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uidropdown

Create drop-down component

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Syntax

dd = uidropdown
dd = uidropdown(parent)
dd = uidropdown(___,Name,Value)

Description

dd = uidropdown creates a drop-down component in a new figure window and returns the DropDown object. MATLAB® calls the uifigure function to create the figure.

dd = uidropdown(parent) creates the drop-down component in the specified parent container. The parent can be a Figure object created using the uifigure function or one of its child containers.

example

dd = uidropdown(___,Name,Value) specifies DropDown properties using one or more name-value arguments. For example, uidropdown("Editable","on") creates a drop-down component that enables typing. Use this option with any of the input argument combinations in the previous syntaxes.

example

Examples

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Open Live Script

Create a drop-down component with the default items.

fig = uifigure;
dd = uidropdown(fig);

Figure contains an object of type uidropdown.

Click anywhere in the component to open the drop-down list.

UI figure with a drop-down component. The drop-down has four options, labeled "Option 1" through "Option 4".

Open Live Script

Create an editable drop-down component in a UI figure. Users can either choose from the existing items by clicking the drop-down arrow or enter their own value as text by clicking the component.

fig = uifigure;
dd = uidropdown(fig,"Editable","on");

Figure contains an object of type uidropdown.

Create a drop-down component in a UI figure and specify the items.

fig = uifigure;
dd = uidropdown(fig,"Items",["Red","Yellow","Blue","Green"]);

UI figure with a drop-down component. The value of the drop-down component is "Red".

Determine the value associated with the selected item. When the ItemsData property is empty (the default), the drop-down component Value property stores the name of the selected item as it appears in the Items property.

value = dd.Value
value =

    'Red'

Associate a hexadecimal color code with each drop-down component item by specifying the ItemsData property.

dd.ItemsData = ["#F00" "#FF0" "#00F" "#0F0"];

When ItemsData is nonempty, the drop-down component Value property stores the data associated with the selected item.

value = dd.Value
value =

    "#F00"

Since R2023a

Create a drop-down UI component with three items.

fig = uifigure;
dd = uidropdown(fig,"Items",["Good","Fair","Poor"]);

Create three background color styles.

s1 = uistyle("BackgroundColor","#77AC30");
s2 = uistyle("BackgroundColor","#EDB120");
s3 = uistyle("BackgroundColor","#F77A8F");

Add the styles to the drop-down component items to change their background colors.

addStyle(dd,s1,"item",1);
addStyle(dd,s2,"item",2);
addStyle(dd,s3,"item",3);

The item background colors update, and the appearance of the component reflects the style of the selected item. The style does not change the color that displays when a user points to an item.

Drop-down UI component with three items. Each item has a different background color: The "Good" item is green, the "Fair" item is yellow, and the "Poor" item is red. The "Fair" item is selected and appears at the top of the component as yellow. The mouse cursor is pointing to the "Fair" item in the list, so that item is highlighted in blue.

Open Live Script

Create an app that changes the color of a plotted line when an app user makes a selection from a drop-down list.

In a file named plotOptions.m, write a function that implements the app:

  • Create a UI figure and a grid layout manager to lay out the app.

  • Create UI axes and a drop-down component in the grid layout manager.

  • Write a callback function named updatePlot that changes the plot color based on the selected drop-down component item, and assign the function to the ValueChangedFcn callback property. For more information about callbacks, see Create Callbacks for Apps Created Programmatically.

function plotOptions
fig = uifigure;
g = uigridlayout(fig);
g.RowHeight = {'1x','fit','1x'};
g.ColumnWidth = {'1x','fit'};

ax = uiaxes(g);
ax.Layout.Row = [1 3];
ax.Layout.Column = 1;

x = linspace(-2*pi,2*pi);
y = sin(x);
p = plot(ax,x,y,"Color","#F00");

dd = uidropdown(g, ...
    "Items",["Red","Yellow","Blue","Green"], ...
    "ItemsData",["#F00" "#FF0" "#00F" "#0F0"], ...
    "ValueChangedFcn",@(src,event) updatePlot(src,p));
dd.Layout.Row = 2;
dd.Layout.Column = 2;
end

function updatePlot(src,p)
val = src.Value;
p.Color = val;
end

Run the plotOptions function. Select an item from the drop-down list to change the plot color.

plotOptions

Figure contains an axes object and an object of type uigridlayout. The axes object contains an object of type line.

Open Live Script

Create an app that allows a user to choose an image to display. Because the app contains an editable drop-down component, write your code to handle users selecting an existing item and users entering their own value.

In a file named imageApp.m, write a function that implements the app:

  • Create a UI figure and a grid layout manager to lay out the app.

  • Create an editable drop-down component and an image component in the grid layout manager.

  • Write a callback function named updateImage that changes the image based on the selected drop-down component item, and assign the function to the ValueChangedFcn callback property. Query the callback event data to check if the new value was selected from the existing items or was entered by the user, and validate any user-entered value. For more information about callbacks, see Create Callbacks for Apps Created Programmatically.

function imageApp
fig = uifigure;
g = uigridlayout(fig,[2 3]);
g.RowHeight = {22,'1x'};
g.ColumnWidth = {'1x','fit','1x'};

dd = uidropdown(g, ...
    "Editable","on", ...
    "Items",["peppers.png","street1.jpg"]);
dd.Layout.Row = 1;
dd.Layout.Column = 2;

im = uiimage(g,"ImageSource","peppers.png");
im.Layout.Row = 2;
im.Layout.Column = [1 3];

dd.ValueChangedFcn = @(src,event)updateImage(src,event,im,fig);
end

function updateImage(src,event,im,fig)
val = src.Value;
if event.Edited && ~exist(val,"file")
    im.ImageSource = "";
    uialert(fig,"Enter a file on the MATLAB path","Invalid Image")
else
    im.ImageSource = val;
end
end

Run the imageApp function and update the image by selecting an existing item or by entering your own image path.

UI figure window with a drop-down list and an image of cars on a street. The drop-down list has the text "street2.jpg" and a cursor.

Input Arguments

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Parent container, specified as a Figure object created using the uifigure function or one of its child containers: Tab, Panel, ButtonGroup, or GridLayout. If you do not specify a parent container, MATLAB calls the uifigure function to create a new Figure object that serves as the parent container.

Name-Value Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: uidropdown(Items=["Red","Yellow","Blue"]) specifies the options presented in the drop-down component.

Before R2021a, use commas to separate each name and value, and enclose Name in quotes.

Example: uidropdown("Items",["Red","Yellow","Blue"]) specifies the options presented in the drop-down component.

The properties listed here are a subset of the available properties. For the full list, see DropDown.

Value, specified as an element of the Items or ItemsData arrays. By default, Value is the first element in Items.

Specifying Value as an element of Items selects the drop-down item that matches that element. If ItemsData is not empty, then Value must be set to an element of ItemsData, and the drop-down will select the associated item in the list.

When Editable is set to 'on', you can additionally specify Value as a character vector or string scalar.

Drop-down items, specified as a cell array of character vectors, string array, or 1-D categorical array. Duplicate elements are allowed. The drop-down component displays as many options as there are elements in the Items array. If you specify this property as a categorical array, MATLAB uses the values in the array, not the full set of categories.

Example: {'Red','Yellow','Blue'}

Example: {'1','2','3'}

Data associated with each element of the Items property value, specified as a 1-by-n numeric array or a 1-by-n cell array. Duplicate elements are allowed.

For example, if you set the Items value to employee names, you might set the ItemsData value to corresponding employee ID numbers. The ItemsData value is not visible to the app user.

If the number of array elements in the ItemsData value and the Items value do not match, one of the following occurs:

  • When the ItemsData value is empty, then all the elements of the Items value are presented to the app user.

  • When the ItemsData value has more elements than the Items value, then all the elements of the Items value are presented to the app user. MATLAB ignores the extra ItemsData elements.

  • When the ItemsData value is not empty, but has fewer elements than the Items value, the only elements of the Items value presented to the app user are those that have a corresponding element in the ItemsData value.

Example: {'One','Two','Three'}

Example: [10 20 30 40]

Editable state of the drop-down component, specified as 'off' or 'on', or as numeric or logical 1 (true) or 0 (false). A value of 'on' is equivalent to true, and 'off' is equivalent to false. Thus, you can use the value of this property as a logical value. The value is stored as an on/off logical value of type matlab.lang.OnOffSwitchState.

If the Enable property value is 'off', then the app user cannot change the drop-down component text, even if the Editable property value is 'on'.

Value changed callback, specified as one of these values:

  • A function handle.

  • A cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

  • A character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

This callback function executes when the user selects a different option from the drop-down list. It does not execute if the Value property changes programmatically.

This callback function can access specific information about the user’s interaction with the drop-down. MATLAB passes this information in a ValueChangedData object as the second argument to your callback function. In App Designer, the argument is called event. You can query the object properties using dot notation. For example, event.PreviousValue returns the previous value of the drop-down. The ValueChangedData object is not available to callback functions specified as character vectors.

The following table lists the properties of the ValueChangedData object.

PropertyValue
ValueValue of drop-down component after the app user’s most recent interaction
PreviousValueValue of drop-down component before the app user’s most recent interaction
Edited

Logical value that indicates whether the callback was executed as a result of typing a new value into the drop-down component.

  • 0 (false) — The app user selected or typed an element of the Items property of the drop-down component.

  • 1 (true) — The app user typed a value that is not an element of the Items property of the drop-down component.

ValueIndexIndex of drop-down component value in items after the app user’s most recent interaction
PreviousValueIndexIndex of drop-down component value in items before the app user’s most recent interaction
SourceComponent that executes the callback
EventName'ValueChanged'

For more information about writing callbacks, see Callbacks in App Designer.

Drop-down menu opening callback, specified as one of these values:

  • A function handle.

  • A cell array in which the first element is a function handle. Subsequent elements in the cell array are the arguments to pass to the callback function.

  • A character vector containing a valid MATLAB expression (not recommended). MATLAB evaluates this expression in the base workspace.

This property specifies a callback function to execute when the user clicks to open the drop-down menu. A possible use for this callback is to dynamically update the list of entries in the drop-down menu.

This callback function can access specific information about the user’s interaction with the drop-down. MATLAB passes this information in a DropDownOpeningData object as the second argument to your callback function. In App Designer, the argument is called event. You can query the object properties using dot notation. For example, event.Source returns the DropDown object that the user interacts with to trigger the callback. The DropDownOpeningData object is not available to callback functions specified as character vectors.

The following table lists the properties of the DropDownOpeningData object.

PropertyValue
SourceComponent that executes the callback
EventName'DropDownOpening'

For more information about writing callbacks, see Callbacks in App Designer.

Location and size of the drop-down component relative to the parent, specified as the vector [left bottom width height]. This table describes each element in the vector.

ElementDescription
leftDistance from the inner left edge of the parent container to the outer left edge of the drop-down component
bottomDistance from the inner bottom edge of the parent container to the outer bottom edge of the drop-down component
widthDistance between the right and left outer edges of the drop-down component
heightDistance between the top and bottom outer edges of the drop-down component

All measurements are in pixel units.

The Position values are relative to the drawable area of the parent container. The drawable area is the area inside the borders of the container and does not include the area occupied by decorations such as a menu bar or title.

Example: [100 100 100 22]

Version History

Introduced in R2016a

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See Also

Functions

Properties

Tools