Better resize rate limiting

Be more aggressive with resizing, limiting it to once ever 100 ms
instead of after a 500 ms idle period. This avoids unnecessary delays
when entering or leaving full screen, or when maximizing.

4 files changed, 50 insertions, 4 deletions

diff --git a/vncviewer/CConn.cxx b/vncviewer/CConn.cxx
index 3a5c161f..5f943640 100644
--- a/vncviewer/CConn.cxx
+++ b/vncviewer/CConn.cxx
@@ -37,6 +37,7 @@
 #include <rfb/Security.h>
 #include <rfb/fenceTypes.h>
 #include <rfb/Timer.h>
+#include <rfb/screenTypes.h>
 #include <network/TcpSocket.h>
 #ifndef WIN32
 #include <network/UnixSocket.h>
@@ -316,6 +317,16 @@ void CConn::initDone()
     setPreferredEncoding(encNum);
 }
 
+void CConn::setExtendedDesktopSize(unsigned reason, unsigned result,
+                                   int w, int h,
+                                   const rfb::ScreenSet& layout)
+{
+  CConnection::setExtendedDesktopSize(reason, result, w, h, layout);
+
+  if (reason == reasonClient)
+    desktop->setDesktopSizeDone(result);
+}
+
 // setName() is called when the desktop name changes
 void CConn::setName(const char* name)
 {
diff --git a/vncviewer/CConn.h b/vncviewer/CConn.h
index 5c470508..e830ecaa 100644
--- a/vncviewer/CConn.h
+++ b/vncviewer/CConn.h
@@ -57,6 +57,10 @@ public:
 
   void initDone() override;
 
+  void setExtendedDesktopSize(unsigned reason, unsigned result,
+                              int w, int h,
+                              const rfb::ScreenSet& layout) override;
+
   void setName(const char* name) override;
 
   void setColourMapEntries(int firstColour, int nColours,
diff --git a/vncviewer/DesktopWindow.cxx b/vncviewer/DesktopWindow.cxx
index 48b975b2..8e9bc814 100644
--- a/vncviewer/DesktopWindow.cxx
+++ b/vncviewer/DesktopWindow.cxx
@@ -84,6 +84,7 @@ DesktopWindow::DesktopWindow(int w, int h, const char *name,
   : Fl_Window(w, h), cc(cc_), offscreen(nullptr), overlay(nullptr),
     firstUpdate(true),
     delayedFullscreen(false), sentDesktopSize(false),
+    pendingRemoteResize(false), lastResize({0, 0}),
     keyboardGrabbed(false), mouseGrabbed(false),
     statsLastUpdates(0), statsLastPixels(0), statsLastPosition(0),
     statsGraph(nullptr)
@@ -403,6 +404,19 @@ void DesktopWindow::resizeFramebuffer(int new_w, int new_h)
 }
 
 
+void DesktopWindow::setDesktopSizeDone(unsigned result)
+{
+  pendingRemoteResize = false;
+
+  if (result != 0)
+    return;
+
+  // We might have resized again whilst waiting for the previous
+  // request, so check if we are in sync
+  remoteResize();
+}
+
+
 void DesktopWindow::setCursor(int width, int height,
                               const rfb::Point& hotspot,
                               const uint8_t* data)
@@ -690,10 +704,7 @@ void DesktopWindow::resize(int x, int y, int w, int h)
   Fl_Window::resize(x, y, w, h);
 
   if (resizing) {
-    // We delay updating the remote desktop as we tend to get a flood
-    // of resize events as the user is dragging the window.
-    Fl::remove_timeout(handleResizeTimeout, this);
-    Fl::add_timeout(0.5, handleResizeTimeout, this);
+    remoteResize();
 
     repositionWidgets();
   }
@@ -1308,6 +1319,18 @@ void DesktopWindow::remoteResize()
   if (delayedFullscreen)
     return;
 
+  // Rate limit to one pending resize at a time
+  if (pendingRemoteResize)
+    return;
+
+  // And no more than once every 100ms
+  if (msSince(&lastResize) < 100) {
+    Fl::remove_timeout(handleResizeTimeout, this);
+    Fl::add_timeout((100.0 - msSince(&lastResize)) / 1000.0,
+                    handleResizeTimeout, this);
+    return;
+  }
+
   width = w();
   height = h();
 
@@ -1438,6 +1461,8 @@ void DesktopWindow::remoteResize()
     vlog.debug("%s", buffer);
   }
 
+  pendingRemoteResize = true;
+  gettimeofday(&lastResize, nullptr);
   cc->writer()->writeSetDesktopSize(width, height, layout);
 }
 
diff --git a/vncviewer/DesktopWindow.h b/vncviewer/DesktopWindow.h
index 8ac19c45..97c3c00d 100644
--- a/vncviewer/DesktopWindow.h
+++ b/vncviewer/DesktopWindow.h
@@ -55,6 +55,9 @@ public:
   // Resize the current framebuffer, but retain the contents
   void resizeFramebuffer(int new_w, int new_h);
 
+  // A previous call to writeSetDesktopSize() has completed
+  void setDesktopSizeDone(unsigned result);
+
   // New image for the locally rendered cursor
   void setCursor(int width, int height, const rfb::Point& hotspot,
                  const uint8_t* data);
@@ -132,6 +135,9 @@ private:
   bool delayedFullscreen;
   bool sentDesktopSize;
 
+  bool pendingRemoteResize;
+  struct timeval lastResize;
+
   bool keyboardGrabbed;
   bool mouseGrabbed;