katarakt - a simple PDF viewer with three layouts

katarakt is written by Philipp Erhardt.

       Feel free to join the IRC channel #katarakt on freenode.

       Variables and key bindings can be changed by modifying the katarakt.ini file. By default it is read from
       $XDG_CONFIG_HOME.

       Variables must be listed under the section "[Settings]", keys under section "[Keys]". Settings that are
       not present in the config file use the built-in default. For a list of all variables with a short
       explanation see below.

       It’s a PDF viewer. It views PDFs.

       There are currently three layouts. The singlelayout is very simple and only supports scrolling on a per
       page basis. As the name suggests the current page is displayed in the center and zoomed to fit the
       window. It is active by default.

       The gridlayout is much more advanced and offers continuous (smooth, per pixel) scrolling, zooming and
       adjusting the column count. Pages keep their correct relative size and are shown in a grid.

       The presenterlayout is for giving a presentation. It opens a second window, to be viewed on the
       projector, and shows the current and next slide in the main window.

       For every file passed on the command line a separate process is spawned.

q
           Quit katarakt.

       1
           Switch to singlelayout. Views a single page at a time, scaled to fit the screen.

       2
           Switch to gridlayout. Views pages in a continuous fashion, scaled to fit the window width. Supports
           zooming and multiple columns.

       3
           Switch to presenterlayout. Views the current page and a smaller preview of the next page. Also,
           opens a second window that shows only the current page for displaying on a projector.

       Up, Down, Left, Right, k, j, h, l
           Move around (up/down/left/right).

       ^u, ^d
           Scroll up/down half the screen.

       BackSpace, Space, ^b, ^f
           Scroll up/down the screen. By default scrolls 90% to create an overlapping region.

       PgUp, PgDown
           Scroll up/down one page. Kind of swaps the pages in place.

       Home, End, g, G
           Go to the first/last page.

       ^g
           Show gotopage bar.

       /
           Show the search bar. Hitting Esc will hide the results, searching for an empty string will clear
           them. If the search term contains an uppercase letter the search is case sensitive ("smartcase"). If
           you search for the same term twice the next hit starting from the current view is selected.

       ?
           Show the search bar. This next search will be backwards.

       n, N
           Focus next/previous search hit. This does not take the current view into account. For finding the
           next hit around the current view search for the same term again.

       ^n, ^N
           Focus next/previous search hit that is currently not visible.

       ^o, ^i, Alt-Left, Alt-Right
           Move backward/forward through the jump list. Entries are added automatically when jumping.

       m
           Manually add the current page to the jump list.

       -, +, =
           Adjust zoom level (gridlayout only).

       z
           Reset zoom level to default, i.e. fit width (gridlayout only).

       [, ]
           Adjust column count (gridlayout only).

       {, }
           Adjust the column the first page will be displayed in. Useful for reading in a book layout with a
           cover page (gridlayout only).

       ,, .
           Rotate pages left/right.

       t
           Toggle the page number display in the bottom right corner.

       i
           Toggle between normal and inverted color rendering.

       ^c
           Copy the current selection to the global clipboard.

       v
           Swap the mouse buttons for selection and panning. The the left mouse button’s current operation is
           indicated by the mouse cursor.

       f
           Toggle fullscreen.

       r
           Reload the document. This can also be achieved by sending SIGUSR1 to the process.  katarakt reloads
           automatically if the opened file has changed.

       o
           Open a different document; shows a file dialog.

       s
           Show a file dialog to save the current document.

       F9
           Toggle the table of contents.

       x
           Toggle freezing the slide currently displayed in the projector window. When frozen, scrolling only
           affects the main window.

       katarakt - a simple PDF viewer with three layouts

-u, --url
           Instead of opening a local document, download it from the given URL.

       -p, --pageNUM
           Start on page NUM.

       -f, --fullscreen
           Start in fullscreen mode.

       -q, --quittrue|false
           If true, quit on initialization failure. If false, show the window even if an error occured.
           Overrides the config option quit_on_init_fail.

       -s, --single-instancetrue|false
           If true, prevents opening the same document twice and focuses the existing instance. Overrides the
           config option single_instance_per_file.

       --write-default-configFILE
           Write the built-in default configuration to FILE and exit. Hint: on unix systems, you can use
           --write-defaults/dev/stdout to print the defaults.

       -v, --version
           Print version information and exit.

       -h, --help
           Print help and exit.

       GitLab: https://gitlab.cs.fau.de/Qui_Sum/katarakt

Katarakt                                           04/01/2024                                        KATARAKT(1)

katarakt ([OPTIONS] FILE|(-u URL))*

stringdefault_layout
           single: The layout on startup. Possible values: single, grid, presenter.

       stringbackground_color
           0xDF202020: Background color in ARGB Format. Alpha only works when using a compositor.

       stringbackground_color_fullscreen
           0xFF000000: Fullscreen background color in ARGB Format.

       stringunrendered_page_color
           0x40FFFFFF: Color that gets drawn instead of a page that hasn’t been rendered yet. If colors are
           inverted, this gets inverted as well.

       intclick_link_button
           1: The mouse button used for clicking links. Buttons 1-5 are supported.

       intdrag_view_button
           2: The mouse button used for scrolling the view. Double-clicking this button centers the view around
           the location of the click. This is especially useful when using many columns to get an overview.
           Resets the column count to 1.

       intselect_text_button
           1: The mouse button used for text selection. Double- and triple-clicking are supported to select with
           word/line granularity.

       inthide_mouse_timeout
           2000: The delay in milliseconds after which the mouse cursor is hidden. Set to 0 to disable.

       intsmooth_scroll_delta
           30: Pixel offset when moving around.

       floatscreen_scroll_factor
           0.9: Factor for scrolling the screen. Should be <= 1 to create an overlapping region.

       floatjump_padding
           0.2: Distance from the border of the screen to keep for jump targets, e.g. search hits. Moves the
           view so that search hits are centered more.

       intrect_margin
           2: Number of pixels search rects are expanded by.

       intuseless_gap
           2: Gap between two pages in gridlayout in pixels.

       intmin_zoom
           -14: Smallest zoom value.

       intmax_zoom
           30: Biggest zoom value.

       floatzoom_factor
           0.05: Influences the number of steps between min and max.

       intmin_page_width
           50: Pages can not be smaller than this.

       boolquit_on_init_fail
           false: If true, quit katarakt if the document fails to open.

       boolsingle_instance_per_file
           false: If set and katarakt is called with a file that is already shown in another katarakt instance,
           then the other katarakt window is activated instead.

       stringstylesheet
           See http://doc.qt.io/qt-4.8/stylesheet.html. It can be overridden via Qt’s -stylesheet command line
           option. The following example changes the gotopage bar:

               stylesheet="
               GotoLine {
                       margin: 0px;
                       padding: 4px;
                       border-top-right-radius: 6px;
                       border-top: 1px solid black;
                       border-right: 1px solid black;
               }"

       stringpage_overlay_text
           Page %1/%2: The text in the bottom right corner.

       stringicon_theme
           The name of your icon theme. Fill in if auto detection fails.

       intprefetch_count
           4: Number of pages exceeding the currently visible ones to render, back- and forwards respectively.

       floatinverted_color_contrast
           0.5: the contrast when using inverted colors to avoid too much brightness.

       floatinverted_color_brightening
           0.15: amount of brightening when using inverted colors to shift black to gray.

       intmouse_wheel_factor
           120: QT delta for turning the mouse wheel 1 click. Shouldn’t need to be touched.

       boolthumbnail_filter
           true: Enables the higher quality downsampling filter for thumbnails.

       intthumbnail_size
           32: One dimension of square thumbnails saved at run-time for every page that was once rendered.