expose the caching for wallpapers that don't use render() to use

svn path=/trunk/KDE/kdelibs/; revision=952060

private/wallpaper_p.h

@@ -41,8 +41,9 @@ public:
     {
     };
 
-    QString cachePath(const QString &sourceImagePath, const QSize &size,
-                      int resizeMethod, const QColor &color) const;
+    QString cachePath(const QString &key) const;
+    QString cacheKey(const QString &sourceImagePath, const QSize &size,
+                     int resizeMethod, const QColor &color) const;
 
 
     void renderCompleted(int token, const QImage &image,

wallpaper.cpp

@@ -22,6 +22,7 @@
 
 #include <QColor>
 #include <QFile>
+#include <QFileInfo>
 #include <QImage>
 
 #include <kdebug.h>
@@ -29,6 +30,8 @@
 #include <kservicetypetrader.h>
 #include <kstandarddirs.h>
 
+#include <kio/job.h>
+
 #include <version.h>
 
 #include "plasma/private/dataengineconsumer_p.h"
@@ -320,10 +323,10 @@ void Wallpaper::render(const QString &sourceImagePath, const QSize &size,
     }
 
     if (d->cacheRendering) {
-        QString cache = d->cachePath(sourceImagePath, size, resizeMethod, color);
-        if (QFile::exists(cache)) {
-            //kDebug() << "loading cached wallpaper from" << cache;
-            QImage img(cache);
+        QFileInfo info(sourceImagePath);
+        QString cache = d->cacheKey(sourceImagePath, size, resizeMethod, color);
+        QImage img;
+        if (findInCache(cache, img, info.lastModified().toTime_t())) {
             emit renderCompleted(img);
             return;
         }
@@ -333,13 +336,18 @@ void Wallpaper::render(const QString &sourceImagePath, const QSize &size,
     //kDebug() << "rendering" << sourceImagePath << ", token is" << d->renderToken;
 }
 
-QString WallpaperPrivate::cachePath(const QString &sourceImagePath, const QSize &size,
-                                    int resizeMethod, const QColor &color) const
+QString WallpaperPrivate::cacheKey(const QString &sourceImagePath, const QSize &size,
+                                   int resizeMethod, const QColor &color) const
 {
-    const QString id = QString("plasma-wallpapers/%5_%3_%4_%1x%2.png")
+    const QString id = QString("%5_%3_%4_%1x%2")
                               .arg(size.width()).arg(size.height()).arg(color.name())
                               .arg(resizeMethod).arg(sourceImagePath);
-    return KGlobal::dirs()->locateLocal("cache", id);
+    return id;
+}
+
+QString WallpaperPrivate::cachePath(const QString &key) const
+{
+    return KGlobal::dirs()->locateLocal("cache", "plasma-wallpapers/" + key + ".png");
 }
 
 void WallpaperPrivate::renderCompleted(int token, const QImage &image,
@@ -352,13 +360,45 @@ void WallpaperPrivate::renderCompleted(int token, const QImage &image,
     }
 
     if (cacheRendering) {
-        image.save(cachePath(sourceImagePath, size, resizeMethod, color));
+        q->insertIntoCache(cacheKey(sourceImagePath, size, resizeMethod, color), image);
     }
 
     //kDebug() << "rendering complete!";
     emit q->renderCompleted(image);
 }
 
+bool Wallpaper::findInCache(const QString &key, QImage &image, unsigned int lastModified)
+{
+    if (d->cacheRendering) {
+        QString cache = d->cachePath(key);
+        if (QFile::exists(cache)) {
+            if (lastModified > 0) {
+                QFileInfo info(cache);
+                if (info.lastModified().toTime_t() < lastModified) {
+                    return false;
+                }
+            }
+
+            image.load(cache);
+            return true;
+        }
+    }
+
+    return false;
+}
+
+void Wallpaper::insertIntoCache(const QString& key, const QImage &image)
+{
+    //TODO: cache limits?
+    if (d->cacheRendering) {
+        if (image.isNull()) {
+            KIO::file_delete(d->cachePath(key));
+        } else {
+            image.save(d->cachePath(key));
+        }
+    }
+}
+
 } // Plasma namespace
 
 #include "wallpaper.moc"

wallpaper.h

@@ -392,6 +392,33 @@ class PLASMA_EXPORT Wallpaper : public QObject
          */
         void setUsingDiskCache(bool useCache);
 
+        /**
+         * Tries to load pixmap with the specified key from cache.
+         *
+         * @param key the name to use in the cache for this image
+         * @param image the image object to populate with the resulting data if found
+         * @param lastModified if non-zero, the time stamp is also checked on the file,
+         *                     and must be newer than the timestamp to be loaded
+         *
+         * @return true when pixmap was found and loaded from cache, false otherwise
+         * @since 4.3
+         **/
+        bool findInCache(const QString &key, QImage &image, unsigned int lastModified = 0);
+
+        /**
+         * Insert specified pixmap into the cache if usingDiskCache.
+         * If the cache already contains pixmap with the specified key then it is
+         * overwritten.
+         *
+         * @param key the name use in the cache for this image; if the image is specific
+         *            to this wallpaper plugin, consider including the name() as part of
+         *            the cache key to avoid collisions with other plugins.
+         * @param image the image to store in the cache
+         *
+         * @since 4.3
+         **/
+        void insertIntoCache(const QString& key, const QImage &image);
+
     private:
         Q_PRIVATE_SLOT(d, void renderCompleted(int token, const QImage &image,
                                                const QString &sourceImagePath, const QSize &size,