关于 Delphi 10 TDrawGrid：Delphi 10 TDrawGrid – 如何正确刷新行？

Delphi 10 TDrawGrid – How do I get rows to refresh properly?

使用 Delphi 10.2 Tokyo。

我使用 DrawCell 方法使一行中的所有列与所选单元格的颜色相同。这允许我让用户单击不同的单元格，但仍显示”选定”行。

这使用 OnSelectCell 方法使原始行和新选择的行无效。多年来一直使用这种方法。

如果我有一个带有水平滚动条的网格，则当向右滚动并且用户单击单元格时，该网格不会正确绘制。

下面是一个使用 TDrawGrid 和 OnDrawCell 事件和 OnSelectCell 事件的简单示例：

表格 (DFM) 代码：

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object Form1: TForm1
Left = 0
Top = 0
Caption = ‘Form1’
ClientHeight = 299
ClientWidth = 635
Color = clBtnFace
Font.Charset = DEFAULT_CHARSET
Font.Color = clWindowText
Font.Height = –11
Font.Name = ‘Tahoma’
Font.Style = []
OldCreateOrder = False
PixelsPerInch = 96
TextHeight = 13
object DrawGrid1: TDrawGrid
Left = 0
Top = 0
Width = 635
Height = 299
Align = alClient
Color = clWhite
ColCount = 15
DefaultColWidth = 65
DefaultRowHeight = 48
DefaultDrawing = False
DrawingStyle = gdsGradient
RowCount = 12
GradientEndColor = clBtnFace
GradientStartColor = clBtnFace
Options = [goThumbTracking]
ParentShowHint = False
ShowHint = True
TabOrder = 0
OnDrawCell = DrawGrid1DrawCell
OnSelectCell = DrawGrid1SelectCell
ColWidths = (
65
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65)
RowHeights = (
48
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48)
end
end

单位 (PAS) 代码：

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unit Unit1;

interface

uses
Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.Grids, Math;

type
TGridCracker = class(TDrawGrid)// required to access protected method Invalidaterow – info gleaned from Team B member Peter Below on the Internet
private
public
end;

TForm1 = class(TForm)
DrawGrid1: TDrawGrid;
procedure DrawGrid1DrawCell(Sender: TObject; ACol, ARow: Integer; Rect: TRect; State: TGridDrawState);
procedure DrawGrid1SelectCell(Sender: TObject; ACol, ARow: Integer; var CanSelect: Boolean);
private
{ Private declarations }
public
{ Public declarations }
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.DrawGrid1DrawCell(Sender: TObject; ACol, ARow: Integer; Rect: TRect; State: TGridDrawState);
var MyCanvas : TCanvas;
str : string;
MyRect : TRect;
begin
MyCanvas := TDrawGrid(Sender).Canvas;

MyCanvas.Font.Name := ‘Arial’; // drawgrid uses Tahoma 8pt as its default font, not Arial
MyCanvas.Font.Size := 9;
MyCanvas.Brush.Color := TDrawGrid(Sender).FixedColor;
MyCanvas.Font.Color := TDrawGrid(Sender).Font.Color;
MyCanvas.FillRect(Rect);

if (ARow = 0) then begin
str := EmptyStr;
if (ACol > 0) then begin
str := ACol.ToString;
end
else begin
str := ‘TEST’;
end;

MyCanvas.Font.Color := clblack; // clGray;
MyRect.Left := Rect.Left + 1;
MyRect.Top := Rect.Top + 3;
MyRect.Right := Rect.Right – 1;
MyRect.Bottom := Rect.Bottom – 3;
MyCanvas.FillRect(MyRect);
MyCanvas.Brush.Color := clGray;
MyCanvas.FrameRect(MyRect);
MyCanvas.Brush.Color := clWhite;
MyCanvas.Font.Style := MyCanvas.Font.Style + [fsBold];

MyRect.Top := MyRect.Top + 2;
DrawText(MyCanvas.Handle, pChar(str), –1, MyRect, DT_VCENTER or DT_CENTER);

MyCanvas.Font.Style := MyCanvas.Font.Style – [fsBold];
end
else begin
if (ACol = 0) then begin
MyCanvas.Brush.Color := clMaroon;
MyCanvas.FillRect(Rect);
end
else begin//ACol > 0
if ARow = DrawGrid1.Row then begin
MyCanvas.Brush.Color := clBlue;
end
else begin
MyCanvas.Brush.Color := clwhite;
end;

MyCanvas.FillRect(Rect);

// other cell drawing of text happens after here
end;
end;
end;

procedure TForm1.DrawGrid1SelectCell(Sender: TObject; ACol, ARow: Integer; var CanSelect: Boolean);
begin
TGridCracker(Sender).InvalidateRow(TGridCracker(Sender).Row);
TGridCracker(Sender).InvalidateRow(ARow);
end;

end.

运行程序。

单击水平滚动条，使第 14 列可见。

单击第 2 行中的第 13 列。

单击第 3 行中的第 12 列。

注意到真正混乱的选择模式了吗？

这是结果的屏幕截图：

screen

理想情况下，应该有一排蓝色单元格，而不是乱七八糟的。第 3 行应该是纯蓝色。

在 OnSelectCell 方法中调用 DrawGrid1.Refresh 甚至无法修复它。

关于如何使它真正起作用的任何想法？我不能对这个网格使用 RowSelect。

干杯！

Delphi 10 TDrawGrid – How do I get rows to refresh properly?

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