Move 'NativeMethods' docs to direct manipulation guide

This commit is contained in:
Nicolas Gallagher
2017-06-09 14:49:15 -07:00
parent fc86c876e0
commit 79e6dbaab5
3 changed files with 53 additions and 55 deletions

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@@ -68,7 +68,6 @@ Exported modules:
* [`Clipboard`](docs/apis/Clipboard.md)
* [`Dimensions`](docs/apis/Dimensions.md)
* [`I18nManager`](docs/apis/I18nManager.md)
* [`NativeMethods`](docs/apis/NativeMethods.md)
* [`NetInfo`](docs/apis/NetInfo.md)
* [`PanResponder`](http://facebook.github.io/react-native/releases/0.20/docs/panresponder.html#content) (mirrors React Native)
* [`PixelRatio`](docs/apis/PixelRatio.md)

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@@ -1,42 +0,0 @@
# NativeMethods
React Native for Web provides several methods to directly access the underlying
DOM node. This can be useful in cases when you want to focus a view or measure
its on-screen dimensions, for example.
The methods described are available on most of the default components provided
by React Native for Web. Note, however, that they are *not* available on the
composite components that you define in your own app. For more information, see
[Direct Manipulation](../guides/direct-manipulation.md).
## Methods
**blur**()
Removes focus from an input or view. This is the opposite of `focus()`.
**focus**()
Requests focus for the given input or view. The exact behavior triggered will
depend the type of view.
**measure**(callback: (x, y, width, height, pageX, pageY) => void)
For a given view, `measure` determines the offset relative to the parent view,
width, height, and the offset relative to the viewport. Returns the values via
an async callback.
Note that these measurements are not available until after the rendering has
been completed.
**measureLayout**(relativeToNativeNode: DOMNode, onSuccess: (x, y, width, height) => void)
Like `measure`, but measures the view relative to another view, specified as
`relativeToNativeNode`. This means that the returned `x`, `y` are relative to
the origin `x`, `y` of the ancestor view.
**setNativeProps**(nativeProps: Object)
This function sends props straight to the underlying DOM node. See the [direct
manipulation](../guides/direct-manipulation.md) guide for cases where
`setNativeProps` should be used.

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@@ -1,27 +1,68 @@
# Direct manipulation
It is sometimes necessary to make changes directly to a component without using
state/props to trigger a re-render of the entire subtree in the browser, this
is done by directly modifying a DOM node. `setNativeProps` is the React Native
equivalent to setting properties directly on a DOM node. Use direct
manipulation when frequent re-rendering creates a performance bottleneck. Direct
manipulation will not be a tool that you reach for frequently.
React Native for Web provides several methods to directly access the underlying
DOM node. This can be useful when you need to make changes directly to a
component without using state/props to trigger a re-render of the entire
subtree, or when you want to focus a view or measure its on-screen dimensions.
## `setNativeProps` and `shouldComponentUpdate`
The methods described are available on most of the default components provided
by React Native for Web. Note, however, that they are *not* available on the
composite components that you define in your own app.
## Instance methods
**blur**()
Removes focus from an input or view. This is the opposite of `focus()`.
**focus**()
Requests focus for the given input or view. The exact behavior triggered will
depend the type of view.
**measure**(callback: (x, y, width, height, pageX, pageY) => void)
For a given view, `measure` determines the offset relative to the parent view,
width, height, and the offset relative to the viewport. Returns the values via
an async callback.
Note that these measurements are not available until after the rendering has
been completed.
**measureLayout**(relativeToNativeNode: DOMNode, onSuccess: (x, y, width, height) => void)
Like `measure`, but measures the view relative to another view, specified as
`relativeToNativeNode`. This means that the returned `x`, `y` are relative to
the origin `x`, `y` of the ancestor view.
**setNativeProps**(nativeProps: Object)
This function sends props straight to the underlying DOM node. See the [direct
manipulation](../guides/direct-manipulation.md) guide for cases where
`setNativeProps` should be used.
## About `setNativeProps`
`setNativeProps` is the React Native equivalent to setting properties directly
on a DOM node. Use direct manipulation when frequent re-rendering creates a
performance bottleneck. Direct manipulation will not be a tool that you reach
for frequently.
### `setNativeProps` and `shouldComponentUpdate`
`setNativeProps` is imperative and stores state in the native layer (DOM,
UIView, etc.) and not within your React components, which makes your code more
difficult to reason about. Before you use it, try to solve your problem with
`setState` and `shouldComponentUpdate`.
## Avoiding conflicts with the render function
### Avoiding conflicts with the render function
If you update a property that is also managed by the render function, you might
end up with some unpredictable and confusing bugs because anytime the component
re-renders and that property changes, whatever value was previously set from
`setNativeProps` will be completely ignored and overridden.
## Why use `setNativeProps` on Web?
### Why use `setNativeProps` on Web?
Using `setNativeProps` in web-specific code is required when making changes to
`className` or `style`, as these properties are controlled by React Native for
@@ -35,7 +76,7 @@ setOpacityTo(value) {
}
```
## Composite components and `setNativeProps`
### Composite components and `setNativeProps`
Composite components are not backed by a DOM node, so you cannot call
`setNativeProps` on them. Consider this example:
@@ -63,7 +104,7 @@ prop on it and have that work - you would need to pass the style prop down to a
child, unless you are wrapping a native component. Similarly, we are going to
forward `setNativeProps` to a native-backed child component.
## Forward `setNativeProps` to a child
### Forward `setNativeProps` to a child
All we need to do is provide a `setNativeProps` method on our component that
calls `setNativeProps` on the appropriate child with the given arguments.
@@ -86,7 +127,7 @@ class MyButton extends React.Component {
You can now use `MyButton` inside of `TouchableOpacity`!
## `setNativeProps` to clear `TextInput` value
### `setNativeProps` to clear `TextInput` value
Another very common use case of `setNativeProps` is to clear the value of a
`TextInput`. For example, the following code demonstrates clearing the input