Improve scrolling performance in OOP PDF

pdf/out_of_process_instance.cc

Index: pdf/out_of_process_instance.cc
diff --git a/pdf/out_of_process_instance.cc b/pdf/out_of_process_instance.cc
index 9e77ec616ac6e3689de8a7f901d4ad6408343546..05bf4ee1b1c81d40cfc236938639b2939c0c6c66 100644
--- a/pdf/out_of_process_instance.cc
+++ b/pdf/out_of_process_instance.cc
@@ -34,6 +34,7 @@
 #include "ppapi/cpp/module.h"
 #include "ppapi/cpp/point.h"
 #include "ppapi/cpp/private/pdf.h"
+#include "ppapi/cpp/private/var_private.h"
 #include "ppapi/cpp/rect.h"
 #include "ppapi/cpp/resource.h"
 #include "ppapi/cpp/url_request_info.h"
@@ -70,6 +71,8 @@ const char* kJSViewportType = "viewport";
 const char* kJSXOffset = "xOffset";
 const char* kJSYOffset = "yOffset";
 const char* kJSZoom = "zoom";
+// Stop scrolling message (Page -> Plugin)
+const char* kJSStopScrollingType = "stopScrolling";
 // Document dimension arguments (Plugin -> Page).
 const char* kJSDocumentDimensionsType = "documentDimensions";
 const char* kJSDocumentWidth = "width";
@@ -244,7 +247,8 @@ OutOfProcessInstance::OutOfProcessInstance(PP_Instance instance)
       last_progress_sent_(0),
       recently_sent_find_update_(false),
       received_viewport_message_(false),
-      did_call_start_loading_(false) {
+      did_call_start_loading_(false),
+      stop_scrolling_(false) {
   loader_factory_.Initialize(this);
   timer_factory_.Initialize(this);
   form_factory_.Initialize(this);
@@ -355,6 +359,7 @@ void OutOfProcessInstance::HandleMessage(const pp::Var& message) {
       dict.Get(pp::Var(kJSYOffset)).is_int() &&
       dict.Get(pp::Var(kJSZoom)).is_number()) {
     received_viewport_message_ = true;
+    stop_scrolling_ = false;
     double zoom = dict.Get(pp::Var(kJSZoom)).AsDouble();
     int x = dict.Get(pp::Var(kJSXOffset)).AsInt();
     int y = dict.Get(pp::Var(kJSYOffset)).AsInt();
@@ -425,6 +430,8 @@ void OutOfProcessInstance::HandleMessage(const pp::Var& message) {
       reply.Set(pp::Var(kJSAccessibilityJSON), pp::Var(json));
     }
     PostMessage(reply);
+  } else if (type == kJSStopScrollingType) {
+    stop_scrolling_ = true;
   } else {
     NOTREACHED();
   }
@@ -507,6 +514,16 @@ void OutOfProcessInstance::DidChangeView(const pp::View& view) {
   pp::Size view_device_size(view_rect.width() * device_scale,
                             view_rect.height() * device_scale);
 
+  if (!stop_scrolling_) {
+    pp::Point scroll_offset(view.GetScrollOffset());
+    int max_x = document_size_.width() * zoom_ - plugin_dip_size_.width();

[Lei Zhang, 2014/06/23 09:19:41]

Can we share some of the code with line 369?

[raymes, 2014/06/24 00:41:53]

Done.

+    int x = std::max(std::min(scroll_offset.x(), max_x), 0);
+    int max_y = document_size_.height() * zoom_ - plugin_dip_size_.height();
+    int y = std::max(std::min(scroll_offset.y(), max_y), 0);
+    engine_->ScrolledToXPosition(x * device_scale_);
+    engine_->ScrolledToYPosition(y * device_scale_);
+  }
+
   if (view_device_size == plugin_size_ && device_scale == device_scale_)
     return; // We don't care about the position, only the size.