imageviewer

basic imageviewer and slideshow written in freebasic and sdl2
supported image types or extensions:
.bmp, .gif, .gls, .jpg, .jpeg, .png, .pcx, .svg, .webp\

Slideshow effects include a pan scan zoom aka the
'ken burns' effect plus fade in and crossfade.\

Special support for .mp3 this will extract the
cover art from a mp3 and display it if present
and .gls aka shadertoy webgl shaders.

See https://www.shadertoy.com/ for more info.

Haptic support for keyboard, mouse and gamepad.

note: 2026 august merged slideshow repo with imageviewer
https://github.com/thrive4/app.fb.slideshow

usage

imageviewer.exe "path to file or folder"
imageviewer.exe "path to file or folder" fullscreen
imageviewer.exe "path to file or folder" slideshow
imageviewer.exe "path to file or folder" slideshow fullscreen
if no file or path is specified the current dir will be scanned for an image
if the folder has subfolder(s) these will be scanned for images as well
or specify a path via confconf.ini

generate .m3u: imageviewer "path to file or folder" "tag" "tagquery"
example: imageviewer.exe artist beethoven
generates the m3u file beethoven.m3u
which then can be played by imageviewer.exe beethoven.m3u

• simple search so 195 is equivelant of ?195? or 195
• runtime in seconds is not calculated default is #EXTINF:134
• no explicit wildcard support, only searchs on one tag
• supported tags artist, title, album, genre and year

shader demo:
imageviewer.exe media\glsl

install

open zip file and copy contents to preferd folder
this application is portable.
note: for windows all requirements are bundeld in zip
for linux see below.

requirements

windows sdl2 2.32.10.0 or up
https://github.com/libsdl-org/SDL/releases

sdl image 2.8.10.0 or up
https://github.com/libsdl-org/SDL_image/releases

sdl ttf 2.20.2.0 or up
https://github.com/libsdl-org/SDL_image/releases

linux get if needed
sdl2:
sudo apt install libsdl1.2-dev\

sdl_image and sdl_ttf for sdl 2:
sudo apt install libsdl2-image-dev libsdl2-ttf-dev\

verify or check if already installed: ldconfig -p | grep SDL2 or / and: pkg-config --list-all | grep SDL2

performance

windows 7 / windows 10(1903)
ram usage ~20MB / 20MB (pending image size)
handles ~160 / ~200
threads 11 / 16
cpu ~1 (low) / ~2
tested on intel i5-6600T

navigation

  arrow     | dpad left  | mouse left : back
  arrow     | dpad right | mouse right: forward
  num plus  | R2         | scroll up  : zoom in
  num min   | L2         | scroll down: zoom out
  space     | button A   | scroll mid : reset zoom and scaletype
  r / enter | button B   |            : rotate
  z         | button Y   |            : scale type
  i         | button X   |            : display image name
  m         | start      |            : display image metrics
  f1        | back       |            : display help
  f11                                 : toggle fullscreen
  esc                                 : close application

configuration

[general]
mapversion   = 1.2
appversion   = 1.8

[screen]
screenwidth  = 1280
screenheight = 720
fullscreen   = false

[application]
' options de, en, es, fr and nl
locale          = en
' options verbose, full
logtype         = full
' used for debug build
usecons         = false
' options slideshow or image
launch            = image

[clock and date display]
' place ttf in media folder
ttffont       = gisha.ttf
' options dddd, dd mmm yyyy or dd/mm/yyyy
dateformat    = dddd, dd mmm yyyy
' options hh:mm, hh:mm:ss AM/PM, hh:mm AM/PM
timeformat    = hh:mm
' clockposistion options bottomleft, bottomright, topleft, topright
clockposistion = bottomleft
' language date options os, full, short
' full and short use date.ini allowing
' to override the os language
datedisplay = short
' display filename options file, fullpath, folder
imagenametype = folder

[media]
' location images
'mediafolder = g:\data\images\flickr\alpha clock
mediafolder = /media/wah/games/data/images/flickr/alpha clock/
' options shuffle, linear
playtype = linear

[screensaver]
' time passed before screensaver starts in seconds
screensaveinterval = 180
' timer interval between showing next image in microseconds
interval = 10000
' options dimscreen
screensavetype = dimscreen

special thanks

TwinklebearDev SDL 2.0 Tutorial Lesson 3
Tutorial translating to FreeBASIC by Michael "h4tt3n" Schmidt Nissen

djpeters for freebasic shadertoy webgl intergration
https://www.freebasic.net/forum/viewtopic.php?t=24462&hilit=shadertoy

kuan-hsu for poseidonFB works well on linux (pop os)
https://github.com/kuan-hsu/poseidonFB

gisha.ttf courtesy of microsoft corporation (non-commerical use) lekton-bold.ttf courtesy of various authors (non-commerical use)

and many thanks to various authors at shadertoy
for the demo shaders in the media\glsl folder