opengl: refactor GL texture slot mechanism to be more general

Slot mechanism in ImplOpenGLTexture was written to support needs
for FixedTextureAtlas. This commit makes the slot mechanism more
general so it can be used in other kinds of texture atlases like
PackedTextureAtlas.

The ImplOpenGLTexture still tracks slots, but it is not needed to
define beforehand how many slots there are. The deallocation has
been factored out, ImplOpenGLTexture instead calls a callback
function that a slot with a specific "slot id" has been
deallocated.

Change-Id: I23950d325b803969f958d03ebf34805687c4e620

2 files changed, 10 insertions, 4 deletions

diff --git a/vcl/inc/opengl/FixedTextureAtlas.hxx b/vcl/inc/opengl/FixedTextureAtlas.hxx
index 8d104a788c83..bf9ee043fed0 100644
--- a/vcl/inc/opengl/FixedTextureAtlas.hxx
+++ b/vcl/inc/opengl/FixedTextureAtlas.hxx
@@ -13,10 +13,11 @@
 
 #include "opengl/texture.hxx"
 
+struct FixedTexture;
 
 class VCL_PLUGIN_PUBLIC FixedTextureAtlasManager
 {
-    std::vector<ImplOpenGLTexture *> mpTextures;
+    std::vector<std::unique_ptr<FixedTexture>> maFixedTextures;
 
     int mWidthFactor;
     int mHeightFactor;
diff --git a/vcl/inc/opengl/texture.hxx b/vcl/inc/opengl/texture.hxx
index f54604a88340..5bbf26c63a75 100644
--- a/vcl/inc/opengl/texture.hxx
+++ b/vcl/inc/opengl/texture.hxx
@@ -40,7 +40,7 @@ public:
     GLuint mnOptStencil;
 
     std::unique_ptr<std::vector<int>> mpSlotReferences;
-    int mnFreeSlots;
+    std::function<void(int)> mFunctSlotDeallocateCallback;
 
     ImplOpenGLTexture( int nWidth, int nHeight, bool bAllocate );
     ImplOpenGLTexture( int nWidth, int nHeight, int nFormat, int nType, void const * pData );
@@ -58,8 +58,13 @@ public:
         return mnRefCount == 1;
     }
 
-    bool InitializeSlots(int nSlotSize);
-    int  FindFreeSlot();
+    bool InitializeSlotMechanism(int nInitialSlotSize = 0);
+
+    void SetSlotDeallocateCallback(std::function<void(int)> aCallback)
+    {
+        mFunctSlotDeallocateCallback = aCallback;
+    }
+
     GLuint AddStencil();
 };