Fix text wrapping and eliding with implicitWidth.

Update the implicitWidth of the item before continuing with the layout
rather than after it's completed this gives any bindings dependent on
the implicitWidth the opportunity to update the width before the layout
continues.

Task-number: QTBUG-22680
Task-number: QTBUG-24251
Change-Id: I61cd96ad9891b22d8b83937ad2c06719f88976b6
Reviewed-by: Martin Jones <martin.jones@nokia.com>

1 files changed, 41 insertions, 10 deletions

diff --git a/src/quick/items/qquicktext.cpp b/src/quick/items/qquicktext.cpp
index 9f22dfdd08..d7303352c5 100644
--- a/src/quick/items/qquicktext.cpp
+++ b/src/quick/items/qquicktext.cpp
@@ -421,6 +421,10 @@ void QQuickTextPrivate::updateSize()
     //setup instance of QTextLayout for all cases other than richtext
     if (!richText) {
         QRectF textRect = setupTextLayout(&naturalWidth);
+
+        if (internalWidthUpdate)    // probably the result of a binding loop, but by letting it
+            return;      // get this far we'll get a warning to that effect if it is.
+
         layedOutTextRect = textRect;
         size = textRect.size();
         dy -= size.height();
@@ -443,7 +447,13 @@ void QQuickTextPrivate::updateSize()
         if (requireImplicitWidth && q->widthValid()) {
             extra->doc->setTextWidth(-1);
             naturalWidth = extra->doc->idealWidth();
+            const bool wasInLayout = internalWidthUpdate;
+            internalWidthUpdate = true;
+            q->setImplicitWidth(naturalWidth);
+            internalWidthUpdate = wasInLayout;
         }
+        if (internalWidthUpdate)
+            return;
         if (wrapMode != QQuickText::NoWrap && q->widthValid())
             extra->doc->setTextWidth(q->width());
         else
@@ -468,8 +478,6 @@ void QQuickTextPrivate::updateSize()
     qreal iWidth = -1;
     if (!q->widthValid())
         iWidth = size.width();
-    else if (requireImplicitWidth)
-        iWidth = naturalWidth;
     if (iWidth > -1)
         q->setImplicitSize(iWidth, size.height());
     internalWidthUpdate = false;
@@ -697,6 +705,11 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
             layout.endLayout();
             *naturalWidth = layout.maximumWidth();
             layout.clearLayout();
+
+            bool wasInLayout = internalWidthUpdate;
+            internalWidthUpdate = true;
+            q->setImplicitWidth(*naturalWidth);
+            internalWidthUpdate = wasInLayout;
         }
 
         QFontMetrics fm(font);
@@ -704,7 +717,7 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
         return QRect(0, 0, 0, height);
     }
 
-    const qreal lineWidth = q->widthValid() ? q->width() : FLT_MAX;
+    qreal lineWidth = q->widthValid() && q->width() > 0 ? q->width() : FLT_MAX;
     const qreal maxHeight = q->heightValid() ? q->height() : FLT_MAX;
 
     const bool customLayout = isLineLaidOutConnected();
@@ -735,6 +748,7 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
     QTextLine line;
     int visibleCount = 0;
     bool elide;
+    bool widthChanged;
     qreal height = 0;
     QString elideText;
     bool once = true;
@@ -755,13 +769,14 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
                 scaledFont.setPointSize(scaledFontSize);
             layout.setFont(scaledFont);
         }
-        layout.beginLayout();
 
+        layout.beginLayout();
 
         bool wrapped = false;
         bool truncateHeight = false;
         truncated = false;
         elide = false;
+        widthChanged = false;
         int characterCount = 0;
         int unwrappedLineCount = 1;
         int maxLineCount = maximumLineCount();
@@ -864,7 +879,6 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
             br = br.united(line.naturalTextRect());
             line = nextLine;
         }
-
         layout.endLayout();
         br.moveTop(0);
 
@@ -886,8 +900,21 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
                     if (!line.isValid())
                         break;
                 }
+
                 *naturalWidth = qMax(*naturalWidth, widthLayout.maximumWidth());
             }
+
+            bool wasInLayout = internalWidthUpdate;
+            internalWidthUpdate = true;
+            q->setImplicitWidth(*naturalWidth);
+            internalWidthUpdate = wasInLayout;
+
+            const qreal oldWidth = lineWidth;
+            lineWidth = q->widthValid() && q->width() > 0 ? q->width() : FLT_MAX;
+            if (lineWidth != oldWidth && (singlelineElide || multilineElide || canWrap || horizontalFit)) {
+                widthChanged = true;
+                continue;
+            }
         }
 
         // If the next needs to be elided and there's an abbreviated string available
@@ -911,32 +938,36 @@ QRectF QQuickTextPrivate::setupTextLayout(qreal *const naturalWidth)
         if (horizontalFit) {
             if (unelidedRect.width() > lineWidth || (!verticalFit && wrapped)) {
                 largeFont = scaledFontSize - 1;
-                scaledFontSize = (smallFont + largeFont) / 2;
                 if (smallFont > largeFont)
                     break;
+                scaledFontSize = (smallFont + largeFont) / 2;
+                if (pixelSize)
+                    scaledFont.setPixelSize(scaledFontSize);
+                else
+                    scaledFont.setPointSize(scaledFontSize);
                 continue;
             } else if (!verticalFit) {
                 smallFont = scaledFontSize;
-                scaledFontSize = (smallFont + largeFont + 1) / 2;
                 if (smallFont == largeFont)
                     break;
+                scaledFontSize = (smallFont + largeFont + 1) / 2;
             }
         }
 
         if (verticalFit) {
             if (truncateHeight || unelidedRect.height() > maxHeight) {
                 largeFont = scaledFontSize - 1;
-                scaledFontSize = (smallFont + largeFont + 1) / 2;
                 if (smallFont > largeFont)
                     break;
+                scaledFontSize = (smallFont + largeFont) / 2;
+
             } else {
                 smallFont = scaledFontSize;
-                scaledFontSize = (smallFont + largeFont + 1) / 2;
                 if (smallFont == largeFont)
                     break;
+                scaledFontSize = (smallFont + largeFont + 1) / 2;
             }
         }
-
     }
 
     if (eos != multilengthEos)