delphi - TPanel 在包含 TWebBrowser 时不会自动调整大小

Question

我找到了 another Delphi 5 和 Delphi XE6 之间的回归。

我有一个 TPanel，它被设置为其内容的 AutoSize 本身(面板为绿色):

当TPanel包含任何其他控件时，例如一个TListView，面板将自动调整自身大小以适应所包含 ListView 的大小:

但是当包含的控件是 TWebBrowser (或替换 TEmbeddedWB )时，面板将不会自动调整大小:

一定是 TWebBrowser 的错误

自动调整大小肯定需要一些 VCL 管道，TWebBrowser VCL 包装器会出错。我需要知道 XE6 中的问题以及修复方法。

User user1611655 had a good workaround :

I had a similar problem.

It was solved by putting a TPanel "underneath" the TWebBrowser, and aligning the web browser to alClient.

我对解决方法不太感兴趣，作为修复 - 我可以将其添加到我们的其他一堆 VCL 源修复中。实际上，由于我使用了经过改进的 TEmbeddedWB 控件，因此可以将修复程序放在其中；让 TWebBrowser 损坏。

重现步骤

Form1.pas:

unit Unit1;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.ComCtrls, Vcl.ExtCtrls, Vcl.OleCtrls, SHDocVw;

type
  TForm1 = class(TForm)
     Panel1: TPanel;
     WebBrowser1: TWebBrowser;
  private
     { Private declarations }
  public
     { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

end.

Form1.dfm:

object Form1: TForm1
  Left = 0
  Top = 0
  Caption = 'Form1'
  ClientHeight = 248
  ClientWidth = 373
  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 = 32
    Top = 32
     Width = 209
     Height = 97
     AutoSize = True
     BevelOuter = bvNone
     Color = clLime
     ParentBackground = False
     TabOrder = 0
     object WebBrowser1: TWebBrowser
        Left = 0
        Top = 0
        Width = 190
        Height = 161
        ParentShowHint = False
        ShowHint = False
        TabOrder = 0
        ControlData = {
          4C00000023260000E40500000000000000000000000000000000000000000000
          000000004C000000000000000000000001000000E0D057007335CF11AE690800
          2B2E126208000000000000004C0000000114020000000000C000000000000046
          8000000000000000000000000000000000000000000000000000000000000000
          00000000000000000100000000000000000000000000000000000000}
     end
  end
end

Answer 1

该问题是由两个回归引起的。

• TWinControl.AlignControls 中的一个
• 另一个是由 TOleControl.SetBounds 中的更改引起的，尽管实际的错误是在 TWinControl.WMWindowPosChanged 中。

“永远不会自动调整大小”错误

我在 Stackoverflow 问题 TPanel does not AutoSize when containing a TPanel 中详细描述的第一个错误:

procedure TWinControl.AlignControls(AControl: TControl; var Rect: TRect);
begin
   //...snip

   // Apply any constraints
   if Showing and ((sfWidth in FScalingFlags) or (sfHeight in FScalingFlags)) then
      DoAdjustSize;

   //...snip
end;

这里的错误是，除非存在 sfWidth 或 sfHeight 缩放标志，否则它不会调用 DoAdjustSize。

解决方法是不要试图超越自己，并且无论如何DoAdjustSize:

procedure TWinControl.AlignControls(AControl: TControl; var Rect: TRect);
begin
   //...snip

   // Apply any constraints
   //QC125995: Don't look to scaling flags to decide if we should adjust size
   if Showing {and ((sfWidth in FScalingFlags) or (sfHeight in FScalingFlags))} then
      DoAdjustSize;

   //...snip
end;

“调整大小时不自动调整大小”错误

先前的修复使面板在包含子 TControl 或 TWinControl 时自动调整大小。但是当面板包含TOleControl时，还有另一个错误。该错误是在 Delphi XE 中引入的。与上面的错误不同，这个错误是由于某人认为自己很聪明而引起的，这个错误要微妙得多。

当调整TOleControl的大小时，会调用它的SetBounds方法。这是原始的功能代码:

procedure TOleControl.SetBounds(ALeft, ATop, AWidth, AHeight: Integer);
begin
   if ((AWidth <> Width) and (Width > 0)) or ((AHeight <> Height) and (Height > 0)) then
   begin
      //...snip: perhaps tweak AWidth and AHeight
   end;

   inherited SetBounds(ALeft, ATop, AWidth, AHeight);
end;

在 XE2 时间范围内，代码已更改为，以便通知底层 Ole 控件其边界即将更改:

procedure TOleControl.SetBounds(ALeft, ATop, AWidth, AHeight: Integer);
var
   LRect: TRect;
begin
   if ((AWidth <> Width) and (Width > 0)) or ((AHeight <> Height) and (Height > 0)) then
   begin
      //...snip: perhaps tweak AWidth and AHeight

      //Notify the underlying Ole control that its bounds are about to change
      if FOleInplaceObject <> nil then
      begin
         LRect := Rect(Left, Top, Left+AWidth, Top+AHeight);
         FOleInplaceObject.SetObjectRects(LRect, LRect);
      end;
   end;

   inherited SetBounds(ALeft, ATop, AWidth, AHeight);
end;

作者不知道的是，这暴露了 TWinControl 中的一个错误。调用IOleInPlaceObject.SetObjectRects的问题是 Ole 控件(例如 Internet Explorer)转身并发送 WM_WindowPosChanged信息。 TWinControl 中的 WMWindowPoschanged 处理程序无法正确处理该消息。

虽然常规 SetBounds 方法正确调用:

procedure SetBounds;
begin
   UpdateAnchorRules;
   UpdateExplicitBounds;
   RequestAlign; //the important one we need
end;

WMWindowPosChanged 方法仅调用:

procedure WMWindowPosChanged;
begin
   UpdateBounds; //which only calls UpdateAnchorRules
end;

这意味着WinControl调整了它的大小；但其父级永远不会重新调整以处理新的自动大小。

修复

修复方法是:

• 根本不要从 SetBounds 调用 IOleInPlaceObject.SetObjectRects。 Delphi 5 没有做到，而且运行得很好

• 更改 WMWindowPosChanged，以便它也调用 RequestAlign:

    procedure TWinControl.WMWindowPosChanged;
    begin
       UpdateBounds;
       RequestAlign; //don't forget to autosize our parent since we're changing our size behind our backs (e.g. TOleControl)
    end;
  

• 更改 UpdateBounds 以同时调用 RequestAlign:

   procedure TWinControl.UpdateBounds;
   begin
      UpdateAnchorRules;
      //UpdateExplicitBounds; SetBounds calls this; why are we not calling it?
      RequestAlign; //in response to WM_WindowPosChanged            
   end;
  

我选择了第四种解决方案；一个完整保留错误的方法，但对我来说已经足够修复它了。

错误在于:

• WMWindowPosChanged 无法正确处理尺寸更改
• 但是SetBounds可以

所以我们首先使用SetBounds。

利用SetBounds中(大部分)正确的代码来完成所有自动调整大小。然后我们可以调用SetObjectRects。当 WMWindowPosChanged 收到其 WM_WindowPosChanging 消息时，它将无事可做 - 因此不会做任何错误。

tl;博士

procedure TOleControl.SetBounds(ALeft, ATop, AWidth, AHeight: Integer);
var
  LRect: TRect;
begin
  if ((AWidth <> Width) and (Width > 0)) or ((AHeight <> Height) and (Height > 0)) then
  begin
     //...snip: perhaps fiddle with AWidth or AHeight

     {Removed. Call *after* inheirted SetBounds
     //Notify the underlying Ole control that its bounds are about to change
     if FOleInplaceObject <> nil then
     begin
        LRect := Rect(Left, Top, Left+AWidth, Top+AHeight);
        FOleInplaceObject.SetObjectRects(LRect, LRect);
     end;}
  end;

  inherited SetBounds(ALeft, ATop, AWidth, AHeight);

  //moved to call *after* SetBounds, we need SetBounds to happen first.       
  //TWinControl's WMWindowPosChanged does not handle autosizing correctly
  //while SetBounds does.
  //Notify the underlying Ole control that its bounds are already about to change
  if FOleInplaceObject <> nil then
  begin
     LRect := Rect(Left, Top, Left+AWidth, Top+AHeight);
     FOleInplaceObject.SetObjectRects(LRect, LRect);
  end;
end;

Note: Any code released into public domain. No attribution required.