Bug 106077 – [Qt] When frame flattening，drag scrollbar, then click link to goto next frame, the page scroll offset is preserved

• Component: Frames
• Status: RESOLVED INVALID

[Chen Zhixiang]

Created attachment 181280 [details]
Simple test case for this bug

Use QtWebKit's demos/browser to test:
Enable frame flattening，
Then drag scrollbar,
then click link in frame to change its src to jump to new frame
(The whole frameset/URL is not changed)
However,
the page's scroll offset is prerved
It should be reset

If disable frame flattening，
The behavor is right:
(1) When click to navigate to new frame, the page scroll offset is reset to 0
(2) Use History's go back, the prevous frame's page scroll offset is still preserved.

[Chen Zhixiang]

Could any one work on QtWebKit give some hints or help? 3x

[Chen Zhixiang]

I've tried set ScrollView::setScrollOffset( IntPoint() ),
or use ScrollView::setScrollPosition( IntPoint() )
But nothing happened

I'm not familiar with WebKit's layout mechanism,
So, .... Please help!

[Chen Zhixiang]

Seems related to Bug 57898.

[Chen Zhixiang]

I've tried add code in void MainResourceLoader::didFinishLoading(double finishTime) , but it doesn't work.

+   frameLoader()->frame()->view()->setScrollPosition( IntPoint() );
+   frameLoader()->frame()->view()->updateScrollbars();

    ASSERT(!documentLoader()->timing()->responseEnd);
    documentLoader()->timing()->responseEnd = finishTime ? finishTime : (m_timeOfLastDataReceived ? m_timeOfLastDataReceived : currentTime());
    frameLoader()->finishedLoading();
    ResourceLoader::didFinishLoading(finishTime);

I'm not customed to webcore's internal layout/painting mechanism, please help!

[Chen Zhixiang]

Try to patch FrameLoader::checkLoadCompleteForThisFrame()（ which calls history()->restoreScrollPositionAndViewState() ）also failed: (Doesn't know why not works):

            // If the user had a scroll point, scroll to it, overriding the anchor point if any.
            if (m_frame->page()) {
                if (isBackForwardLoadType(m_loadType) || m_loadType == FrameLoadTypeReload || m_loadType == FrameLoadTypeReloadFromOrigin)
                    history()->restoreScrollPositionAndViewState();
+                else{
+                    if (FrameView* view = m_frame->view()) {
+                        if (!view->wasScrolledByUser()) {
+                            view->setScrollPosition( IntPoint() );
+                        }
+                    }
+                }
            }

[Chen Zhixiang]

However, if i use the below code, the scrollposition can be reset:


in WebView::loadFinished():

    QWebFrame* pMainFrame = m_page->mainFrame();
    pMainFrame->scroll(0, -2000);

Then why does setScrollPosition( IntPoint() ) NOT effect?

[Chen Zhixiang]

Hey, I've found the reason why setScrollPosition doesn't effect:

The reason is setScrollPosition should be called on main frame ( when do frame flattening, ONLY main frame has the scroll bar)

The fix based on qt-4.8.4: 

d:\qt-everywhere-opensource-src-4.8.4\src\3rdparty\webkit\Source\WebKit\qt\WebCoreSupport\FrameLoaderClientQt.cpp 

//This function is called back after a frame's load & layout is done, adjust the main frame's scroll position if load type is standard;
void FrameLoaderClientQt::dispatchDidLoadMainResource(DocumentLoader* documentLoader) 
{ 
    Frame* frame = documentLoader->frame(); 
    FrameLoader* frameLoader = documentLoader->frameLoader(); 
    if( frame && frameLoader ){ 
        Frame* mainFrame = frame->page()->mainFrame(); 
        if( FrameView* view = mainFrame->view() ){ 
            FrameLoadType loadType = frameLoader->loadType(); 
            if( loadType==FrameLoadTypeStandard ){ 
                //no matter whether frame flattening is enabled, reset scroll position as soon as loadType is standard; 
                view->setScrollPosition( IntPoint() ); 
            } 
        } 
    } 
}

[Chen Zhixiang]

Considering new frame may contain fragment( f.html#anchorNode ), then reset to zero may be not correct), new fix:

void FrameLoaderClientQt::dispatchDidLoadMainResource(DocumentLoader* documentLoader) 
{ 
    Frame* frame = documentLoader->frame(); 
    if( frame->settings() && frame->settings()->frameFlatteningEnabled() ){ 
        FrameLoader* frameLoader = documentLoader->frameLoader(); 
        FrameLoadType loadType = FrameLoadTypeStandard;//default as normal load; 
        if( frameLoader ) 
            loadType = frameLoader->loadType(); 
        if( Frame* mainFrame = frame->page()->mainFrame() ){ 
            if( FrameView* mainFrameView = mainFrame->view() ){ 
                IntPoint scrollPosition;//default as zero; 
                if( FrameView* frameView = frame->view() ){ 
                    scrollPosition = frameView->scrollPosition(); 
                    //get this new frame's scroll position as it may have fragment( a.html#anchorNode ); 
                } 
                if( loadType==FrameLoadTypeStandard ){ 
                    //no matter whether frame flattening is enable, reset scroll position as soon as loadType is standard; 
                    mainFrameView->setScrollPosition( scrollPosition ); 
                } 
            } 
        } 
    } 
}

[Chen Zhixiang]

The final fix:

void FrameLoaderClientQt::dispatchDidLoadMainResource(DocumentLoader* documentLoader)
{
    Frame* frame = documentLoader->frame();
    if( frame && frame->settings() && frame->settings()->frameFlatteningEnabled() ){
        FrameLoader* frameLoader = documentLoader->frameLoader();
        if( frameLoader && frameLoader->loadType()== FrameLoadTypeStandard ){
            if( Frame* mainFrame = frame->page()->mainFrame() ){
                FrameView* mainFrameView = mainFrame->view();
                if( mainFrameView )
                    mainFrameView->setScrollPosition( IntPoint() );
            }
        }
    }
}

The case that frame has fragment works OK, so i dont need to consider it. Thanks giving day!

[Jocelyn Turcotte]

=== Bulk closing of Qt bugs ===

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