react-native/Libraries/Image/RCTImageDownloader.h
Dmitriy Loktev 8e70c7f003 [Image] Add onLoadStart, onLoadProgress, onLoadError events to Image component
Summary:
This PR adds 4 native events to NetworkImage.

![demo](http://zippy.gfycat.com/MelodicLawfulCaecilian.gif)

Using these events I could wrap `Image` component into something like:
```javascript
class NetworkImage extends React.Component {
  getInitialState() {
    return {
      downloading: false,
      progress: 0
    }
  }

  render() {
    var loader = this.state.downloading ?
      <View style={this.props.loaderStyles}>
        <ActivityIndicatorIOS animating={true} size={'large'} />
        <Text style={{color: '#bbb'}}>{this.state.progress}%</Text>
      </View>
      :
      null;

    return <Image source={this.props.source}
      onLoadStart={() => this.setState({downloading: true}) }
      onLoaded={() => this.setState({downloading: false}) }
      onLoadProgress={(e)=> this.setState({progress: Math.round(100 * e.nativeEvent.written / e.nativeEvent.total)});
      onLoadError={(e)=> {
        alert('the image cannot be downloaded because: ', JSON.stringify(e));
        this.setState({downloading: false});
      }}>
      {loader}
    </Image>
  }
}
```
Useful on slow connections and server errors.

There are dozen lines of Objective C, which I don't have experience with. There are neither specific tests nor documentation yet. And I do realize that you're already working right now on better `<Image/>` (pipeline, new asset management, etc.). So this is basically a proof concept of events for images, and if this idea is not completely wrong I could improve it or help somehow.

Closes https://github.com/facebook/react-native/pull/1318
Github Author: Dmitriy Loktev <unknownliveid@hotmail.com>
2015-07-10 06:34:21 -08:00

52 lines
1.8 KiB
Objective-C

/**
* Copyright (c) 2015-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*/
#import <UIKit/UIKit.h>
#import "RCTDownloadTaskWrapper.h"
typedef void (^RCTDataDownloadBlock)(NSData *data, NSError *error);
typedef void (^RCTImageDownloadBlock)(UIImage *image, NSError *error);
@interface RCTImageDownloader : NSObject
+ (RCTImageDownloader *)sharedInstance;
/**
* Downloads a block of raw data and returns it. Note that the callback block
* will not be executed on the same thread you called the method from, nor on
* the main thread. Returns a token that can be used to cancel the download.
*/
- (id)downloadDataForURL:(NSURL *)url
progressBlock:(RCTDataProgressBlock)progressBlock
block:(RCTDataDownloadBlock)block;
/**
* Downloads an image and decompresses it a the size specified. The compressed
* image will be cached in memory and to disk. Note that the callback block
* will not be executed on the same thread you called the method from, nor on
* the main thread. Returns a token that can be used to cancel the download.
*/
- (id)downloadImageForURL:(NSURL *)url
size:(CGSize)size
scale:(CGFloat)scale
resizeMode:(UIViewContentMode)resizeMode
backgroundColor:(UIColor *)backgroundColor
progressBlock:(RCTDataProgressBlock)progressBlock
block:(RCTImageDownloadBlock)block;
/**
* Cancel an in-flight download. If multiple requets have been made for the
* same image, only the request that relates to the token passed will be
* cancelled.
*/
- (void)cancelDownload:(id)downloadToken;
@end