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53 lines
1.8 KiB
53 lines
1.8 KiB
14 years ago
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Dirty marking and rendering
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Chalk organizes layers in the form of a tree, with a grouplayer at the root:
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group1 == image->rootLayer()
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layer2
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layer3
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layer4
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group2
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layer6
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layer7
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adjustmentlayer 1
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layer9
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group3
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adjustmentlayer 2
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layer10
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layer11
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group4
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layer12
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layer13
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In this example, group1 is the rootlayer; layer13 is group3 is shown topmost
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in the layerbox, with group4 right under that, and layer13 is the "highest"
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paint layer in the complete tree.
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Compositing
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At every group level, a projection layer caches the result of compositing
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the layerstack in a projection paint device. The cached projection is then
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composited with the layers of that level, etc, until everything is composited
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onto the projection or the root layer. The image does _not_ have a projection
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anymore.
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We composite from layer2 downwards onto the projection of rootLayer, group1.
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Dirty marking
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In order to do the least possible amount of work (which is very important,
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especially with large amounts of layers and adjustment layers), we keep track
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of which layer is dirty. Groups without dirty layers are not recomposited; this
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dirtiness of course travels upwards, meaning that the rootlayer will always be
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dirty.
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XXX: Should we keep a structure with dirty rects for every layer, so we
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can determine whether the changed rect in a layer is actually in the area
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we are recompositing? I don't think so, since we should always try to keep
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Adjustment layers also keep a copy of the result of their work; if in group 2,
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layer 9 is adjusted, we do not want to composite layer 6 and 7 and filter the
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result through adjustmentlayer 1; we want to composite the changes in layer 9
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directly onto the cached result of the adjustment layer.
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