#include 
#pragma hdrstop
#include "Unit1.h"
//-------------------------------------------------------------------
#pragma package(smart_init)
#pragma resource "*.dfm"
int xleft=0,xright=0,yup=0,ydown=0,retake;
bool draw=true,run=false;
//-------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
    : TForm(Owner)
{
}
//-------------拖拉設定出辨識區塊的範圍-----------------------------
void __fastcall TForm1::Image1StartDrag(TObject *Sender,TDragObject *&DragObject)
{
  retake = Image1->Canvas->Pen->Mode;
  Image1->Canvas->Pen->Mode = pmNotXor;
  Image1->Canvas->Pen->Style = psDash;
  Image1->Canvas->Brush->Style = bsClear;
  Image1->Canvas->Rectangle(xleft,yup,xright,ydown);
}
void __fastcall TForm1::Image1DragOver(TObject *Sender, TObject *Source,
      int X, int Y, TDragState State, bool &Accept)
{
  if (draw)
  {
    xleft = X;
    yup = Y;
    draw = false;
  }
  else Image1->Canvas->Rectangle(xleft,yup,xright,ydown);
  xright = X;
  ydown = Y;
  Image1->Canvas->Rectangle(xleft,yup,xright,ydown);
}
void __fastcall TForm1::Image1EndDrag(TObject *Sender, TObject *Target,
      int X, int Y)
{
  run = true;
  draw = true;
  Image1->Canvas->Pen->Mode = (TPenMode)retake;
  if (xleft > xright)
  {
    X = xleft;
    xleft = xright;
    xright = X;
  }
  if (yup > ydown)
  {
    Y = yup;
    yup = ydown;
    ydown = Y;
  }
}

引言: 我想寫一個在畫布上利用滑鼠將畫布上想要的區塊框出的程式,請各位大大幫我看一下我的程式哪邊有問題

我用了您的程式測試並沒有問題壓?除了會有閃爍的現象 您可以用下面的code解決

void __fastcall TForm1::FormCreate(TObject *Sender)
{
 Form1->DoubleBuffered=true;
}

效果如下圖所示 您也可以參考下面連結的作品 http://delphi.ktop.com.tw/topic.php?TOPIC_ID=34115 【發表】利用滑鼠截取 Image 的部分區域 BY RaynorPao版主 希望沒有誤會您的意思< > 順心< > ～我也是在學習的階段,回答的不好請您多多見諒與指教～ 發表人 - taishyang 於 2003/12/11 21:48:35

引言: 我執行程式後,按滑鼠完全沒反應,不曉得是不是我的程式寫法有誤? 你也是在Form中加上一個Image的方式寫的嗎?