Implement opacity cache for SDL surfaces.

Enabled by default.
Can be disabled in configuration option "alphaCache" if set it to 0.

Reviewed-by: Bertram

4 files changed, 130 insertions, 10 deletions

diff --git a/src/resources/image.cpp b/src/resources/image.cpp
index 82799bce..cd6bda15 100644
--- a/src/resources/image.cpp
+++ b/src/resources/image.cpp
@@ -22,6 +22,7 @@
 #include "resources/image.h"
 
 #include "resources/dye.h"
+#include "resources/resourcemanager.h"
 
 #ifdef USE_OPENGL
 #include "openglgraphics.h"
@@ -37,6 +38,7 @@ bool Image::mUseOpenGL = false;
 int Image::mTextureType = 0;
 int Image::mTextureSize = 0;
 #endif
+bool Image::mEnableAlphaCache = false;
 
 Image::Image(SDL_Surface *image, bool hasAlphaChannel, Uint8 *alphaChannel):
     mAlpha(1.0f),
@@ -48,6 +50,8 @@ Image::Image(SDL_Surface *image, bool hasAlphaChannel, Uint8 *alphaChannel):
     mGLImage = 0;
 #endif
 
+    mUseAlphaCache = Image::mEnableAlphaCache;
+
     mBounds.x = 0;
     mBounds.y = 0;
 
@@ -71,6 +75,7 @@ Image::Image(GLuint glimage, int width, int height, int texWidth, int texHeight)
     mHasAlphaChannel(true),
     mSDLSurface(0),
     mAlphaChannel(0),
+    mUseAlphaCache(false),
     mGLImage(glimage),
     mTexWidth(texWidth),
     mTexHeight(texHeight)
@@ -166,12 +171,28 @@ Image *Image::load(SDL_Surface *tmpImage)
     return _SDLload(tmpImage);
 }
 
+void Image::cleanCache()
+{
+    ResourceManager *resman = ResourceManager::getInstance();
+
+    for (std::map<float, SDL_Surface*>::iterator
+         i = mAlphaCache.begin(), i_end = mAlphaCache.end();
+         i != i_end; ++i)
+    {
+        if (mSDLSurface != i->second)
+            resman->scheduleDelete(i->second);
+        i->second = 0;
+    }
+    mAlphaCache.clear();
+}
+
 void Image::unload()
 {
     mLoaded = false;
 
     if (mSDLSurface)
     {
+        cleanCache();
         // Free the image surface.
         SDL_FreeSurface(mSDLSurface);
         mSDLSurface = NULL;
@@ -211,6 +232,14 @@ bool Image::hasAlphaChannel()
     return false;
 }
 
+SDL_Surface *Image::getByAlpha(float alpha)
+{
+    std::map<float, SDL_Surface*>::iterator it = mAlphaCache.find(alpha);
+    if (it != mAlphaCache.end())
+        return (*it).second;
+    return 0;
+}
+
 void Image::setAlpha(float alpha)
 {
     if (mAlpha == alpha)
@@ -219,10 +248,34 @@ void Image::setAlpha(float alpha)
     if (alpha < 0.0f || alpha > 1.0f)
         return;
 
-    mAlpha = alpha;
-
     if (mSDLSurface)
     {
+        if (mUseAlphaCache)
+        {
+            SDL_Surface *surface = getByAlpha(mAlpha);
+            if (!surface)
+            {
+                if (mAlphaCache.size() > 100)
+                    cleanCache();
+
+                mAlphaCache[mAlpha] = mSDLSurface;
+            }
+            surface = getByAlpha(alpha);
+            if (surface)
+            {
+                mAlphaCache.erase(alpha);
+                mSDLSurface = surface;
+                mAlpha = alpha;
+                return;
+            }
+            else
+            {
+                mSDLSurface = Image::duplicateSurface(mSDLSurface);
+            }
+        }
+
+        mAlpha = alpha;
+
         if (!hasAlphaChannel())
         {
             // Set the alpha value this image is drawn at
@@ -263,6 +316,10 @@ void Image::setAlpha(float alpha)
                 SDL_UnlockSurface(mSDLSurface);
         }
     }
+    else
+    {
+        mAlpha = alpha;
+    }
 }
 
 Image* Image::SDLmerge(Image *image, int x, int y)
@@ -371,6 +428,14 @@ Image* Image::SDLgetScaledImage(int width, int height)
     return scaledImage;
 }
 
+SDL_Surface* Image::duplicateSurface(SDL_Surface* tmpImage)
+{
+    if (!tmpImage || !tmpImage->format)
+        return NULL;
+
+    return SDL_ConvertSurface(tmpImage, tmpImage->format, SDL_SWSURFACE);
+}
+
 Image *Image::_SDLload(SDL_Surface *tmpImage)
 {
     if (!tmpImage)
@@ -560,25 +625,40 @@ Image *Image::getSubImage(int x, int y, int width, int height)
     return new SubImage(this, mSDLSurface, x, y, width, height);
 }
 
+void Image::terminateAlphaCache()
+{
+    cleanCache();
+    mUseAlphaCache = false;
+}
+
 //============================================================================
 // SubImage Class
 //============================================================================
 
 SubImage::SubImage(Image *parent, SDL_Surface *image,
-        int x, int y, int width, int height):
+                   int x, int y, int width, int height):
     Image(image),
     mParent(parent)
 {
-    mParent->incRef();
-
-    mHasAlphaChannel = mParent->hasAlphaChannel();
-    mAlphaChannel = mParent->SDLgetAlphaChannel();
+    if (mParent)
+    {
+        mParent->incRef();
+        mParent->terminateAlphaCache();
+        mHasAlphaChannel = mParent->hasAlphaChannel();
+        mAlphaChannel = mParent->SDLgetAlphaChannel();
+    }
+    else
+    {
+        mHasAlphaChannel = false;
+        mAlphaChannel = 0;
+    }
 
     // Set up the rectangle.
     mBounds.x = x;
     mBounds.y = y;
     mBounds.w = width;
     mBounds.h = height;
+    mUseAlphaCache = false;
 }
 
 #ifdef USE_OPENGL
diff --git a/src/resources/image.h b/src/resources/image.h
index 3e8ad551..815b7764 100644
--- a/src/resources/image.h
+++ b/src/resources/image.h
@@ -39,6 +39,8 @@
 #include <SDL_opengl.h>
 #endif
 
+#include <map>
+
 class Dye;
 class Position;
 
@@ -169,6 +171,15 @@ class Image : public Resource
         Uint8 *SDLgetAlphaChannel() const
         { return mAlphaChannel; }
 
+        SDL_Surface* duplicateSurface(SDL_Surface* tmpImage);
+
+        void cleanCache();
+
+        void terminateAlphaCache();
+
+        static void setEnableAlphaCache(bool n)
+        { mEnableAlphaCache = n; }
+
 #ifdef USE_OPENGL
 
         // OpenGL only public functions
@@ -208,14 +219,22 @@ class Image : public Resource
         /** SDL_Surface to SDL_Surface Image loader */
         static Image *_SDLload(SDL_Surface *tmpImage);
 
+        SDL_Surface *getByAlpha(float alpha);
+
         SDL_Surface *mSDLSurface;
 
         /** Alpha Channel pointer used for 32bit based SDL surfaces */
         Uint8 *mAlphaChannel;
 
-      // -----------------------
-      // OpenGL protected members
-      // -----------------------
+        std::map<float, SDL_Surface*> mAlphaCache;
+
+        bool mUseAlphaCache;
+
+        static bool mEnableAlphaCache;
+
+        // -----------------------
+        // OpenGL protected members
+        // -----------------------
 #ifdef USE_OPENGL
         /**
          * OpenGL Constructor.
diff --git a/src/resources/resourcemanager.cpp b/src/resources/resourcemanager.cpp
index c63b626e..00e4726e 100644
--- a/src/resources/resourcemanager.cpp
+++ b/src/resources/resourcemanager.cpp
@@ -533,3 +533,18 @@ SDL_Surface *ResourceManager::loadSDLSurface(const std::string &filename)
 
     return tmp;
 }
+
+void ResourceManager::scheduleDelete(SDL_Surface* surface)
+{
+    mDeletedSurfaces.insert(surface);
+}
+
+void ResourceManager::clearScheduled()
+{
+    for (std::set<SDL_Surface*>::iterator i = mDeletedSurfaces.begin(),
+         i_end = mDeletedSurfaces.end(); i != i_end; ++i)
+    {
+        SDL_FreeSurface(*i);
+    }
+    mDeletedSurfaces.clear();
+}
diff --git a/src/resources/resourcemanager.h b/src/resources/resourcemanager.h
index 28ab4725..870182e4 100644
--- a/src/resources/resourcemanager.h
+++ b/src/resources/resourcemanager.h
@@ -26,6 +26,7 @@
 #include <map>
 #include <string>
 #include <vector>
+#include <set>
 
 class Image;
 class ImageSet;
@@ -205,6 +206,10 @@ class ResourceManager
          */
         SDL_Surface *loadSDLSurface(const std::string &filename);
 
+        void scheduleDelete(SDL_Surface* surface);
+
+        void clearScheduled();
+
         /**
          * Returns an instance of the class, creating one if it does not
          * already exist.
@@ -227,6 +232,7 @@ class ResourceManager
         static ResourceManager *instance;
         typedef std::map<std::string, Resource*> Resources;
         typedef Resources::iterator ResourceIterator;
+        std::set<SDL_Surface*> mDeletedSurfaces;
         Resources mResources;
         Resources mOrphanedResources;
         time_t mOldestOrphan;