Declaration
procedure AssignRect(Source: TObject; SourceRect: TRect; AssignParams: Boolean = False);
Description
Copies a rectangle from source object. Source can be a 
TIEBitmap, 
TImageEnView or a TBitmap.
If AssignParams is enabled then the 
Params are also copied (if 
ParamsEnabled is true for both source and destination).
Note:
◼Source must have the same 
PixelFormat as the image, or Source can be ie1g and Dest ie24RGB (i.e. Monochrome to RGB conversion)
◼If the 
PixelFormat is ie8p, then you may also need to 
copy the palette
◼When Source is TImageEnView, only the currently selected layer is copied (or the image if there are no layers/selection)
// Copy rect from a TBitmap
iebmp.AssignRect( bmp, Rect( 100, 100, 200, 200 ));
TIEBitmap Assignment and Drawing Methods
TIEBitmap Methods
 | Method | Mode | Purpose | 
 | Assign | From TIEBitmap/TBitmap/TGraphic/TIcon | Copy whole image | 
 | AssignImage | From TIEBitmap | Like assign, but does not copy the alpha channel | 
 | AssignRect | From TIEBitmap/TBitmap | Copy a specified rect | 
 | CopyAndConvertFormat | From TIEBitmap | Copy whole image | 
 | CopyRectTo | To TIEBitmap | Copy rect to another image (without scaling) | 
 | CopyWithMask1 | To TIEBitmap | Copy image using a mask to specify what is copied from the source | 
 | CopyWithMask2 | To TIEBitmap | Copy image using a mask to specify what is replaced in the destintation | 
 | DrawToTIEBitmap | To TIEBitmap | Copies all or part of the image to a specified position and/or size | 
 | JoinBitmaps | From two TIEBitmaps | Draws two bitmaps to a single bitmap | 
 | MergeAlphaRectTo | With TIEBitmap | Merges the alpha channels of two TIEBitmaps using merge rules | 
 | MergeWithAlpha | With TIEBitmap | Merges all or part of two TIEBitmaps with alpha channels to a specified position | 
 | RenderToTIEBitmapEx | To TIEBitmap | Extended drawing of content to a TIEBitmap | 
 | StretchRectTo | To TIEBitmap | Copy rect to dest rect in another image (with scaling) | 
 | SwitchTo | To TIEBitmap | Move content from one TIEBitmap to another | 
 | Method | Mode | Purpose | 
 | Assign | From TIEBitmap/TBitmap/TGraphic/TIcon | Copy whole image | 
 | AssignTo | To TIEBitmap/TBitmap | Copy whole image with optional scaling | 
 | AssignRect | From TIEBitmap/TBitmap | Copy a specified rect | 
 | CopyFromTBitmap | From TBitmap | Copy whole image | 
 | CopyToTBitmap | To TBitmap | Copy whole image | 
 | RenderToTBitmapEx | To TBitmap | Extended drawing of content to a TBitmap |