89 lines
3.0 KiB
Markdown
89 lines
3.0 KiB
Markdown
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title = "Ideas from my Development Setup: Clipboard"
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date = "2020-10-07"
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author = "Ceda EI"
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tags = ["xorg", "linux", "development"]
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keywords = ["xorg", "linux", "development"]
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description = "Things with clipboards: Implicit copying and swapping"
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showFullContent = false
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## Ideas
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The clipboard is a basic yet integral part of every environment. Over time, I
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have had quite a few ideas regarding clipboards. I have implemented the
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following ideas currently:
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### Clipboard Swap
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Inspired by vim's registers, I thought about implementing something similar on
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a system level for Xorg. My current implementation basically swaps the contents
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of the clipboard with another clipboard. Currently, the workflow looks
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something like this.
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- Copy text `abc`: Writes `abc` to the main clipboard.
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- Press ``` Ctrl+` ```: Swaps content of hidden clipboard with main clipboard.
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- Copy text `def`: Writes `def` to the main clipboard.
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- Paste with `Ctrl+v`: Pastes text `def` as expected.
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- Press ``` Ctrl+` ```: Swaps content of hidden clipboard with main clipboard.
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- Paste: Pastes text `abc`.
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### Implicit Copying
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Some time ago, a realization hit me that I practically always select text for
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the sake of copying or cutting it. Cutting is just copying and then deleting
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that text. So everytime I select text, it is for copying it. Due to this, I
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implemented implicit copying where text is copied just by selecting it. So,
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the workflow for copying is reduced from select, ctrl+c, paste to select, paste
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while the workflow for cutting is same.
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## Clipboards in Xorg
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In Xorg, clipboards are called selections. Xorg has three selections:
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Primary, Secondary and Clipboard.
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- Primary: Whenever text is selected, it is copied into primary selection. You
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can paste contents of the primary selection by pressing middle mouse button
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in most applications.
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- Secondary: There is no consensus on what this is supposed to be used for and
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hence it is used by practically nothing.
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- Clipboard: This is the selection that practically every application interacts
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with. Ctrl-C and Ctrl-V are commonly bound to writing to this clipboard.
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## Implementation
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Secondary selection is the perfect selection to swap the contents of Clipboard
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selection with. It is practically never used so nothing will overwrite the
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contents of secondary selection.
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Here is the `clip_swap.sh` which I have bound to ``` Ctrl+` ``` in my i3
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config.
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```bash
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#!/usr/bin/env bash
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x=$(xclip -selection secondary -out)
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xclip -selection clipboard -out | xclip -selection secondary
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echo "$x" | xclip -selection clipboard
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```
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For implementing implicit copying, I basically needed a daemon that watched for
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changes in primary selection and copies them over to clipboard selection. Here
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are the contents of `clip_syncd.sh`
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```bash
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#!/usr/bin/env bash
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# Daemon to synchronize PRIMARY selection with CLIPBOARD selection
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old=""
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while :; do
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new=$(xclip -selection primary -out) || { sleep 0.5; continue; }
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if [[ $new != "$old" ]]; then
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xclip -selection primary -out | xclip -selection clipboard -in
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old="$new"
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fi
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sleep 0.5
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done
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```
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