Fix to ensure thumbnails that are rendered asynchronously out of order get placed in order

into the thumbnail structure.

Also fix to remove race condition between when the page view is updated with a full res
image and the links are displayed.  Previously the thumbnail was getting the link on occasion

1 files changed, 50 insertions, 26 deletions

diff --git a/winrt/mupdf_cpp/MainPage.xaml.cpp b/winrt/mupdf_cpp/MainPage.xaml.cpp
index 1f786e55..9fede380 100644
--- a/winrt/mupdf_cpp/MainPage.xaml.cpp
+++ b/winrt/mupdf_cpp/MainPage.xaml.cpp
@@ -442,8 +442,8 @@ void mupdf_cpp::MainPage::RenderThumbs()
                 doc_page->TextBox = nullptr;
                 doc_page->LinkBox = nullptr;
                 if (this->m_ren_status == REN_THUMBS) {
-                    m_thumbnails->Append(doc_page);
-                    /* Flipview object get overwhelmed unless I do this */
+                    m_thumbnails->SetAt(k, doc_page);  /* This avoids out of order returns from task */
+                    /* Flipview object gets overwhelmed unless I do this */
                     if ((k < THUMB_PREADD))
                         SetThumb(k, false);
                 }
@@ -554,18 +554,19 @@ void mupdf_cpp::MainPage::OpenDocument(StorageFile^ file)
             m_currpage = 0;
         }
 
-         /* Initialize all the flipvew items with blanks */
+         /* Initialize all the flipvew items with blanks and the thumbnails. */
         for (int k = 0; k < m_num_pages; k++) 
         {
             /* Blank pages */
             DocumentPage^ doc_page = ref new DocumentPage();
-            doc_page->Image = this->m_BlankBmp;
+            doc_page->Image = m_BlankBmp;
             doc_page->Height = BLANK_HEIGHT;
             doc_page->Width = BLANK_WIDTH;
             doc_page->Content = DUMMY;
             doc_page->TextBox = nullptr;
             doc_page->LinkBox = nullptr;
-            this->m_docPages->Append(doc_page);
+            m_docPages->Append(doc_page);
+            m_thumbnails->Append(doc_page);
             /* Create empty lists for our links and specify that they have not
                been computed for these pages */
             Vector<RectList^>^ temp_link = ref new Vector<RectList^>();
@@ -621,6 +622,7 @@ void mupdf_cpp::MainPage::RenderRange(int curr_page)
 {
     /* Render +/- the look ahead from where we are if blank page is present */
     spatial_info_t spatial_info = InitSpatial(1);
+    bool curr_page_rendered = true;
 
     assert(IsMainThread());
     for (int k = curr_page - LOOK_AHEAD; k <= curr_page + LOOK_AHEAD; k++) 
@@ -636,26 +638,26 @@ void mupdf_cpp::MainPage::RenderRange(int curr_page)
                     create_task(mu_doc->RenderPage(k, ras_size.X, ras_size.Y));
 
                 render_task.then([this, k, ras_size] (InMemoryRandomAccessStream^ ras)
-                {
-                    /* Set up the image brush when rendering is completed, must be on
-                        UI thread */
+                { 
                     UpdatePage(k, ras, ras_size, FULL_RESOLUTION);
-                }, task_continuation_context::use_current());
+                }, task_continuation_context::use_current()).then([this, k, curr_page]()
+                {
+                    if (k == curr_page && this->m_links_on)
+                        AddLinkCanvas();
+                },task_continuation_context::use_current());
+            }
+            else 
+            {
+                /* We did not need to render the curr_page, so add links below if
+                   needed.   Otherwise, we need to wait for the task above to 
+                   complete before we add the links. */
+                if (k == curr_page)
+                    curr_page_rendered = false;
             }
         }
     } 
-    Canvas^ link_canvas = (Canvas^) (this->FindName("linkCanvas"));
-    if (link_canvas != nullptr)
-    {
-        Canvas^ Parent_Canvas = (Canvas^) link_canvas->Parent;
-        if (Parent_Canvas != nullptr)
-        {
-            Parent_Canvas->Children->RemoveAtEnd();
-            delete link_canvas;
-        }
-    }
     m_currpage = curr_page;
-    if (this->m_links_on) 
+    if (this->m_links_on && !curr_page_rendered) 
         AddLinkCanvas();
 }
 
@@ -919,6 +921,10 @@ void mupdf_cpp::MainPage::SearchInDirection(int dir, String^ textToFind)
     {
         my_bar->Value = start;
     }  */
+    if (start < 0)
+        return;
+    if (start > this->m_num_pages - 1)
+        return;
     this->m_search_active = true;
 
     /* Do task lambdas here to avoid UI blocking issues */
@@ -1121,10 +1127,16 @@ void mupdf_cpp::MainPage::AddLinkCanvas()
     }
     /* Go ahead and set our doc item to this in the vertical and horizontal view */
     auto doc_page = this->m_docPages->GetAt(m_currpage);
-    doc_page->LinkBox = m_page_link_list->GetAt(m_currpage);
-    m_page_update = true;
-    this->m_docPages->SetAt(m_currpage, doc_page);
-    m_page_update = false;
+    if (doc_page->LinkBox == nullptr)
+    {
+        if (doc_page->Content == FULL_RESOLUTION)  // We should not be doing links for thumbnails
+        {
+            doc_page->LinkBox = m_page_link_list->GetAt(m_currpage);
+            m_page_update = true;
+            this->m_docPages->SetAt(m_currpage, doc_page);
+            m_page_update = false;
+        }
+    }
 }
 
 /* A link was tapped */
@@ -1269,10 +1281,22 @@ void mupdf_cpp::MainPage::UpdateAppBarButtonViewState()
     VisualStateManager::GoToState(Help, viewState, true); 
 }
 
-void mupdf_cpp::MainPage::ScrollChanged(Platform::Object^ sender, Windows::UI::Xaml::Controls::ScrollViewerViewChangedEventArgs^ e)
+void mupdf_cpp::MainPage::ScrollChanged(Platform::Object^ sender, 
+                                        Windows::UI::Xaml::Controls::ScrollViewerViewChangedEventArgs^ e)
 {
+    ScrollViewer^ scrollviewer = safe_cast<ScrollViewer^> (sender);
+    auto doc_page = this->m_docPages->GetAt(m_currpage);
 
- int zz = 1;
+    if (scrollviewer->ZoomFactor == doc_page->Zoom)
+        return;
+
+    if (!e->IsIntermediate)
+    {
+        doc_page->Zoom = scrollviewer->ZoomFactor;
+        /* Render at new resolution */
+
+
+    }
 }