Improved handling of anchors in wxHTML: scroll to better position (patch #11406).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@62674 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -716,6 +716,7 @@ All (GUI):
   new CheckFit() method for more information.
 - Allow reading GIFs with incorrectly specified animation size.
 - Return number of frames in animated GIF from wxGIFHandler::GetImageCount().
+- Improved anchors handling in wxHTML.
 
 wxGTK:
 

samples/html/test/test.htm

@@ -25,7 +25,11 @@ Agrave = 'à'
 This is - - default text, now switching to
 <CENTER>
 <P>center, now still ctr, now exiting</CENTER>
-exited!.<A HREF="#downtown">[link to down]</A>
+exited!.<A HREF="#downtown">[link to down]</A> 
+<P><A HREF="#centeredbigempty">[link to REALLY Big Text (empty anchor)]</A> 
+ <A HREF="#centeredbig">[link to REALLY Big Text (anchor containing text)]</A>
+<P> <A HREF="#parempty">[link into paragraph (empty anchor)]</A>  <A HREF="#par">[link into paragraph (anchor containing text)]</A> 
+  <A HREF="#emptycontainer">[link to empty container]</A>
 <P>Hello, this *is* default charset (helvetica, probably) and it is displayed
 with one&nbsp; <FONT COLOR="#FF0000">COLOR CHANGE</FONT>. Of course we
 can have as many color changes as we can, what about this <FONT COLOR="#FF0000">M</FONT><FONT COLOR="#FFFF00">A</FONT><FONT COLOR="#33FF33">D</FONT><B><FONT COLOR="#FFFFFF"><FONT SIZE=+1>N</FONT></FONT></B>E<FONT COLOR="#999999">S</FONT><FONT COLOR="#CC33CC">S?</FONT>
@@ -38,7 +42,8 @@ V E R Y T H I N G</U></I></B>.
 <BR>&nbsp;
 <P><BR>
 <CENTER>
-<P>Right now, <FONT COLOR="#0000FF"><FONT SIZE=+4>centered REALLY Big Text</FONT></FONT>,
+<A NAME="emptycontainer"></a>
+<P>Right now, <FONT COLOR="#0000FF"><FONT SIZE=+4><A NAME="centeredbigempty"></a><A NAME="centeredbig">centered REALLY Big Text</a></FONT></FONT>,
 how do you like (space) it?</CENTER>
 
 <DIV ALIGN=right>RIGHT: <FONT SIZE=-2>text-2, </FONT><FONT SIZE=-1>text-1,
@@ -237,14 +242,14 @@ kjegiquw iuqdb qiud iquwd hurray googoo.</FONT></LI>
 <FONT SIZE=+2>fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen
 fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen
 FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN
-fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN</FONT></LI>
+fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen <A NAME="parempty"></a><A NAME="par">(anchor here) fourteen</a> fourteen fourteen fourteen fourteenfourteen FOURTEEN</FONT></LI>
 
 <P><BR><FONT SIZE=-2>fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen
 fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen
 fourteen fourteenfourteen FOURTEEN</FONT>
 <P><FONT SIZE=-2>fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen
-fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen
+fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen fourteen fourteen fourteen fourteenfourteen FOURTEEN fourteen fourteen fourteen
-fourteenfourteen FOURTEEN</FONT>
+fourteen fourteen fourteen fourteen fourteen FOURTEEN</FONT>
 <LI>
 <FONT SIZE=-2>This is item number 15.</FONT></LI>
 </OL>

src/html/htmlwin.cpp

@@ -657,6 +657,16 @@ bool wxHtmlWindow::ScrollToAnchor(const wxString& anchor)
     }
     else
     {
+        // Go to next visible cell in current container, if it exists. This
+        // yields a bit better (even though still imperfect) results in that
+        // there's better chance of using a suitable cell for upper Y
+        // coordinate value. See bug #11406 for additional discussion.
+        const wxHtmlCell *c_save = c;
+        while ( c && c->IsFormattingCell() )
+            c = c->GetNext();
+        if ( !c )
+            c = c_save;
+
         int y;
 
         for (y = 0; c != NULL; c = c->GetParent()) y += c->GetPosY();