Display performance decreased with BlGaussianShadowEffect on BlElement

[LouisePla]

When a BlGaussianShadowEffect is added on a BlElement, the display performance of the application decrease.

Example:

       | space |
	space := OBlSpace new.
	space root layout: (BlFlowLayout horizontal).
	
	1 to: 200 do:[ :i | | e1 e2 e3 e4 e5 |
		e1 := BlElement new.
		e1 size: 100 asPoint.
		e1  background: (Color random).
                "Uncomment the effect below to see display performance decreased"
		"e1 effect:  (BlGaussianShadowEffect
		  	color: ((Color fromHexString: '010532') alpha: 0.08)
		  	width: 2
		  	offset: 0 @ 2)."
		space root addChild: e1.
	].
	
	space show

[plantec]

well, afaik gaussian effect is not natively computed by Cairo but with a dedicated algorithm in Alexandrie...
so I would not use it for such number of elements in the same parent

[tinchodias]

This may have improved now that elements with shadows that don't change keep cached,

To add some numbers:

block := [ :isShadowEnabled |
   | space |
	space := BlSpace new.
	space root layout: (BlFlowLayout horizontal).
	
	1 to: 200 do: [ :i |
		| e1 |
		e1 := BlElement new.
		e1 size: 100 asPoint.
		e1 background: Color random.
		
		isShadowEnabled ifTrue: [
			e1 effect: (BlGaussianShadowEffect
			  	color: Color red
			  	width: 2
			  	offset: 0 @ 2) ].

		space root addChild: e1 ].
	
	space root asForm ].

{ false. true } collect: [ :each |
	[ block value: each ] timeToRun asMilliSeconds ]

"---> #(32   1034)"


{ false. true } collect: [ :each |
	[ block value: each ] bench ]

"---> #('35.025 per second' '0.955 per second')"

[tinchodias]

Let's keep the topic in #669