Question

我在TMemo中使用TScrollBox来显示一些文字，并在顶部使用TLabel作为标题信息。有时备忘录比滚动框宽，当然Horizontal scroll bar可用于向左和向右滚动以查看备忘录中的文本。我希望标签总是以滚动框可见区域为中心。我可以通过设置Label1.Left:= (Scrollbox1.Width div 2) - (Label1.Width div 2);来实现这一点，它可以工作，但它有点闪烁，在来回滚动时摇晃。备忘录顺利进行，标签没有。

这是单位：

unit Unit1;

interface

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

type

  TScrollBox=Class(VCL.Forms.TScrollBox)
    procedure WMHScroll(var Message: TWMHScroll); message WM_HSCROLL;
  private
    FOnScrollHorz: TNotifyEvent;
  public
   Property OnScrollHorz:TNotifyEvent read FOnScrollHorz Write FonScrollHorz;
  End;

  TForm1 = class(TForm)
    ScrollBox1: TScrollBox;
    Label1: TLabel;
    Memo1: TMemo;
    procedure FormCreate(Sender: TObject);
    procedure ScrollBox1Resize(Sender: TObject);
  private
    procedure MyScrollHorz(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TScrollBox.WMHScroll(var Message: TWMHScroll);
begin
   inherited;
   if Assigned(FOnScrollHorz) then  FOnScrollHorz(Self);
end;

procedure TForm1.MyScrollHorz(Sender: TObject);
begin
    Label1.Left:= (Scrollbox1.Width div 2) - (Label1.Width div 2);
end;

procedure TForm1.ScrollBox1Resize(Sender: TObject);
begin
  Label1.Left:= (Scrollbox1.Width div 2) - (Label1.Width div 2);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
  ScrollBox1.OnScrollHorz := MyScrollHorz;
end;

end.

和dfm：

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 212
  ClientWidth = 458
  Color = clBtnFace
  DoubleBuffered = True
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  OnCreate = FormCreate
  PixelsPerInch = 96
  TextHeight = 13
  object ScrollBox1: TScrollBox
    Left = 0
    Top = 0
    Width = 458
    Height = 212
    HorzScrollBar.Smooth = True
    HorzScrollBar.Tracking = True
    Align = alClient
    BiDiMode = bdLeftToRight
    DoubleBuffered = True
    ParentBiDiMode = False
    ParentDoubleBuffered = False
    TabOrder = 0
    OnResize = ScrollBox1Resize
    ExplicitHeight = 337
    object Label1: TLabel
      Left = 192
      Top = 30
      Width = 69
      Height = 13
      BiDiMode = bdLeftToRight
      Caption = 'Details header'
      ParentBiDiMode = False
    end
    object Memo1: TMemo
      Left = 24
      Top = 70
      Width = 700
      Height = 89
      Lines.Strings = (
        'Details...')
      TabOrder = 0
    end
  end
end

我尝试使用DoubleBuffered，但没有帮助。

有关如何让Label1在没有闪烁/摇晃的情况下移动的任何建议，与滚动时Memo1一样顺畅吗？

修改

设计最终将是我在表单上有3个或滚动框，每个包含最多3个带标题的备忘录。滚动需要通过滚动框，因为同一滚动框中的所有备忘录需要同时滚动。这意味着我不知道如何将标签放在表单或面板上，然后放在表单上，滚动框外：

编辑2：

以下答案确实提供了良好的解决方案，但他们确实需要将Labels置于Scrollbox之外，并放在Form本身。然后直接在Scrollbox's上按scroll bars scroll bars或Form移动。这确实会产生预期效果，但是Labels不再属于Scrollbox，会给您带来一些不便。

Answer 1

- “备忘录顺利进行，标签没有。”

那是因为你试图阻止它移动。分离您的OnScrollHorz处理程序，标签将顺利移动。但这不是你想要的，它不会再以形式为中心。

问题是，在inherited调用（WM_HSCROLL）期间，标签随备忘录一起移动。在默认处理之后，您重新定位标签，因此闪烁。

您可以公开在默认滚动（OnBeforeHorzScroll）之前将触发的其他事件处理程序，并在触发时隐藏标签。当平滑地居中时，它会导致标签瞬间消失的不同类型的闪烁。仍然可能不太令人满意。

解决方案是使用一个控件，该控件是表单的父级，是滚动框的兄弟。您不能使用TLabel这样做，因为它是图形控件，但您可以使用TStaticText。如果 static 在设计时意外地落在滚动框后面，IDE的“结构窗格”可能会派上用场。

Answer 2

你可以这样做：

而不是ScrollBox在表单上放置ScrollBar。将其对齐方式设置为底部（或者如果您希望拥有更多列，则可以手动设置其大小和位置，或者您可以将每个列放在其自己的面板中）。然后设置备忘录的大小并将标签放置在表单的中心。设置备忘录的大小（可能是通过代码动态）后，请输入以下代码：

ScrollBar1.Min:=0-Memo1.Left;
ScrollBar1.Max:=Memo1.Width-Form1.ClientWidth+Memo1.Left;

最后一件事是设置ScrollBar OnChange事件：

procedure TForm1.ScrollBar1Change(Sender: TObject);
begin
  Memo1.Left:=0-ScrollBar1.Position;
  Memo2.Left:=0-ScrollBar1.Position;
  ...
  MemoXY.Left:=0-ScrollBar1.Position;
end;

您的表单应如下所示：

完成！您有一个稳定的居中标签和平滑可滚动的备忘录。

修改

这是一个版本，在他自己的Panel中各有3列，还有垂直滚动条：

整个源代码：

unit Unit1; interface uses Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms, Dialogs, StdCtrls, ExtCtrls; type TForm1 = class(TForm) Panel1: TPanel; Panel2: TPanel; Panel3: TPanel; Label1: TLabel; Label2: TLabel; Label3: TLabel; Label4: TLabel; Label5: TLabel; Label6: TLabel; Memo1: TMemo; Memo2: TMemo; Memo3: TMemo; Memo4: TMemo; Memo5: TMemo; Memo6: TMemo; ScrollBar1: TScrollBar; ScrollBar2: TScrollBar; ScrollBar3: TScrollBar; ScrollBar4: TScrollBar; ScrollBar5: TScrollBar; ScrollBar6: TScrollBar; procedure FormCreate(Sender: TObject); procedure ScrollBarHChange(Sender: TObject); procedure ScrollBarVChange(Sender: TObject); procedure FormResize(Sender: TObject); private { Private declarations } public { Public declarations } end; var Form1: TForm1; implementation {$R *.dfm} procedure TForm1.FormCreate(Sender: TObject); var cycle: Integer; begin //GENERATE YOUR COMPONENTS HERE //sets every components tag to its default top position //(you can do this in any other way for example using array) for cycle:=0 to Form1.ComponentCount-1 do begin if(Form1.Components[cycle] is TControl)then Form1.Components[cycle].Tag:=(Form1.Components[cycle] as TControl).Top end; end; procedure TForm1.FormResize(Sender: TObject); begin //changes the panels sizes and positions Panel1.Width:=Form1.ClientWidth div 3; Panel2.Width:=Form1.ClientWidth div 3; Panel3.Width:=Form1.ClientWidth div 3; Panel2.Left:=Panel1.Width+1; Panel3.Left:=Panel1.Width+Panel2.Width+1; //if you dont want all scrollbars to reset on window resize, you need to handle the positioning of elements when window (and panels) size is changing ScrollBar1.Position:=ScrollBar1.Min; ScrollBar2.Position:=ScrollBar2.Min; ScrollBar3.Position:=ScrollBar3.Min; ScrollBar4.Position:=ScrollBar4.Min; ScrollBar5.Position:=ScrollBar5.Min; ScrollBar6.Position:=ScrollBar6.Min; //make these tests on the widest element of each panel (8 is just a margin so the memo has some space on the right) if((Memo1.Left+Memo1.Width)>(Panel1.ClientWidth-ScrollBar4.Width-8))then begin ScrollBar1.Enabled:=true; ScrollBar1.Max:=Memo1.Width-Panel1.ClientWidth+Memo1.Left+ScrollBar4.Width+8; end else ScrollBar1.Enabled:=false; if((Memo3.Left+Memo3.Width)>(Panel2.ClientWidth-ScrollBar5.Width-8))then begin ScrollBar2.Enabled:=true; ScrollBar2.Max:=Memo3.Width-Panel1.ClientWidth+Memo3.Left+ScrollBar5.Width+8; end else begin ScrollBar2.Position:=ScrollBar2.Min; ScrollBar2.Enabled:=false; end; if((Memo5.Left+Memo5.Width)>(Panel3.ClientWidth-ScrollBar6.Width-8))then begin ScrollBar3.Enabled:=true; ScrollBar3.Max:=Memo5.Width-Panel1.ClientWidth+Memo5.Left+ScrollBar6.Width+8; end else ScrollBar3.Enabled:=false; //make these tests on the bottom element of each panel (16 is just a margin so the memo has some space on the bottom) if((Memo2.Top+Memo2.Height)>(Panel1.ClientHeight-ScrollBar1.Height-16))then begin ScrollBar4.Enabled:=true; ScrollBar4.Max:=Memo2.Top+Memo2.Height-Panel1.ClientHeight+ScrollBar1.Height+16; end else ScrollBar4.Enabled:=false; if((Memo4.Top+Memo4.Height)>(Panel2.ClientHeight-ScrollBar2.Height-16))then begin ScrollBar5.Enabled:=true; ScrollBar5.Max:=Memo4.Top+Memo4.Height-Panel2.ClientHeight+ScrollBar2.Height+16; end else ScrollBar5.Enabled:=false; if((Memo6.Top+Memo6.Height)>(Panel3.ClientHeight-ScrollBar3.Height-16))then begin ScrollBar6.Enabled:=true; ScrollBar6.Max:=Memo6.Top+Memo6.Height-Panel3.ClientHeight+ScrollBar3.Height+16; end else ScrollBar6.Enabled:=false; end; procedure TForm1.ScrollBarHChange(Sender: TObject); var cycle: Integer; begin for cycle:=0 to ((Sender as TScrollBar).Parent as TPanel).ControlCount-1 do begin if(((Sender as TScrollBar).Parent as TPanel).Controls[cycle] is TMemo)then (((Sender as TScrollBar).Parent as TPanel).Controls[cycle] as TMemo).Left:=0-(Sender as TScrollBar).Position+8; end; end; procedure TForm1.ScrollBarVChange(Sender: TObject); var cycle: Integer; begin for cycle:=0 to ((Sender as TScrollBar).Parent as TPanel).ControlCount-1 do begin if(not (((Sender as TScrollBar).Parent as TPanel).Controls[cycle] is TScrollBar))then (((Sender as TScrollBar).Parent as TPanel).Controls[cycle] as TControl).Top:=(((Sender as TScrollBar).Parent as TPanel).Controls[cycle] as TControl).Tag-(Sender as TScrollBar).Position; end; end; end.

和.dfm：

object Form1: TForm1 Left = 0 Top = 0 Caption = 'Form1' ClientHeight = 473 ClientWidth = 769 Color = clBtnFace Font.Charset = DEFAULT_CHARSET Font.Color = clWindowText Font.Height = -11 Font.Name = 'Tahoma' Font.Style = [] OldCreateOrder = False OnCreate = FormCreate OnResize = FormResize DesignSize = ( 769 473) PixelsPerInch = 96 TextHeight = 13 object Panel1: TPanel Left = 0 Top = 0 Width = 257 Height = 473 Anchors = [akLeft, akTop, akBottom] BevelOuter = bvNone BorderStyle = bsSingle TabOrder = 0 object Label1: TLabel Left = 104 Top = 16 Width = 31 Height = 13 Caption = 'Label1' end object Label2: TLabel Left = 104 Top = 152 Width = 31 Height = 13 Caption = 'Label2' end object Memo1: TMemo Left = 8 Top = 32 Width = 497 Height = 89 Lines.Strings = ( 'Memo1') TabOrder = 0 end object Memo2: TMemo Left = 8 Top = 168 Width = 497 Height = 89 Lines.Strings = ( 'Memo2') TabOrder = 1 end object ScrollBar1: TScrollBar AlignWithMargins = True Left = 0 Top = 452 Width = 236 Height = 17 Margins.Left = 0 Margins.Top = 0 Margins.Right = 17 Margins.Bottom = 0 Align = alBottom PageSize = 0 TabOrder = 2 OnChange = ScrollBarHChange ExplicitWidth = 253 end object ScrollBar4: TScrollBar Left = 236 Top = 0 Width = 17 Height = 452 Align = alRight Enabled = False Kind = sbVertical PageSize = 0 TabOrder = 3 OnChange = ScrollBarVChange ExplicitTop = 248 ExplicitHeight = 121 end end object Panel2: TPanel Left = 256 Top = 0 Width = 257 Height = 473 Anchors = [akLeft, akTop, akBottom] BevelOuter = bvNone BorderStyle = bsSingle TabOrder = 1 object Label3: TLabel Left = 104 Top = 16 Width = 31 Height = 13 Caption = 'Label3' end object Label4: TLabel Left = 104 Top = 152 Width = 31 Height = 13 Caption = 'Label4' end object Memo3: TMemo Left = 8 Top = 32 Width = 497 Height = 89 Lines.Strings = ( 'Memo3') TabOrder = 0 end object Memo4: TMemo Left = 8 Top = 168 Width = 497 Height = 89 Lines.Strings = ( 'Memo4') TabOrder = 1 end object ScrollBar2: TScrollBar AlignWithMargins = True Left = 0 Top = 452 Width = 236 Height = 17 Margins.Left = 0 Margins.Top = 0 Margins.Right = 17 Margins.Bottom = 0 Align = alBottom PageSize = 0 TabOrder = 2 OnChange = ScrollBarHChange ExplicitWidth = 253 end object ScrollBar5: TScrollBar Left = 236 Top = 0 Width = 17 Height = 452 Align = alRight Enabled = False Kind = sbVertical PageSize = 0 TabOrder = 3 OnChange = ScrollBarVChange ExplicitTop = 248 ExplicitHeight = 121 end end object Panel3: TPanel Left = 512 Top = 0 Width = 257 Height = 473 Anchors = [akLeft, akTop, akBottom] BevelOuter = bvNone BorderStyle = bsSingle TabOrder = 2 object Label5: TLabel Left = 104 Top = 16 Width = 31 Height = 13 Caption = 'Label5' end object Label6: TLabel Left = 104 Top = 152 Width = 31 Height = 13 Caption = 'Label6' end object Memo5: TMemo Left = 8 Top = 32 Width = 497 Height = 89 Lines.Strings = ( 'Memo5') TabOrder = 0 end object Memo6: TMemo Left = 8 Top = 168 Width = 497 Height = 89 Lines.Strings = ( 'Memo6') TabOrder = 1 end object ScrollBar3: TScrollBar AlignWithMargins = True Left = 0 Top = 452 Width = 236 Height = 17 Margins.Left = 0 Margins.Top = 0 Margins.Right = 17 Margins.Bottom = 0 Align = alBottom PageSize = 0 TabOrder = 2 OnChange = ScrollBarHChange ExplicitWidth = 253 end object ScrollBar6: TScrollBar Left = 236 Top = 0 Width = 17 Height = 452 Align = alRight Enabled = False Kind = sbVertical PageSize = 0 TabOrder = 3 OnChange = ScrollBarVChange ExplicitTop = 248 ExplicitHeight = 121 end end end

Answer 3

为什么不使用两个滚动框。

您可以使用一个进行垂直滚动。在它上面放置标签和第二个滚动框，上面有备忘录。

此第二个滚动框将在需要时用于水平滚动。

或许甚至更好的解决方案是将TMemo替换为其他控件，如TRichEdit，它实现了自己的滚动条。所以你只有一个像现在这样的滚动框，当文本变宽时，TRichEdit会自己滚动它。

如何使标签在滚动框中平滑居中？

3 个答案: