Merge pull request #7 from TheEightBot/copilot/fix-fitpolicy-height-issue

Author: michaelstonis

samples/MauiPdfViewerSample/PdfTestPage.xaml

@@ -44,7 +44,7 @@
         </ResourceDictionary>
     </ContentPage.Resources>
 
-    <ScrollView BackgroundColor="{StaticResource SurfaceColor}">
+       <ScrollView BackgroundColor="{StaticResource SurfaceColor}">
         <VerticalStackLayout Spacing="20"
                              Padding="20,20,20,32">
             <!-- Lean hero copy so phones see controls immediately -->
@@ -157,14 +157,15 @@
                         </Border.StrokeShape>
                         <pdf:PdfView x:Name="PdfViewer"
                                      Source="sample.pdf"
-                                     HeightRequest="460"
+                                     HeightRequest="200"
                                      HorizontalOptions="FillAndExpand"
                                      VerticalOptions="FillAndExpand"
                                      EnableZoom="True"
                                      EnableSwipe="True"
                                      EnableTapGestures="False"
                                      PageSpacing="10"
                                      EnableAntialiasing="True"
+                                     FitPolicy="Height"
                                      UseBestQuality="True"
                                      EnableAnnotationRendering="True"
                                      DocumentLoaded="OnDocumentLoaded"
@@ -239,6 +240,17 @@
                                 Clicked="OnToggleAnnotationsClicked"
                                 Grid.Column="1"/>
                     </Grid>
+                    <Grid ColumnDefinitions="Auto,*" ColumnSpacing="12">
+                        <Label Text="Fit policy"
+                               TextColor="#CBD5F5"
+                               VerticalOptions="Center"
+                               Grid.Column="0"/>
+                        <Button x:Name="ToggleFitPolicyButton"
+                                Style="{StaticResource GhostButtonStyle}"
+                                Text="Height"
+                                Clicked="OnToggleFitPolicyClicked"
+                                Grid.Column="1"/>
+                    </Grid>
                     <Grid ColumnDefinitions="Auto,*" ColumnSpacing="12">
                         <Label Text="Tap gestures"
                                TextColor="#CBD5F5"
@@ -307,5 +319,5 @@
                 </VerticalStackLayout>
             </toolkit:Expander>
         </VerticalStackLayout>
-    </ScrollView>
+     </ScrollView>
 </ContentPage>

samples/MauiPdfViewerSample/PdfTestPage.xaml.cs

@@ -14,6 +14,21 @@ public partial class PdfTestPage : ContentPage
         Colors.Beige
     };
 
+    // Start at Height to match the XAML default (FitPolicy="Height")
+    private int _fitPolicyIndex = 1;
+    private readonly FitPolicy[] _fitPolicies = new[]
+    {
+        FitPolicy.Width,
+        FitPolicy.Height,
+        FitPolicy.Both
+    };
+    private readonly string[] _fitPolicyNames = new[]
+    {
+        "Width",
+        "Height",
+        "Both"
+    };
+
     private int _displayModeIndex = 0;
     private readonly PdfDisplayMode[] _displayModes = new[]
     {
@@ -140,6 +155,14 @@ private void OnToggleBackgroundClicked(object? sender, EventArgs e)
         StatusLabel.Text = $"Background color: {_backgroundColors[_backgroundColorIndex]}";
     }
 
+    private void OnToggleFitPolicyClicked(object? sender, EventArgs e)
+    {
+        _fitPolicyIndex = (_fitPolicyIndex + 1) % _fitPolicies.Length;
+        PdfViewer.FitPolicy = _fitPolicies[_fitPolicyIndex];
+        ToggleFitPolicyButton.Text = _fitPolicyNames[_fitPolicyIndex];
+        StatusLabel.Text = $"Fit policy: {_fitPolicyNames[_fitPolicyIndex]}";
+    }
+
     // New Phase 5 event handler
     private void OnToggleDisplayModeClicked(object? sender, EventArgs e)
     {

src/MauiNativePdfView/Platforms/Android/PdfViewAndroid.cs

@@ -320,6 +320,13 @@ private void ConfigureAndLoad(PDFView.Configurator configurator, int pageToResto
             configurator.Password(_source.Password);
         }
 
+        var nativeFitPolicy = _fitPolicy switch
+        {
+            Abstractions.FitPolicy.Height => Com.Ahmer.Pdfviewer.Util.FitPolicy.Height,
+            Abstractions.FitPolicy.Both => Com.Ahmer.Pdfviewer.Util.FitPolicy.Both,
+            _ => Com.Ahmer.Pdfviewer.Util.FitPolicy.Width,
+        };
+
         configurator
             .EnableSwipe(_enableSwipe)
             .EnableDoubleTap(_enableZoom)
@@ -331,6 +338,7 @@ private void ConfigureAndLoad(PDFView.Configurator configurator, int pageToResto
             .PageFling(enablePageFling)
             .NightMode(false)
             .FitEachPage(false)
+            .PageFitPolicy(nativeFitPolicy)
             .EnableAntialiasing(_enableAntialiasing)
             .OnLoad(new LoadCompleteListener(this, pageToRestore))
             .OnPageChange(new PageChangeListener(this))

src/MauiNativePdfView/Platforms/Android/PdfViewHandler.cs

@@ -75,12 +75,12 @@ protected override void ConnectHandler(PDFView platformView)
     {
         base.ConnectHandler(platformView);
 
-        // Apply initial values
-        MapSource(this, VirtualView);
+        // Apply all config properties BEFORE Source so the document loads with the correct settings.
         MapEnableZoom(this, VirtualView);
         MapEnableSwipe(this, VirtualView);
         MapEnableTapGestures(this, VirtualView);
         MapEnableLinkNavigation(this, VirtualView);
+        MapZoom(this, VirtualView);
         MapMinZoom(this, VirtualView);
         MapMaxZoom(this, VirtualView);
         MapPageSpacing(this, VirtualView);
@@ -91,6 +91,9 @@ protected override void ConnectHandler(PDFView platformView)
         MapEnableAntialiasing(this, VirtualView);
         MapUseBestQuality(this, VirtualView);
         MapBackgroundColor(this, VirtualView);
+        MapEnableAnnotationRendering(this, VirtualView);
+        // Source is applied last so LoadDocument() picks up all pre-configured properties.
+        MapSource(this, VirtualView);
     }
 
     protected override void DisconnectHandler(PDFView platformView)

src/MauiNativePdfView/Platforms/iOS/PdfViewHandler.cs

@@ -67,10 +67,9 @@ protected override void ConnectHandler(PdfKit.PdfView platformView)
     {
         base.ConnectHandler(platformView);
 
-        // Apply initial property values
+        // Apply all config properties BEFORE Source so the document loads with the correct settings.
         if (_pdfViewWrapper != null && VirtualView != null)
         {
-            _pdfViewWrapper.Source = VirtualView.Source;
             _pdfViewWrapper.EnableZoom = VirtualView.EnableZoom;
             _pdfViewWrapper.EnableSwipe = VirtualView.EnableSwipe;
             _pdfViewWrapper.EnableTapGestures = VirtualView.EnableTapGestures;
@@ -79,13 +78,16 @@ protected override void ConnectHandler(PdfKit.PdfView platformView)
             _pdfViewWrapper.MinZoom = VirtualView.MinZoom;
             _pdfViewWrapper.MaxZoom = VirtualView.MaxZoom;
             _pdfViewWrapper.PageSpacing = VirtualView.PageSpacing;
-            _pdfViewWrapper.FitPolicy = VirtualView.FitPolicy;
             _pdfViewWrapper.DisplayMode = VirtualView.DisplayMode;
             _pdfViewWrapper.ScrollOrientation = VirtualView.ScrollOrientation;
             _pdfViewWrapper.DefaultPage = VirtualView.DefaultPage;
             _pdfViewWrapper.EnableAntialiasing = VirtualView.EnableAntialiasing;
             _pdfViewWrapper.UseBestQuality = VirtualView.UseBestQuality;
             _pdfViewWrapper.BackgroundColor = VirtualView.BackgroundColor;
+            // FitPolicy modifies DisplayMode internally, so it must be applied after DisplayMode.
+            _pdfViewWrapper.FitPolicy = VirtualView.FitPolicy;
+            // Source is applied last so LoadDocument() picks up all pre-configured properties.
+            _pdfViewWrapper.Source = VirtualView.Source;
         }
     }
 

src/MauiNativePdfView/Platforms/iOS/PdfViewiOS.cs

@@ -10,7 +10,7 @@ namespace MauiNativePdfView.Platforms.iOS;
 /// </summary>
 public class PdfViewiOS : IPdfView, IDisposable
 {
-    private readonly PdfKit.PdfView _pdfView;
+    private readonly NativePdfView _pdfView;
     private PdfSource? _source;
     private bool _disposed;
     private NSObject? _pageChangedObserver;
@@ -21,16 +21,25 @@ public class PdfViewiOS : IPdfView, IDisposable
     private bool _documentLoaded = false;
     private bool _enableAnnotationRendering = true;
     private bool _enableTapGestures = true;
+    private FitPolicy _fitPolicy = FitPolicy.Width;
+    private bool _needsFitReapply = false;
 
     public PdfViewiOS()
     {
-        _pdfView = new PdfKit.PdfView
+        _pdfView = new NativePdfView
         {
             AutoScales = true,
             DisplayMode = PdfKit.PdfDisplayMode.SinglePageContinuous,
             DisplayDirection = PdfDisplayDirection.Vertical
         };
 
+        // Re-apply deferred fit policy once the view has been laid out and has real bounds.
+        _pdfView.LayoutSubviewsAction = () =>
+        {
+            if (_needsFitReapply)
+                ApplyFitPolicy();
+        };
+
         // Subscribe to page change notifications
         _pageChangedObserver = NSNotificationCenter.DefaultCenter.AddObserver(
             PdfKit.PdfView.PageChangedNotification,
@@ -146,26 +155,81 @@ public int PageSpacing
 
     public FitPolicy FitPolicy
     {
-        get => _pdfView.AutoScales ? FitPolicy.Width : FitPolicy.Both;
+        get => _fitPolicy;
         set
         {
-            switch (value)
-            {
-                case FitPolicy.Width:
-                    _pdfView.AutoScales = true;
-                    _pdfView.DisplayMode = PdfKit.PdfDisplayMode.SinglePageContinuous;
-                    break;
-                case FitPolicy.Height:
-                    _pdfView.AutoScales = true;
-                    _pdfView.DisplayMode = PdfKit.PdfDisplayMode.SinglePage;
-                    break;
-                case FitPolicy.Both:
-                    _pdfView.AutoScales = false;
-                    break;
-            }
+            _fitPolicy = value;
+            ApplyFitPolicy();
+        }
+    }
+
+    private void ApplyFitPolicy()
+    {
+        switch (_fitPolicy)
+        {
+            case FitPolicy.Width:
+                _pdfView.AutoScales = true;
+                _pdfView.DisplayMode = PdfKit.PdfDisplayMode.SinglePageContinuous;
+                _needsFitReapply = false;
+                break;
+
+            case FitPolicy.Height:
+                // PdfKit AutoScales only fits width; calculate scale manually.
+                _pdfView.AutoScales = false;
+                _pdfView.DisplayMode = PdfKit.PdfDisplayMode.SinglePageContinuous;
+                _needsFitReapply = !SetManualScale(fitWidth: false, fitHeight: true);
+                break;
+
+            case FitPolicy.Both:
+                // Fit to the smaller of the width/height scale factors so the whole page
+                // is visible. Use SinglePageContinuous to avoid SinglePage's inflated
+                // internal scroll content size.
+                _pdfView.AutoScales = false;
+                _pdfView.DisplayMode = PdfKit.PdfDisplayMode.SinglePageContinuous;
+                _needsFitReapply = !SetManualScale(fitWidth: true, fitHeight: true);
+                break;
         }
     }
 
+    /// <summary>
+    /// Computes and applies ScaleFactor so the current page fits the requested axes.
+    /// Returns <c>true</c> on success, <c>false</c> if the view or page isn't ready yet
+    /// (caller should set <see cref="_needsFitReapply"/> and retry on next layout pass).
+    /// </summary>
+    private bool SetManualScale(bool fitWidth, bool fitHeight)
+    {
+        var page = _pdfView.CurrentPage;
+        if (page == null)
+            return false;
+
+        var viewBounds = _pdfView.Bounds;
+        if (viewBounds.Width <= 0 || viewBounds.Height <= 0)
+            return false;
+
+        var pageRect = page.GetBoundsForBox(PdfDisplayBox.Media);
+        if (pageRect.Width <= 0 || pageRect.Height <= 0)
+            return false;
+
+        nfloat scale;
+        if (fitWidth && fitHeight)
+        {
+            var scaleW = (nfloat)(viewBounds.Width / pageRect.Width);
+            var scaleH = (nfloat)(viewBounds.Height / pageRect.Height);
+            scale = scaleW < scaleH ? scaleW : scaleH;
+        }
+        else if (fitHeight)
+        {
+            scale = (nfloat)(viewBounds.Height / pageRect.Height);
+        }
+        else
+        {
+            scale = (nfloat)(viewBounds.Width / pageRect.Width);
+        }
+
+        _pdfView.ScaleFactor = scale;
+        return true;
+    }
+
     public Abstractions.PdfDisplayMode DisplayMode
     {
         get
@@ -358,7 +422,13 @@ private void LoadDocument()
                     }
                 }
 
-                MainThread.BeginInvokeOnMainThread(() => _pdfView.Document = document);
+                MainThread.BeginInvokeOnMainThread(() =>
+                {
+                    _pdfView.Document = document;
+                    // Re-apply fit policy now that the document is loaded and
+                    // the view has valid bounds to calculate scale against.
+                    ApplyFitPolicy();
+                });
 
                 // Get document metadata
                 var pageCount = (int)document.PageCount;
@@ -553,6 +623,22 @@ public void Dispose()
         _pdfView?.Dispose();
     }
 
+    /// <summary>
+    /// Custom PdfView subclass that fires a callback on each layout pass, allowing
+    /// <see cref="PdfViewiOS"/> to defer fit-policy scale calculations until the view
+    /// has non-zero bounds (which isn't guaranteed when the document first loads).
+    /// </summary>
+    private class NativePdfView : PdfKit.PdfView
+    {
+        internal Action? LayoutSubviewsAction { get; set; }
+
+        public override void LayoutSubviews()
+        {
+            base.LayoutSubviews();
+            LayoutSubviewsAction?.Invoke();
+        }
+    }
+
     /// <summary>
     /// Delegate implementation to intercept link clicks in PDFView.
     /// </summary>