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。