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React Native By Example

You're reading from   React Native By Example Native mobile development with React

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Product type Paperback
Published in Apr 2017
Publisher Packt
ISBN-13 9781786464750
Length 414 pages
Edition 1st Edition
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Author (1):
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Richard Kho Richard Kho
Author Profile Icon Richard Kho
Richard Kho
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Table of Contents (10) Chapters Close

Preface 1. First Project - Creating a Basic To-Do List App FREE CHAPTER 2. Advanced Functionality and Styling the To-Do List App 3. Our Second Project - The Budgeting App 4. Advanced Functionality with the Expenses App 5. Third Project - The Facebook Client 6. Advanced Facebook App Functionality 7. Redux 8. Deploying Your Applications 9. Additional React Native Components

Using onLayout

In our preceding example, we don't need to specify the height of the DatePickerIOS component when expanded. However, there may be scenarios in which you may need to manually get the dimensions of a component.

To calculate a component's height, we can utilize its onLayout property to fire a callback and then use that callback to save properties passed to the callback. The onLayout property is an event that is invoked on mount and layout changes, giving the event object a nativeEvent object that nests the component's layout properties. Using DatePickerIOS as an example, you can pass a callback to its onLayout prop like this:

<DatePickerIOS 
date={ this.state.date }
onDateChange={ (date) => this._onDateChange(date) }
onLayout={ (event) => this._getComponentDimensions(event) }
style={ styles.datePicker }
/>

The event from onLayout gives access to the following...

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