WebView2 (TEdgeBrowser) updated Delphi interface (e.g. ICoreWebView2Controller2)

Question

The default Delphi 10.4.2 TEdgeBrowser interface is currently only the original-release WebView2. However, it seems that to have flicker-free load on non-white backgrounds we need to set the background color using ICoreWebView2Controller2. How to access this (in a backwards-compatible way) from Delphi? I have tried importing the .tlb from Microsoft's updated WebView2 nuget bundle, however Delphi gives an OLE error, so I cannot find a way to generate a Delphi WebView2 interface with the new functions.

Answer 1

To call the ICoreWebView2Controller2 methods, you have to first declare the interface and then at run time use QueryInterface to get a reference on it and finally call the method.

Here after a small unit that I created starting from Microsoft header file:

unit Ovb.WebView2;

interface

uses
    WebView2;

const
    IID_ICoreWebView2Controller2: TGUID = '{C979903E-D4CA-4228-92EB-47EE3FA96EAB}';

type
    COREWEBVIEW2_COLOR = packed record
        A : BYTE;
        R : BYTE;
        B : BYTE;
        G : BYTE;
    end;
    TCOREWEBVIEW2_COLOR = COREWEBVIEW2_COLOR;
    PCOREWEBVIEW2_COLOR = ^COREWEBVIEW2_COLOR;

  ICoreWebView2Controller2 = interface(ICoreWebView2Controller)
      ['{C979903E-D4CA-4228-92EB-47EE3FA96EAB}']
      function get_DefaultBackgroundColor(backgroundColor : PCOREWEBVIEW2_COLOR) : HRESULT; stdcall;
      function put_DefaultBackgroundColor(backgroundColor : TCOREWEBVIEW2_COLOR) : HRESULT; stdcall;
  end;


implementation

end.

You can use it for example like this:

procedure TEdgeViewForm.EdgeBrowser1CreateWebViewCompleted(
    Sender  : TCustomEdgeBrowser;
    AResult : HRESULT);
var
    Ctrl2     : ICoreWebView2Controller2;
    BackColor : TCOREWEBVIEW2_COLOR;
    HR        : HRESULT;
begin
    Sender.ControllerInterface.QueryInterface(IID_ICoreWebView2Controller2, Ctrl2);
    if not Assigned(Ctrl2) then
        raise Exception.Create('ICoreWebView2Controller2 not found');
    // Select red background
    BackColor.A := 255;
    BackColor.R := 255;
    BackColor.G := 0;
    BackColor.B := 0;
    HR := Ctrl2.put_DefaultBackgroundColor(BackColor);
    if not SUCCEEDED(HR) then
        raise Exception.Create('put_DefaultBackgroundColor failed');
end;

I have tested my code using Embarcadero EdgeView demo. The red background is visible so I consider my code as correct.