[geary/mjog/558-webkit-shared-process-redux: 39/47] Composer.WebView: Convert to using messages for JS → client comms

[Michael Gratton <mjog src gnome org>]

commit 27f23cbefedaa6b52b436d3fa4cfa675101cda89
Author: Michael Gratton <mike vee net>
Date:   Fri Aug 28 11:38:06 2020 +1000

    Composer.WebView: Convert to using messages for JS → client comms

 src/client/composer/composer-web-view.vala | 75 ++++++++++++++----------------
 ui/composer-web-view.js                    | 18 ++++---
 2 files changed, 45 insertions(+), 48 deletions(-)
---
diff --git a/src/client/composer/composer-web-view.vala b/src/client/composer/composer-web-view.vala
index 24a2740ca..57b7e1e41 100644
--- a/src/client/composer/composer-web-view.vala
+++ b/src/client/composer/composer-web-view.vala
@@ -33,8 +33,8 @@ public class Composer.WebView : Components.WebView {
     private const string SPACER = "<div><br /></div>";
 
     // WebKit message handler names
-    private const string CURSOR_CONTEXT_CHANGED = "cursorContextChanged";
-    private const string DRAG_DROP_RECEIVED = "dragDropReceived";
+    private const string CURSOR_CONTEXT_CHANGED = "cursor_context_changed";
+    private const string DRAG_DROP_RECEIVED = "drag_drop_received";
 
     /**
      * Encapsulates editing-related state for a specific DOM node.
@@ -152,8 +152,8 @@ public class Composer.WebView : Components.WebView {
         this.user_content_manager.add_style_sheet(WebView.app_style);
         this.user_content_manager.add_script(WebView.app_script);
 
-        register_message_handler(CURSOR_CONTEXT_CHANGED, on_cursor_context_changed);
-        register_message_handler(DRAG_DROP_RECEIVED, on_drag_drop_received);
+        register_message_callback(CURSOR_CONTEXT_CHANGED, on_cursor_context_changed);
+        register_message_callback(DRAG_DROP_RECEIVED, on_drag_drop_received);
 
         // XXX this is a bit of a hack given the docs for is_empty,
         // above
@@ -530,50 +530,43 @@ public class Composer.WebView : Components.WebView {
         return ret;
     }
 
-    private void on_cursor_context_changed(WebKit.JavascriptResult result) {
-        try {
-            cursor_context_changed(
-                new EditContext(Util.JS.to_string(result.get_js_value()))
-            );
-        } catch (Util.JS.Error err) {
-            debug("Could not get text cursor style: %s", err.message);
+    private void on_cursor_context_changed(GLib.Variant? parameters) {
+        if (parameters != null && parameters.classify() == STRING) {
+            cursor_context_changed(new EditContext(parameters as string));
+        } else {
+            warning("Could not get text cursor style");
         }
     }
 
     /**
      *  Handle a dropped image
      */
-    private void on_drag_drop_received(WebKit.JavascriptResult result) {
-
-        try {
-            JSC.Value object = result.get_js_value();
-            string filename = Util.JS.to_string(
-                Util.JS.get_property(object, "fileName")
-            );
-            string filename_unescaped = GLib.Uri.unescape_string(filename);
-
-            string file_type = Util.JS.to_string(
-                Util.JS.get_property(object, "fileType")
-            );
-
-            string content_base64 = Util.JS.to_string(
-                Util.JS.get_property(object, "content")
-            );
-            uint8[] image = GLib.Base64.decode(content_base64);
-
-            if (image.length == 0) {
-                warning("%s is empty", filename);
-                return;
-            }
+    private void on_drag_drop_received(GLib.Variant? parameters) {
+        var dict = new GLib.VariantDict(parameters);
+        string file_name = dict.lookup_value(
+            "fileName", GLib.VariantType.STRING
+        ).get_string();
+        string file_name_unescaped = GLib.Uri.unescape_string(file_name);
+
+        string file_type = dict.lookup_value(
+            "fileType", GLib.VariantType.STRING
+        ).get_string();
+
+        string content_base64 = dict.lookup_value(
+            "content", GLib.VariantType.STRING
+        ).get_string();
+        uint8[] image = GLib.Base64.decode(content_base64);
+
+        if (image.length == 0) {
+            warning("%s is empty", file_name);
+            return;
+        }
 
-            // A simple check to see if the file looks like an image. A problem here
-            // will be this accepting types which won't be supported by WebKit
-            // or recipients.
-            if (file_type.index_of("image/") == 0) {
-                image_file_dropped(filename_unescaped, file_type, image);
-            }
-        } catch (Util.JS.Error err) {
-            debug("Could not get deceptive link param: %s", err.message);
+        // A simple check to see if the file looks like an image. A problem here
+        // will be this accepting types which won't be supported by WebKit
+        // or recipients.
+        if (file_type.index_of("image/") == 0) {
+            image_file_dropped(file_name_unescaped, file_type, image);
         }
     }
 }
diff --git a/ui/composer-web-view.js b/ui/composer-web-view.js
index ca9189903..4fe34ad0b 100644
--- a/ui/composer-web-view.js
+++ b/ui/composer-web-view.js
@@ -1,6 +1,6 @@
 /*
- * Copyright 2016 Software Freedom Conservancy Inc.
- * Copyright 2016 Michael Gratton <mike vee net>
+ * Copyright © 2016 Software Freedom Conservancy Inc.
+ * Copyright © 2016-2020 Michael Gratton <mike vee net>
  *
  * This software is licensed under the GNU Lesser General Public License
  * (version 2.1 or later). See the COPYING file in this distribution.
@@ -35,6 +35,9 @@ ComposerPageState.prototype = {
         this.nextSelectionId = 0;
         this.cursorContext = null;
 
+        this._cursorContextChanged = MessageSender("cursor_context_changed");
+        this._dragDropReceived = MessageSender("drag_drop_received");
+
         document.addEventListener("click", function(e) {
             if (e.target.tagName == "A") {
                 e.preventDefault();
@@ -99,7 +102,9 @@ ComposerPageState.prototype = {
         }, true);
 
         // Handle file drag & drop
-        document.body.addEventListener("drop", state.handleFileDrop, true);
+        document.body.addEventListener("drop", function(e) {
+            state.handleFileDrop(e);
+        }, true);
         document.body.addEventListener("allowDrop", function(e) {
             ev.preventDefault();
         }, true);
@@ -346,9 +351,7 @@ ComposerPageState.prototype = {
             let newContext = new EditContext(cursor);
             if (!newContext.equals(this.cursorContext)) {
                 this.cursorContext = newContext;
-                window.webkit.messageHandlers.cursorContextChanged.postMessage(
-                    newContext.encode()
-                );
+                this._cursorContextChanged(newContext.encode());
             }
         }
 
@@ -396,13 +399,14 @@ ComposerPageState.prototype = {
                 continue;
 
             const reader = new FileReader();
+            const state = this;
             reader.onload = (function(filename, imageType) { return function(loadEvent) {
                 // Remove prefixed file type and encoding type
                 var parts = loadEvent.target.result.split(",");
                 if (parts.length < 2)
                     return;
 
-                window.webkit.messageHandlers.dragDropReceived.postMessage({
+                state._dragDropReceived({
                     fileName: encodeURIComponent(filename),
                     fileType: imageType,
                     content: parts[1]