Scintilla Horizontal Scrollbar - scintilla

Question

How do I make it appear as if it were automatic like the vertical one?
The window is 300 wide so I tried setting SCI_SETSCROLLWIDTH to 300 and then less than 300 with SCI_SETSCROLLWIDTHTRACKING turned on but the scrollbar will either still always show or not show at all.

Answer 1

If you want to show/hide the horizontal SB, you need SCI_SETHSCROLLBAR(bool visible), but you need to know where the end of the line is. So you can try what I have below. It is fairly low impact since you are only looking at the currently visible lines.
Note that I use a Delphi wrapper for the scintilla control/DLL, but the calls can all be made with the regular scintilla messages (same basic names), and I have a few functions I use which are below as well. You could call this where you get the SCN_UPDATEUI message.
function GetFirstVisiblePos: Integer;
begin
Result := PositionFromPoint(0,0);
end;
function GetLastVisiblePos: Integer;
begin
Result := PositionFromPoint(clientwidth,clientheight);
end;
function GetFirstVisibleLine: Integer;
begin
Result := LineFromPosition(GetFirstVisiblePos);
end;
function GetLastVisibleLine: Integer;
begin
Result := LineFromPosition(GetLastVisiblePos);
end;
[...]
var
i: integer;
x, endPos: integer;
needHSB: boolean;
begin
if not WordWrap then //Only need to do this if not wordwrapped
begin
x := ClientWidth ;
needHSB := false;
//Check currently visible lines only
for i := GetFirstVisibleLine to GetLastVisibleLine do
begin
//GetXOffset adds left scroll spacing if we are already scrolled left some.
endPos := PointXFromPosition(GetLineEndPosition(i) ) - x + GetXOffset ;
needHSB := endPos > ClientWidth;
if needHSB then break; //once set, don't need to set again...
end;
SetHScrollBar( needHSB );
end;
end;
Try that and that should do what you are after (if I read the original question correctly). It worked for me, although I was after something a little different originally.
I needed a way to try and control the horizontal scroll width which the sci control does not do automatically (for me anyway; SCI_SETSCROLLWIDTHTRACKING seems to be what you'd use for this but I was never able to get to work (at least in the way it implies it should work in the docs). I came up with the code below. In my app the code is in SCN_UPDATEUI message area.
//Set new scroll width if there's a line longer than the current scroll
//width can show:
if not WordWrap then //Only need to do this if not wordwrapped
begin
//vars: i, x, endPos, LeftScrollPos : integer;
x := ClientWidth ;
//Check currently visible lines only
for i := GetFirstVisibleLine to GetLastVisibleLine do
begin
//GetXOffset adds extra left scroll space if we are already scrolled left some.
//24 is just a fudge factor to add a little visual space after a long line.
endPos := PointXFromPosition(GetLineEndPosition(i) ) - x + GetXOffset + 24;
if endPos > 2000 then //Greater than the control's default
if endPos > ( GetScrollWidth ) then //Only need to proceed if we need more room
begin
LeftScrollPos := GetXOffset; //Store our current left scroll position
SetScrollWidth( endPos ) ; //This sets left scroll to 0, so...
SetXOffset( LeftScrollPos ); //Restore current left scroll position
end;
end;
end;