GuiMeshCache.h

/****************************************************************************
 * libgui
 * Daryl Borth 2026
 * GuiMeshCache.h
 *
 * Platform-agnostic cache of shape meshes. Shapes that look the same (the
 * keys of an on-screen keyboard, the rows of a list) share one mesh instead
 * of tessellating and holding a copy each, and a mesh that keeps being drawn
 * is handed to the video backend (ImageRenderer::createMesh()) to keep in its
 * own ready-to-draw form, so drawing it again costs almost nothing on the CPU.
 ***************************************************************************/
#pragma once

struct GuiMeshKey {
    SHAPE kind;                
    int width;             
    int height;               
    GuiCorners corners;        
    GuiPaint paint;            
    float feather;           
    float tolerance;       
 
    bool operator==(const GuiMeshKey& o) const;
};

class GuiSharedMesh
{
    public:
        const std::vector<MeshVertex>& vertices() const { return mesh.vertices(); }
    private:
        friend class GuiMeshCache;
        explicit GuiSharedMesh(const GuiMeshKey& k);
 
        GuiMeshKey key;
        GuiMesh mesh;
        void * handle;          
        bool noHandle;          
        uint32_t uses;          
        int refs;               
        uint32_t idleStamp;     
};

class GuiMeshCache
{
    public:
        static GuiSharedMesh * acquire(const GuiMeshKey& key);
        static void release(GuiSharedMesh * mesh);
        static void draw(GuiSharedMesh * mesh, float x, float y, float scaleX, float scaleY, uint8_t alpha, std::vector<MeshVertex>& scratch);
        static void flush();
};