A minimal screenshot utility for X11. Shotgun was written to replace maim in my workflow.
Features: - Exports PNG screenshots to file or stdout - Masks off-screen areas on multi-head setups - Supports selections by window ID and geometry - On average, shotgun is more than twice as fast as maim
``` Usage: shotgun [options] [file]
Options: -i, --id ID Window to capture -g, --geometry WxH+X+Y Area to capture -f, --format png/pam Output format -h, --help Print help and exit -v, --version Print version and exit ```
To use with slop (as a replacement for maim -s):
```bash
set -e
sel=$(slop -f "-i %i -g %g") shotgun $sel $* ```
- as the file name if you want to pipe output to something
else)There are several reasons for omitting these features:
- Features that can be replaced trivially by external programs and wrapper
scripts:
- Use ImageMagick's convert and shotgun's -f pam for JPEG output
- slop output is easy to process in a shell script
- Use sleep instead of -d, since slop has to be called separately, this
flag is not necessary
- -x shouldn't even exist in the first place, set $DISPLAY instead
- I never use cursor blending, and I know that most users do not actually care
for it
- -w (geometry relative to another window) is difficult to use and hardly
useful, instead, shotgun always interprets the input geometry relative to the
root window (maim's default is the captured window itself)
- There is rarely a reason to take a screenshot of an XShape window, most of
them are special like slop's selection window or keynav's crosshair.
Supporting XShape properly could add a significant amount of overhead, both in
code length and performance, which are not desirable.
I've claimed that shotgun is twice as fast as maim, here's some supporting evidence:
``` streetwalrus@Akatsuki:~/source/shotgun(master)
xrandr --fb 3840x2160 streetwalrus@Akatsuki:~/source/shotgun(master) for i in {1..10}; do time maim > /dev/null; done maim > /dev/null 0.78s user 0.00s system 107% cpu 0.731 total maim > /dev/null 0.79s user 0.01s system 104% cpu 0.764 total maim > /dev/null 0.75s user 0.02s system 104% cpu 0.727 total maim > /dev/null 0.74s user 0.01s system 110% cpu 0.678 total maim > /dev/null 0.76s user 0.01s system 108% cpu 0.717 total maim > /dev/null 0.73s user 0.02s system 104% cpu 0.711 total maim > /dev/null 0.74s user 0.01s system 106% cpu 0.703 total maim > /dev/null 0.74s user 0.01s system 109% cpu 0.682 total maim > /dev/null 0.82s user 0.02s system 104% cpu 0.799 total maim > /dev/null 0.75s user 0.01s system 105% cpu 0.719 total streetwalrus@Akatsuki:~/source/shotgun(master) for i in {1..10}; do time ./target/release/shotgun > /dev/null; done ./target/release/shotgun > /dev/null 0.31s user 0.01s system 99% cpu 0.320 total ./target/release/shotgun > /dev/null 0.33s user 0.01s system 108% cpu 0.311 total ./target/release/shotgun > /dev/null 0.35s user 0.01s system 109% cpu 0.322 total ./target/release/shotgun > /dev/null 0.35s user 0.01s system 111% cpu 0.327 total ./target/release/shotgun > /dev/null 0.31s user 0.01s system 107% cpu 0.296 total ./target/release/shotgun > /dev/null 0.32s user 0.01s system 109% cpu 0.302 total ./target/release/shotgun > /dev/null 0.36s user 0.00s system 105% cpu 0.338 total ./target/release/shotgun > /dev/null 0.32s user 0.01s system 102% cpu 0.322 total ./target/release/shotgun > /dev/null 0.34s user 0.00s system 105% cpu 0.318 total ./target/release/shotgun > /dev/null 0.33s user 0.01s system 111% cpu 0.303 total ```
Further profiling has shown that the bottleneck in shotgun lies fully within the PNG encoder.
The PNG encoder bottleneck can be avoided by using -f pam. This sets the output format to
Netpbm PAM - an uncompressed binary image format.
By using an uncompressed format both encoding and decoding performance is improved:
```
for i in {1..5}; do time ./target/release/shotgun -f png - > /dev/null; done ./target/release/shotgun -f png - > /dev/null 0.32s user 0.11s system 99% cpu 0.434 total ./target/release/shotgun -f png - > /dev/null 0.31s user 0.05s system 99% cpu 0.369 total ./target/release/shotgun -f png - > /dev/null 0.32s user 0.06s system 99% cpu 0.382 total ./target/release/shotgun -f png - > /dev/null 0.31s user 0.06s system 99% cpu 0.369 total ./target/release/shotgun -f png - > /dev/null 0.26s user 0.08s system 99% cpu 0.343 total
for i in {1..5}; do time ./target/release/shotgun -f pam - > /dev/null; done ./target/release/shotgun -f pam - > /dev/null 0.09s user 0.12s system 98% cpu 0.210 total ./target/release/shotgun -f pam - > /dev/null 0.07s user 0.07s system 99% cpu 0.141 total ./target/release/shotgun -f pam - > /dev/null 0.10s user 0.05s system 99% cpu 0.148 total ./target/release/shotgun -f pam - > /dev/null 0.08s user 0.08s system 99% cpu 0.152 total ./target/release/shotgun -f pam - > /dev/null 0.08s user 0.07s system 99% cpu 0.148 total ```
```
for i in {1..5}; do time ./target/release/shotgun -f png - | convert - jpg:- > /dev/null; done convert - jpg:- > /dev/null 0.59s user 0.16s system 89% cpu 0.842 total convert - jpg:- > /dev/null 0.58s user 0.16s system 95% cpu 0.763 total convert - jpg:- > /dev/null 0.55s user 0.20s system 97% cpu 0.764 total convert - jpg:- > /dev/null 0.53s user 0.15s system 89% cpu 0.758 total convert - jpg:- > /dev/null 0.61s user 0.16s system 100% cpu 0.762 total
for i in {1..5}; do time ./target/release/shotgun -f pam - | convert - jpg:- > /dev/null; done convert - jpg:- > /dev/null 0.24s user 0.11s system 63% cpu 0.557 total convert - jpg:- > /dev/null 0.23s user 0.09s system 70% cpu 0.449 total convert - jpg:- > /dev/null 0.22s user 0.10s system 66% cpu 0.490 total convert - jpg:- > /dev/null 0.21s user 0.11s system 72% cpu 0.434 total convert - jpg:- > /dev/null 0.22s user 0.10s system 69% cpu 0.459 total ```
cargo install.cargo install shotgunpacman -S shotgun