TextEditor: Improve column selection

Add the possibility to more efficient column selection for large
documents using keyboard shortcuts Alt+Shift+PageUp/PageDown/Home/End.

Change-Id: Iaa2d9aeee587f1317dd82d7fef0b01fd5f5f7a55
Reviewed-by: Leena Miettinen <riitta-leena.miettinen@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

doc/qtcreator/src/editors/creator-code-refactoring.qdoc

@@ -153,9 +153,14 @@
 
     \section1 Column Editing
 
-    To apply a change to several rows in a column simultaneously, press
+    To apply a change to several rows in a column simultaneously, hold
-    \key Alt, select the rows, and enter or remove text. The changes are made
+    \key Alt, select the rows using the mouse, and enter or remove text.
-    simultaneously at the cursor position on all the selected rows.
+    The changes are made simultaneously at the cursor position on all the
+    selected rows.
+
+    On Windows and Linux, you can also hold \key {Alt+Shift} and select
+    the rows using the arrow keys and the \key PageUp, \key PageDown,
+    \key Home, \key End keys.
 
     \section1 Applying Refactoring Actions
 

src/plugins/texteditor/texteditor.cpp

@@ -2496,6 +2496,10 @@ void TextEditorWidget::keyPressEvent(QKeyEvent *e)
     case Qt::Key_Down:
     case Qt::Key_Right:
     case Qt::Key_Left:
+    case Qt::Key_PageUp:
+    case Qt::Key_PageDown:
+    case Qt::Key_Home:
+    case Qt::Key_End:
         if (HostOsInfo::isMacHost())
             break;
         if ((e->modifiers()
@@ -2518,6 +2522,22 @@ void TextEditorWidget::keyPressEvent(QKeyEvent *e)
             case Qt::Key_Right:
                 ++d->m_blockSelection.positionColumn;
                 break;
+            case Qt::Key_PageUp:
+                d->m_blockSelection.positionBlock -= verticalScrollBar()->pageStep();
+                if (d->m_blockSelection.positionBlock < 0)
+                    d->m_blockSelection.positionBlock = 0;
+                break;
+            case Qt::Key_PageDown:
+                d->m_blockSelection.positionBlock += verticalScrollBar()->pageStep();
+                if (d->m_blockSelection.positionBlock > document()->blockCount() - 1)
+                    d->m_blockSelection.positionBlock = document()->blockCount() - 1;
+                break;
+            case Qt::Key_Home:
+                d->m_blockSelection.positionBlock = 0;
+                break;
+            case Qt::Key_End:
+                d->m_blockSelection.positionBlock = document()->blockCount() - 1;
+                break;
             default:
                 break;
             }