How to invoke a Delphi callback function from JavaScript in TWebBrowser on Delphi XE6 for all platforms, including iOS and Android?

[DancingFox]

I am developing an application using Delphi XE6 for both Android and iOS. The app will utilize a TWebBrowser to display Google Maps, and I need to facilitate communication between Delphi and JavaScript. Specifically, I want to ‘send’ data from Delphi to JavaScript and also ‘receive’ commands back from JavaScript to Delphi. This functionality is crucial for interaction, such as showing a marker on the map and detecting when a user clicks it. I’ve come across resources about executing JavaScript from Delphi but I’m uncertain about how to trigger a Delphi method from JavaScript. For instance, I have the following procedure in Delphi:

procedure HandleJSFeedback(param1, param2, param3, param4: string);

I want to know how to invoke this procedure through JavaScript within the TWebBrowser and pass four arguments to it. Most of the existing discussions I’ve found are focused on Windows applications, which do not apply to Android, and I’m yet to explore iOS functionalities.

[CreatingStone]

To invoke a Delphi method from JavaScript in TWebBrowser, you can use a JavaScript interface. Here's a basic outline:

1. Define a custom interface in Delphi:

type
  IJavaScriptHelper = interface
    ['{GUID}']
    procedure HandleJSFeedback(const param1, param2, param3, param4: WideString);
  end;

2. Implement the interface in your Delphi code:

type
  TJavaScriptBridge = class(TInterfacedObject, IJavaScriptHelper)
  public
    procedure HandleJSFeedback(const param1, param2, param3, param4: WideString);
  end;

procedure TJavaScriptBridge.HandleJSFeedback(const param1, param2, param3, param4: WideString);
begin
  // Your implementation here
end;

3. Link it to TWebBrowser:

WebBrowser.ComObject.Script := TJavaScriptBridge.Create;

4. Call it from JavaScript:

window.external.HandleJSFeedback('arg1', 'arg2', 'arg3', 'arg4');

This setup allows JavaScript to call your Delphi procedure on Android and iOS. Test thoroughly on both platforms as behavior might slightly differ.

[Emma_Fluffy]

To facilitate invoking Delphi callbacks from JavaScript in a TWebBrowser across all platforms, including Android and iOS, it's crucial to utilize the mobile platform's native features. Here's an alternative approach that emphasizes using platform-specific capabilities while maintaining a similar structure:

1. Understanding Platform Limitations: Unlike the desktop, mobile platforms (Android and iOS) do not always offer direct access to TWebBrowser callbacks. Hence, intermediary bridges or native extensions might be necessary.
2. Android JavaScript Interface: For Android, employ the WebView.addJavascriptInterface method:

JavaHandle := TJavaObject.Create;
WebBrowser.NativeBrowserView.addJavascriptInterface(JavaHandle, 'JSInterface');

3. Implement the Java Method: Create a Java method in your Delphi application that JavaScript can trigger:

@JavascriptInterface
public void HandleJSFeedback(final String param1, final String param2, final String param3, final String param4) {
    // Call Delphi procedure here
}

4. iOS WebKit Messaging: Use WebKit messaging in iOS, where JavaScript sends a message to the native app:

// In JavaScript
webkit.messageHandlers.JSInterface.postMessage({param1: 'value1', param2: 'value2', param3: 'value3', param4: 'value4'});

5. Handle the Message in Delphi: Implement a messaging handler to parse these parameters and invoke your Delphi method:

// Define a handler in Delphi that processes the parameters sent from JavaScript.

It's important to test this integration closely on both Android and iOS, as platform-specific quirks can affect execution. Always consider security implications, like ensuring parameter validation to prevent injection threats.

[Alice45]

To invoke a Delphi callback from JavaScript in TWebBrowser across platforms like Android and iOS, you'll need a structured approach involving platform-specific features:

1. Create a custom interface in Delphi:

type
  IJavaScriptHelper = interface
    ['{GUID}']
    procedure HandleJSFeedback(const param1, param2, param3, param4: WideString);
  end;

2. Implement this interface:

type
  TJavaScriptBridge = class(TInterfacedObject, IJavaScriptHelper)
  public
    procedure HandleJSFeedback(const param1, param2, param3, param4: WideString);
  end;

procedure TJavaScriptBridge.HandleJSFeedback(const param1, param2, param3, param4: WideString);
begin
  // Implementation here
end;

3. Link it to TWebBrowser:

WebBrowser.ComObject.Script := TJavaScriptBridge.Create;

4. Call the procedure from JavaScript:

window.external.HandleJSFeedback('arg1', 'arg2', 'arg3', 'arg4');

For Android, use WebView.addJavascriptInterface, and for iOS, use WebKit messaging for integration. Test thoroughly, considering security implications.

[DancingBird]

Given the need to bridge JavaScript and Delphi on both Android and iOS platforms using TWebBrowser, one must consider native capabilities of each platform to enable seamless interaction.

Approach:

• Delphi Interface Implementation: Start by defining a platform-independent interface in Delphi that mirrors the JavaScript function:

type
  IJavaScriptHandler = interface
    ['{GUID}']
    procedure HandleJSFeedback(const param1, param2, param3, param4: WideString);
  end;

• Platform-Specific Implementations: Implement this interface differently for Android and iOS, utilizing native bridges.

Android:

• Use WebView.addJavascriptInterface to connect JavaScript and Delphi:

JavaHandle := TJavaObject.Create;
WebBrowser.NativeBrowserView.addJavascriptInterface(JavaHandle, 'JSBridge');

• Implement the Java method called by JavaScript:

@JavascriptInterface
public void HandleJSFeedback(final String param1, final String param2, final String param3, final String param4) {
    // Delegate call to Delphi procedure
}

iOS:

• Use WebKit's messageHandlers to communicate with JavaScript:

// In JavaScript
webkit.messageHandlers.JSBridge.postMessage({param1: 'value1', param2: 'value2', param3: 'value3', param4: 'value4'});

• Set up a handler in Delphi to process these parameters:

// Handle incoming messages in Delphi and invoke the procedure

Security Consideration: Ensure you validate and sanitize input parameters to safeguard against injection attacks.

This approach allows for a robust cross-platform solution while leveraging the native APIs of each platform to facilitate JavaScript and Delphi interaction. Always conduct extensive testing to handle platform-specific quirks and differences.