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NextGrid .NET

Custom Draw in NextGrid

Info

Skill:
Version: 1.0.1
Author: Bojan Nikolic
Created:
Updated: 2008-05-13

1. Set column for custom draw

Cell is not drawn in custom mode by default. This is controled by DrawingOptions property of Column:

Table 1: DrawingOptions
Name	Meaning
doNormal	Cells within this column are drawn without custom draw.
doCustom	Cell will be drawn as usuall, but custom code may be added as extra painting layer over existin drawing.
doCustomOnly	Cell must be drawn manualy, even a background
doBackgroundOnly	Background is drawn as first layer (may be selected or not), but additional drawing must be done manualy.

2. Custom Draw Event

If you like to made some custom drawing inside cell, you will need to use OnCustomDrawCell event. This event occur, when every Cell inside Grid is drawn.

This event have next parameters:

Table 2: Parameters
Name	Meaning
ACol	Column Index of currently drawing cell
ARow	Row Index of currently drawing cell
CellRect	TRect of currently drawing cell
CellState	Cell state of currently drawing cell

ACol and ARow parameters are useful for checking cell content of this cell before you draw.

Delphi Example:

if NextGrid1.Cells[ACol, ARow] = 'completed' then

if(NextGrid1.Cells[ACol][ARow] = "completed" {

CellRect help when drawing need to fit inside currently drawing cell.

NextGrid1.Canvas.MoveTo(CellRect.Left, CellRect.Top);
NextGrid1.Canvas.LineTo(CellRect.Right, CellRect.Bottom);

NextGrid1->Canvas->MoveTo(CellRect->Left, CellRect->Top);
NextGrid1->Canvas->LineTo(CellRect->Right, CellRect->Bottom);

This example draw cross line inside current cell.

CellState parameter identify state (if cell selected or not) of currently painted cell.

This parameter is useful for different drawing for selected and non-selected cells.

Full example:

procedure TForm1.NextGrid1CustomDrawCell(Sender: TObject; ACol,
  ARow: Integer; CellRect: TRect; CellState: TCellState);
var
  R: TRect;
begin
  R := CellRect;
  InflateRect(R, -2, -2);
  with NextGrid1.Canvas do
  begin
    if csSelected in CellState then
      Pen.Color := clHighlightText
    else
      Pen.Color := clGray;
    Brush.Color := clRed;
    Rectangle(R);
  end;
end;

Result:

3. Background Custom Draw

Background may be custom drawn too, very similar as drawing custom cells.

This need to be done within OnCustomDrawCellBackground event.

When DefaultDrawing parameter is set to False standard drawing will be skipped, and custom drawing will be applied.

Table 3: Parameters
Name	Meaning
ACol	Column Index of currently drawing cell
ARow	Row Index of currently drawing cell
CellRect	TRect of currently drawing cell
CellState	Cell state of currently drawing cell
DefaultDrawing	When set to False, custom drawing will be used.

Example of drawing "3D" effect cells:

procedure TForm1.NextGrid1DrawCellBackground(Sender: TObject; ACol,
  ARow: Integer; CellRect: TRect; CellState: TCellState;
  var DefaultDrawing: Boolean);
var
  R: TRect;
begin
  if not(csSelected in CellState) then
  begin
    DefaultDrawing := False;
    with NextGrid1.Canvas do
    begin
      R := CellRect;
      Frame3D(NextGrid1.Canvas, R, clBtnHighlight, clBtnShadow, 1);
      Brush.Color := clBtnFace;
      FillRect(R);
    end;
  end;
end;