCallbackProperty, NotifyAccess = protected)
    ValueChanged % ValueChangedFcn callback property will be generated
end


properties (Access = private, Transient, NonCopyable)
    NumericField (1,4) matlab.ui.control.NumericEditField
    GridLayout matlab.ui.container.GridLayout
end

methods (Access=protected)
    function setup(obj)
        % Set the initial position of this component
        obj.Position = [100 100 150 22];
        
        % Layout
        obj.GridLayout = uigridlayout(obj,[1,4], ...
            'RowHeight',{22},'ColumnWidth',{'1x','1x','1x','1x'},...
            'Padding',0,'ColumnSpacing',2);
        
        % Building blocks
        for k = 1:4
            obj.NumericField(k) = uieditfield(obj.GridLayout, 'numeric',...
                'Limits', [0 255], 'RoundFractionalValues', true, ...
                'FontName', 'Courier New', 'FontWeight', 'bold', ...
                'ValueChangedFcn',@(src,event) obj.handleNewValue());
        end
      
    end
    
    function update(obj)
        % Update view
        for k = 1:4
            obj.NumericField(k).Value = obj.Value(k);
        end
    end
end
   
methods (Access=private)
    function handleNewValue(obj)
        obj.Value = [obj.NumericField.Value];  
        
        % Execute the event listeners and the ValueChangedFcn callback property
        notify(obj,'ValueChanged');
    end
end

end

Next, create the component by calling the IPAddressComponent constructor method, which is provided by the ComponentContainer class, and return the object as h. Specify a function that displays the new IP address in the Command Window when the component value changes.

h.ValueChangedFcn = @(src,event) disp("Value changed to: " + num2str(h.Value));

Enter the IP Address 192.168.1.10 into the edit fields. MATLAB® displays the updated IP address in the Command Window.

Tips

• Do not call drawnow within the setup andupdate methods of your UI component class. Such calls can cause unexpected screen updates in apps that use the UI component. Instead, rely on app creators (who use your component) to call drawnow in their app code when they need to trigger a screen update. These calls from outside the component code update all UI components in the app, including those created using the ComponentContainer class.

Version History

Introduced in R2020b