This ticket proposes to add a "-textangle" option to tk/ttk label and a style option.

One aim is to have vertical tab labels for a ttk::notebook widget.

Implementation is in branch 23f52946-rotated-text. Code provided by Emiliano and Christian.

In addition, a bugfix is implemented that ttk::notebook tab flags first/last are flipped when tabs are on right or bottom side of the widget.

Examples

As noted by Christian, style "clam" is subject of first/last painting differences. So, use this style.

Vertical tabs on top

ttk::style theme use clam
ttk::style configure LTab.TNotebook.Tab -textangle 90
pack [ttk::notebook .n -style LTab.TNotebook] -fill both -expand true -padx 10 -pady 10
label .n.l1 -text label -textangle 90
.n add .n.l1 -text 1:label
ttk::label .n.l2 -text ttk::label -textangle 90
.n add .n.l2 -text 2:ttk::label

Vertical tabs on left side

ttk::style theme use clam
ttk::style configure LTab.TNotebook -tabposition ws -tabplacement se
ttk::style configure LTab.TNotebook.Tab -textangle 90
ttk::configureNotebookStyle LTab.TNotebook
pack [ttk::notebook .n -style LTab.TNotebook] -fill both -expand true -padx 10 -pady 10
label .n.l1 -text label -textangle 90
.n add .n.l1 -text 1:label
ttk::label .n.l2 -text ttk::label -textangle 90
.n add .n.l2 -text 2:ttk::label

Vertical tabs on right side

ttk::style theme use clam
ttk::style configure LTab.TNotebook -tabposition es -tabplacement sw
ttk::style configure LTab.TNotebook.Tab -textangle 90
ttk::configureNotebookStyle LTab.TNotebook
pack [ttk::notebook .n -style LTab.TNotebook] -fill both -expand true -padx 10 -pady 10
label .n.l1 -text label -textangle 90
.n add .n.l1 -text 1:label
ttk::label .n.l2 -text ttk::label -textangle 90
.n add .n.l2 -text 2:ttk::label

Vertical tabs on bottom side

ttk::style theme use clam
ttk::style configure LTab.TNotebook -tabposition sw
ttk::style configure LTab.TNotebook.Tab -textangle 90
ttk::configureNotebookStyle LTab.TNotebook
pack [ttk::notebook .n -style LTab.TNotebook] -fill both -expand true -padx 10 -pady 10
label .n.l1 -text label -textangle 90
.n add .n.l1 -text 1:label
ttk::label .n.l2 -text ttk::label -textangle 90
.n add .n.l2 -text 2:ttk::label

Discussion

Starting on 2026-01-30, there was a thread on the core list titled "Angled text". This ticket is to document the content and possibly continue here.

René

Curiosly, I looked if we could have rotated text in label, entry and button.

Currently the following functions (from tkFont.c) are used:

Tk_UnderlineTextLayout()
Tk_DrawTextLayout()

But we already have angled text functions:

TkUnderlineAngledTextLayout()
TkDrawTextLayout()

Currently the usage if #ifdef'd out.

Do anyone know the state of these functions and why they are not used?

Christian

My educated guess is they are #ifdef'd out due to performance reasons. The fact that the Tk_DrawAngledTextLayout() and friends aren't used in labels/buttons and most likely entries, too, is that for non X11 platforms the underlying native platform infrastructure is used. But maybe the ttk variants could benefit from the *AngledTextLayout() functions and provide a -angle option.

Donal

FWIW, in the original implementation of the angled text drawing for the canvas, the guts of the code draws the rotated glyphs (not characters, this is an area where we must be precise) one at a time on platforms other than macOS in order to avoid nasty cumulative grounding bugs in the positioning of the glyphs that meant that the naive approach would have glyphs not being drawn within the rotated bounding box (or even the rectilinear bounding box of that).

It was the same bug on both X11 and Windows, despite the likelihood of shared code being essentially zero. In short, the glyph positions were rounded to integer coordinates in the wrong way, so the error in positioning each glyph would accumulate over a line of text; the easiest way to implement things, but wrong!

The Tk demo of rotated canvas text that rotates the angle in 1° increments remains a pretty stringent test, and not one that had been previously tried on either platform at that time. Maybe things have been fixed since? That would be nice, as it would let us focus on widgets instead. We don't want to do things a glyph at a time, not really, but we must (or at least had to at the time).

Anyway, that's the context for why things are the way they are.

The code to split text into chunks of characters that become single glyphs is probably wrong. Inevitably. 😁

Emiliano

About:

TkUnderlineAngledTextLayout()
TkDrawTextLayout()

Those were implemented by DKF as part of TIP 119. They work on all platforms, but I can only confirm first hand that they work on X11 and Windows.

The functions works as intended. I used them in my Rbc fork here:

https://chiselapp.com/user/egavilan/repository/rbc-tk9/file?name=generic/rbcText.c&ci=tip

and their usage simplified things a lot. Of all the "Angled" family of font functions, I only used TkDrawAngledChars(), as Rbc implements its own text layout code. The only "drawback" is the inclusion of <TkInt.h> since they are not public (yet).

Christian

There's already a hidden undocumented knob named "-tabplacement". Combine it like so

ttk::style configure LTab.TNotebook -tabposition ws -tabplacement se
ttk::style configure LTab.TNotebook.Tab -textangle 90 ...

and the effect is almost as I have imagined. However, there are subtle problems in the ttk layoutery which I tried to solve in this check-in (which includes your enhancements to angled text from today):

https://androwish.org/home/info/ffcf6812d35de3b9

The most important takeaway is the reversal of the TTK_STATE_USER1 and TTK_STATE_USER2 bits depending on the placement to flag the first and last tab item, respectively, for rendering in the "clam" theme. There might still be other undetected subtle visual problems. But in principle, everything seems to be in place already.

Code import from Androwish

New branch 23f52946-rotated-text includes the code import:

• [7b003125]: Emilianos rotated label patch from https://androwish.org/home/info/de7c0ee843
• [dbc9773d]: Christians refinements from https://androwish.org/home/info/ffcf6812d35de3b9. Changes to ttkWinXPTheme.c are applied to ttkWinVistaTheme.c, State USER1/2 are now FIRST/LAST.

Fixed by TIP 751, which is merged by commit [2c172fbd]. Thanks for all. Closing bug. Harald

Thanks for the answer.

The substituted font issue is Tk bug 3249f7d4

I would love to get the TIP stabilized, one day left:

• I agree to only apply -width/-height if 0/90/180/270. It would also be ok to apply it on any angle but this is not critical.
• I would love to also have it in ttk::label -width option.

Thanks for all, Harald

Dear Emiliano, thanks for the demo. That is great.

What I observe:

• With "Courier", the font is not rotated, but always left to right. Nevertheless, the starting point and windows dimensions get rotated. It looks, like the center points are given, but it is pained from the left ("H" and "W").
• About the constraints: to change the state while animating often gives different results. It looks like the widget memories the width if constraint. If you switch constraint on and off, this changes the size. All constraints must be set on/off to get a final view without surrounding whitespace. It is hard to control and to get consistent results.
• I was not able to get a horizontal size of 1 by setting height to 1 and not setting width. It does not go below 2 in painting.
• If setting height=3 and width=1, it is getting a smaller horizontal size than when not setting height
• I don't see much use of -width and -height with rotated text. It is hard to get what it does.

I have to say, that all those are edge cases.

Thanks for all, Harald

Attached a slightly modified demo. This exercises the difference between "Courier" and "Courier New" fonts on Windows

Attached a simple demo which exercises the -width and -height constraints on a tk label with animated rotating text.

After discussion with Emiliano and Christian:

* The bug branch is re-renamed [23f52946-rotated-text] * Emilianos branch [label-angled-text] is now the tip branch [tip-751-labels-rotated-text]

Christian noted, that Emilianos branch is better suited for 9.1, while his branch is 8.6.

Thanks for all, Harald

This RFE ticket is now TIP-751. The branch was renamed to tip-751-labels-rotated-text.

Ticket [01153381] is now fixed and the corresponding code (which contains also several further notebook-related improvements) is now merged to branch 23f52946-rotated-text, too.

The notepad side paint bugfix by Christian is now in ticket [01153381].

I have made a few additions to the original text, like an example for vertical tabs on bottom side and invocations of the library procedure ttk::configureNotebookStyle, as described in the ttk_notebook man page.