awtk/3rd/agg/doc/AggCP-Gradients1_readme.txt
2018-05-27 11:52:44 +08:00

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AGG Contribution Pack - Gradients 1 (AGG CP - Gradients 1)
http://milan.marusinec.sk/aggcp
For Anti-Grain Geometry - Version 2.4
http://www.antigrain.org
Contribution Created By:
Milan Marusinec alias Milano
milan@marusinec.sk
Copyright (c) 2007-2008
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How To Install
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1. Copy \examples and \include directories directly to the \agg-2.4 directory.
2. MS Visual Studio: In Solution Explorer click "Add Existing Project ..."
from \examples\win32_api\gradients_contour subdirectory.
3. Build, Run, Enjoy.
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About
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This AGG Contribution Pack (CP) extends existing set of gradient functions
found in AGG 2.4 and later and is not a part of original source code
distribution package, so you have to download and install this CP separately.
Following additional gradient functions are included:
gradient_contour
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located in "agg_span_gradient_contour.h"
Creates color transitions from shape defined by an arbitrary (in fact any)
path. It computes so called Distance Transform (DT) from image produced by
only stroking the path, which is then the source of color level in
the underlying gradient function.
Contour gradient can be used in two forms:
One is to define shape for contour different from shape of object being drawn.
Second is to use the same shape for contour and for drawing (AutoContour).
gradient_conic_angle
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located in "gradients_contour.cpp"
Assymetric conic gradient (also called angle) is the same as conic, but the ray
of light with color transitions going counter clockwise travels whole circle
instead of just half (as with conic).
Note: Implementation of this one is so tiny, it doesn't have it's own header
file. If you want to use it, just copy and paste it from the demo file.
gradient_image
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located in "agg_span_gradient_image.h"
Bitmap gradient is very similar to pattern fill, but works in the framework
of gradient functions interfaces. Because of that all interpolator
transformations from gradient span generator can be applied to this kind
of fill (all affine transformations, perspective, bilinear & warp).
Note: This gradient function doesn't generates indexes for colors used.
When constructing the span_gradient object, the color function type is
eg. agg::one_color_function<agg::rgba8> and instance of that color
function is retrieved by calling special function of gradient_image
class -> gradient_func.color_function().
See the "gradients_countour.cpp" demo for more details.
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