Split Panel

<cs-split-panel>

Stable

Since 0.1

Split panels display two adjacent panels separated by a draggable divider, letting users resize each side to suit their workflow.

    Start
  
    End

<cs-split-panel>
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

<style>
  .split-demo {
    height: 200px;
    background: var(--cs-color-surface-lowered);
    display: flex;
    align-items: center;
    justify-content: center;
    overflow: hidden;
  }
</style>

Examples

Initial Position

Set the position attribute to change the divider’s starting position, given as a percentage of the available space (50 by default). To set it in pixels instead, use the position-in-pixels attribute.

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    End

<cs-split-panel position="75">
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

    Start
  
    End

<cs-split-panel position-in-pixels="150">
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

Orientation

Set the orientation attribute to vertical and provide a height to render the split panel in a vertical orientation where the start and end panels are stacked.

    Start
  
    End

<cs-split-panel orientation="vertical" class="panel-demo">
  <div slot="start" class="split-demo" style="height: 100%;">
    Start
  </div>
  <div slot="end" class="split-demo" style="height: 100%;">
    End
  </div>
</cs-split-panel>

Snapping

To snap panels at specific positions while dragging, add the snap attribute with one or more space-separated values. Values must be in pixels or percentages. For example, to snap the panel at 100px and 50%, use snap="100px 50%". You can also customize how close the divider must be before snapping with the snap-threshold attribute.

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      End

<div class="split-panel-snapping">
  <cs-split-panel snap="100px 50%">
    <div slot="start" class="split-demo">
      Start
    </div>
    <div slot="end" class="split-demo">
      End
    </div>
  </cs-split-panel>

  <div class="split-panel-snapping-dots"></div>
</div>

<style>
  .split-panel-snapping {
    position: relative;
  }

  .split-panel-snapping-dots::before,
  .split-panel-snapping-dots::after {
    content: '';
    position: absolute;
    bottom: -12px;
    width: 6px;
    height: 6px;
    border-radius: 50%;
    background: var(--cs-color-neutral-fill-loud);
    transform: translateX(-3px);
  }

  .split-panel-snapping-dots::before {
    left: 100px;
  }

  .split-panel-snapping-dots::after {
    left: 50%;
  }
</style>

Disabled

Add the disabled attribute to prevent the divider from being repositioned.

    Start
  
    End

<cs-split-panel disabled>
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

Primary Panel

By default, both panels will grow or shrink proportionally when the host element is resized. If a primary panel is designated, it will maintain its size and the secondary panel will grow or shrink to fit the remaining space. You can set the primary panel to start or end using the primary attribute.

Try resizing the example below with each option and notice how the panels respond.

  
      Start
    
      End
    
    None
    Start
    End

<div class="split-panel-primary">
  <cs-split-panel>
    <div slot="start" class="split-demo">
      Start
    </div>
    <div slot="end" class="split-demo">
      End
    </div>
  </cs-split-panel>

  <cs-divider></cs-divider>

  <cs-select label="Primary Panel" class="panel-select">
    <cs-option value="" selected>None</cs-option>
    <cs-option value="start">Start</cs-option>
    <cs-option value="end">End</cs-option>
  </cs-select>
</div>

<script>
  const container = document.querySelector('.split-panel-primary');
  const splitPanel = container.querySelector('cs-split-panel');
  const select = container.querySelector('cs-select');

  select.addEventListener('change', () => (splitPanel.primary = select.value));
</script>

Min & Max

To set a minimum or maximum size of the primary panel, use the --min and --max custom properties. Since the secondary panel is flexible, size constraints can only be applied to the primary panel. If no primary panel is designated, these constraints will be applied to the start panel.

This examples demonstrates how you can ensure both panels are at least 150px using --min, --max, and the calc() function.

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    End

<cs-split-panel style="--min: 150px; --max: calc(100% - 150px);">
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

Nested Split Panels

Create complex layouts that can be repositioned independently by nesting split panels.

    Start
  
        Top
      
        Bottom

<cs-split-panel>
  <div slot="start" class="split-demo panel-demo">
    Start
  </div>
  <div slot="end">
    <cs-split-panel orientation="vertical" class="panel-demo">
      <div slot="start" class="split-demo" style="height: 100%;">
        Top
      </div>
      <div slot="end" class="split-demo" style="height: 100%;">
        Bottom
      </div>
    </cs-split-panel>
  </div>
</cs-split-panel>

Customizing the Divider

You can target the divider part to apply CSS properties to the divider. To add a custom handle, slot an icon into the divider slot. When customizing the divider, make sure to think about focus styles for keyboard users.

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    End

<cs-split-panel style="--divider-width: 20px;">
  <cs-icon slot="divider" name="drag_indicator"></cs-icon>
  <div slot="start" class="split-demo">
    Start
  </div>
  <div slot="end" class="split-demo">
    End
  </div>
</cs-split-panel>

Here’s a more elaborate example that changes the divider’s color and width and adds a styled handle.

  
      Start
    
      End

<div class="split-panel-divider">
  <cs-split-panel>
    <cs-icon slot="divider" name="drag_indicator"></cs-icon>
    <div slot="start" class="split-demo">
      Start
    </div>
    <div slot="end" class="split-demo">
      End
    </div>
  </cs-split-panel>
</div>

<style>
  .split-panel-divider cs-split-panel {
    --divider-width: 4px;
  }

  .split-panel-divider cs-split-panel::part(divider) {
    background-color: var(--cs-color-cerise-50);
  }

  .split-panel-divider cs-icon {
    position: absolute;
    border-radius: var(--cs-border-radius-l);
    background: var(--cs-color-cerise-50);
    color: white;
    padding: var(--cs-space-xs) var(--cs-space-2xs);
  }

  .split-panel-divider cs-split-panel::part(divider):focus-visible {
    background-color: var(--cs-color-sky-50);
  }

  .split-panel-divider cs-split-panel:focus-within cs-icon {
    background-color: var(--cs-color-sky-50);
    color: white;
  }
</style>

API

Importing

If you're using the autoloader or a hosted project, components load on demand — no manual import needed. To cherry-pick this component, use one of the following snippets.

npm

Self-Hosted

React

import '@cruglobal/cornerstone-components/components/split-panel/split-panel.js';

import './cornerstone/components/split-panel/split-panel.js';

import CsSplitPanel from '@cruglobal/cornerstone-components/react/split-panel/index.js';

Slots

Learn more about using slots.

Name	Description
`divider`	The divider. Useful for slotting in a custom icon that renders as a handle.
`end`	Content to place in the end panel.
`start`	Content to place in the start panel.

Attributes & Properties

Learn more about attributes and properties.

Property	Attribute	Description	Type	Default	Reflects
`disabled`	`disabled`	Disables resizing. Note that the position may still change as a result of resizing the host element.	`boolean`	`false`	Yes
`orientation`	`orientation`	Sets the split panel's orientation.	`'horizontal' \| 'vertical'`	`'horizontal'`	Yes
`position`	`position`	The current position of the divider from the primary panel's edge as a percentage 0-100. Defaults to 50% of the container's initial size.	`number`	`50`	Yes
`positionInPixels`	`position-in-pixels`	The current position of the divider from the primary panel's edge in pixels.	`number`	—	—
`primary`	`primary`	If no primary panel is designated, both panels will resize proportionally when the host element is resized. If a primary panel is designated, it will maintain its size and the other panel will grow or shrink as needed when the host element is resized.	`'start' \| 'end' \| undefined`	—	—
`snap`	`snap`	One or more space-separated values at which the divider should snap. Values can be in pixels or percentages, e.g. `"100px 50%"`.	`string \| undefined`	—	—
`snapThreshold`	`snap-threshold`	How close the divider must be to a snap point until snapping occurs.	`number`	`12`	—

Events

Learn more about events.

Name	Description
`cs-reposition`	Emitted when the divider's position changes.

CSS Custom Properties

Learn more about CSS custom properties.

Name	Description	Default
`--divider-hit-area`	The invisible region around the divider where dragging can occur. This is usually wider than the divider to facilitate easier dragging.	`12px`
`--divider-width`	The width of the visible divider.	`4px`
`--max`	The maximum allowed size of the primary panel.	`100%`
`--min`	The minimum allowed size of the primary panel.	`0`

CSS Parts

Learn more about CSS parts.

Name	Description	CSS selector
`divider`	The divider that separates the start and end panels.	`::part(divider)`
`end`	The end panel.	`::part(end)`
`panel`	Targets both the start and end panels.	`::part(panel)`
`start`	The start panel.	`::part(start)`

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