As the subject states, let me make a (relatively) short summary of some
proposed changes and additions to the evas gfx api -- and I'll deal with only
gradients and a possible vgfx-objs api, leaving transforms (mostly) and filters
for later.
First, changes to the current gradient api. This would replace the current
api with the following one:
(1) For creating gradients:
**********************
Evas_Object *evas_object_gradient_[type]_add(e);
where the types are: linear and radial (and possibly later also angular,
rectangular, triangular, sinusoidal, ...)
(2) For setting gradient geometries (of a given type):
*************************************************
void evas_object_gradient_[type]_fill_set(obj, [geometry desc]);
Where the [geom desc] is:
(a) for linear grads,
void evas_object_gradient_linear_fill_set(obj, Evas_Coord x0, Evas_Coord y0,
Evas_Coord x1, Evas_Coord y1);
(b) for radial grads,
void evas_object_gradient_radial_fill_set(obj, Evas_Coord cx0, Evas_Coord cy0,
float rx, float ry);
And we'd leave any other types for later as desired.
(3) For setting the gradient geometry's "spread" (or repeat, or extend) mode:
************************************************************************
void evas_object_gradient_fill_spread_set(obj, int tile_mode);
(4) For modifying the gradient geometry via a transform:
***************************************************
void evas_object_gradient_fill_transform_set(obj, Evas_Transform *t);
where an 'Evas_Transform' is defined as:
struct Evas_Transform
{
float mxx, mxy, mxz;
float myx, myy, myz;
float mzx, mzy, mzz;
};
ie. a 3x3 tmatrix which can be used to define a projective transformation
or an affine one by ignoring the mzx,mzy,mzz components. Only affine ones
supported for grad geometries (though the obj itself may support proj
ones).
(5) For clearing/defining the gradient obj's "spectrum":
***************************************************
void evas_object_gradient_clear(obj);
ie. remove any stops or data or whatnot from the gradient.
void evas_object_gradient_color_np_stop_insert(obj, r, g, b, a, float pos);
ie. insert a NON_PREMUL color at the given pos (clamped to be in [0,1])
And *possibly* also similar premul such, as exist currently:
void evas_object_gradient_color_stop_insert(obj, r, g, b, a, float pos);
void evas_object_gradient_alpha_stop_insert(obj, a, float pos);
void evas_object_gradient_color_data_set(obj, *data, len, has_alpha);
void evas_object_gradient_alpha_data_set(obj, *data, len);
That's it for basic gradient support (one could add more types, and one
could add some funcs to query/modify stops if desired).
The reasons for proposing these changes?
To allow for direct support of gradients with various possible engine backends
(eg. xrender, cairo, OpenVG, ... others).
To have an api which is 'fitted' to what most all vgfx specs/lib-apis support
with gradients.
To more easily enable and represent various uses of gradients (including vgfx
related ones like "texturing" of geometric figures with them).
This then leads to a proposed api for vgfx-objects in evas -- and recall,
by
"vgfx-objects", we mean objs that can be "filled and/or stroked" (eg. lines,
rects,
polys, paths, ... maybe text) with a color or a "texture" (aka a paint or a
pattern).
Which I'll leave for a 'part II' of this thread...
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