[DimitarCC]

This pull request introduces significant improvements to GPU memory management for GUI and web overlay textures, aiming to make texture eviction more predictable and to avoid sudden stalls or out-of-memory errors, especially when sharing GPU resources with a web browser (HbbTV). The changes implement a soft texture budget, allow for gradual eviction of textures, and add new controls for when and how web overlay textures are released.

Texture budget and eviction improvements:

• Added a soft texture budget (ENIGMA_TEX_BUDGET_MB), which can be set via environment variable or is learned automatically after the first out-of-memory event; this budget governs how many textures are kept in memory, and textures are now released gradually over multiple frames instead of all at once. [1] [2] [3] [4] [5]
• Modified the evictLRU and trimTo methods in gTextureManager to accept a max_count parameter, limiting how many textures are deleted per frame to avoid UI stalls. [1] [2] [3] [4]

Web overlay texture lifecycle management:

• Introduced a callback (setOnShow) that is triggered before the web overlay becomes visible, ensuring that cached GUI textures are released to free up GPU memory for the browser. [1] [2]
• Implemented logic to keep web overlay textures alive for a configurable grace period (ENIGMA_WEB_OVERLAY_IDLE_MS) after the overlay is hidden, releasing them when idle to reclaim GPU memory efficiently. [1] [2] [3] [4]

Web overlay upload modes and robustness:

• Added a new "destroy" upload mode (ENIGMA_WEB_OVERLAY_UPLOAD=destroy) that deletes the previous frame's texture and waits for the GPU to finish before allocating a new one, ensuring minimal GPU memory use by the overlay. [1] [2] [3]

These updates collectively make texture management more robust and responsive, particularly in environments where GPU memory is shared between the GUI and web browser layers.