delphi中TDBGrid的使用

 

procedure TMainForm.DBGrid1DrawColumnCell(Sender: TObject;
const Rect: TRect; DataCol: Integer; Column: TColumn;State: TGridDrawState);
var i :integer;
begin
if gdSelected in State then Exit;
//定义表头的字体和背景颜色：
   for i :=0 to (Sender as TDBGrid).Columns.Count-1 do
   begin
     (Sender as TDBGrid).Columns[i].Title.Font.Name :='宋体'; //字体
     (Sender as TDBGrid).Columns[i].Title.Font.Size :=9; //字体大小
     (Sender as TDBGrid).Columns[i].Title.Font.Color :=$000000ff; //字体颜色(红色)
     (Sender as TDBGrid).Columns[i].Title.Color :=$0000ff00; //背景色(绿色)
   end;
//隔行改变网格背景色：
if Query1.RecNo mod 2 = 0 then
   (Sender as TDBGrid).Canvas.Brush.Color := clInfoBk //定义背景颜色
else
   (Sender as TDBGrid).Canvas.Brush.Color := RGB(191, 255, 223); //定义背景颜色
//定义网格线的颜色：
   DBGrid1.DefaultDrawColumnCell(Rect,DataCol,Column,State);
with (Sender as TDBGrid).Canvas do //画 cell 的边框
begin
   Pen.Color := $00ff0000; //定义画笔颜色(蓝色)
   MoveTo(Rect.Left, Rect.Bottom); //画笔定位
   LineTo(Rect.Right, Rect.Bottom); //画蓝色的横线
   Pen.Color := $0000ff00; //定义画笔颜色(绿色)
   MoveTo(Rect.Right, Rect.Top); //画笔定位
   LineTo(Rect.Right, Rect.Bottom); //画绿色的竖线
end;
end;
-----------------------------------------------
procedure TForm1.DBGrid1DrawDataCell(Sender: TObject; const Rect: TRect; Field: TField; State: TGridDrawState);
begin
if (gdFocused in State) then
begin
   if (Field.FieldName = DBComboBox1.DataField ) then
   begin
     DBComboBox1.Left := Rect.Left + DBGrid1.Left;
     DBComboBox1.Top := Rect.Top + DBGrid1.top;
     DBComboBox1.Width := Rect.Right - Rect.Left;
     DBComboBox1.Height := Rect.Bottom - Rect.Top;
     DBComboBox1.Visible := True;
   end;
end;
end;

-----------------------------------------------

procedure TForm1.DBGrid1ColExit(Sender: TObject);
begin
If DBGrid1.SelectedField.FieldName = DBComboBox1.DataField then
   begin
     DBComboBox1.Visible := false;
   end;
end;

-----------------------------------------------

在DbGrid的DrawColumnCell事件中编写如下代码：

Case DataCol Mod 2 = 0 of
True: DbGrid1.Canvas.Brush.Color:= clBlue; file://偶数列用蓝色
False: DbGrid1.Canvas.Brush.Color:= clAqua; file://奇数列用浅绿色
End;
DbGrid1.Canvas.Pen.Mode:=pmMask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
-----------------------------------------------
Case DataCol Mod 2 = 0 of
True: DbGrid1.Canvas.Brush.Color:= clBlue; file://偶数列用蓝色
False: DbGrid1.Canvas.Brush.Color:= clAqua; file://奇数列用浅绿色
End;
If ((State = [gdSelected]) or (State=[gdSelectedgdFocused])) then
If Not DbGrid1.SelectedRows.CurrentRowSelected then
DbGrid1.Canvas.Brush.Color:=clRed; file://当前选中单元格显示红色
DbGrid1.Canvas.Pen.Mode:=pmMask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
-----------------------------------------------
设置DbGrid控件的Options属性中的dgRowSelect属性为真，Color属性为clAqua(背景色)
在DbGrid的DrawColumnCell事件中编写如下代码：
if ((State = [gdSelected]) or (State=[gdSelected gdFocused])) then
DbGrid1.Canvas.Brush.color:=clRed; file://当前行以红色显示，其它行使用背景的浅绿色
DbGrid1.Canvas.pen.mode:=pmmask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
-----------------------------------------------
if ((State = [gdSelected]) or (State=[gdSelectedgdFocused])) then
begin
Case DataCol Mod 2 = 0 of
True : DbGrid1.Canvas.Brush.color:=clRed; file://当前选中行的偶数列显示红色
False: DbGrid1.Canvas.Brush.color:=clblue; file://当前选中行的奇数列显示蓝色
end;
DbGrid1.Canvas.pen.mode:=pmmask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
end;
-----------------------------------------------
横向斑马线， 同时以红色突显当前行效果。
file://其它属性设置同3，将上述代码修改为：
Case Table1.RecNo mod 2 = 0 of file://根据数据集的记录号进行判断
True : DbGrid1.Canvas.Brush.color:=clAqua; file://偶数行用浅绿色显示
False: DbGrid1.Canvas.Brush.color:=clblue; file://奇数行用蓝色表示
end;
if ((State = [gdSelected]) or (State=[gdSelectedgdFocused])) then file://选中行用红色显示
DbGrid1.Canvas.Brush.color:=clRed;
DbGrid1.Canvas.pen.mode:=pmMask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
-----------------------------------------------
双向斑马线效果：即行间用不同色区分，同时，选中行以纵向斑马线效果区分不同的列。

file://其它属性设置同3，将上述代码修改为：
Case Table1.RecNo mod 2 = 0 of file://根据数据集的记录号进行判断
True : DbGrid1.Canvas.Brush.color:=clAqua; file://偶数行用浅绿色显示
False: DbGrid1.Canvas.Brush.color:= clblue; file://奇数行用蓝色表示
end;
If ((State = [gdSelected]) or (State=[gdSelectedgdFocused])) then
Case DataCol mod 2 = 0 of
True : DbGrid1.Canvas.Brush.color:=clRed; file://当前选中行的偶数列用红色
False: DbGrid1.Canvas.Brush.color:= clGreen; file://当前选中行的奇数列用绿色表示
end;
DbGrid1.Canvas.pen.mode:=pmMask;
DbGrid1.DefaultDrawColumnCell (Rect
DataCol
Column
State);
-----------------------------------------------
DBGrid不支持鼠标的上下移动的解决代码(感谢 wangxian11 提供)自己捕捉WM_MOUSEWHEEL消息处理
private
OldGridWnd : TWndMethod;
procedure NewGridWnd (var Message : TMessage);
public

procedure TForm1.NewGridWnd(var Message: TMessage);
var
IsNeg : Boolean;
begin
if Message.Msg = WM_MOUSEWHEEL then
begin
   IsNeg := Short(Message.WParamHi) < 0;
   if IsNeg then
     DBGrid1.DataSource.DataSet.MoveBy(1)
   else
     DBGrid1.DataSource.DataSet.MoveBy(-1)
end
else
   OldGridWnd(Message);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
OldGridWnd := DBGrid1.WindowProc ;
DBGrid1.WindowProc := NewGridWnd;
end;
-----------------------------------------------

dbgrid中移动焦点到指定的行和列   dbgrid是从TCustomGrid继承下来的，它有col与row属性，只不过是protected的，不能直接访问，要处理一下，可以这样：
Query1.first;
TDrawGrid(dbgrid1).col:=1;
dbgrid1.setfocus;
-----------------------------------------------
procedure TForm1.DBGrid1DrawDataCell(Sender: TObject; const Rect: TRect;Field: TField; State: TGridDrawState);
　　begin
　　 if Table1.Fieldbyname(′Salary′).value<=SpinEdit1.value then
　　 DBGrid1.Canvas.Brush.Color:=ColorGrid1.ForeGroundColor
　　 else
　 　 DBGrid1.Canvas.Brush.Color:=ColorGrid1.BackGroundColor;
　　 DBGrid1.Canvas.FillRect(Rect);
　　 DBGrid1.Canvas.TextOut(Rect.left＋2,Rect.top＋2,Field.AsString);
　　end;

-----------------------------------------------
1.为SpinEdit1构件的OnChange事件编写响应代码：

　　procedure TForm1.SpinEdit1Change(Sender: TObject);
　　begin
　　 DBGrid1.refresh; //刷新是必须的
　　end;

　　当SpinEdit1构件的值有所改变时，重新刷新DBGrid1。

2.为ColorGrid1的OnChange事件编写响应代码：

　　procedure TForm1.ColorGrid1Change(Sender: TObject);
　　begin
　　 DBGrid1.refresh;    //刷新是必须的
　 end;

　　当ColorGrid1的值有所改变时，即鼠标的右键或左键单击ColorGrid1重新刷新DBGrid1。

3.为Form1窗体（主窗体）的OnCreate事件编写响应代码：

　　procedure TForm1.FormCreate(Sender: TObject);
　　begin
　　 ColorGrid1.ForeGroundIndex:=9;
　 　 ColorGrid1.BackGroundIndex:=15;
　end;

-----------------------------------------------
判断Grid是否有滚动条？
if (GetWindowlong(Stringgrid1.Handle, GWL_STYLE) and WS_VSCROLL) <> 0 then
   ShowMessage('Vertical scrollbar is visible!');
if (GetWindowlong(Stringgrid1.Handle, GWL_STYLE) and WS_HSCROLL) <> 0 then
   ShowMessage('Horizontal scrollbar is visible!');

-----------------------------------------------

1、 数据表的建立
在Delphi的工具菜单中选择Database desktop，在数据库DBDemos下建立一个名为
example.db的数据表。数据表的字段和内容如下：
            
Name Age Wage
张山 25 500
王武 57 1060
李市 30 520
刘牛 28 390

   2、创建基于TDBGrid的TColoredDBGrid组件
   在Delphi组件菜单中，选择New Component,在弹出对话框中作以下设置：

Ancestor Type =   TDBGrid
Class Name   =   TColoredDBGrid

   然后单击OK按钮，Delphi自动完成组件基本框架的定义。增添OnDRawColoredDBGrid事件并
使它出现在Object Inspector的Events中以便在应用程序中设定改变行颜色的条件。重载
DrawCell方法，只能自己绘制单元格。不能通过在OnDrawColumnCell来设置颜色，因为在
OnDrawColumnCell改变单元格的颜色会再次触发OnDrawColumnCell。
   下面就是所创建组件的源程序 。

   3、建立应用程序进行验证。
   在Delphi文件菜单中选择New建立新的应用程序工程Project1和主窗体Form1，设置Form1的
Caption属性为“控制DBGrid行颜色的示例”。在主窗体上添加Data Source、Table、Button和
ColoredDBGrid组件。设置各组件的属性如下：

Table1.Database=’DBDemos’
Table1.Tablename=’example.db’
Datasource1.Dataset=Table1
ColoredDBGrid1.Datasource=DataSource1
Button1.Caption=’退出’

   在ColoredDBGrid1的onDRawColoredDBGrid事件中输入下列代码，设定由Wage（工资）来决
定在ColoredDBGrid1各行的颜色。

procedure TForm1.ColoredDBGrid1 DRawColoredDBGrid (Sender: TObject; Field: TField; var Color: TColor; var Font: TFont);
Var
   p : Integer;
begin
   p := Table1.FindField('wage').AsInteger;
//取得当前记录的Wage字段的值。
   if (p < 500) then begin                
//程序将根据wage值设置各行的颜色。
     Color := clGreen;
     Font.Style := [fsItalic];     
//不仅可以改变颜色,还可以改变字体
   end;
   if(p >= 500) And (p < 800) then
     Color := clRed;
   if(p >=800) then begin
     Color := clMaroon;
     Font.Style := [fsBold];
   end;
end;

-----------------------------------------------
unit NewDBGrid;

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs, DB, Grids, DBGrids, Excel97;
type
TDrawFieldCellEvent = procedure(Sender: TObject; Field: TField;
   var Color: TCOlor; var Font: TFont; Row: Longint) of object;
//新的数据控件由 TDBGrid 继承而来
TNewDBGrid = class(TDBGrid)

private
//私有变量
   FWZebra: Boolean; //是否显示斑马颜色
   FWFirstColor: TColor; //单数行颜色
   FWSecondColor: TCOlor; //双数行颜色
   FDrawFieldCellEvent: TDrawFieldCellEvent;
   procedure AutoInitialize; //自动初使化过程
   procedure AutoDestroy;
   function GetWFirstColor: TColor;
//FirstColor 的读写函数及过程
   procedure SetWFirstColor(Value: TColor);
   function GetWSecondColor: TCOlor;
   procedure SetWSecondColor(Value: TColor);
   function GetWZebra: Boolean;
   procedure SetWZebra(Value: Boolean);

protected
   procedure Scroll(Distance: Integer); override;
//本控件的重点过程
   procedure DrawCell(Acol, ARow: Longint; ARect:
     TRect; AState: TGridDrawState); override;

public
   constructor Create(AOwner: TComponent); override;
   destructor Destroy; override;

published
   property WZebra: Boolean read GetWZebra write SetWZebra;
   property OnDblClick;
   property OnDragDrop;
   property OnKeyUp;
   property OnKeyDown;
   property OnKeyPress;
   property OnEnter;
   property OnExit;
   property OnDrawDataCell;
   property WFirstColor: TColor
     read GetWFirstColor write SetWFirstColor;
   property WSecondColor: TColor
     read GetWSecondColor write SetWSecondColor;
end;

procedure Register;

implementation

procedure Register;
begin
RegisterComponents('Data Controls', [TNewDBGrid]);
end;

procedure TNewDBGrid.AutoInitialize;
begin
FWFirstColor := RGB(239, 254, 247);
FWSecondColor := RGB(249, 244, 245);
{可以在次添加需要的其它控件及初使化参数}
end;

procedure TNewDBGrid.AutoDestroy;
begin
{在这里释放自己添加参数等占用的系统资源}
end;

procedure TNewDBGrid.SetWZebra(Value: Boolean);
begin
FWZebra := Value;
Refresh;
end;

function TNewDBGrid.GetWZebra: Boolean;
begin
Result := FWZebra;
end;

function TNewDBGrid.GetWFirstColor: TColor;
begin
Result := FWFirstColor;
end;

procedure TNewDBGrid.SetWFirstColor(Value: TColor);
begin
FWFirstColor := Value;
Refresh;
end;

function TNewDBGrid.GetWSecondColor: TColor;
begin
Result := FWSecondColor;
end;

procedure TNewDBGrid.SetWSecondColor(Value: TColor);
begin
FWSecondColor := Value;
Refresh;
end;

constructor TNewDBGrid.Create(AOwner: TComponent);
begin
inherited Create(AOwner);
AutoInitialize;
end;

destructor TNewDBGrid.Destroy;
begin
AutoDestroy;
inherited Destroy;
end;
//实现斑马效果

procedure TNewDBGrid.DrawCell(ACol, ARow:
Longint; ARect: TRect; AState: TGridDrawState);
var
OldActive: Integer;
Highlight: Boolean;
Value: string;
DrawColumn: Tcolumn;
cl: TColor;
fn: TFont;
begin
{如果处于控件装载状态,则直接填充颜色后退出}
if csLoading in ComponentState then
begin
   Canvas.Brush.Color := Color;
   Canvas.FillRect(ARect);
   Exit;
end;
if (gdFixed in AState) and (ACol - IndicatorOffset < 0) then
begin
   inherited DrawCell(ACol, ARow, ARect, AState);
   Exit;
end;
{对于列标题,不用任何修饰}
if (dgTitles in Options) and (ARow = 0) then
begin
   inherited DrawCell(ACol, ARow, ARect, AState);
   Exit;
end;
if (dgTitles in Options) then Dec(ARow);
Dec(ACol, IndicatorOffset);
if (gdFixed in AState) and ([dgRowLines, dgColLines] * Options =
   [dgRowLines, dgColLines]) then
begin
{缩减ARect,以便填写数据}
   InflateRect(ARect, -1, -1);
end
else
   with Canvas do
   begin
     DrawColumn := Columns[ACol];
     Font := DrawColumn.Font;
     Brush.Color := DrawColumn.Color;
     Font.Color := DrawColumn.Font.Color;
     if FWZebra then //如果属性WZebra为True则显示斑马纹
       if Odd(ARow) then
         Brush.Color := FWSecondColor
       else
         Brush.Color := FWFirstColor;
     if (DataLink = nil) or not DataLink.Active then
       FillRect(ARect)
     else
     begin
       Value := '';
       OldActive := DataLink.ActiveRecord;
       try
         DataLink.ActiveRecord := ARow;
         if Assigned(DrawColumn.Field) then
         begin
           Value := DrawColumn.Field.DisplayText;
           if Assigned(FDrawFieldCellEvent) then
           begin
             cl := Brush.Color;
             fn := Font;
             FDrawFieldCellEvent(self, DrawColumn.Field, cl, fn, ARow);
             Brush.Color := cl;
             Font := fn;
           end;
         end;
         Highlight := HighlightCell(ACol, ARow, Value, AState);
         if Highlight and (not FWZebra) then
         begin
           Brush.Color := clHighlight;
           Font.Color := clHighlightText;
         end;
         if DefaultDrawing then
           DefaultDrawColumnCell(ARect, ACol, DrawColumn, AState);
         if Columns.State = csDefault then
           DrawDataCell(ARect, DrawColumn.Field, AState);
         DrawColumnCell(ARect, ACol, DrawColumn, AState);
       finally
         DataLink.Activerecord := OldActive;
       end;
       if DefaultDrawing and (gdSelected in AState) and
         ((dgAlwaysShowSelection in Options) or Focused)
         and not (csDesigning in Componentstate)
         and not (dgRowSelect in Options)
         and (ValidParentForm(self).ActiveControl = self) then
       begin
//显示当前光标处为蓝底黄字,同时加粗显示
         Windows.DrawFocusRect(Handle, ARect);
         Canvas.Brush.COlor := clBlue;
         Canvas.FillRect(ARect);
         Canvas.Font.Color := clYellow;
         Canvas.Font.Style := [fsBold];
         DefaultDrawColumnCell(ARect, ACol, DrawColumn, AState);
       end;
     end;
   end;
if (gdFixed in AState) and ([dgRowLines, dgColLines] * Options =
   [dgRowLines, dgColLines]) then
begin
   InflateRect(ARect, -2, -2);
   DrawEdge(Canvas.Handle, ARect, BDR_RAISEDINNER, BF_BOTTOMRIGHT);
   DrawEdge(Canvas.Handle, ARect, BDR_SUNKENINNER, BF_TOPLEFT);
end;
end;
//如果移动光标等,则需要刷新显示DBGrid

procedure TNewDBGrid.Scroll(Distance: Integer);
begin
inherited Scroll(Distance);
refresh;
end;

end.

-----------------------------------------------

在DBGrid控件中显示图形　　如果在数据库中设置了一个为BLOB类型的字段用于保存图形,在使用DBGrid控件显示时,在表格中显示的是BLOB,而无法显示出图形,当然,有一些第三方控件可以显示出图形,但是要去找第三方控件不是一件容易的事,而且有些好用的都需要付费。能不能在DBGrid中显示图形呢？答案是肯定的。
　　在DBGrid的OnDrawCell事件中加入如下代码即可在DBGrid控件中显示图形。
var
Bmp: TBitmap;
begin
if (Column.Field.DataTyp = ftBLOB) or (Column.Field.DataTyp = ftGraphic) then
begin
   Bmp:=TBitmap.Create;
   try
     Bmp.Assign(Column.Field);
     DBGrid1.Canvas.StretchDraw(Rect,Bmp);
     Bmp.Free;
   Except
     Bmp.Free;
   end;
end;
end;

-----------------------------------------------
将 DBGrid 中的内容输出至 Excel 或 ClipBoard
//注意:下面的方法必须包含 ComObj, Excel97 单元
//-----------------------------------------------------------
// if toExcel = false, export dbgrid contents to the Clipboard
// if toExcel = true, export dbgrid to Microsoft Excel
procedure ExportDBGrid(toExcel: Boolean);
var
   bm: TBookmark;
   col, row: Integer;
   sline: String;
   mem: TMemo;
   ExcelApp: Variant;
begin
   Screen.Cursor := crHourglass;
   DBGrid1.DataSource.DataSet.DisableControls;
   bm := DBGrid1.DataSource.DataSet.GetBookmark;
   DBGrid1.DataSource.DataSet.First;

   // create the Excel object
   if toExcel then
   begin
     ExcelApp := CreateOleObject('Excel.Application');
     ExcelApp.WorkBooks.Add(xlWBatWorkSheet);
     ExcelApp.WorkBooks[1].WorkSheets[1].Name := 'Grid Data';
   end;

   // First we send the data to a memo
   // works faster than doing it directly to Excel
   mem := TMemo.Create(Self);
   mem.Visible := false;
   mem.Parent := MainForm;
   mem.Clear;
   sline := '';

   // add the info for the column names
   for col := 0 to DBGrid1.FieldCount-1 do
     sline := sline + DBGrid1.Fields[col].DisplayLabel + #9;
   mem.Lines.Add(sline);

   // get the data into the memo
   for row := 0 to DBGrid1.DataSource.DataSet.RecordCount-1 do
   begin
     sline := '';
     for col := 0 to DBGrid1.FieldCount-1 do
       sline := sline + DBGrid1.Fields[col].AsString + #9;
     mem.Lines.Add(sline);
     DBGrid1.DataSource.DataSet.Next;
   end;

   // we copy the data to the clipboard
   mem.SelectAll;
   mem.CopyToClipboard;

   // if needed, send it to Excel
   // if not, we already have it in the clipboard
   if toExcel then
   begin
     ExcelApp.Workbooks[1].WorkSheets['Grid Data'].Paste;
     ExcelApp.Visible := true;
   end;

   FreeAndNil(mem);
// FreeAndNil(ExcelApp);
   DBGrid1.DataSource.DataSet.GotoBookmark(bm);
   DBGrid1.DataSource.DataSet.FreeBookmark(bm);
   DBGrid1.DataSource.DataSet.EnableControls;
   Screen.Cursor := crDefault;
end;

-----------------------------------------------
数据网格自动适应宽度///////源代码开始
uses
Math;

function DBGridRecordSize(mColumn: TColumn): Boolean;
{ 返回记录数据网格列显示最大宽度是否成功 }
begin
Result := False;
if not Assigned(mColumn.Field) then Exit;
mColumn.Field.Tag := Max(mColumn.Field.Tag,
   TDBGrid(mColumn.Grid).Canvas.TextWidth(mColumn.Field.DisplayText));
Result := True;
end; { DBGridRecordSize }

function DBGridAutoSize(mDBGrid: TDBGrid; mOffset: Integer = 5): Boolean;
{ 返回数据网格自动适应宽度是否成功 }
var
I: Integer;
begin
Result := False;
if not Assigned(mDBGrid) then Exit;
if not Assigned(mDBGrid.DataSource) then Exit;
if not Assigned(mDBGrid.DataSource.DataSet) then Exit;
if not mDBGrid.DataSource.DataSet.Active then Exit;
for I := 0 to mDBGrid.Columns.Count - 1 do begin
   if not mDBGrid.Columns[I].Visible then Continue;
   if Assigned(mDBGrid.Columns[I].Field) then
     mDBGrid.Columns[I].Width := Max(mDBGrid.Columns[I].Field.Tag,
       mDBGrid.Canvas.TextWidth(mDBGrid.Columns[I].Title.Caption)) + mOffset
   else mDBGrid.Columns[I].Width :=
     mDBGrid.Canvas.TextWidth(mDBGrid.Columns[I].Title.Caption) + mOffset;
   mDBGrid.Refresh;
end;
Result := True;
end; { DBGridAutoSize }
///////源代码结束

///////使用示例开始
procedure TForm1.DBGrid1DrawColumnCell(Sender: TObject; const Rect: TRect;
DataCol: Integer; Column: TColumn; State: TGridDrawState);
begin
DBGridRecordSize(Column);
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
DBGridAutoSize(DBGrid1);
end;
///////使用示例结束