你能帮忙把这个非常小的 C++ 组件翻译成 Delphi 吗? [英] Can you help translating this very small C++ component to Delphi?

问题描述

我正在将以下 C++ 组件翻译成 Delphi:

I'm translating the following C++ component to Delphi:

http://borland.newsgroups.archived.at/public.delphi.vcl.components.using.win32/200708/0708225318.html

但它不起作用...我正在附上翻译后的代码，可以请一位专业人士看一下吗?

But it's not working... I'm attaching the translated code, could one of the pros take a look?

谢谢！

代码如下:

unit ComboBoxPlus;

interface

uses
  SysUtils, Classes, Controls, StdCtrls, Messages, Types, Windows, Graphics;

type
  TComboBoxPlus = class(TComboBox)
  private
    FClickedItem: Integer;
    FListHandle: HWND;
    ListWndProcPtr: Longint;
    OldListWndProc: Pointer;

    function GetIsEnabled(Index: Integer): Boolean;
    procedure SetIsEnabled(Index: Integer; Value: Boolean);
  protected
    procedure WndProc(var Message: TMessage);
    procedure ListWndProc(var Message: TMessage); virtual;
    procedure DrawItem(Index: Integer; Rect: TRect;
      State: TOwnerDrawState);
  public
    constructor Create(AOwner: TComponent); override;
    destructor Destroy; override;
    property Enabled[Index: Integer]: Boolean read GetIsEnabled write SetIsEnabled;
  published
    { Published declarations }
  end;

procedure Register;

implementation

procedure Register;
begin
  RegisterComponents('Win32', [TComboBoxPlus]);
end;

constructor TComboBoxPlus.Create(AOwner: TComponent);
begin
  inherited Create(AOwner);
  Style := csOwnerDrawFixed;
  Height := 21;
  ItemHeight := 17;
  ListWndProcPtr := Longint(Classes.MakeObjectInstance(ListWndProc));
end;

destructor TComboBoxPlus.Destroy;
begin
  if FListHandle <> 0 then
    SetWindowLong(FListHandle, GWL_WNDPROC, Longint(OldListWndProc));

  FreeObjectInstance(Pointer(ListWndProcPtr));

  inherited Destroy;
end;

function TComboBoxPlus.GetIsEnabled(Index: Integer): Boolean;
begin
  if Boolean(Items.Objects[Index]) then Result := false
  else Result := true;
end;

procedure TComboBoxPlus.SetIsEnabled(Index: Integer; Value: Boolean);
begin
  if Value then
    Items.Objects[Index] := TObject(false)
  else
    Items.Objects[Index] := TObject(true);
end;

procedure TComboBoxPlus.DrawItem(Index: Integer; Rect: TRect;
  State: TOwnerDrawState);
begin
  if odSelected in State then
  begin
    if not Boolean(Items.Objects[Index]) then
    begin
      Canvas.Brush.Color := clHighlight;
      Canvas.Font.Color := clHighlightText;
      Canvas.FillRect(Rect);
    end else
    begin
      Canvas.Brush.Color := Color;
      Canvas.Font.Color := clGrayText;
      Canvas.FillRect(Rect);
      Canvas.DrawFocusRect(Rect);
    end;
  end else
  begin
    if not Boolean(Items.Objects[Index]) then
    begin
      Canvas.Brush.Color := Color;
      Canvas.Font.Color := Font.Color;
    end else
    begin
      Canvas.Brush.Color := Color;
      Canvas.Font.Color := clGrayText;
    end;
    Canvas.FillRect(Rect);
  end;
  Canvas.TextOut(Rect.Left + 3, Rect.Top + (((Rect.Bottom - Rect.Top) div 2) -
    (Canvas.TextHeight('Wg') div 2)), Items.Strings[Index]);
end;

procedure TComboBoxPlus.WndProc(var Message: TMessage);
begin
  if (Message.Msg = WM_CTLCOLORLISTBOX) then
  begin
    if FListHandle = 0 then
    begin
      FListHandle := HWnd(Message.LParam);
      inherited WndProc(Message);
      OldListWndProc := Pointer(SetWindowLong(FListHandle, GWL_WNDPROC, ListWndProcPtr));
      exit;
    end;
  end;

  inherited WndProc(Message);
end;

procedure TComboBoxPlus.ListWndProc(var Message: TMessage);
var
  R: TRect;
  X, Y: Integer;
begin
  if (Message.Msg = WM_LBUTTONDOWN) or (Message.Msg = WM_LBUTTONUP) then
  begin
    X := Message.LParamLo;
    Y := Message.LParamHi;

    Windows.GetClientRect(FListHandle, R);

    if PtInRect(R, Point(X, Y)) then
    begin
      FClickedItem := SendMessage(FListHandle, LB_GETTOPINDEX, 0, 0) + (Y div ItemHeight);
      if (not Enabled[FClickedItem]) then
      begin
        Message.Result := 0;
        exit;
      end;
    end;
  end else if (Message.Msg = WM_LBUTTONDBLCLK) then
  begin
    Message.Result := 0;
    exit;
  end;

  Message.Result := CallWindowProc(OldListWndProc, FListHandle, Message.Msg,
    Message.WParam, Message.LParam);
end;

end.

推荐答案

午夜过后我累了 - 对不起我的愚蠢.它正在进行以下修改:

It's after midnight I'm tired - sorry about my stupidity. It's working with the following modifications:

procedure WndProc(var Message: TMessage); override;
procedure ListWndProc(var Message: TMessage);
procedure DrawItem(Index: Integer; Rect: TRect;
  State: TOwnerDrawState); override;

(添加两个覆盖并取出虚拟)

(add two overrides and take out the virtual)

最后要整理的是，如果在没有键盘键的情况下选择了禁用的项目，不要让组合框关闭！

The last thing to sort out is not to let the combobox close up if the disabled item is selected without keyboard keys!

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