From 432cb1b77561b5168df32d27703f5b642b6c285f Mon Sep 17 00:00:00 2001
From: Jason Woofenden <jason@jasonwoof.com>
Date: Fri, 4 Mar 2016 23:48:30 -0500
Subject: [PATCH] determine text/character position with range api

---
 editor.coffee |   89 ++++++++++++++++++++++++++-------------------------------
 1 file changed, 41 insertions(+), 48 deletions(-)

diff --git a/editor.coffee b/editor.coffee
index 0d6e761..956ade0 100644
--- a/editor.coffee
+++ b/editor.coffee
@@ -19,6 +19,12 @@ TYPE_TEXT = peach_parser.TYPE_TEXT
 TYPE_COMMENT = peach_parser.TYPE_COMMENT
 TYPE_DOCTYPE = peach_parser.TYPE_DOCTYPE
 
+debug_dot_at = (doc, x, y) ->
+	el = doc.createElement 'div'
+	el.setAttribute 'style', "position: absolute; left: #{x}px; top: #{y}px; width: 1px; height: 3px; background-color: red"
+	doc.body.appendChild el
+	#console.log(new Error().stack)
+
 # text nodes don't have getBoundingClientRect(), so use selection api to find
 # it.
 get_text_bounding_rect = (el) ->
@@ -27,7 +33,7 @@ get_el_bounds = (el) ->
 		rect = el.getBoundingClientRect()
 	else
 		# text nodes don't have getBoundingClientRect(), so use range api
-		range = document.createRange()
+		range = el.ownerDocument.createRange()
 		range.selectNodeContents el
 		rect = range.getBoundingClientRect()
 	doc = el.ownerDocument.documentElement
@@ -43,55 +49,39 @@ get_el_bounds = (el) ->
 
 # figure out the x/y coordinates of where the cursor should be if it's at
 # position ``i`` within text node ``n``
-#
-# implementation: insert a span tag where we want the cursor, and ask the
-# browser where it put that span
 window.cursor_to_xyh = cursor_to_xyh = (n, i) ->
-	parent = n.el.parentNode
-	els = []
-	txts = []
+	range = document.createRange()
 	plus_width = false
-	if n.text.length < 2
-		bounds = get_el_offset n.el
-		if i is 1
-			plus_width = true
+	if n.text.length is 0
+		range.setStart n.el, i
+		range.setEnd n.el, i
+	if i is n.text.length
+		range.setStart n.el, i - 1
+		range.setEnd n.el, i
+		plus_width = true
 	else
-		if i is 0 # cursor at start of text
-			check_i = 0
-			txts.push n.text.substr 0, 1
-			txts.push n.text.substr 1
-		else if i is n.text.length # cursor at end of text
-			check_i = 1
-			plus_width = true
-			txts.push n.text.substr 0, n.text.length - 1
-			txts.push n.text.substr n.text.length - 1
+		range.setStart n.el, i
+		range.setEnd n.el, i + 1
+	# chromium returns bogus results with getBoundingClientRect() when zero width and/or height
+	rect = range.getClientRects()
+	if rect.length > 0
+		if plus_width
+			# chromium returns multiple rects for the space that is broken
+			# across lines by word-wrap (firefox doesn't)
+			rect = rect[rect.length - 1]
 		else
-			check_i = 1
-			txts.push n.text.substr 0, i
-			txts.push n.text.substr i, 1
-			txts.push n.text.substr i + 1
-		for txt, txt_i in txts
-			el = n.el.ownerDocument.createTextNode txt
-			if txt_i is check_i
-				span = n.el.ownerDocument.createElement 'span'
-				span.appendChild el
-				el = span
-			els.push el
-			parent.insertBefore el, n.el
-		parent.removeChild n.el
-		bounds = get_el_bounds els[check_i]
-		parent.insertBefore n.el, els[0]
-		for el in els
-			parent.removeChild el
-	ret = x: bounds.x, y: bounds.y, h: bounds.h
+			rect = rect[0]
+	else
+		return x: 0, y: 0, w: 0, h: 0 # TODO return null, fix callers
+	ret = {
+		x: rect.left
+		y: rect.top
+		w: rect.width ? (rect.right - rect.left)
+		h: rect.height ? (rect.top - rect.bottom)
+	}
 	if plus_width
-		ret.x += bounds.w
-	# fudge case where bounds are BS because we're on non-significant whitespace
-	if i > 0
-		first = cursor_to_xyh n, 0
-		if ret.x <= first.x and ret.y is first.y
-			# no need for a loop here, because recursion
-			ret = cursor_to_xyh n, i - 1
+		ret.x += ret.w
+	debug_dot_at n.el.ownerDocument, ret.x, ret.y
 	return ret
 
 # encode text so it can be safely placed inside an html attribute
@@ -284,9 +274,11 @@ find_loc_cursor_position = (tree, loc) ->
 				after_i = c.text.length
 				after = cursor_to_xyh c, after_i
 				if loc.y < before.y + before.h and loc.x < before.x
-					continue # before first char on first line
+					# console.log 'before first char on first line'
+					continue
 				if loc.y > after.y and loc.x > after.x
-					continue # after last char on last line
+					# console.log 'after last char on last line'
+					continue
 				if loc.y < before.y
 					console.log "Warning: click in bounding box but above first line"
 					continue # above first line (runaround?)
@@ -462,6 +454,8 @@ class PeachHTML5Editor
 		@clear_dom()
 		instantiate_tree @tree, @idoc.body
 	move_cursor: (cursor) ->
+		loc = cursor_to_xyh cursor[0], cursor[1]
+		return if loc is null
 		@cursor = cursor
 		# replace cursor, to reset blink animation
 		if @cursor_visible
@@ -470,7 +464,6 @@ class PeachHTML5Editor
 		@idoc.body.appendChild @cursor_el
 		@cursor_visible = true
 		# TODO figure out x,y coords for cursor
-		loc = cursor_to_xyh cursor[0], cursor[1]
 		@cursor_el.style.left = "#{loc.x}px"
 		@cursor_el.style.top = "#{loc.y}px"
 
-- 
1.7.10.4