User_guide |

## 4.2: Minimize and maximize

When a `uix.BoxPanel` has its `MinimizeFcn` filled in, a minimize/maximize button (▴/▾) is shown in the upper-right of the title-bar. When the user clicks this button the specified function is called. Since the behaviour of the parent container is different in different use-cases, it is up to the user to write some code to actually resize the panel. Note that minimizing a panel to its title-bar only really makes sense inside a `uix.VBox` or `uix.VBoxFlex`.

The following simple example shows how to add minimize/maximize functionality to a box full of panels. Save the code into a file called "minimizeexample.m" to run it.

(The code for this example can be found here: [ view | edit | run ] )

#### Create the layout with three panels

Open a new figure window and add three panels.

    function minimizeexample()
    width = 200;
    pheightmin = 20;
    pheightmax = 100;

    % Create the window and main layout
    fig = figure( 'Name', 'Collapsable GUI example', ...
                  'NumberTitle', 'off', ...
                  'Toolbar', 'none', ...
                  'MenuBar', 'none' );
    box = uix.VBox( 'Parent', fig );

    panel{1} = uix.BoxPanel( 'Title', 'Panel 1', 'Parent', box );
    panel{2} = uix.BoxPanel( 'Title', 'Panel 2', 'Parent', box );
    panel{3} = uix.BoxPanel( 'Title', 'Panel 3', 'Parent', box );
    set( box, 'Heights', pheightmax*ones(1,3) );

    % Add some contents.
    uicontrol( 'Style', 'PushButton', 'String', 'Button 1', 'Parent', panel{1} );
    uicontrol( 'Style', 'PushButton', 'String', 'Button 2', 'Parent', panel{2} );
    uicontrol( 'Style', 'PushButton', 'String', 'Button 3', 'Parent', panel{3} );

    % Resize the window
    pos = get( fig, 'Position' );
    set( fig, 'Position', [pos(1,1:2),width,sum(box.Heights)] );

#### Add the minimize/maximize callback

We set each panel to call the same minimize/maximize function. This function is nested inside the main function so that it has access to the main function's variables. A better way to do this is to make the main function into a class, but this nested-function approach is fine for simple applications.

Note that as soon as we set the "MinimizeFcn" property the minimize/maximize icon appears in the top-right of each panel. We use a cell-array to pass an extra argument, the panel number, to the minimize function. This extra argument appears after the usual `eventSource` and `eventData` arguments.

    % Hook up the minimize callback.
    set( panel{1}, 'MinimizeFcn', {@nMinimize, 1} );
    set( panel{2}, 'MinimizeFcn', {@nMinimize, 2} );
    set( panel{3}, 'MinimizeFcn', {@nMinimize, 3} );

    %-------------------------------------------------------------------------%

        function nMinimize( eventSource, eventData, whichpanel )
            % A panel has been maximized/minimized
            s = get( box, 'Heights' );
            pos = get( fig, 'Position' );
            panel{whichpanel}.Minimized = ~panel{whichpanel}.Minimized;
            if panel{whichpanel}.Minimized
                s(whichpanel) = pheightmin;
            else
                s(whichpanel) = pheightmax;
            end
            set( box, 'Heights', s );

            % Resize the figure, keeping the top stationary
            delta_height = pos(1,4) - sum( box.Heights );
            set( fig, 'Position', pos(1,:) + [0 delta_height 0 -delta_height] );
        end % Minimize

    end % Main function

#### Click the minimize buttons

Minimizing the middle panel causes it to shrink to just its title-bar and the window shrinks accordingly. The "Minimize" icon is replaced by a "Maximise" icon.

Re-maximizing the panel would cause it to re-appear in full and the window to grow again.

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