[windows] with solution! cannot make transparentBackground

[iiiSnow]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

On Windows, setting

initialSettings: InAppWebViewSettings(
  transparentBackground: true,
)

does not take effect — the background remains white.

Expected Behavior

transparentbackground

Steps with code example to reproduce

Set

initialSettings: InAppWebViewSettings(
  transparentBackground: true,
)

Run on Windows

Observe that the background is not transparent

Stacktrace/Logs

no logs

Flutter version

v3.32.6

Operating System, Device-specific and/or Tool

windows

Plugin version

v6.1.4

Additional information

🔍 Issue Analysis

1️⃣ File
windows/flutter/ephemeral/.plugin_symlinks/flutter_inappwebview_windows/windows/in_app_webview/in_app_webview.cpp

Lines 208–213:

wil::com_ptr<ICoreWebView2Controller2> webViewController2; 
if (succeededOrLog(webViewController->QueryInterface(IID_PPV_ARGS(&webViewController2)))) {
  if (!settings->transparentBackground) {
    webViewController2->put_DefaultBackgroundColor({ 0, 255, 255, 255 });
  }
}

The logic for transparentBackground is inverted here.
It should apply a transparent background when transparentBackground == true, not the opposite.

2️⃣ Same file, lines 1441–1445:

wil::com_ptr<ICoreWebView2Controller2> webViewController2;
if (succeededOrLog(webViewController->QueryInterface(IID_PPV_ARGS(&webViewController2)))) {
  if (fl_map_contains_not_null(newSettingsMap, "transparentBackground") && settings->transparentBackground != newSettings->transparentBackground) {
    BYTE alpha = newSettings->transparentBackground ? 0 : 255;
    webViewController2->put_DefaultBackgroundColor({ alpha, 255, 255, 255 });
  }
}

Here, newSettings->transparentBackground is always false,
so alpha never becomes 0.
When I forced alpha = 0, the transparent background worked correctly.

Notes

I’m not very familiar with C++, so I didn’t open a PR.
Just wanted to report this so you can double-check and fix it. 🙏

Linked: commitid: f3bf4b8
f3bf4b8

Self grab

• I'm ready to work on this issue!

[iiiSnow]

#2475