filereader | 易学教程

Specify the type returned from FileReader readAsDataURL() as PNG and not TIFF?

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问题 I'm getting an image that has been pasted into the content editable div and during paste the types in listed in the Clipboard include " image/png " and " image/tiff ". When I get that image using a FileReader and readAsDataURL the base64 image string it returns is a TIFF , " data:image/tiff, ". Is there a way to specify to the FileReader to return a PNG , " data:image/png "? Related question here. 回答1: You don't. FileReader.readAsDataURL() only converts the binary data held in the passed Blob

How can I get an images data in base64 from a file input without FileReader() in Javascript?

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问题 Is there a way to get the image data without FileReader()? I'm looking for an older non-browser specific way to do it in javascript. 来源： https://stackoverflow.com/questions/20007106/how-can-i-get-an-images-data-in-base64-from-a-file-input-without-filereader-in

Adding support for dynamic file loaders in c#

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问题 If I have a Console App in C# that reads in files of a certain format and converts them to business objects, I design this by having an IReader interface so that I can support different formats, eg XML, CSV, pipe delimited etc, and have different concrete classes for each file format. If the requirement is to be able to load new file readers (new formats) in dynamically without having to recompile, is there a way I can accomplish that? The only way I can think of is somehow using XSD or reg

Read content of SP.File object as text using JSOM

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问题 as the title suggests, I am trying to read the contents of a simple text file using JSOM. I am using a Sharepoint-hosted addin for this, the file I am trying to read resides on the host web in a document library. Here's my JS code: function printAllListNamesFromHostWeb() { context = new SP.ClientContext(appweburl); factory = new SP.ProxyWebRequestExecutorFactory(appweburl); context.set_webRequestExecutorFactory(factory); appContextSite = new SP.AppContextSite(context, hostweburl); this.web =

How to multi-thread an ANTLR parser in java

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问题 I have my program that is proving slow in reading a file and then parsing it with antlr grammar. To improve performance of this I would like to multi-thread the parsing? Read File: LogParser pa = new LogParser(); LogData logrow; String inputLine; int a=0; try { //feed line by line FileReader fr = new FileReader(jFileChooser1.getSelectedFile()); BufferedReader reader = new BufferedReader(fr); while ((inputLine = reader.readLine()) != null) { try { a++; jProgressBar.setValue(a); pa.parse

How to read or convert an image blob url into an image?

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问题 I have an image that is stored in local storage. On load the image is displayed. componentDidMount() { const reader = new FileReader(); reader.onload = e => { this.setState({ blob: e.target.result }); }; reader.readAsDataURL(this.props.file); } render() { return ( <div> <img src={this.state.blob} /> </div> ) } The file object looks like this: lastModified:1535424554987 name:"test.jpeg" preview:"blob:http://localhost:8080/b52098ca-087f83c778f0" size:41698 type:"image/jpeg" webkitRelativePath:"

Order issue with append in a file reader

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问题 I got a Jquery function that read a FilesList and display in an IMG html object the image. function load_images(files) { for (var i = 0; i < files.length; i++) { // Validate the image type if(validate_file(files[i])) { var reader = new FileReader(); reader.onload = function(e) { $(".upload_thumbnails").append(render_thumb(e.target.result, i)); // Return a string with the img object }; } reader.readAsDataURL(f); } } But my images are not append in the sequential order of the fileList. The

Read Text file and fill the data in Array.

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问题 Im pretty sure im just asking a silly question but, jut say in have a txt file that has this data on it UniPub;112 Binara St;ACT MooseHeads;54 Cohen St;ACT Cube;24 Mawson St;ACT Ill read it in my application using this code: package au.edu.canberra.g30813706; import java.io.BufferedReader; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStreamReader; import java.util.ArrayList; import java.util.Arrays;

前端图片上传那些事儿

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前端图片上传那些事儿本文讲的图片上传，主要是针对上传头像的。大家都知道，上传头像一般都会分成以下 4 个步骤：选择图片 -> 预览图片 -> 裁剪图片 -> 上传图片接下来，就详细的介绍每个步骤具体实现。选择图片选择图片有什么好讲的呢？不就一个 input[type=file] ，然后点击就可以了吗？确实是这样的，但是，我们想要做得更加的友好一些，比如需要过滤掉非图片文件，或只允许从摄像头拍照获取图片等，还是需要进行一些简单配置的。下面就先来看看最简单的选择图片： <input type="file" /> 这时候，点击这个 input , 在 iOS 手机的显示如下：其中的 “浏览” 选项，可以查看到非图片类型的文件，这并不是我们想要的结果，毕竟我们只想要图片类型。可以通过 accept 属性来实现，如下： <input type="file" accept="image/*"> 这样就可以过滤掉非图片类型了。但是图片的类型可能也太多了，有些可能服务器不支持，所以，如果想保守一些，只允许 jpg 和 png 类型，可以写成这样： <input type="file" accept="image/jpg, image/jpeg, image/png"> 或： <input type="file" accept=".jpg, .jpeg, .png"> OK,

Read in number file and calculate average in java

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问题 I have a txtfile called "averages" that looks like: 1 4 5 3 -1 2 8 9 3 2 -1 4 8 15 16 23 42 -1 3 -1 I want to be able to read in each line and calculate the average of each line whenever a "-1" is reached. I have written the code to read in the file and print it to the command line, I'm just having trouble finding the averages of each line. Any help would be greatly appreciated. Thanks! import java.io.*; import java.util.*; public class Test { public static void main(String[] args) {