Bug 187553 - REGRESSION (r232356): After zooming a page in and out, it's possible to temporarily have missing tiles (google.com, apple.com)
Summary: REGRESSION (r232356): After zooming a page in and out, it's possible to tempo...
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
Keywords: InRadar
Depends on:
Reported: 2018-07-11 07:02 PDT by Antti Koivisto
Modified: 2018-07-12 13:11 PDT (History)
4 users (show)

See Also:

patch (4.15 KB, patch)
2018-07-12 05:27 PDT, Antti Koivisto
simon.fraser: review+
Details | Formatted Diff | Diff
patch (4.15 KB, patch)
2018-07-12 11:41 PDT, Antti Koivisto
no flags Details | Formatted Diff | Diff

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Description Antti Koivisto 2018-07-11 07:02:17 PDT
We ignore zoom scale from UI process if it doesn't match the last remote layer tree transaction. However nothing guarantees that we receive the real scale again until user interacts with the page. After r232356 this can cause visibly missing tiles, before the problem was covered by creating too many of them.
Comment 1 Antti Koivisto 2018-07-12 05:08:03 PDT
Comment 2 Antti Koivisto 2018-07-12 05:08:33 PDT
I mean <rdar://problem/41863803>
Comment 3 Antti Koivisto 2018-07-12 05:27:19 PDT
Created attachment 344839 [details]
Comment 4 Simon Fraser (smfr) 2018-07-12 11:26:57 PDT
Comment on attachment 344839 [details]

View in context: https://bugs.webkit.org/attachment.cgi?id=344839&action=review

> Source/WebKit/WebProcess/WebPage/WebPage.h:1669
> +    float m_lastTransactionPageScaleFactor { 0 };

We store page scale as a double in RemoteLayerTreeTransaction and we've certainly had bugs with float/double precision mismatch before, so should this be a double, and/or do matching with epsilon?

> Source/WebKit/WebProcess/WebPage/WebPage.h:1670
> +    uint64_t m_lastTransactionIDWithScaleChange { 0 };

I wish we had a typedef for transactionIDs :(
Comment 5 Antti Koivisto 2018-07-12 11:41:55 PDT
Created attachment 344865 [details]
Comment 6 WebKit Commit Bot 2018-07-12 13:11:37 PDT
Comment on attachment 344865 [details]

Clearing flags on attachment: 344865

Committed r233780: <https://trac.webkit.org/changeset/233780>
Comment 7 WebKit Commit Bot 2018-07-12 13:11:39 PDT
All reviewed patches have been landed.  Closing bug.