fix: scroll cursor line to top editor for long inline preview (#5514)

* fix: scroll cursor to top for long inline preview

* fix: calculation of pixels to scroll top in setGhostText

* revert: changes to pixelposition calc

* fix: whitespace

Author: akoreman

src/autocomplete/inline_test.js

@@ -274,11 +274,15 @@ module.exports = {
         // of the container
         editor.execCommand("insertstring", "\n".repeat(200));
 
-        var deltaY;
+        var deltaY, row;
         var initialScrollBy = editor.renderer.scrollBy;
-        editor.renderer.scrollBy = function(varX, varY) {
+        var initialScrollToRow = editor.renderer.scrollToRow;
+        editor.renderer.scrollBy = function(_, varY) {
             deltaY = varY;
         };
+        editor.renderer.scrollToRow = function(varRow) {
+            row = varRow;
+        };
 
         inline.show(editor, completions[6], "l");
         editor.renderer.$loop._flush();
@@ -295,8 +299,9 @@ module.exports = {
 
             setTimeout(() => {
                 // Should scroll as much as possbile while keeping the cursor on screen
-                assert.strictEqual(deltaY, 490);
+                assert.strictEqual(row, 202);
                 editor.renderer.scrollBy = initialScrollBy;
+                editor.renderer.scrollToRow = initialScrollToRow;
                 done();
             }, 50); 
         }, 50);  

src/virtual_renderer.js

@@ -1781,18 +1781,18 @@ class VirtualRenderer {
             var el = this.container;
             var height = el.getBoundingClientRect().height;
             var ghostTextHeight = textLines.length * this.lineHeight;
-            var fitsY = ghostTextHeight < height - pixelPosition.top;
+            var fitsY = ghostTextHeight < (height - pixelPosition.top);
 
             // If it fits, no action needed
             if (fitsY) return;
 
             // If it can fully fit in the screen, scroll down until it fits on the screen
-            // if it cannot fully fit, scroll so that the cursor is at the top of the screen
-            // to fit as much as possible.
+            // if it cannot fully fit, scroll so that the row with the cursor
+            // is at the top of the screen.
             if (ghostTextHeight < height) {
                 this.scrollBy(0, (textLines.length - 1) * this.lineHeight);
             } else {
-                this.scrollBy(0, pixelPosition.top);
+                this.scrollToRow(insertPosition.row);
             }   
         }