Material: fix placeholder text y position when control is too small

Ensure that it's sensibly positioned despite its size.

Fixes: QTBUG-111515
Pick-to: 6.5 6.5.0
Change-Id: I71816c461ff1d2f85e010bf871ab1b7ef2ccaf6e
Reviewed-by: Oliver Eftevaag <oliver.eftevaag@qt.io>

src/quickcontrols/material/TextArea.qml

@@ -50,6 +50,7 @@ T.TextArea {
         controlHasActiveFocus: control.activeFocus
         controlHasText: control.length > 0
         controlImplicitBackgroundHeight: control.implicitBackgroundHeight
+        controlHeight: control.height
     }
 
     background: MaterialTextContainer {

src/quickcontrols/material/TextField.qml

@@ -50,6 +50,7 @@ T.TextField {
         controlHasActiveFocus: control.activeFocus
         controlHasText: control.length > 0
         controlImplicitBackgroundHeight: control.implicitBackgroundHeight
+        controlHeight: control.height
     }
 
     background: MaterialTextContainer {

src/quickcontrols/material/impl/qquickmaterialplaceholdertext.cpp

@@ -9,6 +9,7 @@
 #include <QtGui/qpainterpath.h>
 #include <QtQml/qqmlinfo.h>
 #include <QtQuickTemplates2/private/qquicktheme_p.h>
+#include <QtQuickTemplates2/private/qquicktextarea_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -100,13 +101,25 @@ bool QQuickMaterialPlaceholderText::shouldAnimate() const
         : !m_controlHasText && !text().isEmpty();
 }
 
+void QQuickMaterialPlaceholderText::updateY()
+{
+    setY(shouldFloat() ? floatingTargetY() : normalTargetY());
+}
+
 qreal QQuickMaterialPlaceholderText::normalTargetY() const
 {
+    auto *textArea = qobject_cast<QQuickTextArea *>(parentItem());
+    if (textArea && m_controlHeight >= textArea->implicitHeight()) {
+        // TextArea can be multiple lines in height, and we want the
+        // placeholder text to sit in the middle of its default-height
+        // (one-line) if its explicit height is greater than or equal to its
+        // implicit height - i.e. if it has room for it. If it doesn't have
+        // room, just do what TextField does.
+        return (m_controlImplicitBackgroundHeight - m_largestHeight) / 2.0;
+    }
+
     // When the placeholder text shouldn't float, it should sit in the middle of the TextField.
-    // We could just use the control's height minus our height instead of the members, but
-    // that doesn't work for TextArea, which can be multiple lines in height and hence taller.
-    // In that case, we want the placeholder text to sit in the middle of its default-height (one-line).
-    return (m_controlImplicitBackgroundHeight - m_largestHeight) / 2.0;
+    return (m_controlHeight - height()) / 2.0;
 }
 
 qreal QQuickMaterialPlaceholderText::floatingTargetY() const
@@ -142,10 +155,34 @@ void QQuickMaterialPlaceholderText::setControlImplicitBackgroundHeight(qreal con
         return;
 
     m_controlImplicitBackgroundHeight = controlImplicitBackgroundHeight;
-    setY(shouldFloat() ? floatingTargetY() : normalTargetY());
+    updateY();
     emit controlImplicitBackgroundHeightChanged();
 }
 
+/*!
+    \internal
+
+    Exists so that we can call updateY when the control's height changes,
+    which is necessary for some y position calculations.
+
+    We don't really need it for the actual calculations, since we already
+    have access to the parent item, from which the property comes, but
+    it's simpler just to use it.
+*/
+qreal QQuickMaterialPlaceholderText::controlHeight() const
+{
+    return m_controlHeight;
+}
+
+void QQuickMaterialPlaceholderText::setControlHeight(qreal controlHeight)
+{
+    if (qFuzzyCompare(m_controlHeight, controlHeight))
+        return;
+
+    m_controlHeight = controlHeight;
+    updateY();
+}
+
 qreal QQuickMaterialPlaceholderText::verticalPadding() const
 {
     return m_verticalPadding;
@@ -185,8 +222,7 @@ void QQuickMaterialPlaceholderText::controlGotActiveFocus()
 
         m_focusInAnimation->start(QAbstractAnimation::DeleteWhenStopped);
     } else {
-        const int newY = shouldFloat() ? floatingTargetY() : normalTargetY();
-        setY(newY);
+        updateY();
     }
 }
 
@@ -212,16 +248,14 @@ void QQuickMaterialPlaceholderText::controlLostActiveFocus()
 
         m_focusOutAnimation->start(QAbstractAnimation::DeleteWhenStopped);
     } else {
-        const int newY = shouldFloat() ? floatingTargetY() : normalTargetY();
-        setY(newY);
+        updateY();
     }
 }
 
 void QQuickMaterialPlaceholderText::maybeSetFocusAnimationProgress()
 {
-    const bool shouldWeFloat = shouldFloat();
-    setY(shouldWeFloat ? floatingTargetY() : normalTargetY());
-    setScale(shouldWeFloat ? floatingScale : 1.0);
+    updateY();
+    setScale(shouldFloat() ? floatingScale : 1.0);
 }
 
 void QQuickMaterialPlaceholderText::componentComplete()

src/quickcontrols/material/impl/qquickmaterialplaceholdertext_p.h

@@ -34,6 +34,7 @@ class QQuickMaterialPlaceholderText : public QQuickPlaceholderText
     Q_PROPERTY(qreal verticalPadding READ verticalPadding WRITE setVerticalPadding NOTIFY verticalPaddingChanged FINAL)
     Q_PROPERTY(qreal controlImplicitBackgroundHeight READ controlImplicitBackgroundHeight
         WRITE setControlImplicitBackgroundHeight NOTIFY controlImplicitBackgroundHeightChanged FINAL)
+    Q_PROPERTY(qreal controlHeight READ controlHeight WRITE setControlHeight FINAL)
     QML_NAMED_ELEMENT(FloatingPlaceholderText)
     QML_ADDED_IN_VERSION(6, 5)
 
@@ -54,6 +55,9 @@ public:
     qreal controlImplicitBackgroundHeight() const;
     void setControlImplicitBackgroundHeight(qreal controlImplicitBackgroundHeight);
 
+    qreal controlHeight() const;
+    void setControlHeight(qreal controlHeight);
+
     qreal verticalPadding() const;
     void setVerticalPadding(qreal verticalPadding);
 
@@ -69,6 +73,7 @@ private:
     bool shouldFloat() const;
     bool shouldAnimate() const;
 
+    void updateY();
     qreal normalTargetY() const;
     qreal floatingTargetY() const;
 
@@ -85,6 +90,7 @@ private:
     int m_largestHeight = 0;
     qreal m_verticalPadding = 0;
     qreal m_controlImplicitBackgroundHeight = 0;
+    qreal m_controlHeight = 0;
     QPointer<QParallelAnimationGroup> m_focusInAnimation;
     QPointer<QParallelAnimationGroup> m_focusOutAnimation;
 };

tests/auto/quickcontrols/qquickmaterialstyle/data/tst_material.qml

@@ -7,6 +7,7 @@ import QtTest
 import QtQuick.Templates as T
 import QtQuick.Controls
 import QtQuick.Controls.Material
+import QtQuick.Controls.Material.impl as MaterialImpl
 
 TestCase {
     id: testCase
@@ -953,4 +954,40 @@ TestCase {
         verify(item)
         compare(item["__isDiscrete"], data.expectTickmarks)
     }
+
+    Component {
+        id: textFieldComponent
+        TextField {}
+    }
+
+    Component {
+        id: textAreaComponent
+        TextArea {}
+    }
+
+    function test_placeholderText() {
+        {
+            // The non-floating placeholder text should be in the middle of TextField regardless of its height.
+            let textField = createTemporaryObject(textFieldComponent, testCase, { placeholderText: "TextField" })
+            verify(textField)
+            let placeholderTextItem = textField.children[0]
+            verify(placeholderTextItem as MaterialImpl.FloatingPlaceholderText)
+            compare(placeholderTextItem.y, (textField.height - placeholderTextItem.height) / 2)
+            textField.height = 10
+            compare(placeholderTextItem.y, (textField.height - placeholderTextItem.height) / 2)
+            textField.destroy()
+        }
+
+        {
+            // The non-floating placeholder text should be near the top of TextArea while it has room, but when it
+            // doesn't have room, it should start behaving like TextField's.
+            let textArea = createTemporaryObject(textAreaComponent, testCase, { placeholderText: "TextArea" })
+            verify(textArea)
+            let placeholderTextItem = textArea.children[0]
+            verify(placeholderTextItem as MaterialImpl.FloatingPlaceholderText)
+            compare(placeholderTextItem.y, (placeholderTextItem.controlImplicitBackgroundHeight - placeholderTextItem.largestHeight) / 2)
+            textArea.height = 10
+            compare(placeholderTextItem.y, (textArea.height - placeholderTextItem.height) / 2)
+        }
+    }
 }