RFR: 8238954: Improve performance of tiled snapshot rendering [v13]

[Frederic Thevenet]

On Mon, 29 Jun 2020 21:32:33 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> Frederic Thevenet has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   Fill test image with a bilinear gradient instead of random noise.
>
> modules/javafx.graphics/src/main/java/com/sun/javafx/tk/quantum/QuantumToolkit.java line 1612:
> 
>> 1611:                         int bTileHeight = tileHeight;
>> 1612:                         while (bTileHeight == tileHeight && bOffset < h) {
>> 1613:                             renderTile(x, xOffset, y, bOffset, mTileWidth, bTileHeight, buffer, rf, tileRttCache,
>> pImage);
> 
> It looks like the "B" and the "R" loops are reversed. This isn't causing any actual problems, but is confusing since it
> doesn't match the comment or the diagram above. The comment for this block says "B" tiles, but actually, it is the "R"
> tiles in the diagram that this is looping over. At the end of the main loop, `mTileWIdth` and `mTileHeight` will be set
> to the size of the corner tile. Given this, the tiles of `mTileWidth` X `tileHeight` will be the right hand column.
> Once you fix this, you will need to surround this `while` loop in a check for `if (mTileWidth > 0)`

You're right: the comments and variable names are swapped. Will fix it (and obviously add the extra condition that
prevents attempts to render 0 width/height tiles).  Thanks.

-------------

PR: https://git.openjdk.java.net/jfx/pull/112