引言: danielj您好: 參考這個方法試試 How do I draw on top of a TPanel ? http://www.tek-tips.com/gpviewthread.cfm/qid/585086/pid/101/lev2/4/lev3/29 HAVE A NICE DAY FOR YOU

引言: 請問axsoft，我看過這篇文章了，但我確不知道為何可以這麼用，可以解釋一下嗎?另外，我試過若在程式中手動new一個這篇文章中的TPanelCanvasHack類別，再寫字，就沒有任何反應，這……為什麼??

deal您好:
  我不太清楚你怎麼寫的,如果您只單單寫個TPanelCanvasHack Class,
  新增了一個Canvas的屬性,但是沒有把TCanvas類別的屬性也繼承了,
  當然不會有任何反應了.    下面的範例,我用比較簡單的方法寫一個不一樣的用法,
 src="http://delphi.ktop.com.tw/loadfile.php?TOPICID=11167227&CC=249753">
/---------------------------------------------------------------------------    #include 
#pragma hdrstop    #include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
TForm1 *Form1;
TPanel *Panel1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------    void __fastcall TForm1::Button1Click(TObject *Sender)
{
 TControlCanvas *PanelCanvas = new TControlCanvas;
 PanelCanvas->Control=Panel1;
 SetBkMode(PanelCanvas->Handle, TRANSPARENT); //加了這行就不會有上圖文字白底色出現了
 PanelCanvas->TextOutA(50,50,"TPanel 文字定點輸出");
 delete PanelCanvas;
}
//---------------------------------------------------------------------------    void __fastcall TForm1::FormCreate(TObject *Sender)
{
  Panel1=new TPanel(Form1);
  Panel1->Parent=Form1;
  Panel1->Left=4;
  Panel1->Width=200;
  Panel1->Height=100;
  
}
//---------------------------------------------------------------------------

引言: deal您好: 我不太清楚你怎麼寫的,如果您只單單寫個TPanelCanvasHack Class, 新增了一個Canvas的屬性,但是沒有把TCanvas類別的屬性也繼承了, 當然不會有任何反應了. < face="Verdana, Arial, Helvetica"> 謝謝axsoft的回應，你的程式我可以了解，但你提到「只單單寫個TPanelCanvasHack Class,新增了一個Canvas的屬性,但是沒有把TCanvas類別的屬性也繼承了,當然不會有任何反應了」，可是VCL不是不允許多重繼承嗎?那我要如何讓TPanelCanvasHack能同時繼承TCanvas的屬性呢?請指導一下!!謝謝!

大家可以透過繼承TPanel元件產生一個新元件TPanelDraw    步驟一.
        PanelDraw.h
//---------------------------------------------------------------------------    #ifndef PanelDrawH
#define PanelDrawH
//---------------------------------------------------------------------------
#include 
#include 
#include 
#include <Forms.hpp>
#include 
//---------------------------------------------------------------------------
class PACKAGE TPanelDraw : public TPanel
{
private:
protected:
public:
        __fastcall TPanelDraw(TComponent* Owner);
        __property Canvas;
 
__published:
};
//---------------------------------------------------------------------------
#endif    PanelDraw.cpp
//---------------------------------------------------------------------------    #include 
#pragma hdrstop    #include "PanelDraw.h"
#pragma package(smart_init)
//---------------------------------------------------------------------------
// ValidCtrCheck is used to assure that the components created do not have
// any pure virtual functions.
//    static inline void ValidCtrCheck(TPanelDraw *)
{
        new TPanelDraw(NULL);
}
//---------------------------------------------------------------------------
__fastcall TPanelDraw::TPanelDraw(TComponent* Owner)
        : TPanel(Owner)
{
}
//---------------------------------------------------------------------------
namespace Paneldraw
{
        void __fastcall PACKAGE Register()
        {
                 TComponentClass classes[1] = {__classid(TPanelDraw)};
                 RegisterComponents("Standard", classes, 0);
        }
}
//---------------------------------------------------------------------------    步驟二.將以上程式存檔為PanelDraw.cpp與PanelDraw.h    步驟三.開啟一新的Package將剛剛寫的PanelDraw.cpp加入Package中
    步驟四.選擇Package|Option,在Description填入PanelDraw v0.01以方便以後
       在Install Packge中的辨識

    步驟五.將Package存檔為PanelEx.bpk(建議不要存成與PanelDraw同檔名,會不
       小心把元件程式內容覆蓋掉)
    步驟六,選擇上圖Package中的Install,安裝TPanelDraw元件
    步驟七.開啟一新Project,然後在Form上放入一個TPanelDraw與TButton
程式碼如下:
Unit1.cpp
//---------------------------------------------------------------------------    #include 
#pragma hdrstop    #include "Unit1.h"
//---------------------------------------------------------------------------
#pragma package(smart_init)
#pragma link "PanelDraw"
#pragma resource "*.dfm"
TForm1 *Form1;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------    void __fastcall TForm1::Button1Click(TObject *Sender)
{
 PanelDraw1->Canvas->TextOutA(50,50,"定點輸出文字");
}
//---------------------------------------------------------------------------
        之前誤導大家真是抱歉....
    < class="code">
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