# Split

> Two panes with a draggable divider. A native Pyzed component for Python desktop GUIs, with a live preview, code examples and its API.

Source: https://albakore.github.io/pyzed/library/split/

:::tip[In plain words]
Two areas side by side (or one above the other) with a line you drag to resize them.
:::

Separates two widgets with a draggable divider in the theme's border color (accent while dragging). The `ratio` is yours: store it in `on_resize(ratio)`. `vertical=True` stacks the panes. `pz.split` is the base version with configurable `color`, `hover_color`, `thickness` and `handle`.

`ui.split` · Category: [Workspace](https://albakore.github.io/pyzed/library/#workspace) · [Full reference →](https://albakore.github.io/pyzed/reference/ui/#split)

**Code:**

```python
t = pz.theme.current()
pane = lambda title, bg: pz.container(ui.label(title), padding=12, width="fill", height="fill", bg=bg)
ui.split(pane("Left", t.panel),
         ui.split(pane("Top", t.editor), pane("Bottom", t.background), vertical=True),
         ratio=0.4, on_resize=on_resize)
```

## When to use

- For side-by-side editors, a preview next to its source, or an editor above a terminal.
- For one resizable side panel, [Resizable](https://albakore.github.io/pyzed/library/resizable/) is simpler.

## Usage

```python
import pyzed as pz
from pyzed import ui

class Panes(pz.App):
    def __init__(self):
        self.ratio = 0.3

    def view(self):
        return ui.split(self.sidebar(), self.editor(), ratio=self.ratio,
                        on_resize=lambda r: setattr(self, "ratio", r))
```

## Variants

:::note[About these captures]
Each capture is recorded by pyzed itself, off-screen at 2x, in One Dark or One Light to match this site's theme, and cropped to the component so it shows at its real size. The pointer hovers, presses or types into it; a component that does not react to the pointer cycles through a few themes. With reduced motion you see the first frame. Open **Code** under a capture to see the snippet that draws it; free names such as `on_save` stand for your own callbacks.
:::

### Direction

```python
t = pz.theme.current()
ui.split(pz.container(ui.label("A"), padding=10, width="fill", height="fill", bg=t.panel),
         pz.container(ui.label("B"), padding=10, width="fill", height="fill"), on_resize=on_resize)
```

```python
t = pz.theme.current()
ui.split(pz.container(ui.label("Top"), padding=10, width="fill", height="fill", bg=t.panel),
         pz.container(ui.label("Bottom"), padding=10, width="fill", height="fill"), vertical=True)
```

```python
t = pz.theme.current()
ui.split(pz.container(ui.label("25%"), padding=10, width="fill", height="fill", bg=t.panel),
         pz.container(ui.label("75%"), padding=10, width="fill", height="fill"), ratio=0.25)
```

## Events

Split has **1 event of its own**, listed below. Like every widget it also has the **18 common events** (`click`, `double_click`, `right_click`, `mouse_enter`, `drag`, `key_down`, `resize`…), attached with `.on(...)`: see [Events](https://albakore.github.io/pyzed/guides/events/) and [Events of every component](https://albakore.github.io/pyzed/library/events/).

| Event | Of | Handler gets | When |
| --- | --- | --- | --- |
| `on_resize` | `ui.split`, `pz.split` | `(ratio)` | Callable that receives the new ratio. |

**Handler gets** is what Pyzed passes to your callable: `()` means nothing. Any handler can also be a message (a value that is not callable), which goes to `update()`.

### Handling the events

The same events written three ways. **Imperative**: methods of the app change `self`. **Declarative**: the handlers produce messages and one `update()` decides. **Functional**: a pure function draws an immutable state and asks for changes with `set_state(...)`. See [Imperative, declarative and functional](https://albakore.github.io/pyzed/guides/code-styles/).

**Imperative:**

```python
class Panes(pz.App):
    def __init__(self):
        self.ratio = 0.3

    def view(self):
        return ui.split(ui.muted(f"Sidebar ({self.ratio:.0%})"), main_view(), ratio=self.ratio,
                        on_resize=lambda r: setattr(self, "ratio", r))   # the share of the first pane
```

**Declarative:**

```python
from dataclasses import dataclass

@dataclass
class Ratio:
    value: float

class Panes(pz.App):
    ratio = 0.3

    def update(self, message):
        match message:
            case Ratio(value):
                self.ratio = value

    def view(self):
        return ui.split(ui.muted("Sidebar"), main_view(), ratio=self.ratio, on_resize=Ratio)
```

**Functional:**

```python
from dataclasses import dataclass

@dataclass(frozen=True)
class State:
    ratio: float = 0.3

def view(state, set_state):
    return ui.split(ui.muted("Sidebar"), main_view(), ratio=state.ratio,
                    on_resize=lambda r: set_state(ratio=r))
```

## Properties and API

### `ui.split`

```python
split(
    first,
    second,
    *,
    ratio=0.5,
    on_resize=None,
    vertical=False,
    min_size=80,
    theme=None,
    **kwargs,
)
```

`pz.split` with the divider in the theme's border color (accent while dragging).

| Property | Default | Description |
| --- | --- | --- |
| `first` | *required* | First pane. |
| `second` | *required* | Second pane. |
| `ratio` | `0.5` | Proportion of the first pane (0–1). |
| `vertical` | `False` | Vertical orientation. |
| `min_size` | `80` | Minimum size of each pane. |
| `theme` | `None` | Theme to use instead of the current one (`pyzed.theme.current()`). |
| `**kwargs` | — | Same as `pz.split`. |

Events: `on_resize` ([events](#events)).

[Full reference →](https://albakore.github.io/pyzed/reference/ui/#split)

### `pz.split`

```python
split(
    first,
    second,
    *,
    ratio=0.5,
    on_resize=None,
    vertical=False,
    min_size=80.0,
    min_size_second=None,
    color=None,
    hover_color=None,
    thickness=1.0,
    handle=8.0,
    width=None,
    height=None,
)
```

Two panes with a draggable divider. For the theme style use `ui.split`.

| Property | Default | Description |
| --- | --- | --- |
| `first` | *required* | First pane. |
| `second` | *required* | Second pane. |
| `ratio` | `0.5` | Proportion of the first pane (0–1). The split keeps the ratio the user drags to until this changes. |
| `vertical` | `False` | Stacks the panes top/bottom. |
| `min_size` | `80.0` | Minimum size of the first pane. |
| `min_size_second` | `None` | Minimum size of the second pane. |
| `color` | `None` | Divider color. |
| `hover_color` | `None` | Divider color on hover or while dragging. |
| `thickness` | `1.0` | Line thickness. |
| `handle` | `8.0` | Width of the draggable area. |
| `width` | `None` | Width: pixels, `"fill"`, `"shrink"` or `"fill:N"` (proportion). |
| `height` | `None` | Height: pixels, `"fill"`, `"shrink"` or `"fill:N"` (proportion). |

Events: `on_resize` ([events](#events)).

[Full reference →](https://albakore.github.io/pyzed/reference/widgets/#split)

## Related

- [Resizable](https://albakore.github.io/pyzed/library/resizable/): A panel whose edge can be dragged to resize it.
- [Panel](https://albakore.github.io/pyzed/library/panel/): A dockable, resizable side panel.
- [Workspace](https://albakore.github.io/pyzed/library/workspace/): The layout of an editor-style window: title bar, docks, center, status bar.