From 2fff1c473f018329dc26f28a95b2c9b9420fa145 Mon Sep 17 00:00:00 2001
From: John McLear <john@mclear.co.uk>
Date: Thu, 7 Jan 2021 20:09:54 +0000
Subject: [PATCH] change in buffer management

---
 src/static/js/scroll.js            | 14 +++++---------
 tests/frontend/specs/pageupdown.js | 19 ++++++++++++++-----
 2 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/static/js/scroll.js b/src/static/js/scroll.js
index 8c9661843..31a9dccd2 100644
--- a/src/static/js/scroll.js
+++ b/src/static/js/scroll.js
@@ -354,15 +354,15 @@ Scroll.prototype.movePage = function (direction) {
   // if the buffer of a fixed value isn't working as intended
   const linePosition = caretPosition.getPosition();
   const buffer = 25;
-
-  let pixelsToScroll = viewport.top - viewport.bottom;
-
+  // we need to remember that lineoffset needs to be removed too..
+  let offset = linePosition.bottom - viewport.top;
+  let pixelsToScroll = viewport.top - viewport.bottom + offset;
   if (direction === 'up') {
     // buffer pixels unscrolled our safety net here.  You can't use the current or previous
     // line height because it might be a very long line..
-    pixelsToScroll = -Math.abs(pixelsToScroll + buffer);
+    pixelsToScroll = -Math.abs(pixelsToScroll + buffer/2);
   } else {
-    pixelsToScroll = Math.abs(pixelsToScroll + buffer);
+    pixelsToScroll = Math.abs(pixelsToScroll + buffer/2);
   }
 
   this.outerWin.scrollBy(0, pixelsToScroll);
@@ -371,12 +371,10 @@ Scroll.prototype.movePage = function (direction) {
 
 Scroll.prototype.getFirstVisibleCharacter = function (direction, rep) {
   const viewport = this._getViewPortTopBottom();
-  console.log('viewport', viewport);
   const editor = parent.document.getElementsByTagName('iframe');
   const lines = $(editor).contents().find('div');
   // const currentLine = $(editor).contents().find('#innerdocbody');
   const currentLine = rep.lines.atIndex(rep.selEnd[0]);
-  console.log('currentLine', currentLine);
   const modifiedRep = {};
   modifiedRep.selStart = [];
   modifiedRep.selEnd = [];
@@ -389,7 +387,6 @@ Scroll.prototype.getFirstVisibleCharacter = function (direction, rep) {
 
     // is each line in the viewport?
     if (lineBase > viewport.top) {
-      top.console.log('returning', index);
       modifiedRep.selEnd[0] = index;
       modifiedRep.selStart[0] = index;
       modifiedRep.selEnd[1] = 0;
@@ -405,7 +402,6 @@ Scroll.prototype.getFirstVisibleCharacter = function (direction, rep) {
 
   // oh dear, looks like the original line is still the first in the viewport..
   // we will need to move the rep X chars within that original position.
-  console.log('CANT SEE NEXT LiNE!');
   modifiedRep.selStart[0] = rep.selStart[0];
   modifiedRep.selEnd[0] = rep.selEnd[0];
 
diff --git a/tests/frontend/specs/pageupdown.js b/tests/frontend/specs/pageupdown.js
index c0edcf1e8..8d9793f7f 100644
--- a/tests/frontend/specs/pageupdown.js
+++ b/tests/frontend/specs/pageupdown.js
@@ -357,7 +357,7 @@ describe('Shift Page Up/Down', function () {
       },
     });
   });
-/*
+
   it('highlights lines on shift page down and releases them on page up', async function () {
     await helper.edit('xxx', 1); // caret is offset 6
 
@@ -391,8 +391,18 @@ describe('Shift Page Up/Down', function () {
     });
     await helper.waitForPromise(() => helper.padInner$.document.getSelection().type === 'Range');
   });
-*/
-  it('BROKEN JM TO FIX - highlights from end of document on page up then releases them on shift page down', async function () {
+
+  it('Highlights from end of document on page up then releases them on shift page down', async function () {
+    // TODO: JM NEEDS HELP:  Why isn't this working?  It works if you do the same in browser..
+    throw new Error("I NEED HELPZ PLZ")
+
+    await helper.waitForPromise(() => helper.caretLineNumber() >= 201);
+    // make sure we're at bottom
+    helper.pageDown({
+      pressAndHold: true,
+    });
+    await helper.waitForPromise(() => helper.caretLineNumber() >= 201);
+
     helper.pageUp({
       shift: true,
     });
@@ -403,7 +413,6 @@ describe('Shift Page Up/Down', function () {
     });
     await helper.waitForPromise(() => helper.padInner$.document.getSelection().type === 'Caret');
   });
-/*
   it('highlights from end of document on page up twice and retains on single page down', async function () {
     helper.pageUp({
       shift: true,
@@ -451,7 +460,7 @@ describe('Shift Page Up/Down', function () {
   xit('highlights (a few lines) range backwards (rep.selFocusAtStart) then hit page down, selStart should be initial selEnd and selEnd further than original selEnd', async function () {
     throw new Error("JM TO DO")
   });
-*/
+
 });
 
 describe('Press and Hold Page Up/Down', function () {