Fixed mouse wheel handling in vertical drum picker without animation.

Telegram/SourceFiles/ui/widgets/vertical_drum_picker.cpp

@@ -11,6 +11,11 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "styles/style_basic.h"
 
 namespace Ui {
+namespace {
+
+constexpr auto kAlmostIndex = float64(.99);
+
+} // namespace
 
 PickerAnimation::PickerAnimation() = default;
 
@@ -26,6 +31,23 @@ void PickerAnimation::jumpToOffset(int offset) {
 			value);
 		_updates.fire(_result.current - was);
 	};
+	if (anim::Disabled()) {
+		auto value = float64(0.);
+		const auto diff = _result.to - _result.from;
+		const auto step = std::min(
+			kAlmostIndex,
+			1. / (std::max(1. - kAlmostIndex, std::abs(diff) + 1)));
+		while (true) {
+			value += step;
+			if (value >= 1.) {
+				callback(1.);
+				break;
+			} else {
+				callback(value);
+			}
+		}
+		return;
+	}
 	_animation.start(
 		std::move(callback),
 		0.,
@@ -94,20 +116,14 @@ VerticalDrumPicker::VerticalDrumPicker(
 	}, lifetime());
 
 	_animation.updates(
-	) | rpl::distinct_until_changed(
 	) | rpl::start_with_next([=](PickerAnimation::Shift shift) {
 		increaseShift(shift);
-		if (anim::Disabled()) {
-			animationDataFromIndex();
-			_animation.jumpToOffset(0);
-		}
 	}, lifetime());
 }
 
 void VerticalDrumPicker::increaseShift(float64 by) {
 	{
 		// Guard input.
-		constexpr auto kAlmostIndex = .99;
 		if (by >= 1.) {
 			by = kAlmostIndex;
 		} else if (by <= -1.) {