942 increase all fonts in plot

[GuiMacielPereira]

Summary of Changes

• Added widget to set all fonts in plot to a given value, present when Plot Options is opened.
• Added another widget to control scaling of all fonts

Description of work:

• Three main components were altered: the GUI window (also called view) class, the cut and slice plots classes, and the PlotOptionsPresenter class (which functions and the link between the GUI and the internal class for controlling plot options)
• The GUI window: Added four widgets in total: two checkboxes and two line edits:
• Added functions in Plot Options class that controls how the checkboxes interact with the line edits and between themselves (can't check the two checkboxes simultaneously, and can only edit line edits if checkbox is checked)
• Added signals in Plot Options class that are caught by PlotOptionsPresenter in plot_options_presenter.py to signal whether the two new fields (for setting all font sizes and scaling all font sizes) are part of the modified values. Added a new function also in this class that removes elements from the dictionary of modified values. This function is triggered when user unticks either of the checkboxes, so that any changes previously made are internally discarded from the dict of modified values. Similarly, when a checkbox is ticked, the default values are loaded ontomodified values and any sunbsequent edit by the user in the Gui apdatest these values.
• In cut_plot.py, the implementation of setting and scaling all fonts is contained whithin the funcitons CutPlot.all_fonts_size and CutPlot.scale_all_fonts respectively. These two functions are implemented by getter and setter decorators.
• Added tests for cut and slice plots, on the implementation of setting and scaling all fonts. Added another test in cut_options_presenter_test.py to confirm that data transfer between GUI view and internal class is happening successfully.
• Manually confirmed that all functunality is preserved whether the plot options window is kept open or not.

To test:

• Open plot options window and play around with the new widgets.
  • Change fonts of plot one by one to different sizes and check that setting all fonts to the same size works.
  • Change fonts to different sizes again and check that scaling all fonts preserves proportions.
  • Enable and disable checkboxes and confirm that plot fonts remain unaltered.
  • Check that it is not possible to simultaneously setect both checkboxes.
  • Enable one checkbox but don't edit the corresponding line, changes should still be applied to plot
  • Change one of the values in the tests for slice and cut plots and check that test fails.
  • In cut_options_presenter_test.py, comment out any line that calls self.presenter._value_modified and check that test fails (this is the equivalent of no checkboxes being ticked)

Fixes #942 .

[robertapplin]

Last thing I just spotted, is when you give a ridiculously large number as the font size such as 10e7, I get this error:

Traceback (most recent call last):
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/backends/backend_agg.py", line 405, in draw
    self.figure.draw(self.renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/artist.py", line 74, in draw_wrapper
    result = draw(artist, renderer, *args, **kwargs)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper
    return draw(artist, renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/figure.py", line 3082, in draw
    mimage._draw_list_compositing_images(
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/image.py", line 131, in _draw_list_compositing_images
    a.draw(renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/artist.py", line 51, in draw_wrapper
    return draw(artist, renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axes/_base.py", line 3064, in draw
    self._update_title_position(renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axes/_base.py", line 3008, in _update_title_position
    ax.yaxis.get_tightbbox(renderer)  # update offsetText
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axis.py", line 1253, in get_tightbbox
    self._update_label_position(renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axis.py", line 2506, in _update_label_position
    bboxes, bboxes2 = self._get_tick_boxes_siblings(renderer=renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axis.py", line 2056, in _get_tick_boxes_siblings
    tlb, tlb2 = axis._get_ticklabel_bboxes(ticks_to_draw, renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axis.py", line 1232, in _get_ticklabel_bboxes
    return ([tick.label1.get_window_extent(renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/axis.py", line 1232, in <listcomp>
    return ([tick.label1.get_window_extent(renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/text.py", line 915, in get_window_extent
    bbox, info, descent = self._get_layout(self._renderer)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/text.py", line 313, in _get_layout
    _, lp_h, lp_d = _get_text_metrics_with_cache(
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/text.py", line 97, in _get_text_metrics_with_cache
    return _get_text_metrics_with_cache_impl(
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/text.py", line 105, in _get_text_metrics_with_cache_impl
    return renderer_ref().get_text_width_height_descent(text, fontprop, ismath)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/backends/backend_agg.py", line 238, in get_text_width_height_descent
    font = self._prepare_font(prop)
  File "/home/mlc47243/mambaforge/envs/mantidnightly/lib/python3.10/site-packages/matplotlib/backends/backend_agg.py", line 275, in _prepare_font
    font.set_size(size, self.dpi)
RuntimeError: In set_size: Could not set the fontsize (invalid pixel size; error code 0x17)

A similar problem probably happens for the scale option. We might want to set a sensible maximum possible value for font size?

[GuiMacielPereira]

• Changed 'scale font' in variable names to 'increment font', as it describes more accurately what it does.
• Added a double validator, so string input like 'bad' is not allowed.
• Handled very big or very small font sizes by introducing if statements that set font size to reasonable limits: 1 or 1000.
  • I tried imposing a range of (1, 1000) directly on the validator but it caused a worse user experience (for example, no longer able to type numbers with decimal places, and text field would get automatically set to 0.0 after an invalid input - which, in itself, is also an invalid input)
• Changed GUI description to Increment all font sizes

[GuiMacielPereira]

I just realised that I will need to write a release note for these changes?

[robertapplin]

The tooltip change looks good

I think the next step is:

• Make the font box empty if there is more than one font size. In this is the case, if Apply is clicked, then the font sizes to use should be the ones displayed in the tooltip
• Populate the font box if there is only one font size. Use this font size for everything when Apply is clicked

It should then be possible to remove the top checkbox

[GuiMacielPereira]

Overall Changes:

• UI is much simpler and more intuitive:

• 

• Real-time updating of fonts, not dependent of clicking 'OK' button
• When using the QLineEdit field, can revert changes to font sizes by pressing backspace until field is empy again, akin to a "preview" functunality