Automatic shadows?

[David Karger]

Given that there is a standard recommendation for Shadows (diagonally to the right) it would be nice if we could specify that a marker should use a "default shadow" (e.g. by setting shadowIcon=true) and have gmaps construct it for us.

[Ben Appleton]

In browsers with Canvas one could generate a shadow image for a custom icon. However I don't think this is possible in IE7/8. So our usual approach in this case is to promote or publish a library or web service that adds this functionality on top of the API.

Android brevity

On Dec 21, 2011 6:17 AM, "David Karger" <david....@gmail.com> wrote:

Given that there is a standard recommendation for Shadows (diagonally to the right) it would be nice if we could specify that a marker should use a "default shadow" (e.g. by setting shadowIcon=true) and have gmaps construct it for us.

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[Berry Ratliff]

On Dec 21, 12:27 am, Ben Appleton <apple...@google.com> wrote:
> In browsers with Canvas one could generate a shadow image for a custom
> icon. However I don't think this is possible in IE7/8. So our usual
> approach in this case is to promote or publish a library or web service
> that adds this functionality on top of the API.

Even canvas has obstacles. The alpha component must be examined to
determine the non-transparent sections of the marker. The
"getImageData" method is not very efficient. The icon might reside in
a different domain. The "getImageData" method cannot access an image
from another domain. The "transform / setTransform" methods can
change shapes but cannot change colors. I am not aware of another
option.

[David Karger]

If you want your shadow to reflect the icon's transparency it's more challenging.  But if you just want a uniformly grey shadow, you can get it by drawing "over" the icon using "destination-in" compositing (and approprite transformations).

[Berry Ratliff]

The marker may not be rectangular. Unless it fills the entire image
file, its opacity must be examined to determine its shape. You could
supply a "path" but it would not be automatic. I am not aware of a
"globalCompositeOperation" to combine the "alpha" of one set of pixels
with the "color" of another set of pixels.