Effects

[fool-in-the-rain]

Hi, our work is already deeply indebted to the effects which made presentations so lively in Pharo 7 with Skia. Could these effects, such as BlGaussianShadowEffect, and drop shadow, be revived for the current implementation of Cairo Alexandrie? The gaussian effect is huge.

If you could also consider some creative opportunities for the mesh gradient, that is another effect which would help rivet peoples' attention. Anything to help shine a light on the underlying technology is a big plus for us.

[tinchodias]

Hi, we now have shadows. Since this commit. Feedback welcome!

Warning: we plan to improve performance with:

• caching
• taking advantage of each particular geometry

---

There is the Gaussian shadow:

		aBlElement effect:
			(BlGaussianShadowEffect
				color: Color orange
				width: 5
				offset: 0@0 )

From our regression tests:

---

And also the "simple" shadow, that is like the Gaussian with width=0, i.e. sharp edges. Example:

		aBlElement effect:
			(BlSimpleShadowEffect
				color: Color orange
				offset: 1 @ 1 ) 

[tinchodias]

[astares]

Cool!

[tinchodias]

There was a visual bug in some cases, that is fixed with my latest commit on Alexandrie.

(For the record: it took me some debug time to detect the bug happened when the pixel width of the Cairo surface was different than it's stride)

[tinchodias]

The mesh gradient is already implement in Athens-Cairo, so shouldn't be hard to port it to Alexandrie, and add a new Bloc paint.

I am taking a glance at COLR spec and they call it sweep gradient.

[tinchodias]

Correction: the sweep gradient is an application of the mesh gradient. Here is a cairo test that shows how to do it: https://gitlab.freedesktop.org/cairo/cairo/-/blob/master/test/mesh-pattern-conical.c

[tinchodias]

We keep open issue 333 for conical gradient and close this, which is too wide