在鼠标上方更改矩形区域的颜色。 [英] Change the color of a rectangular area on mouse over.

问题描述

我有一个在WM_PAINT消息中绘制的矩形。现在我想像按钮一样模拟这个矩形部分。当我将鼠标光标移到矩形区域时，它的背景颜色应该改变，当我把光标从它上面取出时它应该是原来的颜色。



如何我可以使用Win32 API捕获此鼠标悬停事件吗？我怀疑必须使用许多鼠标消息来克服这个问题。但是我在捕获鼠标效果方面取得了如下成功：

I have a rectangle which is drawn in the WM_PAINT message. Now I want to simulate this rectangular portion like a button. When I bring the mouse cursor into the rectangular area its background color should be changed and when i bring the cursor out of it it should be in its original color.

How can I catch this mouse-over event using Win32 API ? I suspect many mouse messages must be used to overcome this. However i am succesful in catching the mouse-in effect as follows:

//The rectangle is just a structure with 4-values(x1, y1, x2, y2).
case WM_MOUSEMOVE:
   int x = LOWORD(lParam);
   int y = HIWORD(lParam);

   if(X_and_Y_are_inside_the_rectangle)
   {
      //get_a_dc
      //paint_the_rectangle_with_another_color
      //release_dc
   }
   else
   {
      //if i uncomment the following line even the mouse-in effect 
      //won't work
      
      //InvalidateRect(hwnd, NULL, TRUE);
   }
return 0;

case WM_PAINT:
    //get_a_dc
    //paint_the_rectangle_with_original_color
    //release_dc
    return 0;

问题简介：

如何在Win32 API中捕获特定矩形区域的鼠标输入和鼠标移出事件？



仅限问题在于捕获这两个消息之王而不是像GDI库那样的任何东西。

推荐答案

#define INSIDE_RECT   1
#define OUTSIDE_RECT -1

static int iHoverRect;

case WM_CREATE:
    iHoverRect = OUTSIDE_RECT;
    return 0;

case WM_MOUSEMOVE:
    int x = LOWORD(lParam);
    int y = HIWORD(lParam);

    if(iHoverRect == OUTSIDE_RECT)
    {
        if(is_points_in_rect)
        {
            iHoverRect = INSIDE_RECT;
            //mouse-in event here
        }
    }
    else
    {
        if(!is_points_in_rect)
        {
            iHoverRect = OUTSIDE_RECT;
            //mouse-out event here
        }
    }

    return 0;

您应该只在WM_PAINT消息处理程序内部绘制。例如（伪代码）：

You should draw only inside WM_PAINT message handler. For instance (pseudo-code):

case WM_MOUSEMOVE:
   int x = LOWORD(lParam);
   int y = HIWORD(lParam);

   if(X_and_Y_are_inside_the_rectangle)
   {
     if ( colorRect != colorInside)
     {
        colorRect = colorInside;
        InvalidateRect
        UpdateWindow
     }
   }
   else
   {
     if ( colorRect != colorOutside)
     {
        colorRect = colorOutside;
        InvalidateRect
        UpdateWindow
     }
   }
return 0;

case WM_PAINT:
    get_a_dc
    paint the rectangle with colorRect
    release_dc
    return 0;

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