Notice when lines are sticking out of the width of the editor

Issue #5639

src/display/update_lines.js

@@ -1,6 +1,6 @@
 import { heightAtLine } from "../line/spans.js"
 import { getLine, lineAtHeight, updateLineHeight } from "../line/utils_line.js"
-import { paddingTop, textHeight } from "../measurement/position_measurement.js"
+import { paddingTop, textHeight, charWidth } from "../measurement/position_measurement.js"
 import { ie, ie_version } from "../util/browser.js"
 
 // Read the actual heights of the rendered lines, and update their
@@ -9,7 +9,8 @@ export function updateHeightsInViewport(cm) {
   let display = cm.display
   let prevBottom = display.lineDiv.offsetTop
   for (let i = 0; i < display.view.length; i++) {
-    let cur = display.view[i], height
+    let cur = display.view[i], wrapping = cm.options.lineWrapping
+    let height, width = 0
     if (cur.hidden) continue
     if (ie && ie_version < 8) {
       let bot = cur.node.offsetTop + cur.node.offsetHeight
@@ -18,6 +19,10 @@ export function updateHeightsInViewport(cm) {
     } else {
       let box = cur.node.getBoundingClientRect()
       height = box.bottom - box.top
+      // Check that lines don't extend past the right of the current
+      // editor width
+      if (!wrapping && cur.text.firstChild)
+        width = cur.text.firstChild.getBoundingClientRect().right - box.left - 1
     }
     let diff = cur.line.height - height
     if (height < 2) height = textHeight(display)
@@ -27,6 +32,14 @@ export function updateHeightsInViewport(cm) {
       if (cur.rest) for (let j = 0; j < cur.rest.length; j++)
         updateWidgetHeight(cur.rest[j])
     }
+    if (width > cm.display.sizerWidth) {
+      let chWidth = Math.ceil(width / charWidth(cm.display))
+      if (chWidth > cm.display.maxLineLength) {
+        cm.display.maxLineLength = chWidth
+        cm.display.maxLine = cur.line
+        cm.display.maxLineChanged = true
+      }
+    }
   }
 }