Lazarus的Grid控件用着很不爽，今天跟踪到底！

(2011-03-29 21:54:11)

转载▼

标签： lazarus stringgrid drawcell delphi aliyagoo it

分类： --Lazarus程序

Grid：

TStringGrid = class(TCustomStringGrid) 

TCustomStringGrid =class(TCustomDrawGrid)  

TCustomDrawGrid=class(TCustomGrid)

TCustomGrid=class(TCustomControl)

 

从StringGrid开始追踪，DrawCell到底怎么画出来的：

procedure TCustomStringGrid.DrawCell(aCol, aRow: Integer; aRect:TRect;
  aState: TGridDrawState);
begin
  inherited DrawCell(aCol, aRow, aRect,aState);

【

procedureTCustomDrawGrid.DrawCell(aCol,aRow: Integer; aRect: TRect;
  aState:TGridDrawState);
var
  OldDefaultDrawing: boolean;
begin
  if Assigned(OnDrawCell) and not(CsDesigning inComponentState) then begin
   PrepareCanvas(aCol, aRow, aState);
    ifDefaultDrawing then
     Canvas.FillRect(aRect);

//从这里看以看出，不管DefaultDrawing是否为真，ONCraw事件都会执行
   OnDrawCell(Self,aCol,aRow,aRect,aState)
  end else begin

    //如果在设计阶段或者没有设置DrawCell过程，则使用默认的方法。
   OldDefaultDrawing:=FDefaultDrawing;
   FDefaultDrawing:=True;
    try
     PrepareCanvas(aCol, aRow, aState);
   finally
     FDefaultDrawing:=OldDefaultDrawing;
    end;
   DefaultDrawCell(aCol,aRow,aRect,aState);

【

procedureTCustomDrawGrid.DefaultDrawCell(aCol, aRow: Integer; var aRect:TRect;
  aState: TGridDrawState);
begin
  if goColSpanning in Options thenCalcCellExtent(acol, arow, aRect);

 Canvas.FillRect(aRect);

  ifCellNeedsCheckboxBitmaps(aCol,aRow) then
   DrawCellCheckboxBitmaps(aCol,aRow,aRect);

  ifFTitleStyle<>tsNative then
   DrawColumnText(aCol,aRow,aRect,aState);

  if (goFixedRowNumberingin Options) and (FixedCols >= 1) and (aCol = 0)then
   DrawCellAutonumbering(aCol, aRow, aRect, IntToStr(aRow));
end;                                                      

】
  end;
  DrawCellGrid(aCol,aRow,aRect,aState);
  if FTitleStyle=tsNative then
   DrawColumnText(aCol,aRow,aRect,aState);
end;         

】
  if DefaultDrawing then begin
    ifColumns.Enabled and (gdFixed in aState) and
     (aCol>=FixedCols) and (aRow=0) then
     //inherited already did
    else
    if notCellNeedsCheckboxBitmaps(aCol, aRow) then
     DrawCellText(aCol, aRow, aRect, aState, Cells[aCol,aRow]);
  end;
end;               

 

 

 

procedure TCustomGrid.DrawCell(aCol, aRow: Integer; aRect:TRect;
  aState: TGridDrawState);
begin
  //===============aliyagoo===============
 PrepareCanvas(aCol, aRow, aState);
  Canvas.FillRect(aRect);
  DrawCellGrid(aCol,aRow,aRect,aState);
end;