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Highlight all occurances of a selected word in AvalonEdit using an IBackgroundRenderer

I am relatively new to C# and I'm working on a simple application that makes use of AvalonEdit as a small code editor embedded in the bottom of the UI.
I want to highlight all occurrences of a selected word. Right now I have this working using a DocumentColorizingTransformer as outlined by Suplanus in this question.
My code is basically identical to the implementation posted there, but it has its downsides. Mainly that the default highlighting is fighting with the new LineTransformers highlighting and there are visual artifacts that can't be avoided.
So I came across this question where Siegfried (partially) explains a way to accomplish this by using an IBackgroundRenderer class. Unfortunately there isn't a lot of code to go on. Just an outline of how to structure the draw function. There is another question where trigger_segfault posts some similar code utilizing an IBackgroundRenderer but the goal is not to highlight matching words, but search results.
So I've kind of cobbled together what I can between all of these questions and arrived here:
(Removed. See bottom of post for working code)
My question is simply, how do I pass in the matching words? Do I assign an event handler to the "SelectionChanged" event: txtSvgSource.TextArea.SelectionChanged += ValidateSelection; and then implement a setter in my HighlightSelectedWordBackgroundRenderer class to update currentResults?
I just don't understand how to pass in the words to highlight.
I'd like to move away from my current DocumentColorizingTransformer approach and properly implement the IBackgroundRenderer instead.
Anyone with experience using AvalonEdit that could point me in the right direction, your help would be extremely appreciated!
Thanks so much.
Edit 2:
I figured everything out. Here's the final working code if anyone finds this useful:
using ICSharpCode.AvalonEdit;
using ICSharpCode.AvalonEdit.Document;
using ICSharpCode.AvalonEdit.Rendering;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Media;
namespace SVGRecolorTool {
public class SearchResult : TextSegment {
/// <summary>The regex match for the search result.</summary>
public Match Match { get; }
/// <summary>Constructs the search result from the match.</summary>
public SearchResult(Match match) {
this.StartOffset = match.Index;
this.Length = match.Length;
this.Match = match;
}
}
public class HighlightSelectedWordBackgroundRenderer : IBackgroundRenderer {
private TextEditor _editor;
TextSegmentCollection<SearchResult> currentResults = new TextSegmentCollection<SearchResult>();
public HighlightSelectedWordBackgroundRenderer(TextEditor editor) {
_editor = editor;
Background = new SolidColorBrush(Color.FromArgb(90, 255, 255, 255));
Background.Freeze();
}
public KnownLayer Layer {
get { return KnownLayer.Caret; }
}
public void Draw(TextView textView, DrawingContext drawingContext) {
if (!textView.VisualLinesValid)
return;
var visualLines = textView.VisualLines;
if (visualLines.Count == 0)
return;
int viewStart = visualLines.First().FirstDocumentLine.Offset;
int viewEnd = visualLines.Last().LastDocumentLine.EndOffset;
foreach (TextSegment result in currentResults.FindOverlappingSegments(viewStart, viewEnd - viewStart)) {
BackgroundGeometryBuilder geoBuilder = new BackgroundGeometryBuilder();
geoBuilder.AlignToWholePixels = true;
geoBuilder.CornerRadius = 0;
geoBuilder.AddSegment(textView, result);
Geometry geometry = geoBuilder.CreateGeometry();
if (geometry != null) {
drawingContext.DrawGeometry(Background, null, geometry);
}
}
}
public TextSegmentCollection<SearchResult> CurrentResults {
get { return currentResults; }
}
public Brush Background { get; set; }
}
}
_renderer = new HighlightSelectedWordBackgroundRenderer(txtSvgSource);
txtSvgSource.TextArea.TextView.BackgroundRenderers.Add(_renderer);
txtSvgSource.TextArea.SelectionChanged += HighlightSelection;
private void HighlightSelection(object sender, EventArgs e) {
_renderer.CurrentResults.Clear();
if(txtSvgSource.SelectedText.Length > 2) {
string pattern = #"\b" + txtSvgSource.SelectedText + #"\b";
Regex rg = new Regex(pattern);
MatchCollection matchedSelections = rg.Matches(txtSvgSource.Text);
if (matchedSelections.Count > 1) {
foreach (Match result in matchedSelections) {
_renderer.CurrentResults.Add(new SearchResult(result));
}
} else {
_renderer.CurrentResults.Clear();
}
} else {
_renderer.CurrentResults.Clear();
}
txtSvgSource.TextArea.TextView.InvalidateLayer(KnownLayer.Selection);
}

XAMARIN: How to Refresh WebView OnTabReselected?

I'm trying to refresh a WebView when the user reselects a tab that is already selected on Android coding with Xamarin using deprecated Actionbar and TabHost.
I've got this code
public void OnTabReselected(WhatsOnActivity tab, FragmentTransaction ft)
{
WebView whatsOnWebView = FindViewById<WebView>(Resource.Id.webViewWhatsOn);
//tell webview to reload
whatsOnWebView.Reload();
}
and I've tried to put that code into both my MainActivity and inside My WhatsOnActivity
It doesn't crash the app, but it also doesn't reload the tab. In Xamarin, can I use the "WhatsOnActivity" as the tab in my method? I have a feeling that's what I'm doing wrong.. but if I try to use tab ids, they're not recognized by the IDE. Can anyone give me direction on what I've done wrong?
my complete code can be found here:
https://github.com/hexag0d/BitChute_Mobile_Android_a2/blob/2.68/MainActivity.cs
if you're wondering about the context.

Update
Try to set OnClicklistener on your first tab. Set the listener after you add tabs.
TabHost.TabWidget.GetChildAt(0).SetOnClickListener(new MyOnClickListener(tabHost));
And the listener:
public class MyOnClickListener : Java.Lang.Object, IOnClickListener
{
TabHost tabHost;
public MyOnClickListener(TabHost tabHost)
{
this.tabHost = tabHost;
}
public void OnClick(View v)
{
var parentView = ((ViewGroup)((ViewGroup)tabHost.GetChildAt(0)).GetChildAt(1)).GetChildAt(0);
WebView whatsOnWebView = parentView.FindViewById<WebView>(Resource.Id.webViewWhatsOn);
whatsOnWebView.Reload();
tabHost.CurrentTab = 0;
}
}
And the result is:
Original answer
Please try to add an OnTabChangeListener to your TabHost.
For example, In your MainActivity OnCreate():
TabHost tabHost = FindViewById<TabHost>(Android.Resource.Id.TabHost);
tabHost.SetOnTabChangedListener(new MyOnTabChangedListener(tabHost));
And the MyOnTabChangedListener:
public class MyOnTabChangedListener : Java.Lang.Object, IOnTabChangeListener
{
TabHost tabHost;
public MyOnTabChangedListener(TabHost tabHost)
{
this.tabHost = tabHost;
}
public void OnTabChanged(string tabId)
{
if(tabId == "whats_on")
{
var parentView = ((ViewGroup)((ViewGroup)tabHost.GetChildAt(0)).GetChildAt(1)).GetChildAt(0);
WebView whatsOnWebView = parentView.FindViewById<WebView>(Resource.Id.webViewWhatsOn);
whatsOnWebView.Reload();
}
}
}

First off thank you so much to #Billy Liu - MSFT !!! dude is a lifesaver. He knows his Xamarin. Alright, so here's how you can refresh a tab OnClick
//Assemblies
using System;
using System.Threading.Tasks;
using Android.App;
using Android.Content;
using Android.Graphics.Drawables;
using Android.OS;
using Android.Widget;
using Android.Webkit;
using static Android.Widget.TabHost;
using static Android.Views.View;
using Android.Views;
//this assembly is your Activities class, which should contain your class instances
using com.xamarin.example.BitChute.Activities;
EDIT: Put these click listeners inside your MainActivity.cs .. the int inside GetChildAt() represents the tab our listener will respond to. int 0 = tab farthest left and they go up 0 .. 1 .. 2 .. etc .. 1 would mean tab second from the left. Each listener will need it's own listener class instance. I'll show two examples in the next block.
TabHost tabHost = FindViewById<TabHost>(Android.Resource.Id.TabHost);
tabHost.Setup();
tabHost.TabWidget.GetChildAt(0).SetOnClickListener(new WhatsOnClickListener(tabHost));
tabHost.TabWidget.GetChildAt(1).SetOnClickListener(new SubsClickListener(tabHost));
tabHost.TabWidget.GetChildAt(2).SetOnClickListener(new DiscoverClickListener(tabHost));
tabHost.TabWidget.GetChildAt(3).SetOnClickListener(new MyChannelClickListener(tabHost));
tabHost.TabWidget.GetChildAt(4).SetOnClickListener(new SettingsClickListener(tabHost));
EDIT: Create a separate ClickActivity.cs file and then add these listeners into it. you will need to create an OnClickListener instance for each tab. This example is only two of the listeners; but if you're using my template, you will need to use these examples to create another 3 listeners.
public class WhatsOnClickListener : Java.Lang.Object, IOnClickListener
{
TabHost tabHost;
//this int will tell the click listener whether to reload the webview or pop 2 root
static int tbC = 0;
public WhatsOnClickListener(TabHost tabHost)
{
//tell the clicklistener which tabhost to use
this.tabHost = tabHost;
}
//this class handles the click event
public void OnClick(View v)
{
//declare the webview and tell our object where to find the XAML resource
WebView webViewWhatsOn = tabHost.CurrentView.FindViewById<WebView>(Resource.Id.webViewWhatsOn);
//...if the CurrentTab != 0 ... we won't fire the Reload() or LoadUrl()
//..without this logic, the app will crash because our WebViews
//.aren't set to an instance of an object
if (tabHost.CurrentTab == 0)
{
//if tbC int is 0, we will reload the page
if (tbC == 0)
{
//tell whatsOnWebView to Reload
webViewWhatsOn.Reload();
//set the int to one so next time webview will pop to root
tbC = 1;
}
//else if the int is 1, we will pop to root on tab 0
else if (tbC == 1)
{
//tell whatsOnWebView to pop to root
webViewWhatsOn.LoadUrl(#"https://bitchute.com/");
//set the tbC int so that next time webview will reload
tbC = 0;
}
}
//if our current tab isn't zero, we need to set CurrentTab to 0
//this line is critical or our tabs won't work when not selected
tabHost.CurrentTab = 0;
}
}
public class SubsClickListener : Java.Lang.Object, IOnClickListener
{
TabHost tabHost1;
static int tbC = 0;
public SubsClickListener(TabHost tabHost1)
{
this.tabHost1 = tabHost1;
}
public void OnClick(View v)
{
if (tabHost1.CurrentTab == 1)
{
WebView subWebView = tabHost1.CurrentView.FindViewById<WebView>(Resource.Id.webViewSubs);
if (tbC == 0)
{
subWebView.Reload();
tbC = 1;
}
else if (tbC == 1)
{
subWebView.LoadUrl(#"https://bitchute.com/subscriptions/");
tbC = 0;
}
}
tabHost1.CurrentTab = 1;
}
}
hope that helps! I've been trying this for a minute.

Dynamic html news page is not working in C#

I'm trying to create a dynamic news html page.
The problem occurs when I try to create the html dynamically. I'm new to C#, and don't know what's wrong. Here is my c# code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using NewsAPI;
using NewsAPI.Models;
using NewsAPI.Constants;
namespace NewsDemo
{
public partial class Default1 : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
if(!Page.IsPostBack)
{
LoadNewsPage();
}
}
protected void LoadNewsPage()
{
try
{
var newsApiClient = new NewsApiClient("key");
List<string> mylist = new List<string>();
mylist.Add("google-news");
mylist.Add("bbc-news");
mylist.Add("cnn");
mylist.Add("the-new-york-times");
var articlesResponse = newsApiClient.GetTopHeadlines(new TopHeadlinesRequest
{
Sources = mylist,
Language = Languages.EN
});
if (articlesResponse.Status == Statuses.Ok)
{
string resulHtml = "";
resulHtml += "<table>";
foreach (var article in articlesResponse.Articles)
{
resulHtml += string.Format("<tr style='valign:top'>", "");
resulHtml += string.Format("<td width=20%><img src='{0}' width='250px' height='200px'></img></td>", article.UrlToImage);
resulHtml += string.Format("<td width=80%><a href='{0}'><h3>{1}</h3></a>{1}<br>{2}<br>{3}<br><br></td>", article.Url, article.Title, article.Author, article.Description);
resulHtml += string.Format("</tr>", "");
}
resulHtml += string.Format("</table>", "");
Label1.Text = resulHtml;
}
}
catch (Exception ex)
{
throw;
}
}
}
}
Whenever I try to run it, (in VS), Chrome opens and the page never loads. I have no idea what is wrong, as I have a console app that can fetch the news and that works fine.
Any help appreciated.
Thanks!

EDIT
Your comments to my answer helped my understand more.
I think your problem doesn't depend on your code but on a known problem with Chrome+Visual Studio
In short:
Either you can debug with another browser
Or you disable JavaScript debugging
I tested your LoadNewsPage() and it does get HTML just fine.
What seems strange is that you are inserting the HTML into the text of a Label.
Instead of doing that, add this HTML in your markup:
<div id="MyNewsSection" runat="server"></div>
And then replace this
Label1.Text = resulHtml;
with
MyNewsSection.InnerHtml = resulHtml;
Also, as a general debugging help, press F12 when in Chrome: if there are any errors, they will be shown to you.

Namespace is not working properly

I am getting a error for my namespace that says " the type or namespace name could not be found (are you missing a using directive or an assembly reference?) " and have no idea why... i have been trying to figure this one out for hours now... btw i am a newbie with c#
using System;
using System.Data;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using portfolioNamespace;
public partial class DefaultCode : System.Web.UI.Page{
Portfolio myPortfolio;
protected void Page_Load(object sender, EventArgs e){
//declare
myPortfolio = new Portfolio();
populate();
}
private void populate(){
//populate everything
populateMenu();
populateHome();
populateSamples();
populateAbout();
}
private void populateMenu(){
//populate the menu
String[] menu;
menu = myPortfolio.getMyMenu();
repLinks.DataSource = menu;
repLinks.DataBind();
//populates a hidden text box so i can get an array in javascript
for (int i = 0; i<=menu.Length - 1; i++){
dummy.Value = dummy.Value & menu(i) & "-";
}
}
private void populateHome(){
//populate home
homeRepeater.DataSource = myPortfolio.getHomeInfo;
homeRepeater.DataBind();
}
private void populateSamples(){
//populate samples
samplesRepeater.DataSource = myPortfolio.getSamplesInfo;
samplesRepeater.DataBind();
}
private void populateAbout(){
//populate about
aboutRepeater.DataSource = myPortfolio.getAboutInfo;
aboutRepeater.DataBind();
}
}

In your Solution Explorer Right click your References, click Add Reference > Browse, then find your dll file that contains portfolioNamespace and add it to your References.
See documentation for more details: How to: Add or Remove References By Using the Add Reference Dialog Box

You probably haven't created the portfolioNamespace.
You do so by wrapping your code in
namespace portfolioNamespace
{
//your code here
}
Have a read through these references, namespace (C# Reference) and Namespaces (C# Programming Guide)

It is not clear which file is getting error.
whatever the class name is giving error put cursor on that and press CTRL + DOT(.) it will suggest you to add the correct name space

Displaying xml information in label

Bassicly i can load my xml file correctly into a listview but i then want the user to be able to click on the items in the listview and from their display information about that item thats not in the listview but the xml.
So i thought i could load up an xml when the user clicks on the item and somehow fetch that information but it does not display anything on the label. Any help would be appreciated thanx.
XML:
<?xml version = "1.0" encoding="utf-8"?>
<project>
<test>
<code>ss</code>
<name>test</name>
</test>
<test>
<code>ss1</code>
<name>test1</name>
</test>
</project>
code:
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Xml;
using System.Xml.Linq;
namespace form
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
XmlTextReader reader = new XmlTextReader("XMLfile1.xml");
XmlNodeType type;
while (reader.Read())
{
type = reader.NodeType;
if (type == XmlNodeType.Element)
{
if (reader.Name == "name")
{
reader.Read();
listView1.Items.Add(reader.Value);
}
}
}
reader.Close();
}
private void Form1_Load(object sender, EventArgs e)
{
}
private void listView1_SelectedIndexChanged(object sender, EventArgs e)
{
XmlTextReader reader = new XmlTextReader("XMLFile1.xml");
XmlNodeType type;
while (reader.Read())
{
type = reader.NodeType;
if (type == XmlNodeType.Element)
{
if (reader.Name == "test")
{
reader.Read();
codelabel.Text = "s";
}
}
}
}
private void groupBox2_Enter(object sender, EventArgs e)
{
}
}
}

Using these extensions,
Write:
protected string GetName(string code)
{
var item = XElement.Load("XMLfile1.xml").GetEnumerable("test", x =>
new
{
Code = x.Get("code", string.Empty),
Name = x.Get("name", string.Empty)
})
.FirstOrDefault(i => i.Code == code);
if(null != item)
return item.Name;
return "Item not found";
}
This looks up the list from the file, check's each one until it finds the right code and then returns the name value. Then place that value in your control. If I have it wrong that you are searching by name, just exchange the code in the FirstOrDefault line with the return item.Name line.

Create a class that mimics the data in your file. Like:
public class Project
{
public string Code { get; set; }
public string Name { get; set; }
}
Then, you'll read your XML file into what will end up being a List. Take a look at this tutorial:
Simple XML Parsing
private List<Project> _projects;
You would then add your data from the List to your ListView.
foreach(Project proj in _projects)
{
listView1.Items.Add(proj.Name);
}
In your ListView SelectedIndexChanged you can access the proper index of the List to display the proper value to your label.
codeLabel.Text = _projects[listView1.FocusedItem.Index].Code;

The Value property for the test node is empty (it contains only sub-nodes, no text).
I think you should change your code to accumulate the text (with declarations, you can see an example on MSDN) from beginning of test until you read its end tag.
As alternative (if the XML file is not big) you may consider to use LINQ to XML or simply an XmlDocument (it's much more easy to read and you can always have InnerXml of any node). For an example you can look this article on CodeProject.
For a short list of what you can do to parse XML you can read this article (I don't think it's very good but at least it is a...list).