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delphi - 我的自定义控件闪烁。是什么原因造成的以及如何消除它？

转载 作者：行者123 更新时间：2023-12-03 15:28:39 25 4
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简介

我正在编写一个派生自 TScrollBox 的自定义控件，但在克服看似应该很容易解决的问题时遇到了一些困难。

该控件将用于在顶部显示一个静态的标题栏(即，当滚动框滚动时永远不会移动)，然后在标题栏下方我将在自己的列中绘制一些值，例如行号等

这就是控件当前的样子，可以提供更好的想法(非常早期的工作正在进行中):

enter image description here

闪烁问题

我面临的问题是闪烁，我没有找到消除它的简单方法。我有一种感觉，闪烁是因为我试图在标题栏下方绘制而引起的，当闪烁发生时，您实际上可以看到在标题栏下方绘制的值，尽管我的假设可能完全错误。

所有绘图都是在滚动框子级的 TGraphicControl 上完成的，快速滚动时会频繁发生闪烁，使用滚动条按钮时它仍然会闪烁，但频率不那么高。

我无法捕获闪烁并在此处显示为图像，但使用下面的代码，您可以构建并安装到新包中并自行测试:

unit MyGrid;

interface

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

type
  TMyCustomGrid = class(TGraphicControl)
  private
    FFont: TFont;
    FRowNumbers: TStringList;
    FRowCount: Integer;
    FCaptionBarRect: TRect;
    FRowNumbersBackgroundRect: TRect;
    FValuesBackgroundRect: TRect;

    procedure CalculateNewHeight;
    function GetMousePosition: TPoint;
    function RowIndexToMousePosition(ARowIndex: Integer): Integer;
    function GetRowHeight: Integer;
    function RowExists(ARowIndex: Integer): Boolean;
    function GetRowNumberRect(ARowIndex: Integer): TRect;
    function GetRowNumberTextRect(ARowIndex: Integer): TRect;
    function GetValueRect(ARowIndex: Integer): TRect;
    function GetValueTextRect(ARowIndex: Integer): TRect;
    function GetFirstVisibleRow: Integer;
    function GetLastVisibleRow: Integer;
  protected
    procedure Paint; override;

    procedure DrawCaptionBar;
    procedure DrawRowNumbers;
    procedure DrawValues;
    procedure DrawColumnLines;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

  TMyGrid = class(TScrollBox)
  private
    FGrid: TMyCustomGrid;
  protected
    procedure Loaded; override;
    procedure WMVScroll(var Message: TWMVScroll); message WM_VSCROLL;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

const
  FCaptionBarHeight = 20;
  FRowNumbersWidth  = 85;
  FValuesWidth      = 175;
  FTextSpacing      = 5;

implementation

constructor TMyCustomGrid.Create(AOwner: TComponent);
var
  I: Integer;
begin
  inherited Create(AOwner);

  FFont        := TFont.Create;
  FFont.Color  := clBlack;
  FFont.Name   := 'Tahoma';
  FFont.Size   := 10;
  FFont.Style  := [];

  FRowNumbers := TStringList.Create;

  //FOR TEST PURPOSES
  for I := 0 to 1000 do
  begin
    FRowNumbers.Add(IntToStr(I));
  end;

  Canvas.Font.Assign(FFont);
end;

destructor TMyCustomGrid.Destroy;
begin
  FFont.Free;
  FRowNumbers.Free;
  inherited Destroy;
end;

procedure TMyCustomGrid.Paint;
begin
  FCaptionBarRect := Rect(0, 0, Self.Width, GetRowHeight + TMyGrid(Self.Parent).VertScrollBar.Position + 2);
  FRowCount       := FRowNumbers.Count;

  DrawRowNumbers;
  DrawValues;
  DrawCaptionBar;
  DrawColumnLines;
end;

procedure TMyCustomGrid.DrawCaptionBar;
var
  R: TRect;
  S: string;
begin
  {background}
  Canvas.Brush.Color  := clSkyBlue;
  Canvas.Brush.Style  := bsSolid;
  Canvas.FillRect(FCaptionBarRect);

  {text}
  Canvas.Brush.Style := bsClear;
  R := Rect(FTextSpacing, FCaptionBarRect.Top + TMyGrid(Self.Parent).VertScrollBar.Position, FRowNumbersWidth - FTextSpacing, FCaptionBarRect.Bottom);
  S := 'Row No.';
  DrawText(Canvas.Handle, PChar(S), Length(S), R, DT_LEFT or DT_SINGLELINE or DT_VCENTER);

  R := Rect(FTextSpacing + FRowNumbersWidth, FCaptionBarRect.Top + TMyGrid(Self.Parent).VertScrollBar.Position, FValuesWidth - FTextSpacing, FCaptionBarRect.Bottom);
  S := 'Item No.';
  DrawText(Canvas.Handle, PChar(S), Length(S), R, DT_LEFT or DT_SINGLELINE or DT_VCENTER);
end;

procedure TMyCustomGrid.DrawRowNumbers;
var
  I, Y: Integer;
  R: TRect;
  S: string;
begin
  {background}
  FRowNumbersBackgroundRect := Rect(0, FCaptionBarRect.Bottom, FRowNumbersWidth, FCaptionBarRect.Height + GetLastVisibleRow * GetRowHeight + 1);
  Canvas.Brush.Color := clCream;
  Canvas.Brush.Style := bsSolid;
  Canvas.FillRect(FRowNumbersBackgroundRect);

  {text}
  Y := 0;

  // a bit of optimization here, instead of iterating every item in FRowNumbers
  // which would be slow - instead determine the the top and last visible row
  // and paint only that area.
  for I := GetFirstVisibleRow to GetLastVisibleRow do
  begin
    if RowExists(I) then
    begin
      R := GetRowNumberTextRect(I);
      S := FRowNumbers.Strings[I];
      DrawText(Canvas.Handle, PChar(S), Length(S), R, DT_LEFT or DT_SINGLELINE or DT_VCENTER);
      Inc(Y, GetRowHeight);
    end;
  end;
end;

procedure TMyCustomGrid.DrawValues;
var
  I, Y: Integer;
  R: TRect;
  S: string;
begin
  {background}
  FValuesBackgroundRect := Rect(FRowNumbersBackgroundRect.Width, FCaptionBarRect.Bottom, FValuesWidth + FRowNumbersWidth, FCaptionBarRect.Height + GetLastVisibleRow * GetRowHeight + 1);
  Canvas.Brush.Color    := clMoneyGreen;
  Canvas.Brush.Style    := bsSolid;
  Canvas.FillRect(FValuesBackgroundRect);

  {text}
  Y := 0;

  // a bit of optimization here, instead of iterating every item in FRowNumbers
  // which would be slow - instead determine the the top and last visible row
  // and paint only that area.
  for I := GetFirstVisibleRow to GetLastVisibleRow do
  begin
    if RowExists(I) then
    begin
      R := GetValueTextRect(I);
      S := 'This is item number ' + FRowNumbers.Strings[I];
      DrawText(Canvas.Handle, PChar(S), Length(S), R, DT_LEFT or DT_SINGLELINE or DT_VCENTER);
      Inc(Y, GetRowHeight);
    end;
  end;
end;

procedure TMyCustomGrid.DrawColumnLines;
begin
  Canvas.Brush.Style  := bsClear;
  Canvas.Pen.Color    := clBlack;

  {row numbers column}
  Canvas.MoveTo(FRowNumbersBackgroundRect.Right, FCaptionBarRect.Top);
  Canvas.LineTo(FRowNumbersBackgroundRect.Right, FCaptionBarRect.Height + GetLastVisibleRow * GetRowHeight + 1);

  {values column}
  Canvas.MoveTo(FValuesBackgroundRect.Right, FCaptionBarRect.Top);
  Canvas.LineTo(FValuesBackgroundRect.Right, FCaptionBarRect.Height + GetLastVisibleRow * GetRowHeight + 1);
end;

procedure TMyCustomGrid.CalculateNewHeight;
var
  I, Y: Integer;
begin
  FRowCount := FRowNumbers.Count;

  Y := 0;
  for I := 0 to FRowCount -1 do
  begin
    Inc(Y, GetRowHeight);
  end;

  if Self.Height <> Y then
    Self.Height := Y + FCaptionBarHeight + 1;
end;

function TMyCustomGrid.GetMousePosition: TPoint;
var
  P: TPoint;
begin
  Winapi.Windows.GetCursorPos(P);
  Winapi.Windows.ScreenToClient(Self.Parent.Handle, P);
  Result := P;
end;

function TMyCustomGrid.RowIndexToMousePosition(
  ARowIndex: Integer): Integer;
begin
  if RowExists(ARowIndex) then
    Result := ARowIndex * GetRowHeight;
end;

function TMyCustomGrid.GetRowHeight: Integer;
begin
  Result := 18;
end;

function TMyCustomGrid.RowExists(ARowIndex: Integer): Boolean;
var
  I: Integer;
  Y: Integer;
begin
  Result := False;

  Y := 0;
  for I := GetFirstVisibleRow to GetLastVisibleRow -1 do
  begin
    if ARowIndex = I then
    begin
      Result := True;
      Break;
    end;

    Inc(Y, GetRowHeight);
  end;
end;

function TMyCustomGrid.GetRowNumberRect(ARowIndex: Integer): TRect;
begin
  Result.Bottom := RowIndexToMousePosition(ARowIndex) + FCaptionBarHeight + GetRowHeight;
  Result.Left   := 0;
  Result.Right  := FRowNumbersWidth;
  Result.Top    := RowIndexToMousePosition(ARowIndex) + FCaptionBarHeight + 1;
end;

function TMyCustomGrid.GetRowNumberTextRect(ARowIndex: Integer): TRect;
begin
  Result := GetRowNumberRect(ARowIndex);
  Result.Inflate(-FTextSpacing, 0);
end;

function TMyCustomGrid.GetValueRect(ARowIndex: Integer): TRect;
begin
  Result.Bottom := RowIndexToMousePosition(ARowIndex) + FCaptionBarHeight + GetRowHeight;
  Result.Left   := FRowNumbersWidth;
  Result.Right  := FValuesBackgroundRect.Right;
  Result.Top    := RowIndexToMousePosition(ARowIndex) + FCaptionBarHeight + 1;
end;

function TMyCustomGrid.GetValueTextRect(ARowIndex: Integer): TRect;
begin
  Result := GetValueRect(ARowIndex);
  Result.Inflate(-FTextSpacing, 0);
end;

function TMyCustomGrid.GetFirstVisibleRow: Integer;
begin
  Result := TMyGrid(Self.Parent).VertScrollBar.Position div GetRowHeight;
end;

function TMyCustomGrid.GetLastVisibleRow: Integer;
begin
  Result := GetFirstVisibleRow + TMyGrid(Self.Parent).Height div GetRowHeight -1;
end;

constructor TMyGrid.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);

  Self.DoubleBuffered           := True;
  Self.Height                   := 150;
  Self.HorzScrollBar.Visible    := False;
  Self.TabStop                  := True;
  Self.Width                    := 250;

  FGrid                         := TMyCustomGrid.Create(Self);
  FGrid.Align                   := alTop;
  FGrid.Parent                  := Self;
  FGrid.CalculateNewHeight;

  Self.VertScrollBar.Smooth     := False;
  Self.VertScrollBar.Increment  := FGrid.GetRowHeight;
  Self.VertScrollBar.Tracking   := True;
end;

destructor TMyGrid.Destroy;
begin
  FGrid.Free;
  inherited Destroy;
end;

procedure TMyGrid.Loaded;
begin
  inherited Loaded;
  Self.VertScrollBar.Range := FGrid.Height - FGrid.FCaptionBarRect.Height;
end;

procedure TMyGrid.WMVScroll(var Message: TWMVScroll);
begin
  inherited;
  Self.Invalidate;
end;

end.

问题

我应该采取什么不同的措施来克服闪烁？

将滚动框的 DoubleBuffered 设置为 True 似乎没有什么区别。我对 WM_ERASEBACKGROUND 消息进行了一些实验，它只是使滚动框变黑。

我还尝试在滚动框中实现 Canvas ，并将标题栏直接绘制到其上，然后将滚动框上的填充设置为标题栏的高度，并将其余部分绘制在我的 TGraphicControl 上，但这导致更严重的闪烁。此时我不知道到底是什么导致了闪烁以及如何消除它？

最后一件事是如何在使用滚动条拇指时使滚动条以设定的增量滚动？我已将垂直滚动条增量设置为相当于行高，并且在按下滚动条按钮时有效，当使用滚动条拇指上下滚动时，它不是固定增量。我试图让滚动条以增量方式工作，而不是松散地滚动。

最佳答案

快速修复方法是将 Self.Invalidate 替换为 FGrid.Repaint (或 .Update 或 .Refresh >) 在 TMyGrid.WMVScroll 中。您将看到这消除了闪烁，但它仍然演示了拖动滚动条拇指时绘制多个标题栏的问题。说明:Invalidate 将重绘请求放入消息队列中，该请求会被推迟，直到队列为空，因此不会立即处理，即不会在您想要的时候处理。另一方面，Repaint 会立即执行。但通常 Invalidate 应该足够了......

问题的主要根源在于客户端空间内带有“粘性”标题(或标题栏)的布局。每个带有 TControlScrollBar 的窗口控件都使用 ScrollWindow在内部，根据滚动方向，上下“移动”标题栏。你可以阻止with some hacking ，但从设计的角度来看，当滚动条从标题下方开始时，效果也会更好。

然后，您可以选择组件的内部布局:

  • 使用 alTop 对齐的 PaintBox 作为标题，使用 alRight 对齐的 ScrollBar 和 alClient 对齐的 PaintBox 作为网格。这就是Sertac已评论，并且需要在您的组件中使用 3 个控件。
  • 使用 alTop 对齐的 PaintBox 作为标题，使用 alClient 对齐的 ScrollBox，其中使用 alTop 对齐的 PaintBox 作为网格。此设计具有嵌套控件。
  • 使用 TScrollingWinControl，在顶部添加非客户端边框作为标题，并使用 alTop 对齐 PaintBox 作为网格。该组件包含 1 个控件。
  • 使用在顶部添加非客户端边框的 TScrollingWinControl 作为标题，并在其 PaintWindow 方法中绘制网格。这种设计根本不需要额外的控制。
  • ...

作为示例，特此实现第三个选项:

unit MyGrid;

interface

uses
  System.Classes, System.SysUtils, Winapi.Windows, Winapi.Messages,
  Vcl.Controls, Vcl.Forms, Vcl.Graphics, Vcl.ExtCtrls, System.Math,
  System.UITypes;

type
  TMyCustomGrid = class(TScrollingWinControl)
  private const
    DefHeaderHeight = 20;
    DefRowHeight = 18;
    HeaderColor = clSkyBLue;
    RowIdColCaption = 'Row no.';
    RowIdColWidth = 85;
    RowIdColColor = clCream;
    TextSpacing = 5;
    ValueColCaption = 'Item no.';
    ValueColWidth = 175;
    ValueColColor = clMoneyGreen;
  private
    FHeaderHeight: Integer;
    FPainter: TPaintBox;
    FRowHeight: Integer;
    FRows: TStrings;
    function GetRowCount: Integer;
    procedure PainterPaint(Sender: TObject);
    procedure RowsChanged(Sender: TObject);
    procedure SetHeaderHeight(Value: Integer);
    procedure SetRowHeight(Value: Integer);
    procedure SetRows(Value: TStrings);
    procedure UpdatePainter;
    procedure WMEraseBkgnd(var Message: TWMEraseBkgnd); message WM_ERASEBKGND;
    procedure WMNCCalcSize(var Message: TWMNCCalcSize); message WM_NCCALCSIZE;
    procedure WMNCPaint(var Message: TWMNCPaint); message WM_NCPAINT;
    procedure WMVScroll(var Message: TWMScroll); message WM_VSCROLL;
  protected
    function CanResize(var NewWidth, NewHeight: Integer): Boolean; override;
    procedure Click; override;
    procedure CreateParams(var Params: TCreateParams); override;
    function DoMouseWheel(Shift: TShiftState; WheelDelta: Integer;
      MousePos: TPoint): Boolean; override;
    procedure PaintWindow(DC: HDC); override;
    property AutoScroll default True;
    property HeaderHeight: Integer read FHeaderHeight write SetHeaderHeight
      default DefHeaderHeight;
    property RowCount: Integer read GetRowCount;
    property RowHeight: Integer read FRowHeight write SetRowHeight
      default DefRowHeight;
    property Rows: TStrings read FRows write SetRows;
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
  end;

  TMyGrid = class(TMyCustomGrid)
  public
    procedure Test;
  published
    property AutoScroll;
    property HeaderHeight;
    property RowHeight;
  end;

implementation

function Round(Value, Rounder: Integer): Integer; overload;
begin
  if Rounder = 0 then
    Result := Value
  else
    Result := (Value div Rounder) * Rounder;
end;

{ TMyCustomGrid }

function TMyCustomGrid.CanResize(var NewWidth, NewHeight: Integer): Boolean;
begin
  Result := inherited CanResize(NewWidth, NewHeight);
  NewHeight := FHeaderHeight + Round(NewHeight - FHeaderHeight, FRowHeight);
end;

procedure TMyCustomGrid.Click;
begin
  inherited Click;
  SetFocus;
end;

constructor TMyCustomGrid.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  ControlStyle := [csCaptureMouse, csClickEvents, csOpaque, csDoubleClicks];
  AutoScroll := True;
  TabStop := True;
  VertScrollBar.Tracking := True;
  VertScrollBar.Increment := DefRowHeight;
  Font.Name := 'Tahoma';
  Font.Size := 10;
  FHeaderHeight := DefHeaderHeight;
  FRowHeight := DefRowHeight;
  FPainter := TPaintBox.Create(Self);
  FPainter.ControlStyle := [csOpaque, csNoStdEvents];
  FPainter.Enabled := False;
  FPainter.Align := alTop;
  FPainter.OnPaint := PainterPaint;
  FPainter.Parent := Self;
  FRows := TStringList.Create;
  TStringList(FRows).OnChange := RowsChanged;
  UpdatePainter;
end;

procedure TMyCustomGrid.CreateParams(var Params: TCreateParams);
begin
  inherited CreateParams(Params);
  with Params.WindowClass do
    Style := Style and not (CS_HREDRAW or CS_VREDRAW);
end;

destructor TMyCustomGrid.Destroy;
begin
  FRows.Free;
  inherited Destroy;
end;

function TMyCustomGrid.DoMouseWheel(Shift: TShiftState; WheelDelta: Integer;
  MousePos: TPoint): Boolean;
var
  Delta: Integer;
begin
  with VertScrollBar do
  begin
    Delta := Increment * Mouse.WheelScrollLines;
    if WheelDelta > 0 then
      Delta := -Delta;
    Position := Min(Round(Range - ClientHeight, Increment), Position + Delta);
  end;
  Result := True;
end;

function TMyCustomGrid.GetRowCount: Integer;
begin
  Result := FRows.Count;
end;

procedure TMyCustomGrid.PainterPaint(Sender: TObject);
const
  TextFlags = DT_LEFT or DT_SINGLELINE or DT_VCENTER or DT_NOPREFIX;
var
  C: TCanvas;
  FromIndex: Integer;
  ToIndex: Integer;
  I: Integer;
  BackRect: TRect;
  TxtRect: TRect;
begin
  C := FPainter.Canvas;
  FromIndex := (C.ClipRect.Top) div FRowHeight;
  ToIndex := Min((C.ClipRect.Bottom) div FRowHeight, RowCount - 1);
  for I := FromIndex to ToIndex do
  begin
    BackRect := Bounds(0, I * FRowHeight, RowIdColWidth, FRowHeight);
    TxtRect := BackRect;
    TxtRect.Inflate(-TextSpacing, 0);
    C.Brush.Color := RowIdColColor;
    C.FillRect(BackRect);
    DrawText(C.Handle, FRows.Names[I], -1, TxtRect, TextFlags);
    BackRect.Left := RowIdColWidth;
    BackRect.Width := ValueColWidth;
    Inc(TxtRect.Left, RowIdColWidth);
    Inc(TxtRect.Right, ValueColWidth);
    C.Brush.Color := ValueColColor;
    C.FillRect(BackRect);
    DrawText(C.Handle, FRows.ValueFromIndex[I], -1, TxtRect, TextFlags);
    C.MoveTo(BackRect.Left, BackRect.Top);
    C.LineTo(BackRect.Left, BackRect.Bottom);
    BackRect.Offset(ValueColWidth, 0);
    C.Brush.Color := Brush.Color;
    C.FillRect(BackRect);
    C.MoveTo(BackRect.Left, BackRect.Top);
    C.LineTo(BackRect.Left, BackRect.Bottom);
  end;
end;

procedure TMyCustomGrid.PaintWindow(DC: HDC);
begin
  if FPainter.Height < ClientHeight then
  begin
    ExcludeClipRect(DC, 0, 0, ClientWidth, FPainter.Height);
    FillRect(DC, ClientRect, Brush.Handle);
  end;
end;

procedure TMyCustomGrid.RowsChanged(Sender: TObject);
begin
  UpdatePainter;
end;

procedure TMyCustomGrid.SetHeaderHeight(Value: Integer);
begin
  if FHeaderHeight <> Value then
  begin
    FHeaderHeight := Value;
    RecreateWnd;
  end;
end;

procedure TMyCustomGrid.SetRowHeight(Value: Integer);
begin
  if FRowHeight <> Value then
  begin
    FRowHeight := Value;
    VertScrollBar.Increment := FRowHeight;
    UpdatePainter;
    Invalidate;
  end;
end;

procedure TMyCustomGrid.SetRows(Value: TStrings);
begin
  FRows.Assign(Value);
end;

procedure TMyCustomGrid.UpdatePainter;
begin
  FPainter.Height := RowCount * FRowHeight;
end;

procedure TMyCustomGrid.WMEraseBkgnd(var Message: TWMEraseBkgnd);
begin
  Message.Result := 1;
end;

procedure TMyCustomGrid.WMNCCalcSize(var Message: TWMNCCalcSize);
begin
  inherited;
  Inc(Message.CalcSize_Params.rgrc0.Top, HeaderHeight);
end;

procedure TMyCustomGrid.WMNCPaint(var Message: TWMNCPaint);
const
  TextFlags = DT_LEFT or DT_SINGLELINE or DT_VCENTER or DT_NOPREFIX;
var
  DC: HDC;
  OldFont: HFONT;
  Brush: HBRUSH;
  R: TRect;
begin
  DC := GetWindowDC(Handle);
  OldFont := SelectObject(DC, Font.Handle);
  Brush := CreateSolidBrush(ColorToRGB(HeaderColor));
  try
    FillRect(DC, Rect(0, 0, Width, FHeaderHeight), Brush);
    SetBkColor(DC, ColorToRGB(HeaderColor));
    SetRect(R, TextSpacing, 0, RowIdColWidth - TextSpacing, FHeaderHeight);
    DrawText(DC, RowIdColCaption, -1, R, TextFlags);
    Inc(R.Left, RowIdColWidth);
    Inc(R.Right, ValueColWidth);
    DrawText(DC, ValueColCaption, -1, R, TextFlags);
    MoveToEx(DC, RowIdColWidth, 0, nil);
    LineTo(DC, RowIdColWidth, FHeaderHeight);
    MoveToEx(DC, RowIdColWidth + ValueColWidth, 0, nil);
    LineTo(DC, RowIdColWidth + ValueColWidth, FHeaderHeight);
  finally
    SelectObject(DC, OldFont);
    DeleteObject(Brush);
    ReleaseDC(Handle, DC);
  end;
  inherited;
end;

procedure TMyCustomGrid.WMVScroll(var Message: TWMScroll);
begin
  Message.Pos := Round(Message.Pos, FRowHeight);
  inherited;
end;

{ TMyGrid }

procedure TMyGrid.Test;
var
  I: Integer;
begin
  for I := 0 to 40 do
    Rows.Add(Format('%d=This is item number %d', [I, I]));
end;

end.

有关您的代码的一些一般性评论:

  • 您的祖先 TMyCustomGrid 不能没有您的后代 TMyGrid，这通常是禁忌。顺便说一句，代码 TMyGrid(Self.Parent).VertScrollBar.Position 等于 -Top，这样就无需了解其后代。
  • 无需创建字体。 TControl 已有字体，只需发布​​即可。
  • 除非您想要来自 TScrollBox 的边框选项，否则一般来说最好从 - 在本例中 - TScrollingWinControl 下降，因为只有这样您才能控制哪些属性应该发布。

One last thing is how can I make the scrollbar scroll at a set increment when using the scrollbar thumb?

通过调整 WM_VSCROLL 中的滚动位置，如上面的代码所示:

procedure TMyCustomGrid.WMVScroll(var Message: TWMScroll);
begin
  if FRowHeight <> 0 then
    Message.Pos := (Message.Pos div FRowHeight) * FRowHeight;
  inherited;
end;

关于delphi - 我的自定义控件闪烁。是什么原因造成的以及如何消除它？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/32769321/

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