使用mouseDown在图像上创建矩形C++/CLI

Question

我在调试该程序时遇到了困难。我试图模仿微软桌面上的功能，你可以拖动到一个矩形。
我们想使它成为：
1.为了开始绘制矩形，您按下鼠标。
2.通过向下拖动mosue创建矩形的形状和大小。
3.通过点击鼠标结束矩形的绘制
4.我们希望能够跟踪起点和终点。


到目前为止，我们有

private: System::Void pictureBox1_Paint(System::Object^ sender, System::Windows::Forms::PaintEventArgs^ e) { 

     // e->Graphics; 
     //put pen where it belongs.. 
     Pen^ blackPen = gcnew Pen(Color::Black,3.0f); 

     if(drawing) 
     { 
     e->Graphics->DrawRectangle(blackPen, *getRect(ROIlocation1->X, ROIlocation1->Y, ROIlocation2->X, ROIlocation2->Y)); 
     } 
     //pictureBox1->Invalidate(); 
    } 
private: System::Void pictureBox1_MouseDown(System::Object^ sender, System::Windows::Forms::MouseEventArgs^ e) { 

     currentPos = startPos = e->Location; 
     ROIlocation1 = startPos; 
     drawing = true; 
     pictureBox1->Invalidate(); 
    } 

private: System::Void pictureBox1_MouseUp(System::Object^ sender, System::Windows::Forms::MouseEventArgs^ e) { 


     //NEW 
     if (drawing){ 
      drawing = false; 
      //getRect(startPos->X, startPos->Y, currentPos->X, currentPos->Y); 
      pictureBox1->Invalidate(); 
     } 

    } 

private: System::Void pictureBox1_MouseMove(System::Object^ sender, System::Windows::Forms::MouseEventArgs^ e) { 


     //NEW 
     currentPos=e->Location; 
     ROIlocation2=currentPos; 
     if(drawing) pictureBox1->Invalidate(); 



    } 

这是与getRect功能：

System::Drawing::Rectangle^ getRect(int xOne, int yOne, int xTwo, int yTwo){ 
// ms drawRect(x,y,w,h) wants the upper left corner of the rectangle, and the width and height. 
// we are given two sets of coordinates. the user can draw the rectangle in four ways, 
// not necessarily starting with the upper right hand corner of the rectangle. 
// this function will return a rectangle with the appropriate attributes 
// that the user expects. 

int ulpX = std::min(xOne, xTwo); // upper left point x 
int ulpY = std::max(yOne, yTwo); //upper left point y 
int h = abs(xOne - xTwo); //height 
int w = abs(yOne - yTwo); //width 


return gcnew System::Drawing::Rectangle(ulpX, ulpY, w, h); 

} 

我们所遇到的问题是矩形不断走动，好像它不会将第一次点击的位置保留在图像上作为其位置。

Answer 1

想通了什么问题了：

int w = abs(xOne - xTwo); //width 
int h = abs(yOne - yTwo); //height