duilib的所有控件均绘制在唯一的真实窗口之中，本篇就具体看下这个绘制的过程。所有的绘制过程均在WM_PAINT消息处理过程中完成。由窗口及消息篇可以看到，窗口消息处理最终流到了CPaintManagerUI::MessageHandler中。包括WM_PAINT在内消息均在此函数中处理，我们仅关注WM_PAINT消息
case WM_PAINT:
{
// Should we paint?
RECT rcPaint = { };
if( !::GetUpdateRect(m_hWndPaint, &rcPaint, FALSE) ) return true;
if( m_pRoot == NULL ) {
PAINTSTRUCT ps = { };
::BeginPaint(m_hWndPaint, &ps);
::EndPaint(m_hWndPaint, &ps);
return true;
}
// Do we need to resize anything?
// This is the time where we layout the controls on the form.
// We delay this even from the WM_SIZE messages since resizing can be
// a very expensize operation.
if( m_bUpdateNeeded ) {
m_bUpdateNeeded = false;
RECT rcClient = { };
::GetClientRect(m_hWndPaint, &rcClient);
if( !::IsRectEmpty(&rcClient) ) {
if( m_pRoot->IsUpdateNeeded() ) {
m_pRoot->SetPos(rcClient);
if( m_hDcOffscreen != NULL ) ::DeleteDC(m_hDcOffscreen);
if( m_hDcBackground != NULL ) ::DeleteDC(m_hDcBackground);
if( m_hbmpOffscreen != NULL ) ::DeleteObject(m_hbmpOffscreen);
if( m_hbmpBackground != NULL ) ::DeleteObject(m_hbmpBackground);
m_hDcOffscreen = NULL;
m_hDcBackground = NULL;
m_hbmpOffscreen = NULL;
m_hbmpBackground = NULL;
}
else {
CControlUI* pControl = NULL;
while( pControl = m_pRoot->FindControl(__FindControlFromUpdate, NULL, UIFIND_VISIBLE | UIFIND_ME_FIRST) ) {
pControl->SetPos( pControl->GetPos() );
}
}
// We'll want to notify the window when it is first initialized
// with the correct layout. The window form would take the time
// to submit swipes/animations.
if( m_bFirstLayout ) {
m_bFirstLayout = false;
SendNotify(m_pRoot, _T("windowinit"), , , false);
}
}
}
// Set focus to first control?
if( m_bFocusNeeded ) {
SetNextTabControl();
}
//
// Render screen
//
// Prepare offscreen bitmap?
if( m_bOffscreenPaint && m_hbmpOffscreen == NULL )
{
RECT rcClient = { };
::GetClientRect(m_hWndPaint, &rcClient);
m_hDcOffscreen = ::CreateCompatibleDC(m_hDcPaint);
m_hbmpOffscreen = ::CreateCompatibleBitmap(m_hDcPaint, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top);
ASSERT(m_hDcOffscreen);
ASSERT(m_hbmpOffscreen);
}
// Begin Windows paint
PAINTSTRUCT ps = { };
::BeginPaint(m_hWndPaint, &ps);
if( m_bOffscreenPaint )
{
HBITMAP hOldBitmap = (HBITMAP) ::SelectObject(m_hDcOffscreen, m_hbmpOffscreen);
int iSaveDC = ::SaveDC(m_hDcOffscreen);
if( m_bAlphaBackground ) {
if( m_hbmpBackground == NULL ) {
RECT rcClient = { };
::GetClientRect(m_hWndPaint, &rcClient);
m_hDcBackground = ::CreateCompatibleDC(m_hDcPaint);;
m_hbmpBackground = ::CreateCompatibleBitmap(m_hDcPaint, rcClient.right - rcClient.left, rcClient.bottom - rcClient.top);
ASSERT(m_hDcBackground);
ASSERT(m_hbmpBackground);
::SelectObject(m_hDcBackground, m_hbmpBackground);
::BitBlt(m_hDcBackground, ps.rcPaint.left, ps.rcPaint.top, ps.rcPaint.right - ps.rcPaint.left,
ps.rcPaint.bottom - ps.rcPaint.top, ps.hdc, ps.rcPaint.left, ps.rcPaint.top, SRCCOPY);
}
else
::SelectObject(m_hDcBackground, m_hbmpBackground);
::BitBlt(m_hDcOffscreen, ps.rcPaint.left, ps.rcPaint.top, ps.rcPaint.right - ps.rcPaint.left,
ps.rcPaint.bottom - ps.rcPaint.top, m_hDcBackground, ps.rcPaint.left, ps.rcPaint.top, SRCCOPY);
}
m_pRoot->DoPaint(m_hDcOffscreen, ps.rcPaint);//绘制控件
for( int i = ; i < m_aPostPaintControls.GetSize(); i++ ) {
CControlUI* pPostPaintControl = static_cast<CControlUI*>(m_aPostPaintControls[i]);
pPostPaintControl->DoPostPaint(m_hDcOffscreen, ps.rcPaint);
}
::RestoreDC(m_hDcOffscreen, iSaveDC);
::BitBlt(ps.hdc, ps.rcPaint.left, ps.rcPaint.top, ps.rcPaint.right - ps.rcPaint.left,
ps.rcPaint.bottom - ps.rcPaint.top, m_hDcOffscreen, ps.rcPaint.left, ps.rcPaint.top, SRCCOPY);
::SelectObject(m_hDcOffscreen, hOldBitmap); if( m_bShowUpdateRect ) {
HPEN hOldPen = (HPEN)::SelectObject(ps.hdc, m_hUpdateRectPen);
::SelectObject(ps.hdc, ::GetStockObject(HOLLOW_BRUSH));
::Rectangle(ps.hdc, rcPaint.left, rcPaint.top, rcPaint.right, rcPaint.bottom);
::SelectObject(ps.hdc, hOldPen);
}
}
else
{
// A standard paint job
int iSaveDC = ::SaveDC(ps.hdc);
m_pRoot->DoPaint(ps.hdc, ps.rcPaint);//绘制控件
::RestoreDC(ps.hdc, iSaveDC);
}
// All Done!
::EndPaint(m_hWndPaint, &ps);
}
// If any of the painting requested a resize again, we'll need
// to invalidate the entire window once more.
if( m_bUpdateNeeded ) {
::InvalidateRect(m_hWndPaint, NULL, FALSE);
}
return true;
在::BeginPaint(m_hWndPaint, &ps)和::EndPaint(m_hWndPaint, &ps)中间是窗口绘制部分，duilib包含了两种方式：双缓存方式（解决闪烁问题）和标准方式，默认为双缓存方式。两种方式最终都调用了m_pRoot->DoPaint，m_pRoot为控件容器，且DoPaint为虚函数，实际调用了CContainerUI::DoPaint
void CContainerUI::DoPaint(HDC hDC, const RECT& rcPaint)
{
RECT rcTemp = { };
if( !::IntersectRect(&rcTemp, &rcPaint, &m_rcItem) ) return; CRenderClip clip;
CRenderClip::GenerateClip(hDC, rcTemp, clip);
CControlUI::DoPaint(hDC, rcPaint); if( m_items.GetSize() > ) {
RECT rc = m_rcItem;
rc.left += m_rcInset.left;
rc.top += m_rcInset.top;
rc.right -= m_rcInset.right;
rc.bottom -= m_rcInset.bottom;
if( m_pVerticalScrollBar && m_pVerticalScrollBar->IsVisible() ) rc.right -= m_pVerticalScrollBar->GetFixedWidth();
if( m_pHorizontalScrollBar && m_pHorizontalScrollBar->IsVisible() ) rc.bottom -= m_pHorizontalScrollBar->GetFixedHeight(); if( !::IntersectRect(&rcTemp, &rcPaint, &rc) ) {
for( int it = ; it < m_items.GetSize(); it++ ) {
CControlUI* pControl = static_cast<CControlUI*>(m_items[it]);
if( !pControl->IsVisible() ) continue;
if( !::IntersectRect(&rcTemp, &rcPaint, &pControl->GetPos()) ) continue;
if( pControl ->IsFloat() ) {
if( !::IntersectRect(&rcTemp, &m_rcItem, &pControl->GetPos()) ) continue;
pControl->DoPaint(hDC, rcPaint);
}
}
}
else {
CRenderClip childClip;
CRenderClip::GenerateClip(hDC, rcTemp, childClip);
for( int it = ; it < m_items.GetSize(); it++ ) {
CControlUI* pControl = static_cast<CControlUI*>(m_items[it]);
if( !pControl->IsVisible() ) continue;
if( !::IntersectRect(&rcTemp, &rcPaint, &pControl->GetPos()) ) continue;
if( pControl ->IsFloat() ) {
if( !::IntersectRect(&rcTemp, &m_rcItem, &pControl->GetPos()) ) continue;
CRenderClip::UseOldClipBegin(hDC, childClip);
pControl->DoPaint(hDC, rcPaint);
CRenderClip::UseOldClipEnd(hDC, childClip);
}
else {
if( !::IntersectRect(&rcTemp, &rc, &pControl->GetPos()) ) continue;
pControl->DoPaint(hDC, rcPaint);
}
}
}
} if( m_pVerticalScrollBar != NULL && m_pVerticalScrollBar->IsVisible() ) {
if( ::IntersectRect(&rcTemp, &rcPaint, &m_pVerticalScrollBar->GetPos()) ) {
m_pVerticalScrollBar->DoPaint(hDC, rcPaint);
}
} if( m_pHorizontalScrollBar != NULL && m_pHorizontalScrollBar->IsVisible() ) {
if( ::IntersectRect(&rcTemp, &rcPaint, &m_pHorizontalScrollBar->GetPos()) ) {
m_pHorizontalScrollBar->DoPaint(hDC, rcPaint);
}
}
}
控件容器绘制完自己后，遍历子控件（包括子控件容器）调用其DoPaint，完成子控件绘制
void CControlUI::DoPaint(HDC hDC, const RECT& rcPaint)
{
if( !::IntersectRect(&m_rcPaint, &rcPaint, &m_rcItem) ) return; // 绘制循序：背景颜色->背景图->状态图->文本->边框
if( m_cxyBorderRound.cx > || m_cxyBorderRound.cy > ) {
CRenderClip roundClip;
CRenderClip::GenerateRoundClip(hDC, m_rcPaint, m_rcItem, m_cxyBorderRound.cx, m_cxyBorderRound.cy, roundClip);
PaintBkColor(hDC);
PaintBkImage(hDC);
PaintStatusImage(hDC);
PaintText(hDC);
PaintBorder(hDC);
}
else {
PaintBkColor(hDC);
PaintBkImage(hDC);
PaintStatusImage(hDC);
PaintText(hDC);
PaintBorder(hDC);
}
}
最终的绘制都是通过渲染引擎CRenderEngine实现的。
这样看来，整个绘制思路还是很清晰的：CPaintManagerUI::MessageHandler（WM_PAINT）--->CContainerUI::DoPaint--->CControlUI::DoPaint--->CRenderEngine。