Horizontal autoscroll on focus does not properly scroll node into view if column width is larger than client width

[vincentparrett]

From [email protected] on December 04, 2013 20:15:41

What steps will reproduce the problem? 1. Create a virtualstringtree with header and 2 columns
2. TreeOption: toDisableAutoscrollOnFocus is FALSE, toFullRowSelect is FALSE
3. Make the width of the first column wider than the clientwidth of the treeview
4. Fill the treeview with nodes. What is the expected output? What do you see instead? I expect the focused node to become fully visible (automatic horizontal scroll to include the right margin of the node caption)
Instead the automatic horizontal scroll scrolls the right margin of the column into view. When the next node is focused, the window is scrolled to the left again. And so on. What version of the product are you using? On what operating system? 5.2.2 Please provide any additional information below. I currently work around this by patching the ScrollIntoView(node, center, horizontally) method along the following lines:

if Horizontally then
// 2) scroll horizontally
ScrolledHorizontally := ScrollIntoView(FFocusedColumn, Center);

// My patch: use the node rect for scrolling
if (R.Right > ClientWidth) then begin
VScrollBarVisible := (ScrollBarOptions.Scrollbars in [{$if CompilerVersion >=24}System.UITypes.TScrollStyle.{$ifend}ssBoth, {$if CompilerVersion >=24}System.UITypes.TScrollStyle.{$ifend}ssVertical]) and
(ScrollBarOptions.AlwaysVisible or (Integer(FRangeY) > ClientHeight));
SetOffsetX(FOffsetX - R.right + ClientWidth);
ScrolledHorizontally := TRUE;
end;
end;

Original issue: http://code.google.com/p/virtual-treeview/issues/detail?id=397

[vincentparrett]

From [email protected] on March 05, 2014 05:04:17

I'm not sure this is related but here's another horizontal scroll bug: in a combination of VST control anchors and option ScrollOnFocus we could get incorrect horizontal scroll on window maximize (see screenshots)

In brief:

• VST properties are
  object vstStations: TVirtualStringTree
  Left = 6
  Top = 15
  Width = 147
  Height = 448
  Anchors = [akLeft, akTop, akBottom]
  Header.AutoSizeIndex = 0
  Header.Font.Charset = DEFAULT_CHARSET
  Header.Font.Color = clWindowText
  Header.Font.Height = -13
  Header.Font.Name = 'Tahoma'
  Header.Font.Style = []
  Header.Options = [hoVisible]
  IncrementalSearch = isVisibleOnly
  Indent = 10
  ParentShowHint = False
  ScrollBarOptions.ScrollBars = ssVertical
  ShowHint = True
  TabOrder = 0
  Columns = <
  item
  Options = [coAllowClick, coEnabled, coParentBidiMode, coParentColor, coResizable, coShowDropMark, coVisible, coSmartResize, coAllowFocus]
  Position = 0
  Width = 143
  end>
  end
• Focus a node, maximize the window
  => you'll see unneeded scroll (screen#2).
  OR, sometimes things would seem OK, but now return the window to normal state and try selecting other node - you'll see missing repaint. Sample project attached. Bug was tested on Win7 x64 with latest trunk revision.

Attachment: VSTtest.zip screenshot 2014-03-05 002.png screenshot 2014-03-05 003.png clipboard.png

[vincentparrett]

From [email protected] on March 05, 2014 05:08:06

Additions:
#1 - screen of initial state
#2 - screen of wrong scroll
#3 - screen of missing repaint / wrong scroll

• bug doesn't occur (or maybe not noticeable) when autoscroll-on-focus option is disabled or Header is autosized.

[joachimmarder]

@Fr0sT-Brutal: Is this problem still present? Unfortunately the links are not working any longer.

[joachimmarder]

I checked the repro simply using the grid demo in the Advanced sample project. I could not find any bad behavior unless the client width is smaller than the column width, as described in repro step 3. This is why I am going to change the issue title to make this clear.

The patch seems incomplete because VScrollBarVisible is assigned but never used.