// 新建项目后要将对话框的Border属性改成Resizing

// WndResize.h
#pragma once
#include <Afxtempl.h>

class CWndResize
{
protected:
    struct SSiszeData
    {
        HWND hWndCtrl; //窗口句柄
        double fLeft, fTop, fRight, fBottom; //位置相对比例

        SSiszeData();
        void Init(HWND hParent, RECT rcParent, HWND hCtrl);  //初始化 (记录窗口原始坐标位置)
        RECT GetRect(RECT rcParent);  //获取窗口坐标
    };

public:
    INT_PTR Bind(HWND hParent);  //初始化
    void ResizeWindow();         //缩放窗口控件

protected:
    HWND m_hParentWnd;
    CArray <SSiszeData, const SSiszeData &>m_SizeArray;
    CRect m_rcOrgRect;
};

// WndResize.cpp
#include "pch.h"
#include "WndResize.h"

CWndResize::SSiszeData::SSiszeData()
{
    memset(this, 0, sizeof(*this));
}

//初始化 (记录窗口原始坐标位置)
void CWndResize::SSiszeData::Init(HWND hParent, RECT rcParent, HWND hCtrl)
{
    ASSERT(hParent && hCtrl);

    hWndCtrl = hCtrl;

    //获取控件的坐标
    RECT rcCtrl;
    GetWindowRect(hCtrl, &rcCtrl);
    POINT ptLT = { rcCtrl.left, rcCtrl.top };
    POINT ptRB = { rcCtrl.right, rcCtrl.bottom };
    ScreenToClient(hParent, &ptLT);
    ScreenToClient(hParent, &ptRB);

    //计算相对位置
    double cx = rcParent.right - rcParent.top;
    double cy = rcParent.bottom - rcParent.top;
    fLeft = ptLT.x / cx;
    fTop = ptLT.y / cy;
    fRight = ptRB.x / cx;
    fBottom = ptRB.y / cy;
}

//获取窗口坐标
RECT CWndResize::SSiszeData::GetRect(RECT rcParent)
{
    RECT rcCtrl = { 0,0,0,0 };
    if (hWndCtrl)
    {
        int cx = rcParent.right - rcParent.left;
        int cy = rcParent.bottom - rcParent.top;
        rcCtrl.left = (LONG)(cx * fLeft);
        rcCtrl.top = (LONG)(cy * fTop);
        rcCtrl.right = (LONG)(cx * fRight);
        rcCtrl.bottom = (LONG)(cy * fBottom);
    }

    return rcCtrl;
}

//初始化
INT_PTR CWndResize::Bind(HWND hParent)
{
    ASSERT(hParent && IsWindow(hParent));

    m_hParentWnd = hParent;
    GetClientRect(hParent, &m_rcOrgRect);

    m_SizeArray.RemoveAll();
    HWND hWndCtrl = NULL;
    while (true)
    {
        hWndCtrl = FindWindowEx(hParent, hWndCtrl, NULL, NULL);
        if (!hWndCtrl) break;

        SSiszeData tmp;
        tmp.Init(hParent, m_rcOrgRect, hWndCtrl);
        m_SizeArray.Add(tmp);
    }
    return m_SizeArray.GetSize();
}

//缩放窗口控件
//这个函数最好写成回调函数, 让用户自己来设置第三方控件大小的适应
void CWndResize::ResizeWindow()
{
    CRect rcClient;
    GetClientRect(m_hParentWnd, &rcClient);
    if (m_hParentWnd && m_SizeArray.GetSize() > 0 && rcClient != m_rcOrgRect)
    {
        for (INT_PTR i = 0; i < m_SizeArray.GetSize(); i++)
        {
            SSiszeData *pData = &m_SizeArray[i];
            if (!pData) continue;
            CRect rcCtrl = pData->GetRect(rcClient);
            // 如果控件有第三方控件, 比如OpenCV的视图窗口嵌入到MFC窗口
            // 此时最好拖一个图片框，让OpenCV的视图窗恰好覆盖该图片框
            // 保证图片框始终与OpenCV的视图窗始终一样大
            MoveWindow(pData->hWndCtrl, rcCtrl.left, rcCtrl.top, rcCtrl.Width(), rcCtrl.Height(), TRUE);
            // 假设图片框在m_SizeArray中的索引是0也许有多个视图, 不妨扩展结构体SSiszeData, 让它保存控件的ID
            // 这样就不用费力的去猜索引与控件的对应关系了, 我这里只是一个例子所以...
            if (i == 0)  
            {
                         // 调整OpenCV视图的大小
            }
        }
        m_rcOrgRect = rcClient;
    }
}

// ResizeWindowDlg.h
#pragma once

class CResizeWindowDlg : public CDialogEx
{
    ... ...
private:
    afx_msg LRESULT WindowProc(UINT uMsg, WPARAM wParam, LPARAM lParam);
    CWndResize m_wndResize;

// 实现
protected:
    HICON m_hIcon;

    // 生成的消息映射函数
    ... ...
    afx_msg void OnSize(UINT nType, int cx, int cy);
    DECLARE_MESSAGE_MAP()
};

// WndResize.cpp
#include "pch.h"
#include "framework.h"
#include "ResizeWindow.h"
#include "ResizeWindowDlg.h"
#include "afxdialogex.h"

BOOL CResizeWindowDlg::OnInitDialog()
{
    ... ...
    m_wndResize.Bind(m_hWnd);

    return TRUE;
}

void CResizeWindowDlg::OnSize(UINT nType, int cx, int cy)
{
    CDialogEx::OnSize(nType, cx, cy);
    m_wndResize.ResizeWindow();
}

LRESULT CResizeWindowDlg::WindowProc(UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    enum DragMask
    {
        _DragNull = 0x00,
        _DragLeft = 0x01,
        _DragTop = 0x02,
        _DragRight = 0x04,
        _DragBottom = 0x08,
    };
    static UINT nEnterDrag = _DragNull;                 //拖拽标记
    switch (uMsg)
    {
        case WM_NCHITTEST:
        {
            CPoint point((SHORT)(LOWORD(lParam)), (SHORT)(HIWORD(lParam))); //鼠标位置
            CRect rcRect;                                                   //窗口位置 
            GetWindowRect(&rcRect);

            const int cx = GetSystemMetrics(SM_CXDRAG);
            const int cy = GetSystemMetrics(SM_CYDRAG);

            CRect rcLeftTop(rcRect.left, rcRect.top, rcRect.left + cx, rcRect.top + cy);               // 左上角
            if (rcLeftTop.PtInRect(point)) return HTTOPLEFT;
            CRect rcRightBottom(rcRect.right - cx, rcRect.bottom - cy, rcRect.right, rcRect.bottom);   //右下角
            if (rcRightBottom.PtInRect(point)) return HTBOTTOMRIGHT;
            CRect rcLeft(rcRect.left, rcRect.top, rcRect.left + cx, rcRect.bottom);                    //左边框
            if (rcLeft.PtInRect(point)) return HTLEFT;
            CRect rcTop(rcRect.left, rcRect.top, rcRect.right, rcRect.top + cx);                       //上边框
            if (rcTop.PtInRect(point)) return HTTOP;
            CRect rcBottom(rcRect.left, rcRect.bottom - cy, rcRect.right, rcRect.bottom);              //下边框
            if (rcBottom.PtInRect(point)) return HTBOTTOM;
            CRect rcRihgt(rcRect.right - cx, rcRect.top, rcRect.right, rcRect.bottom);                 //右边框
            if (rcRihgt.PtInRect(point)) return HTRIGHT;
            break;
        }
        case WM_NCLBUTTONDOWN:
        {
            UINT nHittest = (UINT)wParam;
            //在边框时捕捉焦点
            nEnterDrag = _DragNull;
           if (nHittest == HTTOPLEFT)      nEnterDrag |= _DragTop | _DragLeft;
           if (nHittest == HTTOP)          nEnterDrag |= _DragTop;
           if (nHittest == HTLEFT)         nEnterDrag |= _DragLeft;
           if (nHittest == HTBOTTOMRIGHT)  nEnterDrag |= _DragRight | _DragBottom;
           if (nHittest == HTBOTTOM)       nEnterDrag |= _DragBottom;
           if (nHittest == HTRIGHT)        nEnterDrag |= _DragRight;
           if (nEnterDrag != _DragNull)  SetCapture();
           break;
        }
        case WM_LBUTTONUP: case WM_NCLBUTTONUP:
        {
            //鼠标抬起时释放焦点
            if (nEnterDrag)
            {
                ReleaseCapture();
                nEnterDrag = _DragNull;
            }
            break;
        }
        case WM_MOUSEMOVE:
        {
            //拖拽操作
            if (nEnterDrag != _DragNull)
            {
                CPoint point((SHORT)(LOWORD(lParam)), (SHORT)(HIWORD(lParam)));
                ClientToScreen(&point);
                CRect rcRect;
                GetWindowRect(&rcRect);
                if (nEnterDrag & _DragTop)    rcRect.top = point.y;       //top
                if (nEnterDrag & _DragLeft)   rcRect.left = point.x;      //left
                if (nEnterDrag & _DragRight)  rcRect.right = point.x;     //right
                if (nEnterDrag & _DragBottom) rcRect.bottom = point.y;    //bottom
                MoveWindow(&rcRect);
            }
        break;
        }
    }

    return CDialog::WindowProc(uMsg, wParam, lParam);
}