Graphics32

Appearance

Member Filters
Show Inherited
Show Protected
Show abstract
GR32_Layers🞂GR32_LayersUnit

GR32_Layers

Provides classes, interfaces, and types for managing interactive 2D image and vector layers, mouse handling, and rubberband selection controls.

Description ​

The GR32_Layers unit implements the layer framework in Graphics32. It provides a comprehensive set of classes and tools for creating and managing visual layers rendered on top of visual controls or bitmaps.

Key capabilities provided by GR32_Layers include:

  • Layer Management: TLayerCollection manages ordered lists of layers, Z-ordering, visibility, mouse capture, coordinate transformation, and invalidation notifications.
  • Base Layer Framework: TCustomLayer provides fundamental layer behaviors, visibility options (LOB_*), hit testing, mouse/keyboard event dispatching, and invalidation hooks.
  • Positioned & Bitmap Layers: TPositionedLayer, TCustomIndirectBitmapLayer, TIndirectBitmapLayer, TCustomBitmapLayer, and TBitmapLayer support moving, scaling, clipping, and rendering 32-bit bitmaps with optional alpha-channel hit testing.
  • Rubberband Selection & Manipulation: TCustomRubberBandLayer, TPolygonRubberbandLayer, and TRubberbandLayer provide design-time or interactive visual frames with draggable control vertices and sizing handles for interactive object transformation.
  • Notification Interfaces: Standard interfaces (ILayerNotification, IUpdateRectNotification, ILayerUpdateNotification, ILayerListNotification, etc.) enable low-coupling event propagation and customization.