EM Font Size Performance
david.grieve at oracle.com
Thu Apr 19 19:51:48 UTC 2018
I was thinking about https://bugs.openjdk.java.net/browse/JDK-8177635
There is also https://bugs.openjdk.java.net/browse/JDK-8187955
On 4/19/18 3:02 PM, Nir Lisker wrote:
> I think this is the issue:
> https://bugs.openjdk.java.net/browse/JDK-8088615. There's also
> - Nir
> On Thu, Apr 19, 2018 at 1:42 PM, David Grieve <david.grieve at oracle.com
> <mailto:david.grieve at oracle.com>> wrote:
> Resolving the relative size involves a lot of lookup. You have to
> go up the scene-graph from the child to find a font style. If you
> get to the root and haven't found a font style, then use the
> default font. Performance in this area could be vastly improved by
> passing the size from either a font style or the default font down
> the scene-graph as styles are evaluated. There are other style
> lookups that could benefit from this as well, resolving looked-up
> colors for example. I believe I created a bug for this a long time
> On 4/19/18 5:57 AM, Dean Wookey wrote:
> Hi All,
> In our application we add and remove a lot of nodes to the
> scene graph
> regularly, and also make use of em font sizes to scale certain
> parts of our
> application. We've noticed performance issues when adding
> nodes to the
> scene, and it seems to be related to em sizes in our css.
> As a test we added a chain of 20 stackpanes to a root
> stackpane. On the
> root, we set a font size of 8pt via inline css. We then added
> and removed a
> new tableview from the deepest stackpane 500 times, waiting
> for the node to
> render after each add and remove.
> In each of the experiments, we compared adding tableviews
> without css and
> adding tableviews with an inline css font size of 8pt. We then
> setting different font sizes in the stackpane chain.
> I've attached sample code for these experiments.
> The results (on jdk 9.0.4 - jdk 10 was similar) are as follows:
> Setting a 1em font size on all stackpanes except the root.
> With font on tableview: 14707ms
> Without font on tableview: 27725ms
> Setting a 1em font size on the first child of the root only.
> With font on tableview: 14221ms
> Without font on tableview: 19187ms
> Using the original setup with no additional fonts.
> With font on tableview: 13990ms
> Without font on tableview: 13847ms
> It looks like using a relative font size has a large effect
> wise on descendant nodes. I would expect some amount of font
> size caching
> in the chain of stackpanes since I'm reusing the same chain and
> adding/removing nodes from that chain repeatedly.
> I'm not sure how valid my test is, or how much of an issue
> this really is
> in practice?
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