This is the prerequisite for introducing render nodes and layer textures.
The KrkTexture class provides an API similar to the QSGTexture's API.
The KrkTexture is effectively split in two parts - the generic render graph texture and the platform-specific texture, e.g. OpenGL texture or QImage. The split is necessary to allow implementing atlas textures.
The decoration item puts decoration borders in a texture atlas. This is not feasible currently as every decoration part will need a separate geometry node and we don't have paint nodes yet. It'll be added later.
Note that a scene graph and a render graph are different. A scene graph contains items such as surface items. A render graph specifies how the items must be rendered. For now, there is no render graph, but it will contain things such as texture render nodes, transform nodes, etc.
cc #50 (closed)