问题
I am building a custom browser as part of an interface to a remote website. Their GUI sucks so I'm doing some JavaScript hacks to make it look better.
Currently, to make modifications to their UI I am using the following GreaseMonkey script (on Firefox):
// ==UserScript==
// @name winman-load
// @namespace winman
// @description stuff to do when winman.js loads
// @include https://addons.mozilla.org/en-US/firefox/addon/greasemonkey/
// @version 1
// @grant none
// @run-at document-start
// ==/UserScript==
document.addEventListener("beforescriptexecute", function(e) {
src = e.target.src;
content = e.target.text;
//console.log("src: " + src);
if (src.search("winman.js") > -1) {
console.info("============ new winman ===========\n" + src);
var newContent = "";
$.ajax({
async: false,
type: 'GET',
url: '/script/winman.js',
success: function(data) {
newContent = data.replace('pos += currentPos;', 'pos += currentPos + 100;');
newContent = newContent.replace('var enable = false;', 'var enable = true;');
newContent = newContent.replace('var available = true;', 'var available = false;');
}
});
// Stop original script
e.preventDefault();
e.stopPropagation();
unsafeWindow.jQuery(e.target).remove();
var script = document.createElement('script');
script.textContent = newContent;
(document.head || document.documentElement).appendChild(script);
script.onload = function() {
this.parentNode.removeChild(this);
}
}
});
I want to be able to do something if this nature with CefSharp, where I can modify the scripts on-the-fly as the browser loads the page.
回答1:
Ok I figured this out. You create a RequestHandler with a method like this:
IResponseFilter IRequestHandler.GetResourceResponseFilter(IWebBrowser browserControl, IBrowser browser, IFrame frame, IRequest request, IResponse response) {
var url = new Uri(request.Url);
if (request.Url.Equals(scriptToUpdate, StringComparison.OrdinalIgnoreCase)) {
Dictionary<string, string> dictionary = new Dictionary<string, string>();
dictionary.Add(search1, replace1);
dictionary.Add(search2, replace2);
return new FindReplaceResponseFilter(dictionary);
}
return null;
}
And then for the multiple search/replace you make a FindReplaceResponseFilter:
using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using CefSharp;
namespace CefFilters {
public class FindReplaceResponseFilter : IResponseFilter {
private static readonly Encoding encoding = Encoding.UTF8;
/// <summary>
/// The portion of the find string that is currently matching.
/// </summary>
private int findMatchOffset;
/// <summary>
/// Overflow from the output buffer.
/// </summary>
private readonly List<byte> overflow = new List<byte>();
/// <summary>
/// Number of times the the string was found/replaced.
/// </summary>
private int replaceCount;
private Dictionary<string, string> dictionary;
public FindReplaceResponseFilter(Dictionary<string, string> dictionary) {
this.dictionary = dictionary;
}
bool IResponseFilter.InitFilter() {
return true;
}
FilterStatus IResponseFilter.Filter(Stream dataIn, out long dataInRead, Stream dataOut, out long dataOutWritten) {
// All data will be read.
dataInRead = dataIn == null ? 0 : dataIn.Length;
dataOutWritten = 0;
// Write overflow then reset
if (overflow.Count > 0) {
// Write the overflow from last time.
WriteOverflow(dataOut, ref dataOutWritten);
}
// Evaluate each character in the input buffer. Track how many characters in
// a row match findString. If findString is completely matched then write
// replacement. Otherwise, write the input characters as-is.
for (var i = 0; i < dataInRead; ++i) {
var readByte = (byte) dataIn.ReadByte();
var charForComparison = Convert.ToChar(readByte);
if (replaceCount < dictionary.Count) {
var replace = dictionary.ElementAt(replaceCount);
if (charForComparison == replace.Key[findMatchOffset]) {
//We have a match, increment the counter
findMatchOffset++;
// If all characters match the string specified
if (findMatchOffset == replace.Key.Length) {
// Complete match of the find string. Write the replace string.
WriteString(replace.Value, replace.Value.Length, dataOut, ref dataOutWritten);
// Start over looking for a match.
findMatchOffset = 0;
replaceCount++;
}
continue;
}
// Character did not match the find string.
if (findMatchOffset > 0) {
// Write the portion of the find string that has matched so far.
WriteString(replace.Key, findMatchOffset, dataOut, ref dataOutWritten);
// Start over looking for a match.
findMatchOffset = 0;
}
}
// Write the current character.
WriteSingleByte(readByte, dataOut, ref dataOutWritten);
}
if (overflow.Count > 0) {
//If we end up with overflow data then we'll need to return NeedMoreData
// On the next pass the data will be written, then the next batch will be processed.
return FilterStatus.NeedMoreData;
}
// If a match is currently in-progress we need more data. Otherwise, we're
// done.
return findMatchOffset > 0 ? FilterStatus.NeedMoreData : FilterStatus.Done;
}
private void WriteOverflow(Stream dataOut, ref long dataOutWritten) {
// Number of bytes remaining in the output buffer.
var remainingSpace = dataOut.Length - dataOutWritten;
// Maximum number of bytes we can write into the output buffer.
var maxWrite = Math.Min(overflow.Count, remainingSpace);
// Write the maximum portion that fits in the output buffer.
if (maxWrite > 0) {
dataOut.Write(overflow.ToArray(), 0, (int) maxWrite);
dataOutWritten += maxWrite;
}
if (maxWrite < overflow.Count) {
// Need to write more bytes than will fit in the output buffer.
// Remove the bytes that were written already
overflow.RemoveRange(0, (int) (maxWrite - 1));
}
else {
overflow.Clear();
}
}
private void WriteString(string str, int stringSize, Stream dataOut, ref long dataOutWritten) {
// Number of bytes remaining in the output buffer.
var remainingSpace = dataOut.Length - dataOutWritten;
// Maximum number of bytes we can write into the output buffer.
var maxWrite = Math.Min(stringSize, remainingSpace);
// Write the maximum portion that fits in the output buffer.
if (maxWrite > 0) {
var bytes = encoding.GetBytes(str);
dataOut.Write(bytes, 0, (int) maxWrite);
dataOutWritten += maxWrite;
}
if (maxWrite < stringSize) {
// Need to write more bytes than will fit in the output buffer. Store the
// remainder in the overflow buffer.
overflow.AddRange(encoding.GetBytes(str.Substring((int) maxWrite, (int) (stringSize - maxWrite))));
}
}
private void WriteSingleByte(byte data, Stream dataOut, ref long dataOutWritten) {
// Number of bytes remaining in the output buffer.
var remainingSpace = dataOut.Length - dataOutWritten;
// Write the byte to the buffer or add it to the overflow
if (remainingSpace > 0) {
dataOut.WriteByte(data);
dataOutWritten += 1;
}
else {
// Need to write more bytes than will fit in the output buffer. Store the
// remainder in the overflow buffer.
overflow.Add(data);
}
}
public void Dispose() {}
}
}
Keep in mind that this iterates through left to right, top to bottom, so make sure your search and replaces are in the right order.
来源：https://stackoverflow.com/questions/38096349/modifying-remote-javascripts-as-they-load-with-cefsharp