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diff --git a/sd/source/ui/slidesorter/cache/SlsGenericPageCache.hxx b/sd/source/ui/slidesorter/cache/SlsGenericPageCache.hxx
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+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+/*
+ * This file is part of the LibreOffice project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * This file incorporates work covered by the following license notice:
+ *
+ *   Licensed to the Apache Software Foundation (ASF) under one or more
+ *   contributor license agreements. See the NOTICE file distributed
+ *   with this work for additional information regarding copyright
+ *   ownership. The ASF licenses this file to you under the Apache
+ *   License, Version 2.0 (the "License"); you may not use this file
+ *   except in compliance with the License. You may obtain a copy of
+ *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
+ */
+
+#pragma once
+
+#include "SlsRequestQueue.hxx"
+#include <memory>
+
+#include <vcl/bitmapex.hxx>
+
+namespace sd::slidesorter::cache {
+
+class BitmapCache;
+class QueueProcessor;
+
+/** This basically is the implementation class for the PageCache class.
+*/
+class GenericPageCache
+{
+public:
+    /** The page cache is created with a reference to the SlideSorter and
+        thus has access to both view and model.  This allows the cache to
+        fill itself with requests for all pages or just the visible ones.
+        @param rPreviewSize
+            The size of the previews is expected in pixel values.
+        @param bDoSuperSampling
+            When <TRUE/> the previews are rendered larger and then scaled
+            down to the requested size to improve image quality.
+    */
+    GenericPageCache (
+        const Size& rPreviewSize,
+        const bool bDoSuperSampling,
+        const SharedCacheContext& rpCacheContext);
+
+    ~GenericPageCache();
+
+    /** Change the size of the preview bitmaps.  This may be caused by a
+        resize of the slide sorter window or a change of the number of
+        columns.
+    */
+    void ChangePreviewSize (
+        const Size& rPreviewSize,
+        const bool bDoSuperSampling);
+
+    /** Request a preview bitmap for the specified page object in the
+        specified size.  The returned bitmap may be a preview of the preview,
+        i.e. either a scaled (up or down) version of a previous preview (of
+        the wrong size) or an empty bitmap.  In this case a request for the
+        generation of a new preview is created and inserted into the request
+        queue.  When the preview is available the page shape will be told to
+        paint itself again.  When it then calls this method again if
+        receives the correctly sized preview bitmap.
+        @param rRequestData
+            This data is used to determine the preview.
+        @param bResize
+            When <TRUE/> then when the available bitmap has not the
+            requested size, it is scaled before it is returned.  When
+            <FALSE/> then the bitmap is returned in the wrong size and it is
+            the task of the caller to scale it.
+        @return
+            Returns a bitmap that is either empty, contains a scaled (up or
+            down) version or is the requested bitmap.
+    */
+    BitmapEx GetPreviewBitmap (
+        const CacheKey aKey,
+        const bool bResize);
+    BitmapEx GetMarkedPreviewBitmap (
+        const CacheKey aKey);
+    void SetMarkedPreviewBitmap (
+        const CacheKey aKey,
+        const BitmapEx& rMarkedBitmap);
+
+    /** When the requested preview bitmap does not yet exist or is not
+        up-to-date then the rendering of one is scheduled.  Otherwise this
+        method does nothing.
+        @param rRequestData
+            This data is used to determine the preview.
+        @param bMayBeUpToDate
+            This flag helps the method to determine whether an existing
+            preview that matches the request is up to date.  If the caller
+            knows that it is not then by passing <FALSE/> he tells us that we
+            do not have to check the up-to-date flag a second time.  If
+            unsure use <TRUE/>.
+    */
+    void RequestPreviewBitmap (
+        const CacheKey aKey,
+        const bool bMayBeUpToDate);
+
+    /** Tell the cache to replace the bitmap associated with the given
+        request data with a new one that reflects recent changes in the
+        content of the page object.
+        @return
+            When the key is known then return <TRUE/>.
+    */
+    bool InvalidatePreviewBitmap (const CacheKey aKey);
+
+    /** Call this method when all preview bitmaps have to be generated anew.
+        This is the case when the size of the page objects on the screen has
+        changed or when the model has changed.
+    */
+    void InvalidateCache ();
+
+    /** With the precious flag you can control whether a bitmap can be
+        removed from the cache or reduced in size to make room for other
+        bitmaps or is so precious that it will not be touched.  A typical
+        use is to set the precious flag for the visible pages.
+    */
+    void SetPreciousFlag (const CacheKey aKey, const bool bIsPrecious);
+
+    void Pause();
+    void Resume();
+
+private:
+    std::shared_ptr<BitmapCache> mpBitmapCache;
+
+    RequestQueue maRequestQueue;
+
+    std::unique_ptr<QueueProcessor> mpQueueProcessor;
+
+    SharedCacheContext mpCacheContext;
+
+    /** The current size of preview bitmaps.
+    */
+    Size maPreviewSize;
+
+    bool mbDoSuperSampling;
+
+    /** Both bitmap cache and queue processor are created on demand by this
+        method.
+    */
+    void ProvideCacheAndProcessor();
+};
+
+} // end of namespace ::sd::slidesorter::cache
+
+/* vim:set shiftwidth=4 softtabstop=4 expandtab: */