[Cuis-dev] Morph redrawNeeded

[Jon Hylands]

Hey Juan,

I'm going to have to do some more looking. Like I said before, the draw
code only takes about 30-40ms on the rpi, and that is while I'm moving my
finger on the touch screen (or using a mouse to drag). I'm still only
seeing #drawOn: called every 300ms or so in that case (while moving the
mouse).

I'll see if I can get a simpler example going on the pi.

- Jon


On Wed, 3 May 2023 at 15:45, Juan Vuletich <juan at cuis.st> wrote:

> Hi Jon,
>
> On 5/3/2023 4:01 PM, Jon Hylands via Cuis-dev wrote:
> > Hey Juan,
> >
> > Try the attached in a virgin image. There is definitely something
> > weird going on - #drawOn: is getting called twice when #redrawNeeded
> > is sent. Make sure the Transcript is open.
> >
> > - Jon
>
> This is good. It lets us talk about concrete stuff.
>
> #drawOn: is called twice. You can print the class of the canvas
> argument. It is called once on a BoundsFinderCanvas, and another on a
> VectorCanvas. This Morph is a subclass of PlacedMorph, meaning that it
> has all the VectorGraphics generality available, with some possible
> performance cost. I'll come back to this later.
>
> Now, if I remove the clearing of the startTime variable at the end of
> #drawOn:, open an instance, and close all windows (including the
> Transcript), I see values around 150mS. But, if I move my mouse quickly
> to generate _many_ mouse move events, the times it displays are 0 or 2
> (on a rather fast laptop). It is because Morphic sleeps a bit if there's
> nothing to do. This is essentially to avoid wasting CPU, energy, etc.
> See use of ivar 'pause' in WorldMorph. On the Raspi, 10 to 20 fps should
> be possible.
>
> As I said above, this Morph can be made more efficient. Morphic in Cuis
> lets you do stuff like Sample01Star. Check it. It doesn't say what are
> its 'bounds', what pixels are inside it, etc. It only knows how to draw
> itself and it just works. It is the framework who takes the trouble to
> find out all the details. But his generality has some cost. For
> instance, the need for a BoundsFinderCanvas, and the need to call
> #drawOn: twice: the first call is to find the current bounds of the morph.
>
> But as your example doesn't really need all this, but we want good
> performance on a slow cpu, we can use a more limited style and features,
> that is enough for simple boxes and text (Browsers and other Smalltalk
> tools, SystemWindows, PluggableMorphs all work like this) :
> - Copy the class as #RedrawNeededTest2
> - Change superclass to BoxedMorph
> - Add this method:
> initialize
>      super initialize.
>      extent := `500 at 500`.
>      color := Color black.
>      borderColor := Color white.
>      borderWidth := 1.
> - Make #drawOn: call super drawOn: aCanvas. Remove the call to draw and
> fix the box.
> Doing something similar could make a visible difference in your actual
> application. Or not. Not sure.
>
> Hope this helps,
>
> --
> Juan Vuletich
> cuis.st
> github.com/jvuletich
> researchgate.net/profile/Juan-Vuletich
> independent.academia.edu/JuanVuletich
> patents.justia.com/inventor/juan-manuel-vuletich
> linkedin.com/in/juan-vuletich-75611b3
> twitter.com/JuanVuletich
>
>
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