void init(DataTypeComponent editDtc) {

		if (editDtc == null) {
			editMode = EditMode.NONE;
			editOrdinal = -1;
			this.editComponent = null;
			refresh(0, 0);
			return;
		}

		editMode = EditMode.EDIT;
		editOrdinal = editDtc.getOrdinal();
		this.editComponent = editDtc;

		BitFieldPlacement placement = new BitFieldPlacement(editDtc);
		int bitSize = placement.zeroBitField ? 0 : (placement.rightBit - placement.leftBit + 1);
		bitFieldAllocation =
			new BitFieldAllocation(bitSize, (8 * allocationByteSize) - placement.rightBit - 1);
		updatePreferredSize();
		repaint();
	}
Update the size and offset of the allocation unit.  Since this can
affect the size of this component, its bounds will be updated the component
repainted.
@param byteSize allocation byte size
@param byteOffset offset of allocation from start of composite
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/compositeeditor/BitFieldPlacementComponent.java