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Added notes about blend modes, opacity, and adjustments to docstring

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1 parent 503d7a6 commit 664af29db0707895a0d895cc445e56d4f3891b43 migurski committed Nov 20, 2010
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  1. +17 −0 TileStache/Goodies/Providers/Composite.py
@@ -27,6 +27,23 @@
Many combinations of "src", "mask", and "color" can be used together, but it's
an error to provide all three.
+Layers can be combined through the use of opacity and blend modes. Opacity is
+specified as a value from 0.0-1.0, and blend mode is specified as a string.
+This example layer is blended using the "hard light" mode at 50% opacity:
+
+ {"src": "hillshading", "mode": "hard light", "opacity": 0.5}
+
+Currently-supported blend modes include "screen", "multiply", and "hard light".
+
+Layers can also be affected by adjustments. Adjustments are specified as an
+array of names and parameters. This example layer has been slightly darkened
+using the "curves" adjustment, moving the input value of 181 (light gray)
+to 50% gray while leaving black and white alone:
+
+ {"src": "hillshading", "adjustments": [ ["curves", [0, 181, 255]] ]}
+
+Currently, only the "curves" adjustment is supported.
+
Finally, the stacking feature allows layers to combined in more complex ways.
This example stack combines a background color and foreground layer:

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