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The relayout subtree root concept is intended to handle the case where a node, when it lays itself out for a second time, changes its opinion about what dimensions it should be. In such a situation, the parent, if it based its own opinion about what size _it_ should be on the child's dimensions, would also need to lay itself out again. Thus, when this scenario is possible, the child remembers the parent, and when it would be told to relayout, we actually start the layout with the parent. In practice, this chains, and we end up with nodes that point to ancestors ten or more steps up the tree such that when the inner most child re-lays-out, the whole app ends up relaying out. This patch tries to short-circuit this for the case where the constraints being applied to the child are such that actually, the child has no choice about its dimensions. In that case, the parent can't change dimensions when the child re-lays-out. This makes a huge difference on the stocks demo app. Without this, on the third rendered frame, there are 72 relayoutSubtreeRoot links, the deepest chain is 8 deep, and 9 of the chains are only 1 level deep. With it, there are 63 relayoutSubtreeRoot links, the deepest chain is only 4 deep, and 38 of the chains are only 1 level deep. R=eseidel@chromium.org Review URL: https://codereview.chromium.org/1196553004.
Sky Examples
This directory contains several examples of using Sky. Each of these is an
individual Dart application package. If you wish to run them with sky_tool
then you will want to run pub get inside their directory before running
./packages/sky/sky_tool start.
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Hello, world. The hello world app is a basic app that shows the text "hello, world."
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Stocks. The stocks app is an example of a typical mobile app built using Sky. The app shows a list of all the stocks in the NASDAQ.
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Widgets. The widgets app contains a number of Sky widgets so you can experiment with them in a simple container.