Feature: interactively resizable side bar

[nightroman]

Feature: interactively resizable side bar

ref:

• Discussion

Is your feature request related to a problem? Please describe.

Kind of a usability problem and poor user experience in some cases.

We use TreeView in the side bar (left panel) and render selected item pages
in the main area (right panel). It's a popular UI layout pattern used in apps
like "file explorers", "hierarchical content browsers", etc.

Depending on the tree item text lengths and the depth of expanded items the
fixed width of the side bar (either default or custom but still fixed) may be
insufficient for comfortable viewing and navigating through the tree items.

And I can imagine use cases without TreeView but with dynamic content of the
side bar. The comfortable width may be difficult to predict and set beforehand.

Describe the solution you'd like

The natural solution would be ability to resize the side bar by dragging the
right edge of the bar horizontally, some sort of optional vertical splitter
dividing the application side bar and main areas.

[nightroman]

Here is a poor man solution mentioned in the discussion.
It uses the slider component shown (optionally) at the top.

Part 1. Markup.

@inject IJSRuntime JS

@if (_showSlider)
{
    <Slider TValue="int" Value="@_width1" Max="@_width2" ValueChanged="@SliderValueChanged" />
}

<Layout Sider="true">
    <LayoutSider>
        <LayoutSiderContent>
            ...

Part 2. Code behind.

Code for toggling _showSlider is omitted for simplicity (and implementation is rather opinionated).

    bool _showSlider;
    int _width1, _width2;
    [CascadingParameter] protected Theme Theme { get; set; }

    protected override async Task OnInitializedAsync()
    {
        _width2 = await JS.InvokeAsync<int>("getWindowWidth");
        _width1 = int.Parse(Theme.BarOptions.VerticalWidth.Replace("px", ""));
    }

    async Task SliderValueChanged(int value)
    {
        var coeff = (double)value / _width2;
        _width2 = await JS.InvokeAsync<int>("getWindowWidth");
        _width1 = Math.Max(300, (int)(_width2 * coeff));
        Theme.BarOptions.VerticalWidth = $"{_width1}px";
        Theme.ThemeHasChanged();
    }

Part 3. JavaScript, e.g. in index.html

    <script>
        function getWindowWidth() {
            return window.innerWidth;
        }
    </script>

[njannink]

Our UX designer has also requested this feature. To have a resizable sidebar and to also have it resize automatically when resizing the window. Like having a percentage size + explicit max-size instead of having 1 fixed values / breakpoints

[stsrki]

I can schedule it for 1.2 and we'll see how it goes.

[nightroman]

@stsrki Fantastic news, looking forward to it!

[njannink]

good news @stsrki

for now I will use a css formula to calculate the width
--b-vertical-bar-width: min(350px, max(200px, calc(20vw)));