Starting from v0.99 of the Graphics32 library, implementation of VCL components was changed.
This section describes behavior and properties of TCustomImage32 and TImage32 controls, as well as new realization of layers.
Since TCustomImage32 and TImage32 share the same behavior, I will denote both of them here as TImage32. Most of the discussion concerns TImgView32 as well.
TImage32 is an image displaying visual component, which also holds a collection of layers.
The image is defined as a TBitmap32 object and there exist several properties which specify how it is scaled and positioned within the control's boundaries. I will denote this image as Bitmap Image here.
The layer is, generally speaking, an entity which 'knows' how to combine itself with the back buffer of the control. TImage32 maintains a collection of layers, see 'Using Layers' for details.
When the image paints itself, it runs through several Paint Stages which determine the order in which layers and the bitmap image are painted. This order is completely customizeable.
To avoid flicker and to speed-up scaling and blending operations, each layer and the bitmap image is painted to a back-buffer of the control. See the reference of TImage32 ancestor TCustomPaintBox32 for details of the back-buffer realization.
Finally, TImage32 supports change notification (OnChange event), which is done similar to change notification in TBitmap32. Basically, it redirects change notification from its layers and the bitmap image.
Bitmap Image, Paint Stages, Using Layers, Examples, TBitmap32, TCustomImage32, TCustomImage32.OnChange, TCustomPaintBox32, TImage32
Copyright ©2000-2016 Alex Denisov and the Graphics32 Team - Graphics32 v2.0 - Built on 25-April-2017