CATiledLayer：ドロップシャドーを追加すると、ゆっくりしてメモリが足りなくなるのはなぜですか？

Question

私は、ページごとにPDFを表示する小さなPDFビューを作成して、メモリ使用量を減らしました。うまく動作しますが、メモリが不足し、表示されたページにドロップシャドウを追加するとすぐにスロー（unusabe）になります。プロジェクト全体のコードは以下の通りです。 ViewWillAppear（）メソッドを見ると、影がコメントアウトされています。それについてコメントして、すべてが吸い始めます。これを引き起こしているのは何ですか？シミュレータで見ることもできます。 PDFをズームインしてスクロールすれば、邪魔になります。 Removoe影とすべての問題はありません。

using System; 
using MonoTouch.Foundation; 
using System.IO; 
using MonoTouch.UIKit; 
using System.Text; 
using System.Diagnostics; 
using System.Drawing; 
using MonoTouch.CoreGraphics; 
using MonoTouch.CoreAnimation; 

namespace iOSTest 
{ 
    public class Application 
    { 
     static void Main (string[] args) 
     { 
      UIApplication.Main (args); 
     } 
    } 

    // The name AppDelegate is referenced in the MainWindow.xib file. 
    public partial class AppDelegate : UIApplicationDelegate 
    { 
     // This method is invoked when the application has loaded its UI and its ready to run 
     public override bool FinishedLaunching (UIApplication app, NSDictionary options) 
     { 
      NSUrl u = NSUrl.FromString("http://www.tfl.gov.uk/assets/downloads/standard-tube-map.pdf"); 
      //NSUrl u = NSUrl.FromFilename ("./big.pdf"); 
      this.o = new AppDelegate.PdfViewController (u); 

      this.o.View.Frame = new RectangleF (0, UIApplication.SharedApplication.StatusBarFrame.Height, window.Bounds.Width, window.Bounds.Height - UIApplication.SharedApplication.StatusBarFrame.Height); 
      this.o.View.AutoresizingMask = 
        UIViewAutoresizing.FlexibleWidth 
        | UIViewAutoresizing.FlexibleHeight 
        | UIViewAutoresizing.FlexibleTopMargin 
        | UIViewAutoresizing.FlexibleBottomMargin 
        | UIViewAutoresizing.FlexibleLeftMargin 
        | UIViewAutoresizing.FlexibleRightMargin; 

      window.AddSubview (this.o.View); 
      //this.oViewMain.BackgroundColor = UIColor.Green; 

      //UIApplication.SharedApplication.StatusBarHidden = true; 

      window.MakeKeyAndVisible(); 
      return true; 
     } 

     private PdfViewController o; 


     /// <summary> 
     /// Previews first page of a PDF. 
     /// </summary> 
     public class PdfViewController : UIViewController 
     { 
      public PdfViewController(NSUrl oUrl) : base() 
      { 
       this.oUrl = oUrl; 
      } 

      private NSUrl oUrl; 
      private UIView oContentView; 
      private CGPDFDocument oPdfDoc; 
      private CGPDFPage oPdfPage; 
      private CATiledLayer oTiledLayer; 
      private UIScrollView oScrollView; 
      private RectangleF oPdfPageRect; 

      public override bool ShouldAutorotateToInterfaceOrientation (UIInterfaceOrientation toInterfaceOrientation) 
      { 
       return true; 
      } 

      public override void ViewDidLoad() 
      { 
       this.View = new UIView(); 
       base.ViewDidLoad(); 
      } 

      public override void ViewWillAppear (bool animated) 
      { 
       base.ViewWillAppear (animated); 

       // Setup tiled layer. 
       this.oTiledLayer = new CATiledLayer(); 
       this.oTiledLayer.Delegate = new TiledLayerDelegate (this); 
       this.oTiledLayer.TileSize = new SizeF (1024f, 1024f); 
       this.oTiledLayer.LevelsOfDetail = 4; 
       this.oTiledLayer.LevelsOfDetailBias = 0; 
       this.oTiledLayer.BackgroundColor = UIColor.LightGray.CGColor; 
       this.oTiledLayer.BorderColor = UIColor.Black.CGColor; 
       /* 
       this.oTiledLayer.BorderWidth = 1.0f; 
       this.oTiledLayer.ShadowColor = UIColor.Black.CGColor; 
       this.oTiledLayer.ShadowOffset = new SizeF (20.0f, 20.0f); 
       this.oTiledLayer.ShadowOpacity = 0.7f; 
       this.oTiledLayer.ShadowRadius = 20.0f; 
       */   

       // Setup the view that is hosted by the scroll view. 
       this.oContentView = new UIView(); 
       this.oContentView.Center = this.View.Center; 
       this.oContentView.AutoresizingMask = UIViewAutoresizing.FlexibleLeftMargin 
        | UIViewAutoresizing.FlexibleRightMargin 
        | UIViewAutoresizing.FlexibleTopMargin 
        | UIViewAutoresizing.FlexibleBottomMargin; 

       this.oContentView.Layer.AddSublayer (this.oTiledLayer); 


       // Prepare scroll view. 
       this.oScrollView = new UIScrollView (new RectangleF (new PointF (0, 0), this.View.Bounds.Size)); 
       this.oScrollView.AutoresizingMask = UIViewAutoresizing.FlexibleWidth | UIViewAutoresizing.FlexibleHeight | UIViewAutoresizing.FlexibleTopMargin | UIViewAutoresizing.FlexibleBottomMargin | UIViewAutoresizing.FlexibleLeftMargin | UIViewAutoresizing.FlexibleRightMargin; 
       this.oScrollView.Delegate = new ScrollViewDelegate (this); 
       this.oScrollView.MaximumZoomScale = 4.0f; 
       this.oScrollView.BackgroundColor = UIColor.ScrollViewTexturedBackgroundColor; 
       // Add the view the scroll view hosts. 
       oScrollView.AddSubview (this.oContentView); 
       this.View.AddSubview (this.oScrollView); 
      } 

      public override void ViewDidAppear (bool animated) 
      { 
       base.ViewDidAppear (animated); 

       Console.WriteLine ("Loading PDF: {0}", this.oUrl.ToString()); 
       this.oPdfDoc = CGPDFDocument.FromUrl (this.oUrl.ToString()); 

       // For demo purposes, show first page only. 
       this.oPdfPage = this.oPdfDoc.GetPage (1); 

       this.oPdfPageRect = this.oPdfPage.GetBoxRect (CGPDFBox.Media); 
       this.oTiledLayer.Frame = this.oPdfPageRect; 
       this.oContentView.Frame = this.oPdfPageRect; 
       this.oContentView.Center = this.View.Center; 
       this.ResizePage(); 
      } 

      private void ResizePage() 
      { 
       // Adjust PDF page to available space. Keep aspect ration. 
       this.oScrollView.MinimumZoomScale = 0.001f; 
       float fScaleX = this.View.Bounds.Width/this.oPdfPageRect.Width; 
       float fScaleY = this.View.Bounds.Height/this.oPdfPageRect.Height; 
       float fScale = 0.9f * (fScaleX > fScaleY ? fScaleY : fScaleX); 
       this.oScrollView.SetZoomScale (fScale, false); 
       this.oScrollView.MinimumZoomScale = fScale; 
      } 

      public override void ViewDidUnload() 
      { 
       base.ViewDidUnload(); 
       this.oPdfPage.Dispose(); 
       this.oPdfDoc.Dispose(); 
       this.oContentView.Dispose(); 
       this.oPdfPage = null; 
       this.oPdfDoc = null; 
       this.oContentView = null; 
      } 

      public override void DidRotate (UIInterfaceOrientation fromInterfaceOrientation) 
      { 
       base.DidRotate (fromInterfaceOrientation); 

       this.ResizePage(); 
      } 

      public class TiledLayerDelegate : CALayerDelegate 
      { 
       public TiledLayerDelegate(PdfViewController oParentController) : base() 
       { 
        this.oParentController = oParentController; 
       } 

       private PdfViewController oParentController; 

       public override void DrawLayer (CALayer layer, CGContext context) 
       { 
        context.SaveState(); 
        context.SetRGBFillColor (1.0f, 1.0f, 1.0f, 1.0f); 
        context.FillRect (context.GetClipBoundingBox()); 
        context.TranslateCTM (0.0f, layer.Bounds.Size.Height); 
        context.ScaleCTM (1.0f, -1.0f); 
        context.ConcatCTM (this.oParentController.oPdfPage.GetDrawingTransform (CGPDFBox.Media, layer.Bounds, 0, true)); 
        context.DrawPDFPage (this.oParentController.oPdfPage); 
        context.RestoreState(); 
       } 
      } 

      public class ScrollViewDelegate : UIScrollViewDelegate 
      { 
       public ScrollViewDelegate(PdfViewController oParentController) : base() 
       { 
        this.oParentController = oParentController; 
       } 

       private PdfViewController oParentController; 

       public override UIView ViewForZoomingInScrollView (UIScrollView scrollView) 
       { 
        return this.oParentController.oContentView; 
       } 

       public override void DidZoom (UIScrollView scrollView) 
       { 
        // Override to center PDF page. 
        float fX = scrollView.Bounds.Width > scrollView.ContentSize.Width ? (scrollView.Bounds.Size.Width - scrollView.ContentSize.Width) * 0.5f : 0.0f; 
        float fY = scrollView.Bounds.Height > scrollView.ContentSize.Height ? (scrollView.Bounds.Size.Height - scrollView.ContentSize.Height) * 0.5f : 0.0f; 
        oParentController.oContentView.Center = new PointF (scrollView.ContentSize.Width * 0.5f + fX, scrollView.ContentSize.Height * 0.5f + fY); 
       } 
      } 
     } 

    } 
} 

Answer 1

は層の上に、明示的なshadowPathの設定を見てみましょう。 Apple's docsから：

このプロパティの値は影が 指定されたパスの代わりに、 層の合成さアルファチャンネルを使用して作成され、 非nilです。 パスは、 シャドウの輪郭を定義します。これは、 の非ゼロの巻き取りルールと現在の シャドウカラー、不透明度、およびぼかし radiusを使用して塗りつぶされます。

また、OmniGroupにはa blog post regarding drop shadow performanceもあります。

ない、それはC＃で次のようになりますが、Objective-Cの（あなたのPDFビューが単純なビューであると仮定すると[すなわち、長方形]）で使用できるか確認してください。

[UIBezierPath pathWithRect:pdfView.bounds].CGPath 

pathWithRectがUIBezierPathクラスですメソッド（インスタンスを返す）、CGPathはプロパティ/インスタンスメソッドです。