matlab.graphics.chartcontainer.mixin.Legend Class

Namespace: matlab.graphics.chartcontainer.mixin

Add legend support to chart container subclass

Description

matlab.graphics.chartcontainer.mixin.Legend is a class for adding legend support to charts that inherit from matlab.graphics.chartcontainer.ChartContainer. By inheriting from this class, you can display a legend in your chart. Your users can select options in the figure menu bar or the figure toolbar to show or hide that legend.

Use this syntax to enable legend support for your chart:

classdef MyChart < matlab.graphics.chartcontainer.ChartContainer & ...
                   matlab.graphics.chartcontainer.mixin.Legend
  ...
end

The matlab.graphics.chartcontainer.mixin.Legend class is a handle class.

Class Attributes

Abstract	true
HandleCompatible	true

For information on class attributes, see Class Attributes.

Properties

LegendVisible — Legend visibility

'off' (default) | on/off logical value

Legend visibility, specified as 'on' or 'off', 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.

When this property is set to 'on', the legend is visible in the chart.

Attributes:

GetAccess	public
SetAccess	public
Dependent	true
NonCopyable	true

Methods

Protected Methods

getLegend

Get legend object for legend mixin subclass

Examples

Smooth Line Plot With Legend

Define a SmoothLegendPlot class that plots a set of data using a dotted blue line with a smoothed version of the line.

To define the class, create a file named SmoothLegendPlot.m that contains the following code. The setup method for this class performs these tasks:

• Creates two Line objects with the appropriate DisplayName values to show in the legend

• Makes the legend visible by setting the LegendVisible property to 'on'

• Gets the Legend object and customizes the text color, box edge color, and box line width

classdef SmoothLegendPlot < matlab.graphics.chartcontainer.ChartContainer & ...
        matlab.graphics.chartcontainer.mixin.Legend
    
    properties
        XData (1,:) double = NaN
        YData (1,:) double = NaN
        SmoothColor (1,3) double {mustBeGreaterThanOrEqual(SmoothColor,0),...
            mustBeLessThanOrEqual(SmoothColor,1)} = [0.9290 0.6940 0.1250]
        SmoothWidth (1,1) double = 2
    end
    properties(Access = private,Transient,NonCopyable)
        OriginalLine (1,1) matlab.graphics.chart.primitive.Line
        SmoothLine (1,1) matlab.graphics.chart.primitive.Line
    end
    
    methods(Access = protected)
        function setup(obj)
            ax = getAxes(obj);
            
            % Create line objects. Define line styles and legend names.
            obj.OriginalLine = plot(ax,NaN,NaN,'LineStyle',':',...
                'DisplayName','Original');
            hold(ax,'on')
            obj.SmoothLine = plot(ax,NaN,NaN,...
                'DisplayName','Smooth');
            
            % Make legend visible
            obj.LegendVisible = 'on';
            
            % Get legend and set text color, edge color, and line width
            lgd = getLegend(obj);
            lgd.TextColor = [.3 .3 .3];
            lgd.EdgeColor = [.8 .8 .8];
            lgd.LineWidth = .7;
            hold(ax,'off')
        end
        function update(obj)
            % Update Line data
            obj.OriginalLine.XData = obj.XData;
            obj.OriginalLine.YData = obj.YData;
            obj.SmoothLine.XData = obj.XData;
            obj.SmoothLine.YData = createSmoothData(obj);
            
            % Adjust smooth line appearance
            obj.SmoothLine.LineWidth = obj.SmoothWidth;
            obj.SmoothLine.Color = obj.SmoothColor;
        end
        function sm = createSmoothData(obj)
            % Calculate smoothed data
            v = ones(1,10)*0.1;
            sm = conv(obj.YData,v,'same');
        end
    end
end

Next, create a pair of x and y vectors. Plot x and y by calling the SmoothLegendPlot constructor method, which is inherited from the ChartContainer class. Specify the 'XData' and 'YData' name-value pair arguments and return the chart object as c.

x = 1:1:100;
y = 10*sin(x./5)+8*sin(10.*x+0.5);
c = SmoothLegendPlot('XData',x,'YData',y);

Use c to change the color of the smooth line to red. Notice that the legend also shows the new line color.

c.SmoothColor = [1 0 0];

Version History

Introduced in R2019b