Cactus Image Viewer

by Wassim Alhajomar (@wassimulator)

A single-file handmade image viewer for Windows, written in C/C++.

VIDEO: Watch it in action

Featured on the Handmade Network's Wheel Reinvention Jam.

Consider donating if you like this project

Used libraries

Homemade immediate mode UI, a custom D3D11 renderer, Windows Imaging Component, stb_image and libwebp for decoding, cute_files.h to manage directories on different platforms, FreeType for font loading, and easyexif for fetching image metadata.

Supported codecs

BMP, GIF, ICO, JPEG, JPEG XR, PNG, TIFF, DDS, WEBP. It also supports installed codecs for WIC, check Microsoft Store to get codecs like HEIF, RAW, or AVIF. Here: AV1 Video Extension HEVC Video Extensions HEIF Image Extensions Raw Image Extension

Features

• Standalone executable.
• Crisp font rendering with subpixel antialiasing.
• Scans folder of opened image and allows flipping through supported images within folder, and rotating the view without changing the source files.
• Supports loading image files in the sorted order of the folder, can be optionally disabled to default to alphabetic.
• Support for unicode file names.
• Multithreaded file loading.
• Fullscreen mode with F11.
• Image pan and zoom with fitting modes; to width or height.
• RGB Histograms.
• Adjustable hue, saturation, gamma, and brightness values.
• Image cropping
• Gaussian blur filters
• Ability to save images with current adjustments
• Support for reading and displaying EXIF metadata off of JPEG images and rotation info.
• Pixel color inspector and a quick copy of HEX value to clipboard.
• Animated GIF and WebP support with play/pause and seek controls.
• Quick toggle between nearest-neighbor and linear filtering for pixelart images.
• Pixel grid.
• Multiple UI themes.
• Customizable background color with support for checkerboard with custom colors.
• Drag and drop support for opening image files and folders.
• Switches to turn individual RGB channels off and switch between premultiplied alpha and straight RGB.
• Keyboard controls to pan, zoom, and flip through files and GIF controls.
• Customizable settings to save each image's zoom and pan locations within a session, or to reset image zoom and pan upon file change.

Installation

[Option 1] Standalone EXE from GitHub releases

Download and run the latest standalone CactusViewer.exe file from releases.

[Option 2] Installer from GitHub releases

While the viewer is only one executable, the installer provides the ability to add it to desktop and start menu, add a right click context button to "Open with CactusViewer" and associates it with common image file extensions. Download and run the latest CactusViewer_Setup.exe from releases.

[Option 3] Using Scoop

This will install the standalone CactusViewer.exe using Scoop, which will also add a shortcut to the start menu and add CactusViewer.exe to the PATH environment variable.

1. Install Scoop if you don't already have it.
   • Instructions: https://scoop.sh/
2. Add the Scoop Extras bucket if you don't already have it.
   • scoop bucket add extras
3. Install CactusViewer with Scoop.
   • scoop install extras/cactusviewer

CactusViewer can later be updated with scoop upgrade cactusviewer or scoop upgrade --all (updates all apps installed with Scoop).

Usage

• Opening a file:
  • Drag and drop image file into the viewer, if the file is supported it should load the file and read the folder contents of the file's directory.
  • CactusViewer also supports "Open With..." by choosing it as the program to open an image with.
  • You can also use the command line to open a file by typing: > CactusViewer.exe "path_to_file" (make sure you write the full path of the file!).
• Move the mouse to the bottom of the screen to view controls, click on "config" to see controls and change settings.

Building

Windows

All dependencies are within the repo for your, my, and everyone's convenience. Using an MSVC 64 bit developer terminal:

• run b.bat to build the project in debug mode, output in \bin (the debug version expects the font file in src, so terminal calls need to have bin as the working directory to run also make sure you have D3D11 debug layers from here installed or remove that flag in init_d3d11() when building in debug mode).
• run b.bat release to build the project in release mode, output in \bin

Remarks

• Update 2.0 ditches ImGui and OpenGL, the executable runs now on D3D11 with a handmade immediate mode UI library. If you have Windows, it should work, so please report any bugs!
• For the sake of everyone's sanity, this repo has prebuilt binaries of all the above for Windows x64, I will provide other builds if I make any.

Possible improvements

Possible things to expand on:

• Unlock the supported image resolutions sizes beyond maximum GPU texture sizes, to support images larger than 60MP or 268MP respectively.
• Decode images at lower resolutions at first and only decode full image upon zooming, to improve display speed of large files.
• Providing an optional software renderer backend.