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    41 

    42 #ifndef QVGIMAGEPOOL_P_H

    43 #define QVGIMAGEPOOL_P_H

    44 

    45 //

    46 //  W A R N I N G

    47 //  -------------

    48 //

    49 // This file is not part of the Qt API.  It exists for the convenience

    50 // of other Qt classes.  This header file may change from version to

    51 // version without notice, or even be removed.

    52 //

    53 // We mean it.

    54 //

    55 

    56 #include "qvg.h"

    57 #include <QtCore/qscopedpointer.h>

    58 

    59 QT_BEGIN_NAMESPACE

    60 

    61 class QVGPixmapData;

    62 class QVGImagePoolPrivate;

    63 

    64 class Q_OPENVG_EXPORT QVGImagePool

    65 {

    66 public:

    67     QVGImagePool();

    68     virtual ~QVGImagePool();

    69 

    70     static QVGImagePool *instance();

    71 

    72     // This function can be used from system-specific graphics system

    73     // plugins to alter the image allocation strategy.

    74     static void setImagePool(QVGImagePool *pool);

    75 

    76     // Create a new VGImage from the pool with the specified parameters

    77     // that is not associated with a pixmap.  The VGImage is returned to

    78     // the pool when releaseImage() is called.

    79     //

    80     // This function will call reclaimSpace() when vgCreateImage() fails.

    81     //

    82     // This function is typically called when allocating temporary

    83     // VGImage's for pixmap filters.  The "keepData" object will not

    84     // be reclaimed if reclaimSpace() needs to be called.

    85     virtual VGImage createTemporaryImage(VGImageFormat format,

    86                                          VGint width, VGint height,

    87                                          VGbitfield allowedQuality,

    88                                          QVGPixmapData *keepData = 0);

    89 

    90     // Create a new VGImage with the specified parameters and associate

    91     // it with "data".  The QVGPixmapData will be notified when the

    92     // VGImage needs to be reclaimed by the pool.

    93     //

    94     // This function will call reclaimSpace() when vgCreateImage() fails.

    95     virtual VGImage createImageForPixmap(VGImageFormat format,

    96                                          VGint width, VGint height,

    97                                          VGbitfield allowedQuality,

    98                                          QVGPixmapData *data);

    99 

   100     // Create a permanent VGImage with the specified parameters.

   101     // If there is insufficient space for the vgCreateImage call,

   102     // then this function will call reclaimSpace() and try again.

   103     //

   104     // The caller is responsible for calling vgDestroyImage()

   105     // when it no longer needs the VGImage, as the image is not

   106     // recorded in the image pool.

   107     //

   108     // This function is typically used for pattern brushes where

   109     // the OpenVG engine is responsible for managing the lifetime

   110     // of the VGImage, destroying it automatically when the brush

   111     // is no longer in use.

   112     virtual VGImage createPermanentImage(VGImageFormat format,

   113                                          VGint width, VGint height,

   114                                          VGbitfield allowedQuality);

   115 

   116     // Release a VGImage that is no longer required.

   117     virtual void releaseImage(QVGPixmapData *data, VGImage image);

   118 

   119     // Notify the pool that a QVGPixmapData object is using

   120     // an image again.  This allows the pool to move the image

   121     // within a least-recently-used list of QVGPixmapData objects.

   122     virtual void useImage(QVGPixmapData *data);

   123 

   124     // Notify the pool that the VGImage's associated with a

   125     // QVGPixmapData are being detached from the pool.  The caller

   126     // will become responsible for calling vgDestroyImage().

   127     virtual void detachImage(QVGPixmapData *data);

   128 

   129     // Reclaim space for an image allocation with the specified parameters.

   130     // Returns true if space was reclaimed, or false if there is no

   131     // further space that can be reclaimed.  The "data" parameter

   132     // indicates the pixmap that is trying to obtain space which should

   133     // not itself be reclaimed.

   134     virtual bool reclaimSpace(VGImageFormat format,

   135                               VGint width, VGint height,

   136                               QVGPixmapData *data);

   137 

   138     // Hibernate the image pool because the context is about to be

   139     // destroyed.  All VGImage's left in the pool should be released.

   140     virtual void hibernate();

   141 

   142 protected:

   143     // Helper functions for managing the LRU list of QVGPixmapData objects.

   144     void moveToHeadOfLRU(QVGPixmapData *data);

   145     void removeFromLRU(QVGPixmapData *data);

   146     QVGPixmapData *pixmapLRU();

   147 

   148 private:

   149     QScopedPointer<QVGImagePoolPrivate> d_ptr;

   150 

   151     Q_DECLARE_PRIVATE(QVGImagePool)

   152     Q_DISABLE_COPY(QVGImagePool)

   153 };

   154 

   155 QT_END_NAMESPACE

   156 

   157 #endif