When using React in the browser for example, you sometimes need to directly modify a DOM node, and the same is true for views in mobile apps. Direct manipulation will not be a tool that you reach for frequently; you will typically only be using it for creating continuous animations to avoid the overhead of rendering the component hierarchy and reconciling many views.
Before you use it, try to solve your problem with setState and shouldComponentUpdate. TouchableOpacity uses setNativeProps internally to update the opacity of its child component:. This allows us to write the following code and know that the child will have its opacity updated in response to taps, without the child having any knowledge of that fact or requiring any changes to its implementation:. Let's imagine that setNativeProps was not available. One way that we might implement it with that constraint is to store the opacity value in the state, then update that value whenever onPress is fired:.
This is computationally intensive compared to the original example - React needs to re-render the component hierarchy each time the opacity changes, even though other properties of the view and its children haven't changed. Usually this overhead isn't a concern but when performing continuous animations and responding to gestures, judiciously optimizing your components can improve your animations' fidelity.
Composite components are not backed by a native view, so you cannot call setNativeProps on them. Consider this example:. If you run this you will immediately see this error: Touchable child must either be native or forward setNativeProps to a native component.
This occurs because MyButton isn't directly backed by a native view whose opacity should be set. You can think about it like this: if you define a component with createReactClass you would not expect to be able to set a style 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. All we need to do is provide a setNativeProps method on our component that calls setNativeProps on the appropriate child with the given arguments.
You can now use MyButton inside of TouchableOpacity! A sidenote for clarity: we used the ref callback syntax here, rather than the traditional string-based ref. The reason for this is that TouchableOpacity is actually a composite component, and so in addition to depending on setNativeProps on its child, it also requires that the child perform touch handling.
To do this, it passes on various props that call back to the TouchableOpacity component. TouchableHighlightin contrast, is backed by a native view and only requires that we implement setNativeProps.
Another very common use case of setNativeProps is to clear the value of a TextInput. The controlled prop of TextInput can sometimes drop characters when the bufferDelay is low and the user types very quickly. Some developers prefer to skip this prop entirely and instead use setNativeProps to directly manipulate the TextInput value when necessary.
For example, the following code demonstrates clearing the input when you tap a button:. 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.
By intelligently applying shouldComponentUpdate you can avoid the unnecessary overhead involved in reconciling unchanged component subtrees, to the point where it may be performant enough to use setState instead of setNativeProps.
The methods described here are available on most of the default components provided by React Native. Note, however, that they are not available on composite components that aren't directly backed by a native view. This will generally include most components that you define in your own app. Determines the location on screen, width, and height of the given view and returns the values via an async callback. If successful, the callback will be called with the following arguments:. Note that these measurements are not available until after the rendering has been completed in native.
If you need the measurements as soon as possible and you don't need pageX and pageYconsider using the onLayout prop instead. Determines the location of the given view in the window and returns the values via an async callback.
If the React root view is embedded in another native view, this will give you the absolute coordinates. Like measurebut measures the view relative to an ancestor, specified as relativeToNativeNode.Something like this:. There are a few ways you can avoid this. Some are simple, some less so. The most simple solution, and the easiest to install, is KeyboardAvoidingView.
You can take the base codewhich has the keyboard covering the inputs, and update that so that the inputs are no longer covered. The first thing you have to do is replace the container View with the KeyboardAvoidingView and then add a behavior prop to it.
The image at the top gets pushed out of the view when using this simple implementation. The next option is the react-native-keyboard-aware-scroll-view which gives you a lot of bang for your buck.
The other major benefit to this package is that it will scroll to the input that is in focus, which gives the user a nice experience. Usage is also very easy — you just need to swap out the container Viewagain starting with the base codeand set a few options. First off you want to set the backgroundColor of the ScrollView that way if you were to re-enable scrolling the backgroundColor is always the same.
Next you want to tell the component where the default position is so that, once the keyboard is closed, it goes back to that spot — by omitting this prop the view could get stuck at the top after closing the keyboard, like this.
After the resetScrollToCoords prop you set the contentContainerStyle — this essentially replaces the containing View styles you had before. This is by far the most manual option but also gives you the most control. You then use this animated value to set padding on the bottom of the container to bump all of the content up.
I want to fix that image this time. View and Animated. Image so that the animated values can be leveraged. The fun part is really in the keyboardWillShow and keyboardWillHide functions where the animated values are changing. That leaves you with this. You have a lot of options for what you can do and can really customize the interaction to your hearts content. If you want to save some code you can combine a few options, which is what I tend to do.
For example by combining option 1 and 3 you only have to worry about managing and animating the height of the image. If this article was helpful, tweet it. Learn to code for free.
React Native - Text
Get started. Stay safe, friends. Learn to code from home. Use our free 2, hour curriculum. Something like this: There are a few ways you can avoid this. Example AndroidManifest. Keyboard Aware ScrollView The next option is the react-native-keyboard-aware-scroll-view which gives you a lot of bang for your buck.
Combining these props together you get the following result, which works quite well. Keyboard Module This is by far the most manual option but also gives you the most control.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.react native font size text scaling
Already on GitHub? Sign in to your account. I'd be in favour of it. Interesting to consider how it would interact with flexbox though - perhaps it would only work if the width and height are set explicitly? I'm very new to the JS side of things, but I'd assume that it would shrink rather than wrapping past a specified number of lines.
MattFoley yes, much like the native behavior on UILabel, the font size would decrease to fit the width. If this is set, the text shrinks itself until it can fit in that number of lines or fewer also want a lower bound so we don't end up with illegibly small textgiven the available space provided by its parent. If numberOfLines is not set, then auto-shrinking behavior takes effect only if upper bounds on the width and height of the text component are known.
Example scenarios:. In these scenarios, the text is allowed to wrap and it shrinks until all of the text can fit in the available space and again, we have some lower bound so text doesn't become illegible.
Or are you proposing that we use the existing numberOfLines property, but augment its behavior to include shrinking the text as well as truncating it, with the min size defaulting to current size no shrinking unless otherwise specified?
This is still a big missing piece of React Native. Would love to get moving along But don't worry, it will live on with ProductPains! ProductPains helps the community prioritize the most important issues thanks to its voting feature.
It is easy to use - just login with GitHub. Also, if this issue is a bug, please consider sending a pull request with a fix. We're a small team and rely on the community for bug fixes of issues that don't affect fb apps.
Lmk if I'm missing something. Or can one envision a "willWrap" event trigger where changing the font size in the handler have the rendering be recalculated instead of wrapping? Pick the font size you like for the current view you have Make sure it looks good for the current device you are using in the simulator. Now console. This is going to be the important value that is going to adjust to different sizes.
So in my card we are displaying Cards trading cards but they are pulled from one component, sometimes there are 3 in a row, someones 2 sometimes 1 taking up whole screen.
Could even be 4 or 5. By using dimensions the text size is the same even when you have 3 items in a row or 2 in a row, which provides inconsistent viewing.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. If nothing happens, download GitHub Desktop and try again. If nothing happens, download Xcode and try again. If nothing happens, download the GitHub extension for Visual Studio and try again.
You signed out in another tab or window. Apply viewportContent prop.In the following example, the nested title and body text will inherit the fontFamily from styles. The title and body will stack on top of each other on account of the literal newlines:. Specifies font weight. The values 'normal' and 'bold' are supported for most fonts. Not all fonts have a variant for each of the numeric values, in that case the closest one is chosen.
Specifies text alignment. The value 'justify' is only supported on iOS and fallbacks to left on Android. With some fonts, this padding can make text look slightly misaligned when centered vertically. For best results also set textAlignVertical to center. Default is true. When set to trueindicates that the view is an accessibility element. The default value for a Text element is true. See the Accessibility guide for more information.
When numberOfLines is set, this prop defines how text will be truncated. Used to truncate the text with an ellipsis after computing the text layout, including line wrapping, such that the total number of lines does not exceed this number.
When the scroll view is disabled, this defines how far your touch may move off of the button, before deactivating the button. Once deactivated, try moving it back and you'll see that the button is once again reactivated! Move it back and forth several times while the scroll view is disabled. Ensure you pass in a constant to reduce memory allocations.
Specifies whether fonts should scale to respect Text Size accessibility settings. The default is true. Specifies smallest possible scale a font can reach when adjustsFontSizeToFit is enabled. When trueno visual change is made when text is pressed down.
By default, a gray oval highlights the text on press down. A React component for displaying text. Text supports nesting, styling, and touch handling.Post a Comment. Request Tutorial Advertise Email Notification. Thursday, November 8, This tutorial explains how to display responsive image in react native application. So here we are going to discuss about new library that helps to create responsive image in android or ios device easily.
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In our Earlier post we have provided simp Created By www.TextInput in react native is used to write input field value from the form email, username, password, etcit has the various important features which makes it perfect for any input value, for example, it gives us onchange function to manage input events related work.
It gives power to a simple input where we can design a placeholder to its own design with ease and less html codes. Other than design and work it also has the power to manage events, conditional edit, and rendering which makes it way better than any other option length of input should be less than, or character should be capital or small, etc like conditions.
See in the below example we are using react native component TextInput and passing style to make our input field looks more attractive or according to our need ,onChangeText this is the function which will be used for performing any operation in case of any change in textautoCapitalize this attribute will be used in case if we wanted to get capital letterautoCorrect this attribute allows input fields to get autocorrect in case of any wrong input fields.
If we do not pass any attribute then it will be true. We can pass a few parameters for it, they are given below. Suppose we are writing any big paragraph with multiple pages and we wanted our syntax in such a way that alpha-bet value gets changed according to our given conditions. With the help of these types of attributes, we can reduce human mistakes.
In all android devices, autocomplete is b default true in case if we do not want to use we need to make it false. In case If we do not specify its value, it will be true. Editable : In case we do not want to edit text input then We can make editable false.
Useful to disallow non-editable fields to get edited from the frontend. For example, if maxLength is 6 digit then it will only allow for characters of length 6. Placeholder : It is the string which gets rendered for the first time before entering the actual string.
Below is an example of various TextInput. Here we are going to design a login input box. Tasks which we are performing here are given below in this example. This is a guide to React Native TextInput. Forgot Password? Popular Course in this category.
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How to make your React Native app respond gracefully when the keyboard pops up