VCL 中的 Windows API 函数(6): BeginDeferWindowPos

BeginDeferWindowPos 和 DeferWindowPos、EndDeferWindowPos 是一组一起使用的函数, 可对一组窗口的位置、大小、Z 序等进行调整, 在 ExtCtrls 单元有用到.

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下面先用常规方法实现对 Panel1 中的一组 Button 进行调整, 然后再用上面三个函数重新实现.

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本例效果图:

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代码文件:

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unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    RadioButton1: TRadioButton;
    RadioButton2: TRadioButton;
    procedure RadioButton1Click(Sender: TObject);
    procedure RadioButton2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.RadioButton1Click(Sender: TObject);
var
  num,i: Integer;
  btn: TButton;
  L,T,W,H: Integer;
begin
  num := Panel1.ControlCount;

  L := 10;
  T := 10;
  W := (Panel1.ClientWidth - L * (num+1)) div num;
  H := (Panel1.ClientHeight - T * (num+1)) div num;

  for i := 0 to num - 1 do
  begin
    if Panel1.Controls[i] is TButton then
    begin
      btn := TButton(Panel1.Controls[i]);
      btn.Left := L;
      btn.Top := (H + T) * i + T;
      btn.Width := W;
      btn.Height := H;
    end;
  end;
end;

procedure TForm1.RadioButton2Click(Sender: TObject);
var
  num,i: Integer;
  btn: TButton;
  L,T,W,H: Integer;
begin
  num := Panel1.ControlCount;

  L := 10;
  T := 10;
  W := (Panel1.ClientWidth - L * (num+1)) div num;
  H := (Panel1.ClientHeight - T * (num+1)) div num;

  for i := 0 to num - 1 do
  begin
    if Panel1.Controls[i] is TButton then
    begin
      btn := TButton(Panel1.Controls[i]);
      btn.Left := (W + L) * i + L;
      btn.Top := T;
      btn.Width := W;
      btn.Height := H;
    end;
  end;
end;

end.

窗体文件:

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object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 220
  ClientWidth = 307
  Color = clBtnFace
  Font.Charset = DEFAULT_CHARSET
  Font.Color = clWindowText
  Font.Height = -11
  Font.Name = 'Tahoma'
  Font.Style = []
  OldCreateOrder = False
  PixelsPerInch = 96
  TextHeight = 13
  object Panel1: TPanel
    Left = 8
    Top = 8
    Width = 289
    Height = 161
    Caption = 'Panel1'
    TabOrder = 0
    object Button1: TButton
      Left = 152
      Top = 72
      Width = 75
      Height = 25
      Caption = 'Button1'
      TabOrder = 0
    end
    object Button2: TButton
      Left = 160
      Top = 80
      Width = 75
      Height = 25
      Caption = 'Button2'
      TabOrder = 1
    end
    object Button3: TButton
      Left = 168
      Top = 88
      Width = 75
      Height = 25
      Caption = 'Button3'
      TabOrder = 2
    end
    object Button4: TButton
      Left = 176
      Top = 96
      Width = 75
      Height = 25
      Caption = 'Button4'
      TabOrder = 3
    end
  end
  object RadioButton1: TRadioButton
    Left = 50
    Top = 183
    Width = 113
    Height = 17
    Caption = 'RadioButton1'
    TabOrder = 1
    OnClick = RadioButton1Click
  end
  object RadioButton2: TRadioButton
    Left = 184
    Top = 183
    Width = 113
    Height = 17
    Caption = 'RadioButton2'
    TabOrder = 2
    OnClick = RadioButton2Click
  end
end

用 BeginDeferWindowPos、DeferWindowPos、EndDeferWindowPos 重新实现的代码(窗体和运行效果是一样的):

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unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ExtCtrls;

type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    RadioButton1: TRadioButton;
    RadioButton2: TRadioButton;
    procedure RadioButton1Click(Sender: TObject);
    procedure RadioButton2Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.RadioButton1Click(Sender: TObject);
var
  num,i: Integer;
  btn: TButton;
  L,T,W,H: Integer;
  DeferHandle: THandle;
begin
  num := Panel1.ControlCount;

  L := 10;
  T := 10;
  W := (Panel1.ClientWidth - L * (num+1)) div num;
  H := (Panel1.ClientHeight - T * (num+1)) div num;

  DeferHandle := BeginDeferWindowPos(num); {准备调整一组窗口}
  for i := 0 to num - 1 do
  begin
    if Panel1.Controls[i] is TButton then
    begin
      btn := TButton(Panel1.Controls[i]);
      DeferHandle := DeferWindowPos(DeferHandle,
                                    btn.Handle,
                                    HWND_TOP,                 {此参数决定 Z 序}
                                    L, (H + T) * i + T, W, H, {新的位置与大小}
                                    SWP_NOZORDER              {更多控制, 现在是不改变 Z 序}
                                    );
    end;
  end;
  EndDeferWindowPos(DeferHandle); {实施调整}
end;

procedure TForm1.RadioButton2Click(Sender: TObject);
var
  num,i: Integer;
  btn: TButton;
  L,T,W,H: Integer;
  DeferHandle: THandle;
begin
  num := Panel1.ControlCount;

  L := 10;
  T := 10;
  W := (Panel1.ClientWidth - L * (num+1)) div num;
  H := (Panel1.ClientHeight - T * (num+1)) div num;

  DeferHandle := BeginDeferWindowPos(num);
  for i := 0 to num - 1 do
  begin
    if Panel1.Controls[i] is TButton then
    begin
      btn := TButton(Panel1.Controls[i]);
      DeferHandle := DeferWindowPos(DeferHandle,
                                    btn.Handle,
                                    HWND_TOP,
                                    (W + L) * i + L, T, W, H,
                                    SWP_NOZORDER
                                    );
    end;
  end;
  EndDeferWindowPos(DeferHandle);
end;

end.