Transforming identity by an other transform does not mean we need to
painstakingly apply the individual steps of other to construct a new
transform, it means we can just return other.
Or in math terms:
I * B = B
so just return B.
I was getting assertions that normalize_angle() failed the
result < 260 check. Doing some research on this it turns out
to be a precision issue. If the incomming angle is very slightly
below zero, then adding 360 to it may end up with exactly 360.
I simplified the code a bit to avoid division and rounding, because in
practice most angles will be "just outside" the 0-360 degree anyway.
And i also added a workaround for the "result is 360" case by just
setting it to 0.
sincosf() is really a GCC-specific function that may more may not be
supported on non-GCC compilers, so we want to check for it, otherwise we
use a fallback implementation, not unlike the one in
demos/gtk-demo/gtkgears.c.
E.g. anything involving a scale. This is important when e.g. scrolling
in the node list in the recorder, which scales every recorded node down
to fit in the list.
If somebody does a transform like
scale(5) scale(10) translate(1,1) translate(5,0)
store it instead as
scale(50) translate(6,1)
This way, less memory is consumed and transforms are easier to read.
In particular, this simplifies the typical transforms we do in GTK,
which are just one translation after another.
Floating point values cannot ever be compared for equality. GLib has a
G_APPROX_VALUE macro that lets us compare two value within a provided
precision, so we should use that instead.
Artisanal, homegrown, locally sourced, vegan reference counting has been
replaced by the appropriate API in GLib, which does small things like
saturation and type checking.
gsk/gskenums.h:181: Error: Gsk: multiple "@GSK_TRANSFORM_CATEGORY_2D" parameters for identifier "GskTransformCategory":
* @GSK_TRANSFORM_CATEGORY_2D: The matrix is a 2D matrix. This is equivalent
^
gsk/gsktransform.c:1342: Warning: Gsk: gsk_transform_to_2d: unknown parameter 'm' in documentation comment, should be 'self'
gsk/gsktransform.c:1368: Warning: Gsk: gsk_transform_to_2d: invalid return annotation
gsk/gsktransform.c:1461: Warning: Gsk: gsk_transform_to_translate: unknown parameter 'm' in documentation comment, should be 'self'
Make the API expect a tranform of the proper category instead of
doing the check ourselves and returning TRUE/FALSE.
The benefit is that the mai use case is switch (transform->category)
statements and in those we know the category and don't need to check
TRUE/FALSE.
Using the wrong matrix will now cause a g_warning().
... instead of computing it every time we need it.
This should be faster and we want to use it a lot more prominently.
Also, we have the struct memory available anyway.
In particular, add a per-category querying API for the matrix:
- gsk_transform_to_translate()
- gsk_transform_to_affine()
- gsk_transform_to_2d()
- gsk_transform_to_matrix()
This way, code can use the relevant one for the given category.
