Kiva Quartz backend renders images differently than AGG

[jwiggins]

The easiest way to reproduce this bug is to create a Chaco image plot and set the orientation to 'v'. When comparing the output of Quartz and AGG, the result will be rotated 180º.

[tonysyu]

This discrepancy only occurs when the origin is set to 'top left' or 'bottom right'. The AGG result seems to be the correct one: Setting orientation = 'v' simply switches the x- and y-axes, regardless of where the origin is set. In the Quartz result, a value that was at x (y) moves to w - x (h - y) when the origin is set to 'top left' or 'bottom right'.

[tonysyu]

This may just be a bug in Chaco. In most cases, the rectangle passed to the graphics context is (x0, y0, w, h), where (x0, y0) specifies the lower-left corner. For the case where orientation = v and origin is top left or bottom right, the rectangle is (x1, y1, -w, -h), where (x1, y1) is the upper right corner.