[Octave-bug-tracker] [bug #52940] Regression with "PaperPosition" and printing

[Dan Sebald]

Follow-up Comment #6, bug #52940 (project octave):

I changed the conditional inside acinclude.m4 to verify it is the
QOpenGLWidget object that makes a difference, and it is the difference.

The following may be a clue.  I printed out for both configurations some info
I saw in gl2ps_renderer::draw_axes regarding the


      glGetIntegerv (GL_VIEWPORT, vp);
      gl2psBeginViewport (vp);
std::cerr << "viewport = " << vp[0] << " " << vp[1] << " " << vp[2] << " " <<
vp[3] << "\n";


and the


      gl2psGetOptions (&opts);
std::cerr << "opts = " << opts << "\n";


at various points along the way.  The results are:

QGLWidget

octave:1> graphics_toolkit qt
octave:2> tst_paperpos
viewport = 0 0 560 420
opts = 649
opts = 665
opts = 665
octave:3> tst_paperpos
viewport = 0 0 720 396
opts = 649
opts = 665
opts = 665
octave:4> tst_paperpos
viewport = 0 0 720 396
opts = 649
opts = 665
opts = 665



QOpenGLWidget

octave:1> graphics_toolkit qt
octave:2> tst_paperpos
viewport = 0 0 720 396
opts = 649
opts = 665
opts = 665
octave:3> tst_paperpos
viewport = 0 0 720 485
opts = 649
opts = 665
opts = 665
octave:4> tst_paperpos
viewport = 0 0 720 485
opts = 649
opts = 665
opts = 665


What exactly is happening with the first call versus the following calls, I'm
not sure.  (Both QGLWidget and QOpenGLWidget show the same type of difference;
it could be that the ViewPort at this stage of ::draw_axes() doesn't mean
anything.  It might be in later drawing elements that it comes into play. 
(One would think it should matter, though, seeing that gl2psBeginViewport(vp)
is called.)  Certainly it doesn't seem that the size in the y-direction
matters because the y-axis scale on the plot doesn't change physical scale
between the first and second draw--I roughly measured the 0 to 6 distance and
they are the same...just one offset from the other.  The translation from that
view-port to the page dimensions is probably the important part.

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