eeschema dashed lines are not WYSIWYG (different in print preview, print and schematic)

[Dino Ghilardi]

Some minor incongruencies related to dashed lines (maybe to wxWidgets) print in eeschema.

To reproduce the behaviour:

1 create a new sheet
2 draw a dashed line, 4 grid steps horizontal, 2 grid steps vertical
3 print->preview: In the preview the line is not dashed but solid.
4 print->print: the number of dashes is different in printed version than in on-screen version (On my machine 15 dashes on screen, 17 dashes on the pdf output generated, also 17 in svg print output).

The output from the plot function seems correct for the single line.

-----------------------------------------------------------------
Tested on commit 5aa48e523dd46632564d3a118921f6c1f02abc2f
Tested on tag 5.1.4
-----------------------------------------------------------
Application: Eeschema
Version: (5.1.0-1449-g5aa48e523), release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.52.1 OpenSSL/1.0.2s zlib/1.2.8 libidn2/0.16 libpsl/0.17.0 (+libidn2/0.16) libssh2/1.7.0 nghttp2/1.18.1 librtmp/2.3
Platform: Linux 4.9.0-8-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.69.0
    OpenCASCADE Community Edition: 6.8.0
    Curl: 7.52.1
    Compiler: GCC 6.3.0 with C++ ABI 1010

Build settings:
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

----------------------------------------------------------
Application: Eeschema
Version: (5.1.4), release build
Libraries:
    wxWidgets 3.0.2
    libcurl/7.52.1 OpenSSL/1.0.2s zlib/1.2.8 libidn2/0.16 libpsl/0.17.0 (+libidn2/0.16) libssh2/1.7.0 nghttp2/1.18.1 librtmp/2.3
Platform: Linux 4.9.0-8-amd64 x86_64, 64 bit, Little endian, wxGTK
Build Info:
    wxWidgets: 3.0.2 (wchar_t,wx containers,compatible with 2.8) GTK+ 2.24
    Boost: 1.69.0
    OpenCASCADE Community Edition: 6.8.0
    Curl: 7.52.1
    Compiler: GCC 6.3.0 with C++ ABI 1010

Build settings:
    USE_WX_GRAPHICS_CONTEXT=OFF
    USE_WX_OVERLAY=OFF
    KICAD_SCRIPTING=ON
    KICAD_SCRIPTING_MODULES=ON
    KICAD_SCRIPTING_PYTHON3=OFF
    KICAD_SCRIPTING_WXPYTHON=ON
    KICAD_SCRIPTING_WXPYTHON_PHOENIX=OFF
    KICAD_SCRIPTING_ACTION_MENU=ON
    BUILD_GITHUB_PLUGIN=ON
    KICAD_USE_OCE=ON
    KICAD_USE_OCC=OFF
    KICAD_SPICE=ON

[Seth Hillbrand (sethh)]

Removing milestone.

As long as we are using wxWidgets for printing, we do not control how they draw the dashes. This can even differ between OS.

Similarly, we don't exactly control dashes in DXF or HPGL plots.

[KiCad Janitor (kicad-janitor)]

KiCad bug tracker has moved to Gitlab. This report is now available here: https://gitlab.com/kicad/code/kicad/-/issues/1923