From abc80e046d38293cc7d1f4b933591aa2f6400530 Mon Sep 17 00:00:00 2001
From: Paddy Xu <xupaddy@gmail.com>
Date: Fri, 22 Dec 2017 10:52:37 +0200
Subject: [PATCH] fix Pdf zoom-to-fit issue when switching pages

---
 .../ImagePanel.xaml.cs                        |  4 +--
 .../PdfPageExtension.cs                       |  4 +--
 .../PdfViewerControl.xaml.cs                  | 25 ++++++++++++-------
 3 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
index 17d0b2a..fcaeacb 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.ImageViewer/ImagePanel.xaml.cs
@@ -321,7 +321,7 @@ namespace QuickLook.Plugin.ImageViewer
         public void DoZoomToFit()
         {
             UpdateZoomToFitFactor();
-
+            
             Zoom(ZoomToFitFactor, false, true);
         }
 
@@ -342,7 +342,7 @@ namespace QuickLook.Plugin.ImageViewer
         public void ResetZoom()
         {
             ZoomToFitFactor = 1;
-            Zoom(1d, true);
+            Zoom(1d, true, ZoomToFit);
         }
 
         public void Zoom(double factor, bool suppressEvent = false, bool isToFit = false)
diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfPageExtension.cs b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfPageExtension.cs
index 6fb715c..02a0c50 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfPageExtension.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfPageExtension.cs
@@ -39,8 +39,8 @@ namespace QuickLook.Plugin.PDFViewer
             var dpiX = fixDpi ? scale.Horizontal * DpiHelper.DefaultDpi : 96;
             var dpiY = fixDpi ? scale.Vertical * DpiHelper.DefaultDpi : 96;
 
-            var realWidth = (int) Math.Ceiling(page.Width * (dpiX / 72) * factor);
-            var realHeight = (int) Math.Ceiling(page.Height * (dpiY / 72) * factor);
+            var realWidth = (int) Math.Round(page.Width * scale.Horizontal * factor);
+            var realHeight = (int) Math.Round(page.Height * scale.Vertical * factor);
 
             var bitmap = new WriteableBitmap(realWidth, realHeight, dpiX, dpiY, PixelFormats.Bgr24, null);
             page.Render(bitmap,
diff --git a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
index e6b29e3..37b6ed7 100644
--- a/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
+++ b/QuickLook.Plugin/QuickLook.Plugin.PDFViewer/PdfViewerControl.xaml.cs
@@ -56,8 +56,6 @@ namespace QuickLook.Plugin.PDFViewer
         public ObservableCollection<BitmapSource> PageThumbnails { get; set; } =
             new ObservableCollection<BitmapSource>();
 
-        public PdfDocument PdfHandleForThumbnails { get; private set; }
-
         public PdfDocument PdfHandle { get; private set; }
 
         public int TotalPages => PdfHandle.Pages.Count;
@@ -86,8 +84,6 @@ namespace QuickLook.Plugin.PDFViewer
             }
 
             _pdfLoaded = false;
-            PdfHandleForThumbnails?.Close();
-            PdfHandleForThumbnails = null;
             PdfHandle?.Close();
             PdfHandle = null;
         }
@@ -162,11 +158,20 @@ namespace QuickLook.Plugin.PDFViewer
 
             var pos = pagePanel.GetScrollPosition();
 
-            var factor = pagePanel.ZoomFactor * _viewRenderFactor;
-            factor = Math.Max(factor, MinZoomFactor);
-            factor = Math.Min(factor, MaxZoomFactor);
-            pagePanel.MinZoomFactor = MinZoomFactor / factor;
-            pagePanel.MaxZoomFactor = MaxZoomFactor / factor;
+            double factor;
+            if (pagePanel.ZoomToFit)
+            {
+                factor = Math.Min(pagePanel.ActualHeight / PdfHandle.Pages[CurrentPage].Height,
+                    pagePanel.ActualWidth / PdfHandle.Pages[CurrentPage].Width);
+            }
+            else
+            {
+                factor = pagePanel.ZoomFactor * _viewRenderFactor;
+                factor = Math.Max(factor, MinZoomFactor);
+                factor = Math.Min(factor, MaxZoomFactor);
+                pagePanel.MinZoomFactor = MinZoomFactor / factor;
+                pagePanel.MaxZoomFactor = MaxZoomFactor / factor;
+            }
 
             var image = PdfHandle.Pages[CurrentPage].Render(factor);
 
@@ -242,6 +247,8 @@ namespace QuickLook.Plugin.PDFViewer
 
                         Dispatcher.BeginInvoke(new Action(() => PageThumbnails.Add(bs)));
                     });
+
+                    handle.Close();
                 }
             }).Start();
         }