Fix outline for connected text

For any font where glyphs are connected (any font could
have this, but specifically Arabic and Indic fonts will
typically always connect glyphs, as it is required to
express the language correctly), we would draw the outline
on a per-glyph basis, thus getting outlines that disconnect
the glyphs.

In order to fix this, we have to draw the fill of the glyphs
in a separate pass after the outline has been drawn.

Note that in order for this to look correct, we have to
disable subpixel antialiasing on the fill, which required
some plumbing in the native rendering glyph node. The
outline shaders have also been changed to only draw the
outline and not the fill.

Also contains back-port of d46c406cc67f12e6a0798ef509abbb973b34d39d
in addition to e8d9bc1bcada7d94af5a33d64a9afc860ede5b84.

[ChangeLog][QtQuick][Text] Fixed Outline style on connected glyphs,
especially visible in e.g. Arabic and Indic writing systems.

Fixes: QTBUG-69301
Fixes: QTBUG-83358
Change-Id: If52a940bfb0267384ea002120655aed1310458a1
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
(cherry picked from commit e8d9bc1bcada7d94af5a33d64a9afc860ede5b84)

1 files changed, 16 insertions, 0 deletions

diff --git a/src/quick/items/qquicktextnode.cpp b/src/quick/items/qquicktextnode.cpp
index 9110a0664f..1bdc80c9a5 100644
--- a/src/quick/items/qquicktextnode.cpp
+++ b/src/quick/items/qquicktextnode.cpp
@@ -129,6 +129,22 @@ QSGGlyphNode *QQuickTextNode::addGlyphs(const QPointF &position, const QGlyphRun
         parentNode = this;
     parentNode->appendChildNode(node);
 
+    if (style == QQuickText::Outline && color.alpha() > 0 && styleColor != color) {
+        QSGGlyphNode *fillNode = sg->sceneGraphContext()->createGlyphNode(sg, preferNativeGlyphNode);
+        fillNode->setOwnerElement(m_ownerElement);
+        fillNode->setGlyphs(position + QPointF(0, glyphs.rawFont().ascent()), glyphs);
+        fillNode->setStyle(QQuickText::Normal);
+        fillNode->setPreferredAntialiasingMode(QSGGlyphNode::GrayAntialiasing);
+        fillNode->setColor(color);
+        fillNode->update();
+
+        fillNode->geometry()->setIndexDataPattern(QSGGeometry::StaticPattern);
+        fillNode->geometry()->setVertexDataPattern(QSGGeometry::StaticPattern);
+
+        parentNode->appendChildNode(fillNode);
+        fillNode->setRenderOrder(node->renderOrder() + 1);
+    }
+
     return node;
 }