Selection of structures results in thick black lines

[hpretl]

When I use KLayout 0.29.8 inside a Docker VM based on Ubuntu 22.04LTS, and when I am on a Arm-based Mac (not happening on Intel-based Macs) then I get a thick black selection frame when clicking on a layout structure:

Interestingly, when I hover the mouse over a structure, there is also a black line indicating a to-be selected layout structure, but this black “frame” looks OK:

@klayoutmatthias Any idea what is going on? The problem is that this thick black border on selected items is really annoying, as it overlays other things that would be necessary to see. All other graphical elements in KLayout look fine, just this selection border is too wide.

As a side note, turning off “with halo” or playing around with line width in the Setup Selection does not help.

[martinjankoehler]

FYI, I can also reproduce it using VNC (instead of X11).

It also seems those settings are ignored:

• Line Width
• Vertex Size
• With Halo

whereas Color and Marker fill work.

[martinjankoehler]

Hey @klayoutmatthias,

I did some printf-Logging around

klayout/src/laybasic/laybasic/layMarker.cc

Line 326 in b4dabe2

int line_width = m_line_width < 0 ? mp_view->default_marker_line_width () : m_line_width;

Diff:

diff --git a/src/laybasic/laybasic/layMarker.cc b/src/laybasic/laybasic/layMarker.cc
index 2f08d2289..a7bf71037 100644
--- a/src/laybasic/laybasic/layMarker.cc
+++ b/src/laybasic/laybasic/layMarker.cc
@@ -329,6 +329,10 @@ MarkerBase::get_bitmaps (const Viewport & /*vp*/, ViewObjectCanvas &canvas, lay:
   int dither_pattern = m_dither_pattern < 0 ? mp_view->default_dither_pattern () : m_dither_pattern;
   int line_style = m_line_style < 0 ? mp_view->default_line_style () : m_line_style;
 
+
+  printf("layMarker.cc: line_width=%d, vertex_size=%d, halo=%d\n", 
+         line_width, vertex_size, halo);
+
   if (halo) {
 
     std::vector <lay::ViewOp> ops;

After clicking a shape, I get:

layMarker.cc: line_width=255, vertex_size=255, halo=1
layMarker.cc: line_width=255, vertex_size=255, halo=1
layMarker.cc: line_width=1, vertex_size=0, halo=0
layMarker.cc: line_width=255, vertex_size=255, halo=1

Sometimes after a single-click (no selection -> selection), I even get more events:

layMarker.cc: line_width=1, vertex_size=0, halo=0
layMarker.cc: line_width=1, vertex_size=0, halo=0
layMarker.cc: line_width=255, vertex_size=255, halo=1
layMarker.cc: line_width=255, vertex_size=255, halo=1
layMarker.cc: line_width=1, vertex_size=0, halo=0
layMarker.cc: line_width=255, vertex_size=255, halo=1

255 / 0xFF looks suspicious.

[martinjankoehler]

Compiler warning hints at the reason:

../../../src/laybasic/laybasic/layMarker.cc: In member function \u2018void lay::MarkerBase::get_bitmaps(const lay::Viewport&, lay::ViewObjectCanvas&, lay::CanvasPlane*&, lay::CanvasPlane*&, lay::CanvasPlane*&, lay::CanvasPlane*&)\u2019:
../../../src/laybasic/laybasic/layMarker.cc:326:33: warning: comparison is always false due to limited range of data type [-Wtype-limits]
  326 |   int line_width = m_line_width < 0 ? mp_view->default_marker_line_width () : m_line_width;
      |                    ~~~~~~~~~~~~~^~~
../../../src/laybasic/laybasic/layMarker.cc:327:35: warning: comparison is always false due to limited range of data type [-Wtype-limits]
  327 |   int vertex_size = m_vertex_size < 0 ? mp_view->default_marker_vertex_size () : m_vertex_size;
      |                     ~~~~~~~~~~~~~~^~~
../../../src/laybasic/laybasic/layMarker.cc:328:22: warning: comparison is always false due to limited range of data type [-Wtype-limits]
  328 |   bool halo = m_halo < 0 ? mp_view->default_marker_halo () : (m_halo != 0);
      |               ~~~~~~~^~~

[martinjankoehler]

Root Cause:
MarkerBase::m_line_width should be int, not char!

After applying this fix, it works:

[klayoutmatthias]

Some problems like the signed vs. unsigned char never get resolved ... I usually avoid using char for integers, but this case escaped me. All my gccs, clangs and MSVCs treat it as signed on Windows and Linux.

I even get this warning from clang:

c.x:14:
char c;
c = 128;

gives:
x.c:14:7: warning: implicit conversion from 'int' to 'char' changes value from 128 to -128 [-Wconstant-conversion]

which is rather suggesting that char is signed.

Anyway, problem is fixed. Thanks for the PR.

Matthias