From a6d04eff3b5ffca7fc4032208c3fdcadca49929d Mon Sep 17 00:00:00 2001
From: "Alex A. Naanou" <alex.nanou@gmail.com>
Date: Fri, 18 Aug 2023 13:23:27 +0300
Subject: [PATCH] scroll bounding to screen works...

Signed-off-by: Alex A. Naanou <alex.nanou@gmail.com>
---
 css/grid-n-view.css |  2 ++
 grid-n-view.js      | 83 +++++++++++++++++++++++++++++++++++++--------
 2 files changed, 71 insertions(+), 14 deletions(-)

diff --git a/css/grid-n-view.css b/css/grid-n-view.css
index b24e234..f6344ce 100644
--- a/css/grid-n-view.css
+++ b/css/grid-n-view.css
@@ -271,6 +271,8 @@ body {
 	padding-right: var(--height);
 	padding-left: var(--height);
 
+	/*scroll-margin: var(--gallery-image-scroll-margin);*/
+
 	translate: 0 0;
 
 	border: solid 1px var(--gallery-secondary-color);
diff --git a/grid-n-view.js b/grid-n-view.js
index 277fc4e..2881ca2 100644
--- a/grid-n-view.js
+++ b/grid-n-view.js
@@ -161,6 +161,9 @@ var getTouch = function(evt, id){
 
 // - - - - - - - - - - - - -  - - - - - - - - - - - - - - - - - - - - -
 
+// XXX constrain this to:
+// 		viewport -- DONE but needs to be smoother...
+// 		parent
 // XXX might be a good idea to allow bounds to be:
 // 		string		- css selector
 // 		element		- 
@@ -176,15 +179,26 @@ var moveable = function(elem, options={}){
 		cls,
 		handle,
 		bounds,
+		// can be:
+		// 	'x'
+		// 	'y'
+		// 	undefined
+		lock,
 		start = function(elem, data){
 			bounds 
 				?? (data.bounds = bounds)
 			return data },
 		beforeMove,
+		// can be:
+		// 	'strict'
+		// 	'scroll' / true
+		// 	false
+		keepInView = true,
 		move = function(elem, data){
-			elem.style.left = data.x + 'px'
-			elem.style.top = data.y + 'px'
-		},
+			data.x != null
+				&& (elem.style.left = data.x + 'px')
+			data.y != null
+				&& (elem.style.top = data.y + 'px') },
 		end,
 	} = options
 	handle = typeof(handle) == 'string' ?
@@ -228,27 +242,61 @@ var moveable = function(elem, options={}){
 				return }
 			evt.preventDefault()
 			evt.stopPropagation()
+			// viewport bounding box in elem coordinates...
 			var x = src.clientX 
 			var y = src.clientY
 			data.x =
-				data.bounds != null ?
-					Math.min(data.bounds.right,
-						Math.max(data.bounds.left, 
+				lock == 'x' ?
+					null
+				: data.bounds != null ?
+					Math.min(
+						data.bounds.right,
+						Math.max(
+							data.bounds.left, 
 							x - data.offset.x))
-					: x - data.offset.x
+				: x - data.offset.x
 			data.y =
-				data.bounds != null ?
-					Math.min(data.bounds.bottom,
-						Math.max(data.bounds.top, 
+				lock == 'y' ?
+					null
+				: data.bounds != null ?
+					Math.min(
+						data.bounds.bottom,
+						Math.max(
+							data.bounds.top, 
 							y - data.offset.y))
-					: y - data.offset.y
+				: y - data.offset.y
+			// restrict to viewport...
+			if(keepInView == 'strict'){
+				var bb = elem.getBoundingClientRect()
+				var screen = {
+					top: t = elem.offsetTop - bb.top,
+					left: l = elem.offsetLeft - bb.left,
+					bottom: window.innerHeight + t - elem.offsetHeight,
+					right: window.innerWidth + l - elem.offsetWidth,
+				}
+				data.x = Math.min(
+					screen.right,
+					Math.max(
+						screen.left,
+						data.x))
+				data.y = Math.min(
+					screen.bottom,
+					Math.max(
+						screen.top,
+						data.y)) }
 			// NOTE: we only allow a single requestAnimationFrame(..)
 			// 		to run per frame...
 			if(!data.animate){
 				data.animate = requestAnimationFrame(function(){
 					if(!data){
 						return }
-					move(elem, data)
+					move
+						&& move(elem, data)
+					// keep in view...
+					// NOTE: this works best with CSS's scroll-margin...
+					;(keepInView == 'scroll' 
+							|| keepInView === true)
+						&& elem.scrollIntoView({ block: 'nearest' }) 
 					delete data.animate }) } } }
 	var handleMoveEnd = function(evt){
 		if(data){
@@ -1306,6 +1354,9 @@ var Toolbar = {
 		// toolbar: move...
 		// XXX to drag anywhere on the elem we need to prevent 
 		// 		clicks while dragging...
+		// XXX prevent from scrolling off screen when placed a bottom 
+		// 		and scrolling up -- i.e. keep within viewport and gallery 
+		// 		at all times...
 		moveable(toolbar, {
 			cls: 'moving',
 			handle: '.drag-handle',
@@ -1319,9 +1370,13 @@ var Toolbar = {
 					right: that.gallery.dom.offsetWidth - elem.offsetWidth - 20,
 					bottom: that.gallery.dom.offsetHeight - elem.offsetHeight - 20,
 				} },
+			//keepInView: 'scroll',
+			keepInView: 'strict',
 			move: function(elem, data){
-				elem.style.setProperty('--move-x', data.x + 'px') 
-				elem.style.setProperty('--move-y', data.y + 'px') }, })
+				data.x != null
+					&& elem.style.setProperty('--move-x', data.x + 'px') 
+				data.y != null
+					&& elem.style.setProperty('--move-y', data.y + 'px') }, })
 
 		return this },
 }