qiv (Quick Image Viewer)

Quick Image Viewer (qiv) is a very small and pretty fast GDK3 image
viewer. Features include zoom, maxpect, scale down, fullscreen,
brightness/contrast/gamma correction, slideshow, pan with keyboard and
mouse, rotate left/right, flip, delete (move to .qiv-trash/), jump to
image x, jump forward/backward x images, filename filter, and you can
use qiv to set your X11 desktop background.

These formats are supported by default:

GIF TIFF XPM PNG PPM PNM PGM BMP JPEG SVG ICO TGA ICNS

Optional supported formats:

Format                  | Optional dependenc(y|ies)
------------------------+-----------------------------------------------
HEIF, AVIF              | libheif
------------------------+-----------------------------------------------
JP2 (JPEG2000)          | jp2-pixbuf-loader
------------------------+-----------------------------------------------
PCX                     | pcx-pixbuf-loader
------------------------+-----------------------------------------------
PSD (PhotoShop native)  | gdk-pixbuf-psd
------------------------+-----------------------------------------------
RAW (camera images,     | libopenraw. Note that only a few raw image
    various extensions) | formats will actually display with qiv. These
                        | include .crw (Canon), .erf (Epson), and
                        | .nef (Nikon). YMMV.
------------------------+-----------------------------------------------
WEBP                    | webp-pixbuf-loader
------------------------+-----------------------------------------------
WMF (Windows MetaFile)  | libwmf-type1-fonts (only needed for .wmf files
                        | with embedded text, but all the ones I tested
                        | do have text...)
------------------------+-----------------------------------------------
XCF (Gimp native)       | xcf-pixbuf-loader
------------------------+-----------------------------------------------

These are runtime dependencies, so they can be installed at any time
without rebuilding qiv.

To easily build all the optional dependencies, use sbopkg with the
qiv-allfmt.sqf in the SlackBuild directory.

Build option: By default, qiv uses the filename extensions to
decide which files are images, and only attempts to display files
with recognized extensions such as .png, .jpg, etc. This can be
disabled with qiv's -n option. If you'd prefer to have qiv ignore the
extensions and try to display all files as images, export FILTER=no in
the script's environment. You will be able to re-enable it at runtime
with the -n option.

Upgrade note: Starting with version 3.0.0, qiv no longer uses
imlib2. If you have images that would display in qiv-2.3.x, but not in
3.0.x, *please* contact the SlackBuild maintainer, so I can fix it!