'
'Class description:
'
!short:DBrowse class structure:
Class DBrowse:
~~~~~~~~~~~~~~
Class Browse is adapted for database editation. It could be more database
files with relations (conectedd through relations).


Common use:
~~~~~~~~~~~
LOCAL OBJECT Db OF DBrowse                  //object creation
NET USE Personal                            //database opening
Db:Init()                                   //object initialisation
Db:AddBlock(,"Meno",,FieldBlock("Meno"))    //field is appended for editation
Db:AddBlock(,"Plat",,FieldBlock("Plat"))    //field is appended for editation


As all classes derived from Task, this class don't need processing of methods
Process() and Done(). Initialisation adds a new object of this class on the
top of the stack of classes, and following is a job for task swapper
(method Process() of class Task.)

Source code of class DBrowse is in  C_DBrows.prg

!seealso: c_browse.ngo:Browse c_abrows.ngo:ABrowse c_updbro.ngo:UpDBrowse c_upabro.ngo:UpABrowse c_task.ngo:Task c_color.ngo:Color ob_class.ngo:"Class hierarchy"

!short:~~~~~~~~~~~~~~~~~~~~~~~~
!short:create class DBrowse from Browse
!short:  export:
!short:    var Alias      //""
^BDBrowse:Alias^N: public: character
  Stored Alias workarea, which should be selected when the task is active.

!short:    var RecNo      //0
^BDBrowse:RecNo^N: public: numeric
  Database record number for this task is stored here. It is because
  the other task can during its activity process the command Skip ñN and
  change the selected record of this database. If RecNo==0, after the task
  switching is command Go TOP issued.

!short:    var IndexNo    //0
^BDBrowse:IndexNo^N: public: numeric
  The same as the DBrowse:RecNo, other task can use anything included the
  command SET ORDER.
  Attention:
  No other task exept the methods of class Task should open or close the
  databases. All methods of the library Object.lib assume that at start
  the databases will be opened and closed at the end.

!short:    var FilterNo   //0
^BDBrowse:FilterNo^N: public: numeric
  Information about the filter number (as order number in user defined
  filters (in menu) ), which is written to bottom window border.

!short:    var FilterExp  //""
^BDBrowse:FilterExp^N: public: numeric
  Active filter of selected database of current task (DBrowse:Alias)
  is saved here.

!short:    var FilterBExp //{||false}
^BDBrowse:FilterBExp^N: public: code_block
  If variable FilterExp is not empty (i.e. it contains a valid clipper
  expression in a for of a text string), so the FilterBExp contais this
  expression transformed to form of code block. The reason for this
  is the evaluation speed of the expression.

!short:    var FilterMark //false
^BDBrowse:FilterMark^N: public: :public: logical
  Checkmark of filter type (true = coloring, false = dismissing).

!short:    var OneDbf     //(object of OneDbf)
^BDBrowse:OneDbf^N: public: object_of_OneDbf
  This object contain index, filter & relations definitions.
  See the OneDbf class.

!short:    method New=DBrowseNew                 //o:New() --> self
^BDBrowse:New()^N: public: return self
  The object is filled with default values, the following predcessor
  variables are changed:

  ^UDBrowse:InsBlock^N: public: code_block
    Code block for one row appending to edited table.

  ^UDBrowse:DelBlock^N: public: code_block
    Code block for deleting of current row of edited table.

  ^UDBrowse:InfoBlock^N: public: code_block
    Code block for actual record number, filter and index displaying at the
    bottom window border of current task.

!short:    method DoGet=DBrowseDoGet             //o:DoGet() --> true/false
^BDBrowse:DoGet()^N: private: return true/false
  The method DoGet() of DBrowse class is appended with the virtual record
  management and relations keeping. Look at method TestVrecord() of Browse
  class.

!short:    method PostInit=DBrowsePostInit       //o:PostInit() --> true
^BDBrowse:PostInit()^N: private: return true
  Used for correct window dimensions counting in the Form mode.
  The DoGet() method of Browse class is appended with filling of instvar
  variable DBrowse:Alias with the value returned from clipper function
  Alias(), when it was not entered (was Empty()).

!short:    method SwapForm=DBrowseSwapForm       //o:SwapForm() --> true
^BDBrowse:SwapForm()^N: private: return true
  It is for speed optimalization, the filter setting is not necessary
  everytime.

!short:    method UpDatabase=DBrowseUpDatabase   //o:UpDatabase() --> true
^BDBrowse:UpDatabase()^N: private: return true
  The clipper DbfNtx system is set correctly for this task, the right
  workarea is selected, index, filter and relationskeeping is done
  and the right database record is jumped to in all necessary database
  files.

!short:    method UpFilter=DBrowseUpFilter       //o:UpFilter() --> true
^BDBrowse:UpFilter()^N: private: return true
  Help method for DBrowse:UpDatabase(). The filter is set.

!short:    method VPaint=DBrowseVPaint           //o:VPaint() --> true
^BDBrowse:VPaint()^N: private: return true
  The parent method is appended with database switching.

!short:    method VProcess=DBrowseVProcess       //o:VProcess() --> true
^BDBrowse:VProcess()^N: private: return true
  The parent method is appended with database switching before the proces
  and currend record number keeping after the process.

!short:    endclass