vipsdisp

This program displays an image with libvips and gtk4. This is supposed to be a slightly useful image viewer. It can display huge (many, many GB) images quickly and without using much memory. It supports many scientific and technical image formats, including TIFF, WEBP, JP2K, JXL, AVIF, HEIC, PNG, JPEG, SVS, MRXS, OpenEXR, GIF, PDF, SVG, FITS, Matlab, NIfTI, Analyze, etc. It supports pixel types from 1 bit mono to 128-bit double precision complex.

All of the UI can make finding the details of image display in the sourcecode difficult. See vipsdisp-tiny for a minimal example --- that's a libvips image viewer in about 300 lines of very commented C.

Screenshots

It all works, though see the TODO list below.

Install

This program is on flathub, see:

https://flathub.org/apps/org.libvips.vipsdisp

Just click "install", or enter:

flatpak install flathub org.libvips.vipsdisp

Features

• It supports many scientific and technical image formats, including TIFF, WEBP, JP2K, JXL, HEIC, AVIF, PNG, JPEG, SVS, MRXS, OpenEXR, GIF, PDF, SVG, FITS, Matlab, NIfTI, Analyze, etc. It supports many numeric pixel types, any number of image bands, many colour spaces.

• It doesn't need to keep the whole image in memory. It will only read parts that it needs for display, and it understands most pyramidal image formats. This means you can open and view huge images quickly.

• It has threaded, asynchronous display repaint, so pixels are computed in the background by a pool of workers. The interface stays live even under very heavy load.

• It keeps a sparse pyramid of computed tiles as textures on the GPU. Each frame, it computes the set of visible tiles, and then the GPU scales, positions and composites just those tiles to the screen. CPU load should be low (except for the background workers heh). Hold down i (for "in") or + to do a smooth zoom on the cursor. If you press "d" it toggles a debug display mode which shows the tiles being computed.

• Select Display control bar from the top-right menu and a useful set of visualization options appear. It supports four main display modes: Toilet roll (sorry), Multipage, Animated, and Pages as Bands.

• In Toilet roll mode, a multi-page image is presented as a tall, thin strip of images. In Multipage, you see a single page at a time, with a page-select spinner (you can also use the crtl-< and ctrl-> keys to flip pages). In animated mode, pages flip automatically on a timeout. In pages-as-bands mode, many-page single-band images (eg. OME-TIFF) are presented as a single colour image.

• You can select falsecolour and log-scale filters, useful for many scientific images. Scale and offset sliders let you adjust image brightness to see into darker areas (useful for HDR and many scientific images).

• Select Save as to write an image. It can write most common formats, and lets you set file save options. It can write things like DeepZoom pyramids, PFM, OpenEXR, and so on.

• It uses the gtk4 GUI toolkit, so the interface is fast, attractive and nicely animated. The image is rendered with the GPU, so display ought to be fast.

Build from source

$ cd vipsdisp
$ meson setup build --prefix=~/vips
$ cd build
$ ninja
$ ninja install

And to run:

$ export GSETTINGS_SCHEMA_DIR=/home/john/vips/share/glib-2.0/schemas
$ vipsdisp ~/pics/k2.jpg

Shortcuts

• Cursor keys to scroll around
• Cursor keys plus shift to move by a screen size
• Cursor keys plus ctrl to move to image edges
• Number keys to pick a particular magnification
• Ctrl + number keys to pick a particular zoom out
• 0 for best fit
• d, to toggle debug rendering mode
• i, + / o, - to zoom in and out
• ctrl-<, ctrl->. prev page, next page
• Mouse drag to pan
• Mousewheel to zoom
• Mousewheel + shift/ctrl to pan
• ^O replace image
• ^N new viewer
• ^D duplicate view
• F11 fullscreen

Structure

• TileSource wraps a VipsImage and can produce pyramid tiles on request. It has controls for things like scale and falsecolour.

• TileCache builds a sparse pyramid of tiles and keeps recents.

• Imagedisplay is a GtkDrawingArea subclass that paints a TileCache. It implements a scrollable interface. You can use this as an image view widget in your own code. It takes a float scale factor for zoom and uses that to fetch tiles of the right size from the TileCache.

• Imagewindow is a GtkWindow that contains an Imagedisplay and adds a lot of navigation stuff. It uses the scolled window GtkAdjustment to slide Imagedisplay around.

• SaveOptions is the save-as dialog, and uses libvips introspection to display the optional parameters of the selected saver.

• disp is the main(), VipsdispApp is a GtkApplication subclass

• The UI layout is in the gtk/*.ui xml.

Version bump checklist

Version needs updating in the following places:

• CHANGELOG.md

• meson.build

• org.libvips.vipsdisp.metainfo.xml and some release notes and a date as well.

• org.libvips.vipsdisp.json needs the version number as a git tag.

flatpak

Add the flathub repo:

flatpak remote-add --if-not-exists \
  flathub https://flathub.org/repo/flathub.flatpakrepo

Install the gtk4 SDK and runtime:

flatpak install org.gnome.Sdk//44
flatpak install org.gnome.Platform//44

Allow file. Recent security changes to git will cause submodule checkout to fail inside flatpak. If you get errors like fatal: transport 'file' not allowed, reenable file transport with:

git config --global protocol.file.allow always

Build and try running it:

flatpak-builder --force-clean --user --install build-dir org.libvips.vipsdisp.json
flatpak run org.libvips.vipsdisp ~/pics/k2.jpg

Force a complete redownload and rebuild (should only rarely be necessary) with:

rm -rf .flatpak-builder

Check the files that are in the flatpak you built with:

ls build-dir/files

Uninstall with:

flatpak uninstall vipsdisp

Notes on flatpak build process

• niftiio is annoying to build, skip it.

• x265 is annoying to build, skip it

• we skip imagemagick as well, too huge

Packaging for flathub

Install the appdata checker:

flatpak install flathub org.freedesktop.appstream-glib
flatpak run org.freedesktop.appstream-glib validate org.libvips.vipsdisp.metainfo.xml

Also:

desktop-file-validate org.libvips.vipsdisp.desktop 

Uploading to flathub

Push to master on:

    https://github.com/flathub/org.libvips.vipsdisp 

then check the build status here:

    https://flathub.org/builds/#/apps/org.libvips.vipsdisp

TODO

• use eg. alt-left, alt-right to flip between images in "vipsdisp a.jpg b.jpg" or maybe shift-<, shift->?

• allow eg. "vipsdisp x.svg[scale=10]", the load dialog should have a "load options" expander, and save should have "save options"

• can we move "new_from_file" into a bg thread? the GUI will pause on huge SVGs on zoom change right now

  very difficult with the current structure -- we'd need to separate tilesource and tilecache completely, and perhaps link them with signals

• tile read errors:

  $ ./src/vipsdisp ~/pics/ome/LuCa-7color_Scan1.ome.tiff

    - (vipsdisp:110067): VIPS-WARNING **: 18:05:16.244: 
        error in tile 0 x 256: tiff2vips: 
            out of order read -- at line 3328, but line 256 requested
  

  page 0, subifd 2 and subifd 3 are untiled!!!

  we need to decompress the whole layer before we view :(

• need to separate page and zoom for ome-tiff, since we have many-page subifd pyramids

  • useful for fixing PDF zoom in the way we fixed SVG zoom too

• pages as bands

  $ ./src/vipsdisp ~/pics/ome/LuCa-7color_Scan1.ome.tiff

    flip to last page, zoom, lots of repaint errors
  
    maybe join first N pages (while pages same size) in pages as bands 
    mode?
  
    does not page flip to smaller pages correctly
  
        reset zoom/scroll on pageflip if the page size changes?
  
    same for audi r8 pdf page flip I guess?
  

• info bar:

  • pages as bands ... info bar displays only one band

  • will not display complex numbers correctly ... need to unpack to bands, or does getpoint do this already?

• zooming:

  • better pinch zoom support

    we should take the coordinates of the pinch gesture into account

  • zoom / zoom in menu item could step in by more, and animate the zoom as well?

  • we could shrink tiles on zoom out (we only expand tiles now)

  • before we can do fancy PDF zooming, we'll need to split page and zoom in tile_source_open()

• how should we handle images which include labels, macros, thumbnails?

  • load options? save options?

• flatpak build needs git master libvips

• auto reload on file change, or support F5 for reload?

• header display