Represents a pointer to the upper left corner of the image buffer for a region image (an 8bpp bitmap containing region information).
This property is there to provide a means of direct access to the image buffer for plugins etc.
It is returned as an integer type, but for plugins etc., cast it to an appropriate type (const unsigned char * etc.) and use it.
Do not write a value to the pointer obtained by this property.
Any pointer obtained by Layer.provinceImageBufferForWrite can be written.
Returns NULL (0) if no image has been assigned.
If no image is assigned, the entire area should be considered area number 0.
The size of the image is represented by the Layer.imageWidth and Layer.imageHeight properties.
See Layer.provinceImageBufferPitch for how to calculate the pointer.