From 658df6047703aa24c88dacc0d17fe5076b778186 Mon Sep 17 00:00:00 2001
From: Robert Knight <robert.knight@mendeley.com>
Date: Sun, 14 Jun 2015 00:39:25 +0100
Subject: [PATCH] Use a faster scroll speed under X11

Platforms may report scroll deltas either in
chunks/lines/rows or pixels, depending on the
platform API and device capabilities.

If the platform reports a line/chunk-based delta
then the application needs to convert the delta
into a suitable number of pixels.

This commit just hardcodes it to 57 as
a starting point which matches the value that
Firefox calculates as the max char height
for the root frame on my system.

Fixes #5660
---
 components/servo/Cargo.lock |  2 +-
 ports/cef/Cargo.lock        |  2 +-
 ports/glutin/window.rs      | 22 ++++++++++++++++------
 3 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/components/servo/Cargo.lock b/components/servo/Cargo.lock
index 136ddccb090..7fe068ab664 100644
--- a/components/servo/Cargo.lock
+++ b/components/servo/Cargo.lock
@@ -476,7 +476,7 @@ dependencies = [
 [[package]]
 name = "glutin"
 version = "0.0.26"
-source = "git+https://github.com/servo/glutin?branch=servo#3d39d1bb45a6f76be846ed92f946424e24109141"
+source = "git+https://github.com/servo/glutin?branch=servo#abb5ba69eb6188d24567b47e7b5a289adc595f29"
 dependencies = [
  "android_glue 0.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "cocoa 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/ports/cef/Cargo.lock b/ports/cef/Cargo.lock
index 981d17cec79..e0b2455da70 100644
--- a/ports/cef/Cargo.lock
+++ b/ports/cef/Cargo.lock
@@ -468,7 +468,7 @@ dependencies = [
 [[package]]
 name = "glutin"
 version = "0.0.26"
-source = "git+https://github.com/servo/glutin?branch=servo#3d39d1bb45a6f76be846ed92f946424e24109141"
+source = "git+https://github.com/servo/glutin?branch=servo#abb5ba69eb6188d24567b47e7b5a289adc595f29"
 dependencies = [
  "android_glue 0.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "cocoa 0.1.2 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/ports/glutin/window.rs b/ports/glutin/window.rs
index 83121be8217..83968aebeca 100644
--- a/ports/glutin/window.rs
+++ b/ports/glutin/window.rs
@@ -28,7 +28,7 @@ use compositing::windowing::{MouseWindowEvent, WindowNavigateMsg};
 #[cfg(feature = "window")]
 use euclid::point::Point2D;
 #[cfg(feature = "window")]
-use glutin::{Api, ElementState, Event, GlRequest, MouseButton, VirtualKeyCode};
+use glutin::{Api, ElementState, Event, GlRequest, MouseButton, VirtualKeyCode, MouseScrollDelta};
 #[cfg(feature = "window")]
 use msg::constellation_msg::{KeyState, CONTROL, SHIFT, ALT};
 #[cfg(feature = "window")]
@@ -187,15 +187,25 @@ impl Window {
             Event::MouseWheel(delta) => {
                 if self.ctrl_pressed() {
                     // Ctrl-Scrollwheel simulates a "pinch zoom" gesture.
-                    if delta < 0 {
+                    let dy = match delta {
+                        MouseScrollDelta::LineDelta(_, dy) => dy,
+                        MouseScrollDelta::PixelDelta(_, dy) => dy
+                    };
+                    if dy < 0.0 {
                         self.event_queue.borrow_mut().push(WindowEvent::PinchZoom(1.0/1.1));
-                    } else if delta > 0 {
+                    } else if dy > 0.0 {
                         self.event_queue.borrow_mut().push(WindowEvent::PinchZoom(1.1));
                     }
                 } else {
-                    let dx = 0.0;
-                    let dy = delta as f32;
-                    self.scroll_window(dx, dy);
+                    match delta {
+                        MouseScrollDelta::LineDelta(dx, dy) => {
+                            // this should use the actual line height
+                            // of the frame under the mouse
+                            let line_height = 57.0;
+                            self.scroll_window(dx, dy * line_height);
+                        }
+                        MouseScrollDelta::PixelDelta(dx, dy) => self.scroll_window(dx, dy)
+                    }
                 }
             },
             Event::Refresh => {