Boomer (Windows 7 port)

Zoomer application for Windows. A fullscreen overlay that lets you zoom and pan around a screenshot of your desktop — useful for presentations, streaming, or just squinting at small text.

This is a Windows port of https://github.com/tsoding/boomer.git, which is Linux/X11-only. The math, config format, and shaders are carried over unchanged; the entire windowing/capture/OpenGL-context layer has been rewritten against Win32, GDI, and WGL.

Dependencies

Building requires Nim and the following nimble packages:

$ nimble install winim opengl

Quick Start

Cross-compiling from Linux with mingw-w64:

$ ./build.sh

which is shorthand for:

$ nim c --os:windows --cpu:amd64 --cc:gcc --gcc.exe:x86_64-w64-mingw32-gcc --gcc.linkerexe:x86_64-w64-mingw32-gcc -d:mingw -d:release -o:boomer.exe src/boomer.nim

Copy boomer.exe to the Windows machine and run it:

> boomer.exe

The compiled binary uses the GUI subsystem, so launching it normally (double-click, shortcut) never pops up a console window. Running it from an existing terminal (cmd/PowerShell/Git Bash) still shows its log output there.

Controls

Control	Description
0	Reset the application state (position, scale, velocity, etc).
q or ESC	Quit the application.
r	Reload configuration.
m	Mirror the image.
Ctrl + r	Reload the shaders (only for -d:developer builds).
f	Toggle flashlight effect.
Drag with left mouse button	Move the image around.
Scroll wheel or =/-	Zoom in/out.
Ctrl + Scroll wheel	Change the radius of the flashlight.

Configuration

Configuration file is located at %APPDATA%\boomer\config and has roughly the following format:

<param-1> = <value-1>
<param-2> = <value-2>
# comment
<param-3> = <value-3>

You can generate a new config with boomer.exe --new-config.

Supported parameters:

Name	Description
min_scale	The smallest it can get when zooming out
scroll_speed	How quickly you can zoom in/out by scrolling
drag_friction	How quickly the movement slows down after dragging
scale_friction	How quickly the zoom slows down after scrolling

Command-line flags

Usage: boomer [OPTIONS]
  -d, --delay <seconds: float>  delay execution of the program by provided <seconds>
  -h, --help                    show this help and exit
      --new-config [filepath]   generate a new default config at [filepath]
  -c, --config <filepath>       use config at <filepath>
  -V, --version                 show the current version and exit
  -w, --windowed                windowed mode instead of fullscreen

Experimental Features Compilation Flags

Pass these to the nim c invocation in build.sh to enable optional behavior:

Flag	Description
-d:select	At startup, click a window to track only that window instead of the full desktop.
-d:live	Recapture and re-upload the tracked region every frame instead of taking a single static screenshot.
-d:developer	Load shaders from src/*.glsl at runtime instead of baking them into the binary, and enable Ctrl+R to hot-reload them. Requires running the exe from a directory with a src/ subfolder alongside it — not suitable for distribution.

Known limitations

• No equivalent of the original's -d:mitshm flag — that optimization is specific to X11's MIT-SHM extension and has no counterpart needed on the GDI capture path used here.
• Tested via cross-compilation and manual runs on a Windows 7 VM (VMware, Mesa/SVGA3D driver). Behavior on other GPU drivers hasn't been verified.

References

• Original Linux version: https://github.com/tsoding/boomer.git
• winim — Win32/COM/CLR bindings for Nim
• https://learn.microsoft.com/en-us/windows/win32/opengl/opengl-functions
• https://learn.microsoft.com/en-us/windows/win32/gdi/capturing-an-image

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