Caching / Pre-rendering¶

To allow fast changes between the presentation slides, a few consecutive PDF pages (the number is configurable) are pre-rendered and kept in memory. To avoid excessive memory consumption, cached are only slides that took a significant time to render; this threshold is configurable. In order to further reduce memory consumption, the pre-rendered and cached slides are selectively compressed. The compression factor is typically 10-30, however, it takes some CPU time to compress and uncompress, so there is a trade-off. Small images below a certain (configurable) threshold will not be compressed.

Please refer to the pdfpcrc(5) man page for options to fine-tune the caching algorithm.

Timer¶

If a duration is given (-d option), the timer will show a countdown with the given parameters. If no duration is specified (or if a value of 0 is given to the -d option), the timer will show how much time has been spent. The duration is stored automatically, so you do not need to repeat it for every invocation.

The timer is started if you are navigating away from the first page for the first time. This feature is quite useful as you may want to show the title page of your presentation while people are still entering the room and the presentation has not really begun yet. If you want to start over you can use the 'Ctrl + t' key which will make the presenter reset the timer.

If a duration is given, the timer also provides hints aiding the presenter to judge whether the talk would end on time. There are two modes in which pdfpc can operate. In the old (and the only one available up to, and including pdfpc-4.0.8) mode, at the moment the timer reaches the defined last-minutes value it will change color to indicate your talk is nearing its end, thus mimicking a chairman frantically pantomiming in front of you with five (four, three, ...) fingers up. A drawback of this approach is it is often too late at that moment to alter the presentation pace without ruining to some extent the rest of the talk. On the other hand, the warning indication provides an unnecessary distraction if you have been perfectly conveying the talk and the remaining time is adequate.

Contrary to that, in the new (default) mode, pdfpc tracks your progress continuously, calculating the expected time as (talk_duration)*(current_user_slide_number - 0.5)/(total_number_of_user_slides) and comparing it to the actual wall time since beginning of the talk. If these two numbers differ by more than 60 seconds, the timer changes its color to either orange (indicating you need to speed up) or a blueish one (need to slow down). Once the optimal progress is recovered, the timer becomes white again. In this mode, the last-minutes option (-l) has no effect. The previous behavior can be restored by setting the 'timer-pace-color' option to 'false' in the configuration file, see pdfpcrc(5).

In any case as soon as the timer reaches the zero mark (00:00:00), it will turn red and count further down showing a negative time, to provide information on how many minutes you are overtime.

Notes¶

Textual notes can be displayed for each slide. pdfpc understands the Markdown syntax, which allows for rendering anything from plain text to a very rich formatting, if so desired. A few types of PDF annotations are understood by pdfpc and will be automatically imported and displayed. The PDF annotations can be made using many PDF editors and even viewers; when using LaTeX, the pdfpc package (see below) provides a convenient macro. These "native" PDF notes cannot be edited in pdfpc.

In addition, while in the presentation mode, pressing 'Ctrl + n' will allow you to take or edit notes for the current slide. These notes are stored in the .pdfpc file. The native PDF annotations take precedence over these notes, i.e., if a note exists for a given slide in the .pdfpc file, any PDF annotation on that page will silently override it. While editing a note, the normal keybindings are disabled, e.g., you are not able to change slides. To exit the note editing mode, press the Escape key.

Although mixing the two types of notes is possible, for a given presentation one will likely want to have either only the "native" notes (produced by the same PDF authoring software used for making the slides), or only the "pdfpc" ones. Note that if the PDF presentation changes, the notes stored in the respective .pdfpc file may get out of sync.

pdfpc also supports old-style beamer notes (see the -n option), which are typeset on a half of the "virtual" slide twice as large as the real one. Note that due to a bug in beamer, the auto-grouping feature does not work with such presentations.

Overview mode¶

Pressing the Tab key enters the overview mode, where thumbnails of the slides are shown in a grid. You can select a slide to jump to with the mouse or with the arrow keys. You can also define overlays and the end slide (see next sections) in this mode. Press Escape to exit the mode without making an change.

Overlays¶

Many slide preparation systems allow for overlays, i.e. sets of slides that are logically grouped together as a single, changing slide. Examples include enumerations where bullet items are displayed one after another, or rough "animations", where parts of a picture change from slide to slide. Pdfpc includes facilities for dealing with such overlays.

In this description, we will differentiate between slides (i.e. pages in the PDF document) and "user slides", that are the logical slides. The standard forward movement command (page down, enter, etc.) moves through one slide at a time, as expected. This means that every step in the overlay is traversed. The backward movement command works differently depending on whether the current and previous slides are part of an overlay:

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If the current slide is part of an overlay we just jump to the previous slide. That means that we are in the middle of an overlay and can jump forward and backward through the single steps of it

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If the current slide is not part of an overlay (or if it is the first one), but the previous slides are, we jump to the previous user slide. This means that when going back in the presentation you do not have to go through every step of the overlay, pdfpc just shows the first slide of each overlay. As one typically goes back in a presentation only when looking for a concrete slide, this is more convenient.

The Shift + Page up/down key combinations work on the "user slide" basis. You can use them to skip the rest of an overlay or to jump to the previous user slide, ignoring the state of the current slide.

When going through an overlay, two additional previews may be activated in the presenter view, just below the main view, showing the next and the previous slide in an overlay.

Pdfpc tries to find these overlays automatically by looking into the page labels in the PDF file. For LaTeX this works correctly at least with the beamer class and also modifying the page numbers manually (compiling with pdflatex). If your preferred slide-producing method does not work correctly with this detection, you can supply this information using the 'Ctrl + o' key for each slide that is part of an overlay (except the first one!). The page numbering is also adapted. This information is automatically stored.

Hidden slides¶

When preparing presentation from an existing set of slides, it is sometimes helpful to mark certain slides to be skipped during the talk. The 'Ctrl + h' combination toggles the "hidden" attribute of the current slide, making it essentially invisible. It is still possible to navigate to a hidden slide either in the Overview mode, using the Goto action ('g'), or by hitting 'Shift + n' or 'Shift + p' to switch to the next/previous slide, respectively, ignoring the "hidden" attribute.

End slide¶

Some people like to have some additional, backup slides after the last slide in the actual presentation. Things like bibliographic references or slides referring to specialized questions are typical examples. Pdfpc lets you define which is the last slide in the actual presentation via the 'Ctrl + e' key. This just changes the progress display in the presenter screen, as to have a better overview of how many slides are left.

Page transitions¶

Pdfpc supports almost all standard animated PDF page transitions: blinds, box, cover, dissolve, fade, glitter (except the diagonal one), push, split, uncover, and wipe, including various alignments, angles, and directions (where applicable). The transitions are enabled only for sequential (either forward or backward) movement; in the later case, the transition is "inverted".

Advancing slides automatically is also supported.

Movies¶

Pdfpc can play back movies included in the PDF file. Movies may be started and stopped by clicking within their area. For the presenter, a progress bar is drawn along the bottom of the movie. This expands when the mouse hovers over it, allowing one to seek by clicking or dragging within the progress bar. Switching slides automatically stops playback, and movies will be reset after leaving and returning to a slide.

Movies may be included in PDF files as "screen annotations". In LaTeX, such movies may be added to a presentation with the "multimedia" package. Note that the autoplay option is not yet supported.

pdfpc will also play back movies linked from a hyperlink of type "launch".

See our website ⟨URL: http://pdfpc.github.io/demo/pdfpc-video-example.zip ⟩ for a detailed explanation with examples.

Pointer mode¶

If needed, it is possible to turn on a pointer which draws a red (by default) dot in the place pointed by mouse cursor on both presenter and presentation screens. It is also possible to increase and decrease the pointer size. Additionally, when the pointer is enabled, it is possible to highlight some area of the current slide using the drag mouse motion. The area outside the selected region will be dimmed. You can zoom in the selected area by pressing 'z'; press 'Escape' to exit the zoom mode. You can highlight another region while zoomed in, but there will be no further action on pressing 'z'. Drawing is also disabled in this mode.

Spotlight mode¶

Spotlight mode is similar to the pointer mode: a circular area that moves with the mouse and can be adjusted in size, but instead of highlighting the spot by a different color, it shades the background.

Drawing mode¶

It is possible to turn on a mode which allows drawing over slides with the mouse cursor or a connected tablet. When drawing mode is enabled, drawings can be made on the presenter screen. A separate drawing will be kept in memory for each slide (based on user slide numbers, so consolidating overlay slides). Drawings are presently not saved between sessions.

In the drawing mode, there are two drawing tools, a pen and an eraser. An indicator in the bottom-left corner of the presenter screen will indicate which is active. When in the pen mode, the color and size of the pen will be indicated by the cursor. The pen size can be increased or decreased using hot keys specified in the key bindings. When the eraser tool is active, the size of the cursor indicates the amount to erase.

The color of the pen can be changed through key bindings or using the toolbox.

If you are using a tablet, the pen or eraser tool will be selected based on whether the tablet reports a pen or eraser input device is being used, overriding the normal selection of the drawing tool. Also for pressure-sensitive input devices, the pressure will affect the line width and the eraser size. Both these features can be disabled in the configuration file, if desired.

Monitor Plug and Play¶

Pdfpc can handle monitor plug and play. E.g. if pdfpc was started before the presentation screen was attached to the computer, pdfpc can create and show the presentation screen after the second screen was attached. This allows the user to rehearse the slides and switch to a normal presentation without having the full setup at the computer in advance.

pdfpc files¶

Notes, user-defined overlays, and some additional information are stored in a file with extension "pdfpc". When pdfpc is invoked with a PDF file, it automatically checks for and loads the associated .pdfpc file, if it exists. This means that you normally do not have to deal with this kind of files explicitly.

Beside internal configuration, the following command-line options are saved in the pdfpc file for later usage:

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duration

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end_time

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last_minutes

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notes (position)

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page_transition

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start_time

Appearance¶

With GTK3 it is possible to modify the appearance of pdfpc. There are two locations where pdfpc is looking for files. The default location is /usr/share/pixmaps/pdfpc/pdfpc.css. It can be copied to $XDG_CONFIG_HOME/pdfpc/pdfpc.css and modified to the user's liking.

The geometry of various views (the current/next etc slide) in the presenter window can be adjusted at run time in the "Customization" mode, which is activated by pressing Shift+c. In this mode, mouse-draggable handles will appear. Exit the customization with Escape.

Desktop integration¶

Pdfpc provides a DBus interface that appears on the session bus as io.github.pdfpc. Other applications can, in particular, execute any action listed by --list-actions. It is also possible to control pdfpc from the command line (and write shell scripts) using the dbus-send(1) utility. For example, to advance to the next slide, run

dbus-send --type=method_call --session --dest=io.github.pdfpc
/io/github/pdfpc io.github.pdfpc.TriggerAction string:next

For actions that require an argument, use TriggerActionArg, e.g.,

dbus-send --type=method_call --session --dest=io.github.pdfpc
/io/github/pdfpc io.github.pdfpc.TriggerActionArg string:switchMode
string:pointer

In addition to TriggerAction*, the pdfpc DBus interface exposes the GetNotes method, three properties (NumberOfOverlays, NumberOfSlides, Url) and two signals (OverlayChange and SlideChange).

Remote control¶

Pdfpc has a built-in REST server. When enabled (off by default), it allows for controlling presentations over network, e.g., using a mobile device as a smart controller. (This section will be extended with more details when the REST interface sufficiently stabilizes.)

LaTeX package¶

A tiny LaTeX package is available for pdfpc at CTAN. It provides a convenient way to specify notes and to define certain meta properties of the presentation. For a full documentation, please consult the pdfpc package documentation. You can open it with: