A modest proposal for a new property

Mark Waddingham mark at livecode.com
Wed Sep 27 12:33:02 EDT 2017


On 2017-09-27 03:20, Mark Wieder via use-livecode wrote:
> Been there.
> When they're stacked on top of each other the transparent part of the
> rect is still the object under the cursor, and so obscures what's
> underneath.

Methinks that could be considered a bug :)

The graphic object does do hit-testing based on the content of the 
graphic - but it is not complete/100% accurate for all graphic types.

For opaque rectangles: correct - it checks the point is within the rect.

For non-opaque rectangles: correct - it checks the point is within the 
outline.

For rounded rectangles: incorrect - it uses the same code as rectangle 
(so roundness of corners is not taken into account).

For regular polygons, polygons and curves: correct - it checks if the 
point is within the outline and (if opaque) it checks the point is 
within the polygon.

For lines: correct - it checks whether the point is on the line.

For ovals: incorrect! It checks the point is within the oval defined by 
the rect *but* it does not take into account startangle or angle.

As a pie chart would be a stacked collection of oval graphics with 
different angles/startangles - this is why it doesn't work.

Warmest Regards,

Mark.

-- 
Mark Waddingham ~ mark at livecode.com ~ http://www.livecode.com/
LiveCode: Everyone can create apps




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