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Diffstat (limited to 'sd/source/ui/slidesorter/inc/cache/SlsPageCache.hxx')
| -rw-r--r-- | sd/source/ui/slidesorter/inc/cache/SlsPageCache.hxx | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/sd/source/ui/slidesorter/inc/cache/SlsPageCache.hxx b/sd/source/ui/slidesorter/inc/cache/SlsPageCache.hxx new file mode 100644 index 0000000000..4fb596195e --- /dev/null +++ b/sd/source/ui/slidesorter/inc/cache/SlsPageCache.hxx @@ -0,0 +1,141 @@ +/* -*- 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 <cache/SlsCacheContext.hxx> +#include <vcl/bitmapex.hxx> +#include <memory> + +class Size; + +namespace sd::slidesorter::cache +{ +class GenericPageCache; + +/** The page cache is responsible for the creation and storage of preview + bitmaps of pages that are shown by the slide sorter. + + <p>Bitmaps for previews and a cache are used to speed up the display + (painting) of the slide sorter. But, of course, we have to limit this + time-space-tradeoff by limiting the amount of space that can be use to + store bitmaps.</p> + + <p>There are several strategies employed by this class to shorten the + perceived time that is used to paint the slide sorter: + <ul> + <li>Rendering pages ahead of time. Additionally to rendering the + visible slides we try to render part or all of the slides that are not + (yet) visible. This, of course, makes sense only when the computer is + otherwise idle while doing that.</li> + <li>When the size of the slides on the screen changes we mark the + bitmaps as needing an update but use them while the new bitmap in the + correct size is not available.</li> + <li>Give the UI the chance to handle user events between the rendering + of differe slides.</li> + <li>Limit the amount of space that may be used for storing preview + bitmaps and throw.</li> + </p> + + <p>There is another somewhat similar methods for requesting new previews: + GetPreviewBitmap() schedules a re-rendering (when necessary) and + returns the preview what is currently available, either as a preview of + the preview or, when nothing has changed since the last call, as the + final thing. + </p> +*/ +class PageCache +{ +public: + /** The page cache is created with a reference to the slide sorter so + that it has access to both the view and the model and so can fill + itself with requests for all or just the visible pages. + + It is the task of the PageCacheManager to create new objects of this + class. + */ + PageCache(const Size& rPreviewSize, const bool bDoSuperSampling, + const SharedCacheContext& rpCacheContext); + + ~PageCache(); + + void ChangeSize(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 in the right + size 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& rBitmap); + + /** 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. + */ + void RequestPreviewBitmap(const CacheKey aKey); + + /** Tell the cache that the bitmap associated with the given request + data is not up-to-date anymore. This will invalidate all previews + in other caches that represent the same page as well. + A new preview is requested and will lead + eventually to a repaint of the associated page object. + */ + void 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 or reduced in size to make room for other bitmaps or is so + precious that it will not touched. A typical use is to set the + precious flag for exactly the visible pages. + */ + void SetPreciousFlag(const CacheKey aKey, const bool bIsPrecious); + + void Pause(); + void Resume(); + +private: + std::unique_ptr<GenericPageCache> mpImplementation; +}; + +} // end of namespace ::sd::slidesorter::cache + +/* vim:set shiftwidth=4 softtabstop=4 expandtab: */ |