[Webkit-unassigned] [Bug 17589] Scroll wheel sensitivity ignored on Vista

bugzilla-daemon at webkit.org bugzilla-daemon at webkit.org
Tue Apr 22 07:22:41 PDT 2008


aroben at apple.com changed:

           What    |Removed                     |Added
  Attachment #20747|review?                     |review-
               Flag|                            |

------- Comment #3 from aroben at apple.com  2008-04-22 07:22 PDT -------
(From update of attachment 20747)
Thanks for the patch! This is a good step in the right direction.

This patch won't fix the issue for overflow areas (e.g., <div style="overflow:
scroll">). Overflow areas use RenderLayer::scroll to do their scrolling. We'll
want to fix both at the same time, and hopefully in a way that avoids
duplicating the code you've added.

+        if (!::SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0,
&linesToScroll, 0))

On Vista there's also an SPI_GETWHEELSCROLLCHARS value that we should support
for horizontal scrolling. Since this value isn't present in pre-Vista headers,
you'll have to declare it at the top of this file, like this:

static const UINT SPI_GETWHEELSCROLLCHARS = <the value that Vista uses>;

+            linesToScroll = 3;  // Windows default value 

This should be placed into a named constant at the top of the file, like this:

static const unsigned defaultLinesToScroll = 3;

+            // Like Mozilla, use default font to determine the number of
pixels per line.
+            const FrameView* frameView = static_cast<const FrameView*>(this);
+            const Frame* frame = frameView->frame();
+            int lineStep;
+            if (frame && frame->contentRenderer() &&
+                lineStep = linesToScroll *
+            else
+                lineStep = linesToScroll * LINE_STEP / 2; // fallback value
+            scrollBy(-e.deltaX() * lineStep, -e.deltaY() * lineStep);

This is a layering violation. Classes in platform/ should not in general be
aware of classes outside of platform/, so it seems unfortunate to be
introducing RenderView usage here. We'd also want this change to be made on all
platforms, not just Windows, I believe. This change seems logically distinct
from supporting the system preferences for scrolling amount, so this should be
turned into a separate patch.

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