小编SOU*_*ser的帖子

我有一个奇怪的问题,在不同版本的Delphi中使用接口.以下最小化代码在Delphi XE及更高版本中编译和运行,但在Delphi 7中没有.具体来说,在Delphi 7中编译时,function TForm1.Load: IMoleculeSubject;似乎没有返回正确的结果,即对新创建的实例的正确引用.你能帮忙评论一下原因和可能的解决方法吗？非常感谢!

uInterface.pas

    unit uInterface;

    interface

    type

      IMoleculeSubject = interface
      ['{BEB4425A-186C-45DF-9DCE-C7175DB0CA90}']
      end;

      TMoleculeSubject = class(TInterfacedObject, IMoleculeSubject)
      end;

    implementation

    end.

uBusiness.pas

    unit uBusiness;

    interface

    uses
      uInterface;

    type

      TMoleculeDecorator = class(TMoleculeSubject) 
      private
        FID: Integer;
      public           
        property ID: Integer read FID;
        constructor Create;
      end;

    implementation

    { TMoleculeDecorator }

    constructor TMoleculeDecorator.Create;
    begin
      inherited Create;

      FID := Random(100);
    end;

    end.

Unit1.pas

    unit Unit1;

    interface

    uses
      uInterface, uBusiness,

      Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, 
      Forms, Dialogs;

    type
      TForm1 = …

如下图所示，在JPanel（500X500）上绘制了一个AttributedString。

如FontMetrics.getStringBounds()跟踪输出所示，该 AttributedString 的宽度为 164.0。

java.awt.geom.Rectangle2D$Float[x=0.0,y=-12.064453,w=164.0,h=15.09375]

不过图片建议宽度应该是300-400（因为面板的宽度是500）。

你能帮忙评论原因和解决方法吗？

我的JFrame.java

import javax.swing.*;
import java.awt.*;
import java.awt.font.TextAttribute;
import java.text.AttributedString;

class MyJPanel extends JPanel {
    MyJPanel() {
        setPreferredSize(new Dimension(500,500));
    }

    @Override
    public void paintComponent(Graphics gold) {
        super.paintComponent(gold);
        Graphics2D g = (Graphics2D)gold;
        //
        AttributedString text = new AttributedString("Bunny rabits and flying ponies");
        text.addAttribute(TextAttribute.FONT, new Font("Arial", Font.BOLD, 24), 0, "Bunny rabits".length());
        text.addAttribute(TextAttribute.FOREGROUND, Color.RED, 0, "Bunny rabits".length());

        text.addAttribute(TextAttribute.FONT, new Font("Arial", Font.BOLD & Font.ITALIC, 32), 17, 17 + "flying ponies".length());
        text.addAttribute(TextAttribute.FOREGROUND, Color.BLUE, 17, 17 + …

综述:

请参阅Andreas的知识渊博的评论!

==========================================

如下面的代码所示,TForm7是MDIForm形式,TForm8是MDIChild形式.TForm8包含一个alClient对齐的面板,它还包含一个TPaintBox.如果TForm8的面板的ParentBackground设置为False,我无法从TForm7触发TForm8的paintbox的绘制事件.我想知道为什么会发生这种情况,如何在不明确引用它的情况下触发TForm8的paintbox绘制事件.任何建议表示赞赏!

注意:如果我调用Self.Repaintwithint TForm8,例如在其Click事件中,可以触发TForm8的paintbox的paint事件.只有当我form8.repaint在TForm8外面打电话时才能触发它.我想知道为什么会这样？

可能相关的SO页面:
如何在模态表单处于活动状态时重新绘制父表单？

包含MDIForm表单的单元.

    unit Unit7;

    interface

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

    type
      TForm7 = class(TForm)
        procedure FormShow(Sender: TObject);
        procedure FormClick(Sender: TObject);

      end;

    var
      Form7: TForm7;

    implementation

    {$R *.dfm}

    uses
      Unit8;

    procedure TForm7.FormShow(Sender: TObject);
    begin
      TForm8.Create(Self);
    end;

    procedure TForm7.FormClick(Sender: TObject);
    begin
      TForm8(ActiveMDIChild).Repaint;
    end;

    end.

上述单位的Dfm.

    object Form7: TForm7
      Left = 0
      Top = 0
      Caption = 'Form7'
      ClientHeight = 379
      ClientWidth = 750
      Color = clBtnFace …

如下面的代码示例所示,person_list是一个用户派生类型,包含一个类型绑定过程compare_persons.我希望compare_persons能够接受某个组compareFunc作为其参数之一,因此声明接口部分compareFunc.注意第一个参数compareFunc是类型person_list.(正如您所说,person_list就像TStringList在Delphi的VCL中一样.)

编译无法进行.错误消息是:

[root@localhost new]# ifort -c lib1.f90 
lib1.f90(26): error #6457: This derived type name has not been declared.   [PERSON_LIST]
                    TYPE(person_list) :: persons    !   error #6457: This derived type name has not been declared.   [PERSON_LIST]
-------------------------^
lib1.f90(23): error #6404: This name does not have a type, and must have an explicit type.   [PERSONS]
                FUNCTION compareFunc(persons, index1, index2)    !   error #6404: This name does …

我正在尝试TDropFileTargetMelander DragDrop套件的组件.目标是在拖放文件后执行某些任务.此外,如果在处理过程中出现问题,我希望收到例外情况.

似乎OnDrop吞下了事件处理程序中引发的异常.但是,即使我将raise语句放入组件的源代码中,我仍然无法收到异常.你能帮忙发表评论吗？

示例dfm文件.

    object Form4: TForm4
      Left = 0
      Top = 0
      Caption = 'Form4'
      ClientHeight = 270
      ClientWidth = 392
      Color = clBtnFace
      Font.Charset = DEFAULT_CHARSET
      Font.Color = clWindowText
      Font.Height = -11
      Font.Name = 'Tahoma'
      Font.Style = []
      OldCreateOrder = False
      PixelsPerInch = 96
      TextHeight = 13
      object edt1: TEdit
        Left = 56
        Top = 72
        Width = 257
        Height = 21
        TabOrder = 0
        Text = 'edt1'
      end
      object dropfiletarget2: …

使用TStringStream时,bytes使用其Bytes属性与bytes提取的使用不同TStream.Read.如下所示:

1. 所述bytes使用所提取的TStream.Read表示正确的数据.
2. 在bytes使用它的Bytes属性包含更多的数据.(正确的最后一个字节与错误的字节bytes不同bytes)

你能帮忙评论可能的原因吗？非常感谢您的帮助!

PS:Delphi XE,Windows 7.(似乎在Delphi 7中的TStringStream没有LoadFromFile或SaveToFile.)

PS:可以从SkyDrive下载示例文件:REF_EncodedSample和REF_DecodedSample.(Zlib压缩的图像文件.).

procedure CompareBytes_2;
var
  ss_1: TStringStream;
  ss_2: TStringStream;
  sbytes_Read: TBytes;
  sbytes_Property: TBytes;
  len_sbytes_Read: Integer;
  len_sbytes_Property: Integer;
  filename: string;
begin
  filename := 'REF_EncodedSample';  // textual data
//  filename := 'REF_DecodedSample';  // non-textual data

  ss_1 := TStringStream.Create;
  ss_1.LoadFromFile(filename);
  ss_2 := TStringStream.Create;
  ss_2.LoadFromFile(filename);

  ss_1.SaveToFile(filename+ '_CopyByStringStream_1');
  ss_2.SaveToFile(filename+ '_CopyByStringStream_2');

  len_sbytes_Read := ss_1.Size;
  SetLength(sbytes_Read, len_sbytes_Read); …

以下语句在Delphi XE(Windows 7 x64)下正常运行,但在Delphi XE3(Windows 7 x64)下提供了"Exception class EFOpenError with message ...".它看起来像一个bug.如果是这样,有解决方法吗？

      TFileStream.Create(
        'C:\Test.txt'
        , fmOpenRead,
//        FILE_SHARE_READ);
//        FILE_SHARE_WRITE);
        FILE_SHARE_READ or FILE_SHARE_WRITE);

下面的控制台应用程序给出了"运行时错误"......

为什么会这样？非常感谢 !

PS:相关SO帖子

program Project2;

{$APPTYPE CONSOLE}

type
  TParent = class;
  TParentClass = class of TParent;

  TParent = class
  public
    procedure Work; virtual; abstract;
  end;

  TChild1 = class(TParent)
  public
    procedure Work; override;
  end;

  TChild2 = class(TParent)
  public
    procedure Work; override;
  end;

procedure TChild1.Work;
begin
  WriteLn('Child1 Work');
end;

procedure TChild2.Work;
begin
  WriteLn('Child2 Work');
end;

procedure Test(ImplClass: TParentClass);
var
  ImplInstance: TParent;
begin
  ImplInstance := ImplClass.Create;
  ImplInstance.Work;
  ImplInstance.Free;
end;

begin
  Test(TParent);
  Test(TChild1);
  Test(TChild2);
  Readln;
end.

下面显示的两个程序尝试使用此处描述的技术测试对象是否被释放,对已释放的对象的错误引用.

如果在Delphi 7下编译,下面显示的第一个程序运行正确,但如果在Delphi XE和upper下编译,则错误地运行.也就是说,它输出

 D7          DXE 
True        True
True        True 
True        False
True        True
False       True
False       False

program Project1;

{$APPTYPE CONSOLE}

uses
  SysUtils;

function ValidateObj(Obj: TObject): Pointer;
// see { Virtual method table entries } in System.pas
begin
  Result := Obj;
  if Assigned(Result) then
    try
      if Pointer(PPointer(Obj)^) <> Pointer(Pointer(Cardinal(PPointer(Obj)^) + Cardinal(vmtSelfPtr))^) then
        // object not valid anymore
        Result := nil;
    except
      Result := nil;
    end;
end;

function ValidateObj2(Obj: TObject): Pointer;
type
  PPVmt = ^PVmt;
  PVmt = ^TVmt; …

在这篇SO文章中，建议将IAutoComplete与TStringsAdapter一起使用来实现自动完成。以下代码尝试遵循建议，但无法启用自动完成功能，而无需编译和运行时异常，抱怨接口不匹配/不一致。您能帮忙评论一下根本原因和解决方法吗？

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, AxCtrls, StdVCL, ActiveX, ComObj;

const
  IID_IAutoComplete         = '{00bb2762-6a77-11d0-a535-00c04fd7d062}';
  IID_IAutoComplete2        = '{EAC04BC0-3791-11d2-BB95-0060977B464C}';
  CLSID_AutoComplete: TGUID = '{00BB2763-6A77-11D0-A535-00C04FD7D062}';

type

  IAutoComplete = interface(IUnknown)
    [IID_IAutoComplete]
    function Init(hwndEdit: HWND; punkACL: IUnknown; pwszRegKeyPath: PWideChar;
      pwszQuickComplete: PWideChar): HResult; stdcall;
    function Enable(fEnable: Boolean): HResult; stdcall;
   end;

  IAutoComplete2 = interface(IAutoComplete)
    [IID_IAutoComplete2]
    function SetOptions(dwFlag: DWORD): HResult; stdcall;
    function GetOptions(out dwFlag: DWORD): HResult; stdcall;
  end;

  TStringsAdapterCracker = class(TStringsAdapter);

  TForm1 = class(TForm)
    ComboBox1: TComboBox; …

RoundCube为下面的纯文本电子邮件提供了一个很好的配色方案.

我想知道RoundCube如何做到这一点,以及如何在Delphi中实现这个配色方案？

>>>> Peter says: 
>>>> Peter says: 
>>> Jane says:
>>> Jane says:
>> Peter says: 
>> Peter says:
> Jane says:
> Jane says:
Peter says: 
Peter says: