An easy fix for mouse wheel scrolling

Relates to #116

Signed-off-by: Victor Seiji Hariki <victorseijih@gmail.com>

index.html

@@ -317,6 +317,9 @@
 			src="js/initalize/layers.populate.js"
 			type="text/javascript"></script>
 
+		<!-- Configuration -->
+		<script src="js/config.js" type="text/javascript"></script>
+
 		<!-- Content -->
 		<script src="js/global.js" type="text/javascript"></script>
 		<script src="js/prompt.js" type="text/javascript"></script>

js/config.js

@@ -0,0 +1,9 @@
+/**
+ * This is a file for static unchanging global configurations.
+ *
+ * Do NOT confuse with settings, which are modifiable by either the settings menu, or in the application itself.
+ */
+const config = {
+	// Scroll Tick Limit (How much must scroll to reach next tick)
+	wheelTickSize: 50,
+};

js/lib/input.js

@@ -440,6 +440,12 @@ window.addEventListener(
 window.addEventListener(
 	"wheel",
 	(evn) => {
+		// For firefox, we need to read a delta before deltaMode to force a PIXEL deltaMode read.
+		// If we read deltaMode before a delta read, deltaMode will be LINE.
+		// ref: https://bugzilla.mozilla.org/show_bug.cgi?id=1392460
+		let _discard = evn.deltaY;
+		_discard = evn.deltaMode;
+
 		mouse._contexts.forEach(({name, target, validate}) => {
 			if (!target || (target === evn.target && (!validate || validate(evn)))) {
 				mouse.listen[name].onwheel.emit({

js/ui/tool/dream.js

@@ -1053,18 +1053,29 @@ const dream_img2img_callback = (bb, resolution, state) => {
 /**
  * Generic wheel handler
  */
+let _dream_wheel_accum = 0;
 
 const _dream_onwheel = (evn, state) => {
 	if (!evn.evn.ctrlKey) {
-		// Seems mouse wheel scroll is very different between different browsers.
-		// Will use scroll as just an event to go to the next cursor snap position instead.
-		//
-		// TODO: Someone that has a smooth scrolling mouse should verify if this works with them.
+		if (evn.mode !== WheelEvent.DOM_DELTA_PIXEL) {
+			// We don't really handle non-pixel scrolling
+			return;
+		}
 
-		const v = state.cursorSize - 128 * (evn.delta / Math.abs(evn.delta));
+		// A simple but (I hope) effective fix for mouse wheel behavior
+		_dream_wheel_accum += evn.delta;
 
-		state.cursorSize = state.setCursorSize(v + snap(v, 0, 128));
-		state.mousemovecb(evn);
+		if (Math.abs(_dream_wheel_accum) > config.wheelTickSize) {
+			// Snap to next or previous position
+			const v =
+				state.cursorSize -
+				128 * (_dream_wheel_accum / Math.abs(_dream_wheel_accum));
+
+			state.cursorSize = state.setCursorSize(v + snap(v, 0, 128));
+			state.mousemovecb(evn);
+
+			_dream_wheel_accum = 0; // Zero accumulation
+		}
 	}
 };