| Applies To: | Bitmap | Cursor | Icon |
Description
This property is be used to control the way that Bitmap, Cursor and Icon objects are stored in the workspace.
When you create a Bitmap, Icon or Cursor using ⎕WC, APL asks Windows to allocate a corresponding bitmap, icon or cursor resource. This resource is allocated in Windows memory. If APL were to hold the values of the image properties (CBits, Bits and CMap for a Bitmap; Bits, CMap and Mask for Cursor and Icon objects) internally in the workspace, this data would be duplicated. For large bitmaps this would have a serious impact on memory utilisation and may affect performance. The KeepBits property is provided to allow you to control whether or not APL retains the values of the image properties in the workspace, so that you can choose a strategy to suit your configuration and requirements. KeepBits may take the value 0 or 1.
If KeepBits is 0 the values of the image properties are not stored internally in your workspace. If you save a workspace containing a Bitmap, Cursor or Icon object, the corresponding Windows resource is automatically re-allocated when the workspace is loaded by referring to the associated file. This is the file whose full pathname is defined by the value of the object's File property. It follows that if you adopt this strategy, you must ensure that the File property is set correctly. If APL cannot find the file when the workspace is )LOADed, it cannot re-create the object, and you will get a VALUE ERROR when you subsequently refer to it. A further consideration is the effect on ⎕WG. If KeepBits is 0, and you execute ⎕WG 'CBits' or 'Bits' or 'CMap' or 'Mask', APL obtains these values by requesting the data from Windows.
If KeepBits is set to 1, the contents of the image properties are stored in the workspace, thus duplicating the information which is held by Windows itself. If you save a workspace containing a Bitmap, Cursor or Icon the corresponding Windows resource is automatically re-allocated from the image properties when the workspace is loaded. The value of the File property is ignored. When you execute ⎕WG 'CBits' or 'Bits' or 'CMap' or 'Mask', APL generates the result directly from the stored values held (internally) in the workspace.