[etoys-dev] Book Sprint Questions

Scott Wallace scott.wallace at squeakland.org
Mon Feb 8 03:19:07 EST 2010

On Feb 7, 2010, at 8:38 PM, Steve Thomas wrote:

> 	• If you import an image; from menu choose "set as background";
> 		• THEN... How do you clear the background image?

To reverse the effect of "set as background", simply set the world's color, via its halo, to some color, any color.

There are two quite different uses of the term "background" when referring to the etoys "world", corresponding to two different "layers" of background.  This must be very confusing!

(1)  There is the world's own "color".  This is usually a conventional color, such as white or blue, but if you use the "set as background" feature that Steve refers to, the world's "color" gets set to a kind of "wallpaper" built by replicating the image you designate.  The "wallpaper color" *replaces* the color the world formerly had.  It is *unrelated* to the "background painting" feature.

(2)  Quite separately, the world also has an optional "background painting" which can be created and changed via the "repaint" handle on the world's halo.

Both kinds of "background" can exist at the same time; if you experiment with this you'll quickly learn that the world's "color", whether it's a conventional color or a "wallpaper" pattern derived from a graphic, occupies a layer *behind* the world's "background painting", if any.

Incidentally the world's "pen trails" occupy a layer *between* the color/wallpaper layer and the background-painting layer!


  -- scott

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