焦点时更改CEdit的框架颜色答案

【问题标题】：Change frame color of CEdit when Focus焦点时更改CEdit的框架颜色
【发布时间】：2021-12-30 11:03:38
【问题描述】：

使用以下代码，我的编辑框会在获得焦点时获得红色框和黄色背景。但是，当我输入文本时，起初文本是不可见的，我必须将光标悬停到另一个对话框项才能看到我刚刚输入的文本。为什么我必须更改才能看到文本而无需移动鼠标？

HBRUSH CDialog23::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
    HBRUSH hbr = CDialogEx::OnCtlColor(pDC, pWnd, nCtlColor);
    if (nCtlColor == CTLCOLOR_STATIC || nCtlColor == CTLCOLOR_DLG)
    {
        pDC->SetBkMode(TRANSPARENT);
        pDC->SetBkColor(RGB(255, 255, 255));
        hbr = m_Weiss;
        return hbr;
    }
    if (nCtlColor == CTLCOLOR_LISTBOX)
    {
        pDC->SetBkMode(TRANSPARENT);
        pDC->SetBkColor(RGB(255, 230, 153));
        hbr = m_Gelb;
        return hbr;
    }
    const CWnd* focusWnd = GetParent() ? GetParent()->GetFocus() : nullptr;
    bool hasFocus = focusWnd && focusWnd->GetSafeHwnd() == pWnd->GetSafeHwnd();
    if (hasFocus)
    {
        if (pWnd->GetDlgCtrlID() == pWnd->GetFocus()->GetDlgCtrlID() && nCtlColor != CTLCOLOR_STATIC)
        {
            pDC->SetBkMode(TRANSPARENT);
            pDC->SetBkColor(RGB(255, 230, 153));

            CRect rect;
            pWnd->GetWindowRect(&rect);
            rect.OffsetRect(-rect.left, -rect.top);
            CBrush brush(RGB(255, 0, 0));
            pDC->FrameRect(&rect, &brush);
            ReleaseDC(pDC);
            
            hbr = m_Gelb;
            return hbr;
        }
        else
        {
            pDC->SetBkMode(TRANSPARENT);
            pDC->SetBkColor(RGB(255, 255, 255));
            hbr = m_Weiss;
            return hbr;
        }
    }
    return hbr;
}

【问题讨论】：

标签： c++ mfc

【解决方案1】：

删除ReleaseDC(); 您没有调用获取 DC，调用者将指向 DC 对象的指针传递给您。完全没有必要释放这个 DC。

更新：使用 MEMC（最小编码最大效果）我做了更多的工作并提出了以下解决方案：

从CEdit派生一个类
处理反射消息：EN_SETFOCUS、EN_KILLFOCUS 和 WM_CTLCOLOR

在WM_NCPAINT 处理程序中绘制框架声明成员boolean 变量以确定何时应发生焦点更改。我称它为m_DoChangeBacground。其余如下：

 void CEditChangeFocus::OnEnSetfocus()
 {
     m_DoChangeBacground = true;
 }


 void CEditChangeFocus::OnEnKillfocus()
 {
     m_DoChangeBacground = false;
 }


 HBRUSH CEditChangeFocus::CtlColor(CDC* pDC, UINT nCtlColor)
 {
     // just the sanity check while debugging
     ASSERT(CTLCOLOR_EDIT == nCtlColor);

     if(m_DoChangeBacground)
     {
         pDC->SetBkMode(TRANSPARENT);
         //pDC->SetBkColor(RGB(255, 230, 153));

         return m_YellowBK;  // yellow brush

     }
     // TODO:  Return a non-NULL brush if the parent's handler should not be called
     return nullptr;
 }


 void CEditChangeFocus::OnNcPaint()
 {
     if(m_DoChangeBacground)
     {
         CRect rectWnd;
         GetWindowRect(&rectWnd);
         rectWnd.OffsetRect(-rectWnd.left - 2, -rectWnd.top - 2); // do painting in non client area
         CDC* pDC = GetDC();
         pDC->FrameRect(&rectWnd, &m_RedFrm);
         ReleaseDC(pDC);
     }
     else
     {
         CEdit::OnNcPaint();
     }
     // TODO: Add your message handler code here
     // Do not call CEdit::OnNcPaint() for painting messages
     // WRONG! do call it if not handled by your code
 }

【讨论】：

【解决方案2】：

使用以下代码，我将自定义颜色集中在CEdit：

HBRUSH CMyDlg::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor) 
{
    HBRUSH hbr = CDialog::OnCtlColor(pDC, pWnd, nCtlColor);

    // TODO: Change any attributes of the DC here

    switch(nCtlColor)
    {
    case CTLCOLOR_EDIT:
    case CTLCOLOR_MSGBOX:
        if(IDC_EDIT_HEX == pWnd->GetDlgCtrlID())
        {
            pDC->SetBkColor(RGB(210, 210, 240));
            hbr = static_cast<HBRUSH>(m_pBrush->GetSafeHandle());
        }
        break;
    }

    // TODO: Return a different brush if the default is not desired
    return hbr;
}

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【讨论】：