Fixed wallpaper prescaling issues

Image::SDLgetScaledImage was changed so that it tries to find an existing
scaled version of the image first, and generates it when none exists.
When it needs to generate one, this resource is added to the resource
manager, partly to avoid duplicating the work later but mainly to keep
memory management straightforward.

This function also used to leak the scaled SDL_Surface since it wrongly
assumed that Image::load would free it.

To avoid filling up the memory with scaled wallpapers that are waiting
30 seconds until they will be deleted, the Resource::decRef function was
extended with a parameter that allows telling it what to do with orphans.
Calling decRef with Resource::DeleteImmediately will delete the resource
immediately in case the resource is orphaned.

Reviewed-by: Yohann Ferreira

1 files changed, 26 insertions, 17 deletions

diff --git a/src/gui/widgets/desktop.cpp b/src/gui/widgets/desktop.cpp
index bf833898..baf3e951 100644
--- a/src/gui/widgets/desktop.cpp
+++ b/src/gui/widgets/desktop.cpp
@@ -105,30 +105,39 @@ void Desktop::draw(gcn::Graphics *graphics)
 
 void Desktop::setBestFittingWallpaper()
 {
-    const std::string wallpaperName =
-            Wallpaper::getWallpaper(getWidth(), getHeight());
+    const int width = getWidth();
+    const int height = getHeight();
 
-    Image *nWallPaper = ResourceManager::getInstance()->getImage(wallpaperName);
+    if (width == 0 || height == 0)
+        return;
 
-    if (nWallPaper)
+    const std::string wallpaperName = Wallpaper::getWallpaper(width, height);
+
+    if (wallpaperName.empty())
+        return;
+
+    ResourceManager *resman = ResourceManager::getInstance();
+    Image *wallpaper = resman->getImage(wallpaperName);
+
+    if (wallpaper)
     {
         if (mWallpaper)
-            mWallpaper->decRef();
+            mWallpaper->decRef(Resource::DeleteImmediately);
+
+        mWallpaper = wallpaper;
 
-        if (!nWallPaper->useOpenGL() && (nWallPaper->getWidth() != getWidth()
-            || nWallPaper->getHeight() != getHeight()))
+        // In software mode we try to prescale the image for performance
+        if (!wallpaper->useOpenGL() &&
+                (wallpaper->getWidth() != width ||
+                 wallpaper->getHeight() != height))
         {
-            // We rescale to obtain a fullscreen wallpaper...
-            Image *newRsclWlPpr = nWallPaper->SDLgetScaledImage(getWidth(), getHeight());
-            std::string idPath = nWallPaper->getIdPath();
-
-            // We replace the resource in the resource manager
-            nWallPaper->decRef();
-            ResourceManager::getInstance()->addResource(idPath, newRsclWlPpr);
-            mWallpaper = newRsclWlPpr;
+            if (Image *prescaled = wallpaper->SDLgetScaledImage(width, height))
+            {
+                // Make sure the original can be freed
+                wallpaper->decRef();
+                mWallpaper = prescaled;
+            }
         }
-            else
-                mWallpaper = nWallPaper;
     }
     else
     {