From a1fac4049d79171dc40f0cd416c1358fd4dc2d3c Mon Sep 17 00:00:00 2001
From: "Steinar H. Gunderson" <sgunderson@bigfoot.com>
Date: Sun, 25 Feb 2018 23:30:49 +0100
Subject: [PATCH] When asked to execute JavaScript, defer until the current
 page load is done.

---
 cef_capture.cpp | 29 ++++++++++++++++++++++++++---
 cef_capture.h   | 24 +++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 4 deletions(-)

diff --git a/cef_capture.cpp b/cef_capture.cpp
index 1836eb8..76c5c7f 100644
--- a/cef_capture.cpp
+++ b/cef_capture.cpp
@@ -52,6 +52,7 @@ void CEFCapture::post_to_cef_ui_thread(std::function<void()> &&func)
 void CEFCapture::set_url(const string &url)
 {
 	post_to_cef_ui_thread([this, url] {
+		loaded = false;
 		browser->GetMainFrame()->LoadURL(url);
 	});
 }
@@ -74,9 +75,13 @@ void CEFCapture::set_max_fps(int max_fps)
 void CEFCapture::execute_javascript_async(const string &js)
 {
 	post_to_cef_ui_thread([this, js] {
-		CefString script_url("<theme eval>");
-		int start_line = 1;
-		browser->GetMainFrame()->ExecuteJavaScript(js, script_url, start_line);
+		if (loaded) {
+			CefString script_url("<theme eval>");
+			int start_line = 1;
+			browser->GetMainFrame()->ExecuteJavaScript(js, script_url, start_line);
+		} else {
+			deferred_javascript.push_back(js);
+		}
 	});
 }
 
@@ -106,6 +111,19 @@ void CEFCapture::OnPaint(const void *buffer, int width, int height)
 		FrameAllocator::Frame(), 0, AudioFormat());
 }
 
+void CEFCapture::OnLoadEnd()
+{
+	post_to_cef_ui_thread([this] {
+		loaded = true;
+		for (const string &js : deferred_javascript) {
+			CefString script_url("<theme eval>");
+			int start_line = 1;
+			browser->GetMainFrame()->ExecuteJavaScript(js, script_url, start_line);
+		}
+		deferred_javascript.clear();
+	});
+}
+
 #define FRAME_SIZE (8 << 20)  // 8 MB.
 
 void CEFCapture::configure_card()
@@ -199,3 +217,8 @@ bool NageruCEFClient::GetViewRect(CefRefPtr<CefBrowser> browser, CefRect &rect)
 	rect = CefRect(0, 0, width, height);
 	return true;
 }
+
+void NageruCEFClient::OnLoadEnd(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, int httpStatusCode)
+{
+	parent->OnLoadEnd();
+}
diff --git a/cef_capture.h b/cef_capture.h
index 11cdc33..c497179 100644
--- a/cef_capture.h
+++ b/cef_capture.h
@@ -17,6 +17,7 @@
 #include <set>
 #include <string>
 #include <thread>
+#include <vector>
 
 #undef CHECK
 #include <cef_client.h>
@@ -31,7 +32,7 @@ class CEFCapture;
 
 // A helper class for CEFCapture to proxy information to CEF, without becoming
 // CEF-refcounted itself.
-class NageruCEFClient : public CefClient, public CefRenderHandler
+class NageruCEFClient : public CefClient, public CefRenderHandler, public CefLoadHandler
 {
 public:
 	NageruCEFClient(int width, int height, CEFCapture *parent)
@@ -42,10 +43,21 @@ public:
 		return this;
 	}
 
+	CefRefPtr<CefLoadHandler> GetLoadHandler() override
+	{
+		return this;
+	}
+
+	// CefRenderHandler.
+
 	void OnPaint(CefRefPtr<CefBrowser> browser, PaintElementType type, const RectList &dirtyRects, const void *buffer, int width, int height) override;
 
 	bool GetViewRect(CefRefPtr<CefBrowser> browser, CefRect &rect);
 
+	// CefLoadHandler.
+
+	void OnLoadEnd(CefRefPtr<CefBrowser> browser, CefRefPtr<CefFrame> frame, int httpStatusCode) override;
+
 private:
 	int width, height;
 	CEFCapture *parent;
@@ -76,6 +88,8 @@ public:
 
 	void OnPaint(const void *buffer, int width, int height);
 
+	void OnLoadEnd();
+
 	// CaptureInterface.
 	void set_video_frame_allocator(bmusb::FrameAllocator *allocator) override
 	{
@@ -173,6 +187,14 @@ private:
 	// Tasks waiting for <browser> to get ready. Under <browser_mutex>.
 	std::vector<std::function<void()>> deferred_tasks;
 
+	// Whether the last set_url() (includes the implicit one in the constructor)
+	// has loaded yet. Accessed from the CEF thread only.
+	bool loaded = false;
+
+	// JavaScript waiting for the first page (well, any page) to have loaded.
+	// Accessed from the CEF thread only.
+	std::vector<std::string> deferred_javascript;
+
 	int timecode = 0;
 };
 
-- 
2.39.2