askRetrieveMarkersToPaint abstract method

Returns the markers that should be rendered on the current screen.

This method is called during each paint cycle to get the list of markers that should be visible. The returned markers will be rendered by MarkerDatastorePainter using their individual render methods.

Implementation Guidelines:

• Return only markers within the current visible area
• Apply any zoom-level-based filtering
• Consider marker priority or importance for overlapping markers
• Return markers in rendering order (background to foreground)
• Ensure good performance as this is called frequently

Performance Considerations:

• This method is called on every paint cycle
• Avoid expensive operations like database queries
• Use cached/pre-filtered marker lists when possible
• Consider lazy evaluation for large marker sets

Returns an iterable of markers to be rendered, in drawing order