The problem was a bit more complex than originally anticipated,
and the root of the problem is that the "coordinates" of a pixel
are actually the top left of the pixel, and when we're really
zoomed in, the difference in editor coordinates of the top-left
and the center of the pixel is significant.
So, we need to offset the "start" point when we are painting on
the editor to account for this, based on the current scale. This
patch adds a `editor_stroke_position` in `Tool` which can be used
to compute what point (in editor coords) we should use for a given
pixel and it's corresponding stroke thickness.
Note that this doesn't really work well with the ellipse, since that
is drawn with a different mechanism. Using this new method with the
`EllipseTool` seems to give the same (or slightly worse) results, so
I have not changed anything there for now.
There are quite a few tools that might want to change certain values
based on consistent keyboard shortcuts. This commit allows tools to
hook up a "primary" and "secondary" slider with the base `Tool`
class, which can then handle updating those sliders with the common
shortcuts.
Note that any derived classes that want to override the `on_keydown`
function will manually need to call `Tool::on_keydown()`.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *