Fix autoScroll implementation

The scrolling should not be calculated inside the paint event, this
leads to some incorrect behaviour. It is now calculated separately when
needed.

Patch actually written by Alexis, and I reviewed it.

Task-number: QTBUG-11127
Reviewed-by: Alexis Ménard
(cherry picked from commit bc4c5a2d9c5d3841948bc4443f2229d8d6ec0e95)

2 files changed, 54 insertions, 35 deletions

diff --git a/src/declarative/graphicsitems/qdeclarativetextinput.cpp b/src/declarative/graphicsitems/qdeclarativetextinput.cpp
index 633c01e..624a5aa 100644
--- a/src/declarative/graphicsitems/qdeclarativetextinput.cpp
+++ b/src/declarative/graphicsitems/qdeclarativetextinput.cpp
@@ -100,6 +100,7 @@ void QDeclarativeTextInput::setText(const QString &s)
     if(s == text())
         return;
     d->control->setText(s);
+    d->updateHorizontalScroll();
     //emit textChanged();
 }
 
@@ -337,6 +338,7 @@ void QDeclarativeTextInput::setHAlign(HAlignment align)
         return;
     d->hAlign = align;
     updateRect();
+    d->updateHorizontalScroll();
     emit horizontalAlignmentChanged(d->hAlign);
 }
 
@@ -554,7 +556,9 @@ void QDeclarativeTextInput::setAutoScroll(bool b)
         return;
 
     d->autoScroll = b;
-
+    d->updateHorizontalScroll();
+    //We need to repaint so that the scrolling is taking into account.
+    updateSize(true);
     emit autoScrollChanged(d->autoScroll);
 }
 
@@ -836,6 +840,7 @@ void QDeclarativeTextInput::moveCursor()
     Q_D(QDeclarativeTextInput);
     if(!d->cursorItem)
         return;
+    d->updateHorizontalScroll();
     d->cursorItem->setX(d->control->cursorToX() - d->hscroll);
 }
 
@@ -845,7 +850,6 @@ void QDeclarativeTextInput::moveCursor()
 QRectF QDeclarativeTextInput::positionToRectangle(int x) const
 {
     Q_D(const QDeclarativeTextInput);
-    QFontMetrics fm = QFontMetrics(d->font);
     return QRectF(d->control->cursorToX(x)-d->hscroll,
         0.0,
         d->control->cursorWidth(),
@@ -1012,61 +1016,73 @@ void QDeclarativeTextInput::geometryChanged(const QRectF &newGeometry,
     QDeclarativePaintedItem::geometryChanged(newGeometry, oldGeometry);
 }
 
-void QDeclarativeTextInput::drawContents(QPainter *p, const QRect &r)
+void QDeclarativeTextInputPrivate::updateHorizontalScroll()
 {
-    Q_D(QDeclarativeTextInput);
-    p->setRenderHint(QPainter::TextAntialiasing, true);
-    p->save();
-    p->setPen(QPen(d->color));
-    int flags = QLineControl::DrawText;
-    if(!isReadOnly() && d->cursorVisible && !d->cursorItem)
-        flags |= QLineControl::DrawCursor;
-    if (d->control->hasSelectedText())
-            flags |= QLineControl::DrawSelections;
-    QPoint offset = QPoint(0,0);
-    QFontMetrics fm = QFontMetrics(d->font);
-    int cix = qRound(d->control->cursorToX());
-    QRect br(boundingRect().toRect());
+    Q_Q(QDeclarativeTextInput);
+    QFontMetrics fm = QFontMetrics(font);
+    int cix = qRound(control->cursorToX());
+    QRect br(q->boundingRect().toRect());
     //###Is this using bearing appropriately?
     int minLB = qMax(0, -fm.minLeftBearing());
     int minRB = qMax(0, -fm.minRightBearing());
-    int widthUsed = qRound(d->control->naturalTextWidth()) + 1 + minRB;
-    if (d->autoScroll) {
+    int widthUsed = qRound(control->naturalTextWidth()) + 1 + minRB;
+    if (autoScroll) {
         if ((minLB + widthUsed) <=  br.width()) {
             // text fits in br; use hscroll for alignment
-            switch (d->hAlign & ~(Qt::AlignAbsolute|Qt::AlignVertical_Mask)) {
+            switch (hAlign & ~(Qt::AlignAbsolute|Qt::AlignVertical_Mask)) {
             case Qt::AlignRight:
-                d->hscroll = widthUsed - br.width() + 1;
+                hscroll = widthUsed - br.width() + 1;
                 break;
             case Qt::AlignHCenter:
-                d->hscroll = (widthUsed - br.width()) / 2;
+                hscroll = (widthUsed - br.width()) / 2;
                 break;
             default:
                 // Left
-                d->hscroll = 0;
+                hscroll = 0;
                 break;
             }
-            d->hscroll -= minLB;
-        } else if (cix - d->hscroll >= br.width()) {
+            hscroll -= minLB;
+        } else if (cix - hscroll >= br.width()) {
             // text doesn't fit, cursor is to the right of br (scroll right)
-            d->hscroll = cix - br.width() + 1;
-        } else if (cix - d->hscroll < 0 && d->hscroll < widthUsed) {
+            hscroll = cix - br.width() + 1;
+        } else if (cix - hscroll < 0 && hscroll < widthUsed) {
             // text doesn't fit, cursor is to the left of br (scroll left)
-            d->hscroll = cix;
-        } else if (widthUsed - d->hscroll < br.width()) {
+            hscroll = cix;
+        } else if (widthUsed - hscroll < br.width()) {
             // text doesn't fit, text document is to the left of br; align
             // right
-            d->hscroll = widthUsed - br.width() + 1;
+            hscroll = widthUsed - br.width() + 1;
+        }
+    } else {
+        if(hAlign == QDeclarativeTextInput::AlignRight){
+            hscroll = q->width() - widthUsed;
+        }else if(hAlign == QDeclarativeTextInput::AlignHCenter){
+            hscroll = (q->width() - widthUsed) / 2;
+        } else {
+            hscroll = 0;
         }
+        hscroll -= minLB;
+    }
+}
+
+void QDeclarativeTextInput::drawContents(QPainter *p, const QRect &r)
+{
+    Q_D(QDeclarativeTextInput);
+    p->setRenderHint(QPainter::TextAntialiasing, true);
+    p->save();
+    p->setPen(QPen(d->color));
+    int flags = QLineControl::DrawText;
+    if(!isReadOnly() && d->cursorVisible && !d->cursorItem)
+        flags |= QLineControl::DrawCursor;
+    if (d->control->hasSelectedText())
+            flags |= QLineControl::DrawSelections;
+    QPoint offset = QPoint(0,0);
+    QFontMetrics fm = QFontMetrics(d->font);
+    QRect br(boundingRect().toRect());
+    if (d->autoScroll) {
         // the y offset is there to keep the baseline constant in case we have script changes in the text.
         offset = br.topLeft() - QPoint(d->hscroll, d->control->ascent() - fm.ascent());
     } else {
-        if(d->hAlign == AlignRight){
-            d->hscroll = width() - widthUsed;
-        }else if(d->hAlign == AlignHCenter){
-            d->hscroll = (width() - widthUsed) / 2;
-        }
-        d->hscroll -= minLB;
         offset = QPoint(d->hscroll, 0);
     }
     d->control->draw(p, offset, r, flags);
@@ -1236,6 +1252,7 @@ void QDeclarativeTextInput::moveCursorSelection(int position)
 {
     Q_D(QDeclarativeTextInput);
     d->control->moveCursor(position, true);
+    d->updateHorizontalScroll();
 }
 
 /*!
@@ -1426,6 +1443,7 @@ void QDeclarativeTextInput::selectionChanged()
 void QDeclarativeTextInput::q_textChanged()
 {
     Q_D(QDeclarativeTextInput);
+    d->updateHorizontalScroll();
     updateSize();
     emit textChanged();
     if(hasAcceptableInput() != d->oldValidity){
diff --git a/src/declarative/graphicsitems/qdeclarativetextinput_p_p.h b/src/declarative/graphicsitems/qdeclarativetextinput_p_p.h
index 6865147..8b74bcc 100644
--- a/src/declarative/graphicsitems/qdeclarativetextinput_p_p.h
+++ b/src/declarative/graphicsitems/qdeclarativetextinput_p_p.h
@@ -99,6 +99,7 @@ public:
     void init();
     void startCreatingCursor();
     void focusChanged(bool hasFocus);
+    void updateHorizontalScroll();
 
     QLineControl* control;