在自定义 ComboBox 中绘制文本 [英] Drawing text in a custom ComboBox

问题描述

我正在创建一个新的 CComboBox 派生类，以便绘制其所有区域并使其更具可定制性.我能够绘制它的所有区域，并可以绘制其下拉列表的文本.但是，我不知道如何在控件内绘制文本.不知道为什么，控件的文字没有出现.有谁能够帮我?

I'm creating a new CComboBox-derived class in order to paint all its regions and make it more customizable. I'm able to paint all it's areas and can draw the text of its drop down list. However, I don't know what to do to draw the text inside the control. I don't know why, the text of the control does not appear. Can anybody help me?

头文件

class CEasyComboBox : public CComboBox
{
private:
    bool m_IsMouseOver; // Defines if the mouse is over the control.
    bool m_bDropDownListStyle;  // Type of the drop down list.
    bool m_bIsButtonClick;  // Defines if the button of the object has been clicked or not.
    COLORREF m_clrBack; // Color of the background of the color.
    COLORREF m_clrText; // Color of the text of the control.
    COLORREF m_clrBorder;   // Color of the border of the control.
    COLORREF m_clrArrow;    // Color of the arrow of the control.

public:
    CEasyComboBox();    // Constructor
    virtual ~CEasyComboBox();   // Destructor
    afx_msg void OnMouseLeave();    // Called when the mouse leaves the control.
    afx_msg void OnMouseMove(UINT nFlags, CPoint point);    // Called everytime the mouse changes its location on the control.

protected:
    afx_msg HBRUSH OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor);    // Defines the colors of all existing elements of the control.
    afx_msg void OnPaint(); // Paints the control.
    afx_msg void OnLButtonDown(UINT nFlags, CPoint point);  // Called when user clicks on left button of the mouse.
    DECLARE_MESSAGE_MAP()

private:
    void SetColors();   // Sets all colors of the control.
};

Cpp 文件

CEasyComboBox::CEasyComboBox()
{
    // I set all colros:
    SetColors();
}

CEasyComboBox::~CEasyComboBox()
{
}

BEGIN_MESSAGE_MAP(CEasyComboBox, CComboBox)
    ON_WM_CTLCOLOR()
    ON_WM_PAINT()
    ON_WM_LBUTTONDOWN()
    ON_WM_MOUSELEAVE()
    ON_WM_MOUSEMOVE()
END_MESSAGE_MAP()

void CEasyComboBox::SetColors()
{
    // I define all colors of the object.
    m_clrText = GENERIC_TEXT_COLOR;
    m_clrBack = GENERIC_BACKGROUND_COLOR;
    m_clrBorder = GENERIC_BORDER_COLOR;

    // Depending on the mouse, I define the colrs.
    if (m_IsMouseOver == true)
    {
        // I define all new colors.
        m_clrBack = RGB(86, 81, 78);
    }

    // I define the color of the arrow equal as the borders.
    m_clrArrow = m_clrText;
}

// CEasyComboBox message handlers

HBRUSH CEasyComboBox::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
    // I check which control is going to be painted.
    pDC->SetBkColor(m_clrBack);
    pDC->SetTextColor(m_clrText);
    HBRUSH hbr = CComboBox::OnCtlColor(pDC, pWnd, nCtlColor);
    return hbr;
}

void CEasyComboBox::OnPaint()
{
    // I generate all requiered objects.
    CPaintDC dc(this);
    CRect ClientRect;
    GetClientRect(&ClientRect);

    // I paint the background of the combobox and its borders.
    CBrush brush(m_clrBack);
    CBrush* pOldBrush = dc.SelectObject(&brush);
    dc.FillSolidRect(ClientRect, m_clrBorder);
    ClientRect.DeflateRect(1, 1);
    dc.FillRect(ClientRect, &brush);

    // Depending on the stype of the element, I finish the painting.
    DWORD dwComboStyle = GetStyle();
    BYTE byteComboStyle = (BYTE)dwComboStyle;
    if (byteComboStyle == CBS_SIMPLE)
    {
        dc.SelectObject(pOldBrush);
        return;
    }

    // I resize the client rect.
    int nButtonWidth = ::GetSystemMetrics(SM_CYSIZE);
    DWORD dwExStyles = GetExStyle();
    if (dwExStyles & WS_EX_RIGHT) ClientRect.right = ClientRect.left + nButtonWidth;
    else ClientRect.left = ClientRect.right - nButtonWidth + 4;

    // I draw the button if the mouse is over.
    if (m_IsMouseOver == true) dc.FillSolidRect(&ClientRect, m_clrBorder);
    else dc.FillSolidRect(ClientRect, m_clrBack);

    // I draw the arrow.
    CPoint CenterPoint(ClientRect.CenterPoint());
    ++CenterPoint.y;
    CPoint UpperPoint(CenterPoint.x, CenterPoint.y - 4);
    CPen Pen(PS_SOLID, 1, m_clrArrow);
    CPen* pOldPen = dc.SelectObject(&Pen);
    for (int i = 0; i < 4; ++i)
    {
        dc.MoveTo(CenterPoint);
        VERIFY(dc.LineTo(UpperPoint));

        --CenterPoint.x;
        --CenterPoint.y;
        --UpperPoint.x;
    }

    CenterPoint = ClientRect.CenterPoint();
    ++CenterPoint.y;
    UpperPoint = CenterPoint;
    UpperPoint.y -= 4;
    for (int i = 0; i < 4; ++i)
    {
        dc.MoveTo(CenterPoint);
        VERIFY(dc.LineTo(UpperPoint));

        ++CenterPoint.x;
        --CenterPoint.y;
        ++UpperPoint.x;
    }

    dc.SelectObject(pOldBrush);
    dc.SelectObject(pOldPen);
}

void CEasyComboBox::OnLButtonDown(UINT nFlags, CPoint point)
{
    //the combo gets this message when its Button is pressed
    m_bIsButtonClick = !m_bIsButtonClick;
    CComboBox::OnLButtonDown(nFlags, point);
}

void CEasyComboBox::OnMouseLeave()
{
    // I define the state of the variable.
    m_IsMouseOver = false;
    SetColors();
    CComboBox::OnMouseLeave();
}

void CEasyComboBox::OnMouseMove(UINT nFlags, CPoint point)
{
    // I define the state of the variable.
    if(m_IsMouseOver == false)
    {
        m_IsMouseOver = true;
        SetColors();
    }
    CComboBox::OnMouseMove(nFlags, point);
}

推荐答案

我为你改编了一些我在旧项目中已经做过的事情:

I adapte for you some thing that i have already done in a old project :

HBRUSH CHSpellComboBox::OnCtlColor(CDC* pDC, CWnd* pWnd, UINT nCtlColor)
{
    HBRUSH hBGBrush = CComboBox::OnCtlColor(pDC, pWnd, nCtlColor); 
    switch (nCtlColor)
    {
    case CTLCOLOR_LISTBOX :
        pDC->SetBkColor(RGB(200,0,0));
        break;
    }

    pDC->SetTextColor(RGB(255,255,255));
    hBGBrush = CreateSolidBrush(RGB (0,200,0));

    return hBGBrush;
}

结果:

• 文本颜色:灰色 (255,255,255)
• 文本背景:红色 (255,0,0)
• 组合框区域:绿色 (0,255,0)

这篇关于在自定义 ComboBox 中绘制文本的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！