feat(tauri-apps#474): implement callback for evaluating javascript in…

… webview2

examples/evaluate_javascript.rs

@@ -0,0 +1,66 @@
+// Copyright 2019-2021 Tauri Programme within The Commons Conservancy
+// SPDX-License-Identifier: Apache-2.0
+// SPDX-License-Identifier: MIT
+
+use tao::event::{DeviceEvent, ElementState};
+
+fn main() -> wry::Result<()> {
+  use wry::{
+    application::{
+      event::{Event, StartCause, WindowEvent},
+      event_loop::{ControlFlow, EventLoop},
+      window::WindowBuilder,
+    },
+    webview::WebViewBuilder,
+  };
+
+  let event_loop = EventLoop::new();
+  let window = WindowBuilder::new()
+    .with_title("Hello World")
+    .build(&event_loop)?;
+  let webview = WebViewBuilder::new(window)?
+    .with_url("https://html5test.com")?
+    .build()?;
+
+  event_loop.run(move |event, _, control_flow| {
+    *control_flow = ControlFlow::Wait;
+
+    match event {
+      Event::NewEvents(StartCause::Init) => println!("Wry has started!"),
+      Event::WindowEvent {
+        event: WindowEvent::CloseRequested,
+        ..
+      } => *control_flow = ControlFlow::Exit,
+      Event::DeviceEvent {
+        event: DeviceEvent::Key(raw),
+        ..
+      } => {
+        if raw.state == ElementState::Released {
+          let _ = webview.evaluate_script(
+            format!(
+              "
+              window.__WRY_HEADS__ = Math.random() < 0.5;
+              window.alert(window.__WRY_HEADS__ ? 'Heads!' : 'Tails!');
+              window.__WRY_HEADS__;
+              "
+            )
+            .as_str(),
+            |result| {
+              let heads: bool = serde_json::from_str(result.as_str()).unwrap();
+              println!(
+                "{}",
+                match heads {
+                  true => "Heads!",
+                  false => "Tails!",
+                }
+              )
+            },
+          );
+        }
+      }
+      _ => {
+        let _ = webview.resize();
+      }
+    }
+  });
+}

examples/multi_window.rs

@@ -81,7 +81,7 @@ fn main() -> wry::Result<()> {
       webviews
         .get_mut(&id)
         .unwrap()
-        .evaluate_script("openWindow()")
+        .evaluate_script("openWindow()", || ())
         .unwrap();
       trigger = false;
     }

src/webview/mod.rs

@@ -412,8 +412,8 @@ impl WebView {
   /// [`WebView`]. Use [`EventLoopProxy`] and a custom event to send scripts from other threads.
   ///
   /// [`EventLoopProxy`]: crate::application::event_loop::EventLoopProxy
-  pub fn evaluate_script(&self, js: &str) -> Result<()> {
-    self.webview.eval(js)
+  pub fn evaluate_script(&self, js: &str, callback: impl FnOnce(String) -> () + 'static) -> Result<()> {
+    self.webview.eval(js, callback)
   }
 
   /// Launch print modal for the webview content.

src/webview/webview2/mod.rs

@@ -289,7 +289,7 @@ impl InnerWebView {
               match super::rpc_proxy(&window, js, rpc_handler) {
                 Ok(result) => {
                   if let Some(script) = result {
-                    Self::execute_script(&webview, script)?;
+                    Self::execute_script(&webview, script, |_| ())?;
                   }
                 }
                 Err(e) => {
@@ -545,21 +545,24 @@ impl InnerWebView {
     )
   }
 
-  fn execute_script(webview: &ICoreWebView2, js: String) -> windows::core::Result<()> {
+  fn execute_script(webview: &ICoreWebView2, js: String, callback: impl FnOnce(String) -> () + 'static) -> windows::core::Result<()> {
     unsafe {
       webview.ExecuteScript(
         js,
-        ExecuteScriptCompletedHandler::create(Box::new(|_, _| (Ok(())))),
+        ExecuteScriptCompletedHandler::create(Box::new(|_, result_object_as_json| {
+          callback(result_object_as_json);
+          Ok(())
+        })),
       )
     }
   }
 
   pub fn print(&self) {
-    let _ = self.eval("window.print()");
+    let _ = self.eval("window.print()", |_| ());
   }
 
-  pub fn eval(&self, js: &str) -> Result<()> {
-    Self::execute_script(&self.webview, js.to_string())
+  pub fn eval(&self, js: &str, callback: impl FnOnce(String) -> () + 'static) -> Result<()> {
+    Self::execute_script(&self.webview, js.to_string(), callback)
       .map_err(|err| Error::WebView2Error(webview2_com::Error::WindowsError(err)))
   }