Hi Christina,
Christina Roßmanith schrieb:
Am 29.07.2012 18:25, schrieb Regina Henschel:
Hi Christina,
I'm not sure about what you want to know.
Christina Roßmanith schrieb:
Hi,
just to be sure before I continue my work:
SVG gradient with angle=0° changes color from left to right
(I'm taking this from
http://www.w3.org/TR/SVG/pservers.html#LinearGradientElement)
The svg:gradient does not has an angle, but a start point and an end
point. The start point has the color of the 0%-stop color and the end
point has the color of the 100%-stop color.
You are right, there is no angle but transforms are applied to the
gradient vector (and normal). So the question is what is the direction
of the gradient vector in absence of any transform and the w3c test
suite gives the answer: from left to right (along the positive x axis?)
There is a picture which explains it in SVG 1.1 Section 13 Gradients and
Patterns
http://www.w3.org/TR/SVG/pservers.html
ODF gradient with angle=0° changes color from top to bottom
(I can't find any meaning of the angle attribute here
http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#__RefHeading__1416460_253892949)
I think, that the specification is not clear about the untransformed
direction of the gradient vector. "Gradient vector" is for me the
direction from start color to end color in the way, that a line with
points of same color is perpendicular to the gradient vector.
LibreOffice handles it in the way, that the untransformed gradient
vector is in direction of the positive y-axis, that is on screen from
top to bottom.
That means I have to rotate the gradient orientation 90° ccw when
importing svg gradients.
Do you want to import a svg-picture? Or do you want to implement feature
"ODF1.2 16.40.2<svg:linearGradient>"? Or what are you working on?
I ask, because there are further attributes, which cannot be impressed
directly in a LO gradient: intermediate stop-colors, spreadMethod, and
gradientUnits, which has to be considered to, when calculating an angle.
It is no rotation at all. But you have to convert between two-point
vector and angle.
The draw:angle is the angle the gradient vector is rotated. Where it
has the same rule as other rotations, that it is on screen against
clock, which will be clockwise in calculation because of the top-down
direction of the y-axis.
LibreOffice handles the angle unit as 0.1°, whereas in ODF1.2 the
angle unit defaults to 1°.
That might explain why in a fodg file which I've modified by hand a
gradient angle of "90" is interpreted as "9".
The spec has to be changed to meet the practice. Do you know an ODF1.2
application, that interprets the angle in degree? Shall I write a mail
to OASIS to change it to 0.1°?
Kind regards
Regina
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