Scale QML stream item size up to nearest divisible-by-four size

Task-number: QT3DS-4144
Change-Id: Id1bd2387538a6cf865c59830730d80eb5f93652f
Reviewed-by: Jere Tuliniemi <jere.tuliniemi@qt.io>
Reviewed-by: Antti Määttä <antti.maatta@qt.io>
Reviewed-by: Tomi Korpipää <tomi.korpipaa@qt.io>

3 files changed, 18 insertions, 1 deletions

diff --git a/src/qmlstreamer/q3dsqmlstream.cpp b/src/qmlstreamer/q3dsqmlstream.cpp
index bea6610..caf197f 100644
--- a/src/qmlstreamer/q3dsqmlstream.cpp
+++ b/src/qmlstreamer/q3dsqmlstream.cpp
@@ -74,10 +74,16 @@ QString Q3DSQmlStream::presentationId() const
 /*!
  * \qmlproperty Item QmlStream::item
  * Contains the Item to be streamed as subpresentation.
+ * \note The Item width and height will be scaled up to the nearest divisible-by-four number to
+ * avoid rendering artefacts. If you wish to have pixel perfect outcome, define your QML stream
+ * items to use size that already has dimensions that are divisible by four.
  */
 /*!
  * \property Q3DSQmlStream::item
  * Contains the QQuickItem to be streamed as subpresentation.
+ * \note The Item width and height will be scaled up to the nearest divisible-by-four number to
+ * avoid rendering artefacts. If you wish to have pixel perfect outcome, define your QML stream
+ * items to use size that already has dimensions that are divisible by four.
  */
 QQuickItem *Q3DSQmlStream::item() const
 {
diff --git a/src/qmlstreamer/q3dsqmlstreamrenderer.cpp b/src/qmlstreamer/q3dsqmlstreamrenderer.cpp
index f1879a6..c0cb630 100644
--- a/src/qmlstreamer/q3dsqmlstreamrenderer.cpp
+++ b/src/qmlstreamer/q3dsqmlstreamrenderer.cpp
@@ -392,6 +392,17 @@ void Q3DSQmlStreamRenderer::updateSizes()
 {
     if (m_rootItem->width() > 0 && m_rootItem->height() > 0) {
         m_size = QSize(m_rootItem->width(), m_rootItem->height());
+        // Make the dimensions divisible by four; this prevents rendering artefacts
+        // In worst case scenario this increases the size by 3 pixels in each dimension
+        // TODO: Would it be possible to add transparent pixels around the original stream
+        // to meet the divisible by four -requirement, but render the original amount of pixels?
+        // That way the end result would still be pixel perfect, unlike with this implementation.
+        const int w = m_size.width();
+        const int h = m_size.height();
+        if (w % 4 != 0)
+            m_size.setWidth(w + 4 - w % 4);
+        if (h % 4 != 0)
+            m_size.setHeight(h + 4 - h % 4);
     } else {
         m_rootItem->setWidth(256);
         m_rootItem->setHeight(256);
diff --git a/src/qmlstreamer/q3dsqmlsubpresentationsettings.cpp b/src/qmlstreamer/q3dsqmlsubpresentationsettings.cpp
index 664b9e4..739c6b5 100644
--- a/src/qmlstreamer/q3dsqmlsubpresentationsettings.cpp
+++ b/src/qmlstreamer/q3dsqmlsubpresentationsettings.cpp
@@ -58,7 +58,7 @@ Q3DSSubPresentationSettings::~Q3DSSubPresentationSettings()
 }
 
 /*!
- * \qmlproperty variant SubPresentationSettings::qmlStream
+ * \qmlproperty variant SubPresentationSettings::qmlStreams
  * Contains the QML streams to be used as subpresentations.
  */
 /*!