Multi-row select for Grid control

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Functionality

This code demonstrates how to select multiple rows in a Grid. The code will work no matter how many columns. The object of this code is to allow the user to use the SHIFT+RCLICK or CTRL+RCLICK key to select multiple rows just like a spreadsheet program.

Example

Paste this code into a test view to test it and see how it works. Once compiled, you will see a narrow column on the left that acts as a margin. Clicking this gray cell will highlight the row. Using SHIFT or CTRL and clicking another gray cell will select multiple rows.

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Object oGrid1 is a Grid
  Set Location to 7 26
  Set Size to 116 207
  Set Line_Width to 4 0
  Set Form_Width    0 to 8
  Set Header_Label  0 to ""
  Set Form_Width    1 to 60
  Set Header_Label  1 to "Column 1"
  Set Form_Width    2 to 60      
  Set Header_Label  2 to "Column 2"
  Set Form_Width    3 to 60      
  Set Header_Label  3 to "Column 3"
 
  // BEGIN MULTI-SELECT CODE
  // DO NOT MODIFY
  Set Select_Mode to Multi_Select
  Property Integer[] paiSelected
  Property Integer piLastSelected 0
  Procedure Select_Toggling Integer iItem Integer iState
      Integer iCurrent iCol iLast iCount iFrom iTo iRet iUpdate
      Integer[] aiSelected aiEmpty
      //
      Get Dynamic_Update_State to iUpdate
      Set Dynamic_Update_State to False
      // Get base item
      Move (Current_Item(Self)) to iCurrent
      Move (Mod(iCurrent , Line_Size(Self))) to iCol
      Subtract iCol from iCurrent
      // get list of selected items
      Move (paiSelected(Self)) to aiSelected
      Move (SizeOfArray(aiSelected)) to iCount
      //
      Move (GetAsyncKeyState(VK_CONTROL)) to iRet
      If (iRet<>0) Begin
          If (iState) Begin
              // add selected item
              Move iCurrent to aiSelected[iCount]
              // Update last selected with this item
              Set piLastSelected to iCurrent
              // Select Current row
              For iCol from 0 to (Line_Size(Self)-1)
                  Forward Send Select_Toggling (iCurrent+iCol) iState
              Loop
          End
          Else Begin
              // remove selected item
              For iItem from 0 to (iCount-1)
                  Move aiSelected[iItem] to iLast
                  If (iLast=iCurrent) Move -1 to aiSelected[iItem]
              Loop
              // Update last selected with this item
              Set piLastSelected to -1
          End
      End
      Else Begin
          // If shift is used, we will ignore
          // the state of the clicked row
          // unselect everything
          For iItem from 0 to (iCount-1)
              Move aiSelected[iItem] to iLast
              For iCol from 0 to (Line_Size(Self)-1)
                  Forward Send Select_Toggling (iLast+iCol) False
              Loop
          Loop
          Move aiEmpty to aiSelected
          //
          Move (GetAsyncKeyState(VK_SHIFT)) to iRet
          If ((iRet<>0) and (piLastSelected(Self)<>-1)) Begin
              // select everything in between
              // do not mark this as the last current row,
              // the first item of the shift remains
              If (iCurrent > piLastSelected(Self)) Begin
                  Move (piLastSelected(Self)) to iFrom
                  Move iCurrent to iTo
              End
              Else Begin
                  Move iCurrent to iFrom
                  Move (piLastSelected(Self)) to iTo
              End
              Move 0 to iCount
              For iItem from iFrom to (iTo+3)
                  // Add to array
                  Move iItem to aiSelected[iCount]
                  Increment iCount
                  // select
                  For iCol from 0 to (Line_Size(Self)-1)
                      Forward Send Select_Toggling (iItem+iCol) True
                  Loop
                  // next row
                  Add 3 to iItem
              Loop
          End
          Else Begin
              // no shift or control key was pressed
              // Update last selected with this item
              Move iCurrent to aiSelected[0]
              Set piLastSelected to iCurrent
              // Select Current item
              For iCol from 0 to (Line_Size(Self)-1)
                  Forward Send Select_Toggling (iCurrent+iCol) iState
              Loop
          End
      End
      Set Dynamic_Update_State to iUpdate
      Set paiSelected to aiSelected
  End_Procedure // Select_Toggling
 
  Procedure Mouse_Up Integer iWindowNumber Integer iPosition
      Integer iCol
      Move (Mod(iWindowNumber , Line_Size(Self))) to iCol
      Forward Send Mouse_Up iWindowNumber iPosition
      If (iCol<>1) Send Select_Toggling 0 False
  End_Procedure // Mouse_Up
  // END MULTI-SELECT CODE
 
  //Sample method of how to fill a grid
  Procedure DoFillGrid
      Integer iRow iMaxRows
      Move 20 to iMaxRows
      For iRow from 0 to iMaxRows
          Send Add_Item Msg_None ""
          Send Add_Item Msg_None ("Col 1, row " + String (iRow))
          Send Add_Item Msg_None ("Col 2, row " + String (iRow))
          Send Add_Item Msg_None ("Col 3, row " + String (iRow))
          Set Entry_State item (iRow*4) to False
          Set ItemColor item (iRow*4) to clBtnFace
      Loop
  End_Procedure // DoFillgrid
  Send DoFillgrid
End_Object // oGrid1
 
Object oButton1 is a Button
  Set Size to 14 70
  Set Location to 151 44
  Set Label to "Show Selection"
  // Example on how to get selected rows
  Procedure OnClick
      Integer[] aiSelected
      Integer iItem iCount
      Get paiSelected of oGrid1 to aiSelected
      Move (SizeOfArray(aiSelected)) to iCount
      Showln "Selected Row base_item(s) are"
      For iItem from 0 to (iCount-1)
          Showln (Character(9)) aiSelected[iItem]
      Loop
  End_Procedure // OnClick
End_Object // oButton1
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