duilib中的V和H布局中滚动条问题

转自博客：http://blog.csdn.net/damingg/article/details/41149037

首先看一段xml代码

 <?xml version="1.0" encoding="utf-8"?>
<Window size="300,200" caption="0,0,300,20">
    <HorizontalLayout name="aaaa" bkcolor="#FFEEEEEE" >

        <VerticalLayout name="xxxxxx" float="true" pos="50,20,250,195" hscrollbar="true" vscrollbar="true" sepheight="4" >

            <Label name="child1" text="text1" float="false" pos="0,0,300,200" bordercolor="#FFEE00EE" bkcolor="#FF0000EE" textcolor="#FF010101"/>
            <Label name="child2" text="text2" float="false" pos="0,0,200,200" bordercolor="#FFEE00EE" bkcolor="#FF0000EE" textcolor="#FF01FF01"/>

        </VerticalLayout>

    </HorizontalLayout>
</Window>

这是一个窗口，它包含一个竖的布局，显示出来初始状态是这样的：

在布局中，2个子控件所需要的长和宽，比布局本身的大小要大，所以需要2个滚动条来拉动显示。

我们可以看到横竖两个滚动条。

不过，我们拉动滚动条，却不能完全展示子控件。如下图：

虽然横向滚动条拉到了最右边，但Label控件child1的右边没有展示出来。

检查代码，发现CVerticalLayoutUI的SetPos方法如下：

void CVerticalLayoutUI::SetPos(RECT rc)
{
    ...省略若干代码

    // Process the scrollbar
    ProcessScrollBar(rc, 0, cyNeeded);
}

在最后面，调用了基类CContainerUI的ProcessScrollBar方法，来设置滚动条信息，ProcessScrollBar函数的第二个参数是设置横向滚动条信息，第三个参数是竖向滚动条。此时设置横向的参数为0，竖向的是cyNeeded。显然，这里忽略了横向的，所以在竖向布局VerticalLayout中，横向滚动条不能正常显示。

在CVerticalLayoutUI::SetPos中，所有涉及到cyNeeded的代码如下：

int cyNeeded = 0;
        int cyExpand = 0;
        if( nAdjustables > 0 ) cyExpand = MAX(0, (szAvailable.cy - cyFixed) / nAdjustables);
        // Position the elements
        SIZE szRemaining = szAvailable;
        int iPosY = rc.top;
        if( m_pVerticalScrollBar && m_pVerticalScrollBar->IsVisible() ) {
            iPosY -= m_pVerticalScrollBar->GetScrollPos();
        }
        int iPosX = rc.left;
        if( m_pHorizontalScrollBar && m_pHorizontalScrollBar->IsVisible() ) {
            iPosX -= m_pHorizontalScrollBar->GetScrollPos();
        }
        int iAdjustable = 0;
        int cyFixedRemaining = cyFixed;
        for( int it2 = 0; it2 < m_items.GetSize(); it2++ ) {
            CControlUI* pControl = static_cast<CControlUI*>(m_items[it2]);
            if( !pControl->IsVisible() ) continue;
            if( pControl->IsFloat() ) {
                SetFloatPos(it2);
                continue;
            }

            RECT rcPadding = pControl->GetPadding();
            szRemaining.cy -= rcPadding.top;
            SIZE sz = pControl->EstimateSize(szRemaining);
            if( sz.cy == 0 ) {
                iAdjustable++;
                sz.cy = cyExpand;
                // Distribute remaining to last element (usually round-off left-overs)
                if( iAdjustable == nAdjustables ) {
                    sz.cy = MAX(0, szRemaining.cy - rcPadding.bottom - cyFixedRemaining);
                }
                if( sz.cy < pControl->GetMinHeight() ) sz.cy = pControl->GetMinHeight();
                if( sz.cy > pControl->GetMaxHeight() ) sz.cy = pControl->GetMaxHeight();
            }
            else {
                if( sz.cy < pControl->GetMinHeight() ) sz.cy = pControl->GetMinHeight();
                if( sz.cy > pControl->GetMaxHeight() ) sz.cy = pControl->GetMaxHeight();
                cyFixedRemaining -= sz.cy;
            }

            sz.cx = pControl->GetFixedWidth();
            if( sz.cx == 0 ) sz.cx = szAvailable.cx - rcPadding.left - rcPadding.right;
            if( sz.cx < 0 ) sz.cx = 0;
            if( sz.cx < pControl->GetMinWidth() ) sz.cx = pControl->GetMinWidth();
            if( sz.cx > pControl->GetMaxWidth() ) sz.cx = pControl->GetMaxWidth();

            RECT rcCtrl = { iPosX + rcPadding.left, iPosY + rcPadding.top, iPosX + rcPadding.left + sz.cx, iPosY + sz.cy + rcPadding.top + rcPadding.bottom };
            pControl->SetPos(rcCtrl);

            iPosY += sz.cy + m_iChildPadding + rcPadding.top + rcPadding.bottom;
            cyNeeded += sz.cy + rcPadding.top + rcPadding.bottom;
            szRemaining.cy -= sz.cy + m_iChildPadding + rcPadding.bottom;
        }
        cyNeeded += (nEstimateNum - 1) * m_iChildPadding;

在for循环里，会统计所有非float子控件的高度

在  cyNeeded += sz.cy + rcPadding.top + rcPadding.bottom;  里，sz.cy是1个子控件的高度，而rcPadding = pControl->GetPadding(); 是控件的padding属性，也就是外边距。

最后yNeeded += (nEstimateNum - 1) * m_iChildPadding;  m_iChildPadding是布局的childpadding属性，也就是子控件之间的额外距离。

我们可以仿照cyNeeded的计算方式，来算出cxNeeded。因为是竖向布局，所以 cyNeeded += sz.cy 这里是累加，但是横向值，应该取最宽的控件的值，

所以for循环中的代码应该是这样：

int tmp = sz.cx + rcPadding.left + rcPadding.right;
cxNeeded = (tmp > cxNeeded) ? tmp: cxNeeded;

最后cxNeeded += (nEstimateNum - 1) * m_iChildPadding;

    此时通过对代码的了解，可以得知：布局在计算容量面积时，只计算非float类型的子控件，忽略了float类型的子控件。

算出了布局的宽度后，就应用起来

修改原来的代码为：ProcessScrollBar(rc, cxNeeded, cyNeeded);

改完后，发现问题依然。于是，检查了下ProcessScrollBar的代码，如下

void CContainerUI::ProcessScrollBar(RECT rc, int cxRequired, int cyRequired)
{
    if( m_pHorizontalScrollBar != NULL && m_pHorizontalScrollBar->IsVisible() ) {
        RECT rcScrollBarPos = { rc.left, rc.bottom, rc.right, rc.bottom + m_pHorizontalScrollBar->GetFixedHeight()};
        m_pHorizontalScrollBar->SetPos(rcScrollBarPos);
    }

    if( m_pVerticalScrollBar == NULL ) return;

    if( cyRequired > rc.bottom - rc.top && !m_pVerticalScrollBar->IsVisible() ) {
        m_pVerticalScrollBar->SetVisible(true);
        m_pVerticalScrollBar->SetScrollRange(cyRequired - (rc.bottom - rc.top));
        m_pVerticalScrollBar->SetScrollPos(0);
        m_bScrollProcess = true;
        SetPos(m_rcItem);
        m_bScrollProcess = false;
        return;
    }
    // No scrollbar required
    if( !m_pVerticalScrollBar->IsVisible() ) return;

    // Scroll not needed anymore?
    int cyScroll = cyRequired - (rc.bottom - rc.top);
    if( cyScroll <= 0 && !m_bScrollProcess) {
        m_pVerticalScrollBar->SetVisible(false);
        m_pVerticalScrollBar->SetScrollPos(0);
        m_pVerticalScrollBar->SetScrollRange(0);
        SetPos(m_rcItem);
    }
    else
    {
        RECT rcScrollBarPos = { rc.right, rc.top, rc.right + m_pVerticalScrollBar->GetFixedWidth(), rc.bottom };
        m_pVerticalScrollBar->SetPos(rcScrollBarPos);

        if( m_pVerticalScrollBar->GetScrollRange() != cyScroll ) {
            int iScrollPos = m_pVerticalScrollBar->GetScrollPos();
            m_pVerticalScrollBar->SetScrollRange(::abs(cyScroll));
            if( m_pVerticalScrollBar->GetScrollRange() == 0 ) {
                m_pVerticalScrollBar->SetVisible(false);
                m_pVerticalScrollBar->SetScrollPos(0);
            }
            if( iScrollPos > m_pVerticalScrollBar->GetScrollPos() ) {
                SetPos(m_rcItem);
            }
        }
    }
}

很明显，cxRequired根本没有用到。

对于横向滚动条，只使用了这3行代码：

if( m_pHorizontalScrollBar != NULL && m_pHorizontalScrollBar->IsVisible() ) {
    RECT rcScrollBarPos = { rc.left, rc.bottom, rc.right, rc.bottom + m_pHorizontalScrollBar->GetFixedHeight()};
    m_pHorizontalScrollBar->SetPos(rcScrollBarPos);
}

于是，我们需要仿照设置竖向滚动条的方式，来设置横向滚动条：

void CContainerUI::ProcessScrollBar(RECT rc, int cxRequired, int cyRequired)
{
    while(m_pHorizontalScrollBar)
    {
        if (cxRequired > rc.right - rc.left && !m_pHorizontalScrollBar->IsVisible())
        {
            m_pHorizontalScrollBar->SetVisible(true);
            m_pHorizontalScrollBar->SetScrollRange(cxRequired - (rc.right - rc.left));
            m_pHorizontalScrollBar->SetScrollPos(0);
            m_bScrollProcess = true;
            SetPos(m_rcItem);
            m_bScrollProcess = false;
            break;
        }

        if( !m_pHorizontalScrollBar->IsVisible() ) break;

        int cxScroll = cxRequired - (rc.right - rc.left);
        if (cxScroll <= 0 && !m_bScrollProcess)
        {
            m_pHorizontalScrollBar->SetVisible(false);
            m_pHorizontalScrollBar->SetScrollPos(0);
            m_pHorizontalScrollBar->SetScrollRange(0);
            SetPos(m_rcItem);
        }
        else
        {
            RECT rcScrollBarPos = { rc.left, rc.bottom, rc.right, rc.bottom + m_pHorizontalScrollBar->GetFixedHeight() };
            m_pHorizontalScrollBar->SetPos(rcScrollBarPos);

            if( m_pHorizontalScrollBar->GetScrollRange() != cxScroll ) {
                int iScrollPos = m_pHorizontalScrollBar->GetScrollPos();
                m_pHorizontalScrollBar->SetScrollRange(::abs(cxScroll));
                if( m_pHorizontalScrollBar->GetScrollRange() == 0 ) {
                    m_pHorizontalScrollBar->SetVisible(false);
                    m_pHorizontalScrollBar->SetScrollPos(0);
                }
                if( iScrollPos > m_pHorizontalScrollBar->GetScrollPos() ) {
                    SetPos(m_rcItem);
                }
            }
        }
        break;
    }

    while(m_pVerticalScrollBar)
    {
        if( cyRequired > rc.bottom - rc.top && !m_pVerticalScrollBar->IsVisible() ) {
            m_pVerticalScrollBar->SetVisible(true);
            m_pVerticalScrollBar->SetScrollRange(cyRequired - (rc.bottom - rc.top));
            m_pVerticalScrollBar->SetScrollPos(0);
            m_bScrollProcess = true;
            SetPos(m_rcItem);
            m_bScrollProcess = false;
            break;
        }
        // No scrollbar required
        if( !m_pVerticalScrollBar->IsVisible() ) break;

        // Scroll not needed anymore?
        int cyScroll = cyRequired - (rc.bottom - rc.top);
        if( cyScroll <= 0 && !m_bScrollProcess) {
            m_pVerticalScrollBar->SetVisible(false);
            m_pVerticalScrollBar->SetScrollPos(0);
            m_pVerticalScrollBar->SetScrollRange(0);
            SetPos(m_rcItem);
        }
        else
        {
            RECT rcScrollBarPos = { rc.right, rc.top, rc.right + m_pVerticalScrollBar->GetFixedWidth(), rc.bottom };
            m_pVerticalScrollBar->SetPos(rcScrollBarPos);

            if( m_pVerticalScrollBar->GetScrollRange() != cyScroll ) {
                int iScrollPos = m_pVerticalScrollBar->GetScrollPos();
                m_pVerticalScrollBar->SetScrollRange(::abs(cyScroll));
                if( m_pVerticalScrollBar->GetScrollRange() == 0 ) {
                    m_pVerticalScrollBar->SetVisible(false);
                    m_pVerticalScrollBar->SetScrollPos(0);
                }
                if( iScrollPos > m_pVerticalScrollBar->GetScrollPos() ) {
                    SetPos(m_rcItem);
                }
            }
        }
        break;
    }
}

看看效果

可以看到控件child1的右边框。

HorizontalLayout也有同样的问题，可类似修改。