Thank you very much. 
Can anything affect the orientation of the absolute measurement of Measure? 
It goes from left-to-right and top-to-bottom, no matter how I set the units 
in the context.

On Thursday, March 12, 2015 at 3:14:28 PM UTC+8, Daniel Jones wrote:
>
>
> It can actually actually work both ways: cx and cy give "context units", 
> which by default are between 0 and 1, and go from left-to-right and 
> top-to-bottom, but can be redefined to be anything.
>
> So, this draws a line from the top-left to the bottom-right.
> compose(context(), line([(0cx,0cy), (1cx,1cy)]), stroke("black"))
>
> But I can change the units in the context, it draws a line from the 
> bottom-left to top-right.
> compose(context(units=UnitBox(0,1,1,-1)), line([(0cx,0cy), (1cx,1cy)]), 
> stroke("black"))
>
> UnitBox defines a new coordinate system in which the top-left corner is 
> (0, 1), and the context is 1 unit wide and 1 unit tall, but the height is 
> given as "-1", which somewhat unintuitively flips the orientation of the 
> units.
>
> If you look at the bottom of "coord.jl" in Gadfly, you'll see how the 
> coordinate system for the plot gets set up:
>
>         context(units=UnitBox(
>             coord.xflip ? xmax : xmin,
>             coord.yflip ? ymin : ymax,
>             coord.xflip ? -width : width,
>             coord.yflip ? height : -height,
>             leftpad=xpadding,
>             rightpad=xpadding,
>             toppad=ypadding,
>             bottompad=ypadding),
>
>
>
>
>
>
> On Wednesday, March 11, 2015 at 10:33:35 PM UTC-7, nanaya tachibana wrote:
>>
>> I wanted to contribute to Gadfly.jl and I started from looking into 
>> bar.jl. 
>> I found that the value cy of Measure in Gadfly.jl increases from bottom 
>> to top, but it increases from top to bottom in Compose.jl.
>> What makes Measure work in that way? 
>>
>> I really appreciate any help you can provide.
>>
>>

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