New subject: [1/3] gdiplus: Add a test to check transformation order in GdipMeasureDriverString.

2 Nov 2012


      Thanks for writing tests. It turns out I was a bit confused when I
asked for them.
For some reason, I was was under the impression that
GdipMeasureDriverString would return a measurement in device
coordinates, when it should have been obvious to me that it returns
world coordinates. Looking back at the existing tests confirms that,
since the measurements are the same with a NULL matrix regardless of
world transform.
That means the test I wanted doesn't answer the question I wanted
answered. I'm sorry I created extra work for you with my mistake.
The approach of rotating and scaling still works, but it requires
drawing text and visually inspecting the output. I've written and
attached a test program that does that (with a matrix that rotates by
90 degrees and a world transform with a much greater scale on the Y
axis than the X axis). It shows that things work as I expected. The
text is stretched vertically AFTER the rotation is applied, and it's
easy to see the difference between native's behavior and your patch.
It also appears that the origin point (and presumably the later points
as well) should not have the matrix applied to it. It looks to me like
your patch does not transform the points in the GDI32 codepath, and
thus gets the origin point correct in the testcase. It does transform
them in the SOFTWARE codepath, and if I force that codepath to be
taken, the text draws outside the bounds of the window. So the matrix
shouldn't be passed to transform_and_round_points, and it's not
necessary to add a matrix argument to that function.

Re: [1/3] gdiplus: Add a test to check transformation order in GdipMeasureDriverString.