DefaultFontSize no longer applied to text loaded with LoadHtml() method

[smunnik]

Is there an existing issue for this?

• I have searched both open/closed issues, no issue already exists.

CefSharp Version

135.0.220

Operating System

Windows 11

Architecture

x64

.Net Version

.Net 8.0

Implementation

WPF

Reproduction Steps

Set the DefaultFontSize and then load text via the LoadHtml() method. See modifed code snippet from minimal example below.

<wpf:ChromiumWebBrowser x:Name="Browser" 
                        IsBrowserInitializedChanged="Browser_OnIsBrowserInitializedChanged">

using System.Windows;

namespace CefSharp.MinimalExample.Wpf
{
    public partial class MainWindow : Window
    {
        private const int DefaultFontSize = 36;

        public MainWindow()
        {
            InitializeComponent();
            Browser.BrowserSettings.DefaultFontSize = DefaultFontSize;
        }

        private void Browser_OnIsBrowserInitializedChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            if ((bool)e.NewValue)
            {
                Browser.LoadHtml(
                    $"This message should be displayed in the default font size of {DefaultFontSize} that was specified.",
                    "http://message/");
            }
        }
    }
}

Expected behavior

The DefaultFontSize should be applied to text loaded with the LoadHtml() method.

Actual behavior

DefaultFontSize is ignored - the font size remains the same no matter what value is supplied.

Regression?

Worked in version 125.0.210 – does not work from version 126.2.70 onwards.

Known Workarounds

Manually set the document.body.style.fontSize using EvaluateScriptAsync() method.

<wpf:ChromiumWebBrowser x:Name="Browser" 
                        IsBrowserInitializedChanged="Browser_OnIsBrowserInitializedChanged" 
                        LoadingStateChanged="Browser_OnLoadingStateChanged">

using System.Windows;

namespace CefSharp.MinimalExample.Wpf
{
    public partial class MainWindow : Window
    {
        private const int DefaultFontSize = 36;

        public MainWindow()
        {
            InitializeComponent();
            Browser.BrowserSettings.DefaultFontSize = DefaultFontSize;
        }

        private void Browser_OnIsBrowserInitializedChanged(object sender, DependencyPropertyChangedEventArgs e)
        {
            if ((bool)e.NewValue)
            {
                Browser.LoadHtml(
                    $"This message should be displayed in the default font size of {DefaultFontSize} that was specified.",
                    "http://message/");
            }
        }


        private async void Browser_OnLoadingStateChanged(object sender, LoadingStateChangedEventArgs e)
        {
            if (e.IsLoading)
            {
                return;
            }

            var javascript = $"document.body.style.fontSize = \"{DefaultFontSize}\";";
            await Browser.GetMainFrame().EvaluateScriptAsync($"(function(){{ {javascript} }})();");
        }
    }
}

Does this problem also occur in the CEF Sample Application

Not Tested

Other information

No response

[amaitland]

Converting to discussion as this is unlikely a bug that can be fixed in CefSharp, more likely an upstream issue that would need to be fixed in CEF.

CEF has it's own issue tracker at https://github.com/chromiumembedded/cef/issues

Please make sure you've read the first few paragraphs of https://github.com/cefsharp/CefSharp/wiki/General-Usage

DefaultFontSize is ignored - the font size remains the same no matter what value is supplied.

Does it work for normal urls loaded? Does it make any difference if you use https instead of http?

Worked in version 125.0.210 – does not work from version 126.2.70 onwards.

This is when CefSharp switch to using the Chrome Bootstrap. In M126 you can switch back to using the Alloy Bootstrap to test that it is related.

#4835