File size: 6,634 Bytes
1e92f2d |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 |
# Defining Custom Elements
In our previous example, we started with a paragraph, but we never actually told Slate anything about the `paragraph` block type. We just let it use its internal default renderer, which uses a plain old `<div>`.
But that's not all you can do. Slate lets you define any type of custom blocks you want, like block quotes, code blocks, list items, etc.
We'll show you how. Let's start with our app from earlier:
```jsx
const initialValue = [
{
type: 'paragraph',
children: [{ text: 'A line of text in a paragraph.' }],
},
]
const App = () => {
const [editor] = useState(() => withReact(createEditor()))
return (
<Slate editor={editor} initialValue={initialValue}>
<Editable
onKeyDown={event => {
if (event.key === '&') {
event.preventDefault()
editor.insertText('and')
}
}}
/>
</Slate>
)
}
```
Now let's add "code blocks" to our editor.
The problem is, code blocks won't just be rendered as a plain paragraph, they'll need to be rendered differently. To make that happen, we need to define a "renderer" for `code` element nodes.
Element renderers are just simple React components, like so:
```jsx
// Define a React component renderer for our code blocks.
const CodeElement = props => {
return (
<pre {...props.attributes}>
<code>{props.children}</code>
</pre>
)
}
```
Easy enough.
See the `props.attributes` reference? Slate passes attributes that should be rendered on the top-most element of your blocks, so that you don't have to build them up yourself. You **must** mix the attributes into your component.
And see that `props.children` reference? Slate will automatically render all of the children of a block for you, and then pass them to you just like any other React component would, via `props.children`. That way you don't have to muck around with rendering the proper text nodes or anything like that. You **must** render the children as the lowest leaf in your component.
And here's a component for the "default" elements:
```jsx
const DefaultElement = props => {
return <p {...props.attributes}>{props.children}</p>
}
```
Now, let's add that renderer to our `Editor`:
```jsx
const initialValue = [
{
type: 'paragraph',
children: [{ text: 'A line of text in a paragraph.' }],
},
]
const App = () => {
const [editor] = useState(() => withReact(createEditor()))
// Define a rendering function based on the element passed to `props`. We use
// `useCallback` here to memoize the function for subsequent renders.
const renderElement = useCallback(props => {
switch (props.element.type) {
case 'code':
return <CodeElement {...props} />
default:
return <DefaultElement {...props} />
}
}, [])
return (
<Slate editor={editor} initialValue={initialValue}>
<Editable
// Pass in the `renderElement` function.
renderElement={renderElement}
onKeyDown={event => {
if (event.key === '&') {
event.preventDefault()
editor.insertText('and')
}
}}
/>
</Slate>
)
}
const CodeElement = props => {
return (
<pre {...props.attributes}>
<code>{props.children}</code>
</pre>
)
}
const DefaultElement = props => {
return <p {...props.attributes}>{props.children}</p>
}
```
Okay, but now we'll need a way for the user to actually turn a block into a code block. So let's change our `onKeyDown` function to add a `` Ctrl-` `` shortcut that does just that:
```jsx
// Import the `Editor` and `Transforms` helpers from Slate.
import { Editor, Transforms, Element } from 'slate'
const initialValue = [
{
type: 'paragraph',
children: [{ text: 'A line of text in a paragraph.' }],
},
]
const App = () => {
const [editor] = useState(() => withReact(createEditor()))
const renderElement = useCallback(props => {
switch (props.element.type) {
case 'code':
return <CodeElement {...props} />
default:
return <DefaultElement {...props} />
}
}, [])
return (
<Slate editor={editor} initialValue={initialValue}>
<Editable
renderElement={renderElement}
onKeyDown={event => {
if (event.key === '`' && event.ctrlKey) {
// Prevent the "`" from being inserted by default.
event.preventDefault()
// Otherwise, set the currently selected blocks type to "code".
Transforms.setNodes(
editor,
{ type: 'code' },
{ match: n => Element.isElement(n) && Editor.isBlock(editor, n) }
)
}
}}
/>
</Slate>
)
}
const CodeElement = props => {
return (
<pre {...props.attributes}>
<code>{props.children}</code>
</pre>
)
}
const DefaultElement = props => {
return <p {...props.attributes}>{props.children}</p>
}
```
Now, if you press `` Ctrl-` `` the block your cursor is in should turn into a code block! Magic!
But we forgot one thing. When you hit `` Ctrl-` `` again, it should change the code block back into a paragraph. To do that, we'll need to add a bit of logic to change the type we set based on whether any of the currently selected blocks are already a code block:
```jsx
const initialValue = [
{
type: 'paragraph',
children: [{ text: 'A line of text in a paragraph.' }],
},
]
const App = () => {
const [editor] = useState(() => withReact(createEditor()))
const renderElement = useCallback(props => {
switch (props.element.type) {
case 'code':
return <CodeElement {...props} />
default:
return <DefaultElement {...props} />
}
}, [])
return (
<Slate editor={editor} initialValue={initialValue}>
<Editable
renderElement={renderElement}
onKeyDown={event => {
if (event.key === '`' && event.ctrlKey) {
event.preventDefault()
// Determine whether any of the currently selected blocks are code blocks.
const [match] = Editor.nodes(editor, {
match: n => n.type === 'code',
})
// Toggle the block type depending on whether there's already a match.
Transforms.setNodes(
editor,
{ type: match ? 'paragraph' : 'code' },
{ match: n => Element.isElement(n) && Editor.isBlock(editor, n) }
)
}
}}
/>
</Slate>
)
}
```
And there you have it! If you press `` Ctrl-` `` while inside a code block, it should turn back into a paragraph!
|