File fix-subpixel-positioned-text.patch of Package libqt5-qtdeclarative.19402

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File fix-subpixel-positioned-text.patch of Package libqt5-qtdeclarative.19402

From 40ba29cae5cdb2ebd6330870a0f15e2e75d40de0 Mon Sep 17 00:00:00 2001
From: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>
Date: Tue, 05 May 2020 11:36:24 +0200
Subject: [PATCH] Fix subpixel positioned text with Text.NativeRendering

We would be generating subpixel positioned glyphs based on the
relative positions of the glyphs, ignoring the fractional part
contributed by the origin of the text. So if the text origin was
inside a pixel, the subpixel antialiasing would be wrong and we
would see kerning errors.

This was especially visible when using AlignHCenter on text
with hinting disabled and resizing the item it was aligning to.

Pick-to: 5.15
Task-number: QTBUG-49646
Change-Id: I0e709ba2b5d2440e34c94c6f819befe0a65a113a
---

diff --git a/src/quick/scenegraph/qsgdefaultglyphnode_p.cpp b/src/quick/scenegraph/qsgdefaultglyphnode_p.cpp
index be6ef25..831586c 100644
--- a/src/quick/scenegraph/qsgdefaultglyphnode_p.cpp
+++ b/src/quick/scenegraph/qsgdefaultglyphnode_p.cpp
@@ -789,11 +789,12 @@
                                    const QMargins &margins)
 {
     Q_ASSERT(m_font.isValid());
+    QPointF position(p.x(), p.y() - m_font.ascent());
     QVector<QFixedPoint> fixedPointPositions;
     const int glyphPositionsSize = glyphPositions.size();
     fixedPointPositions.reserve(glyphPositionsSize);
     for (int i=0; i < glyphPositionsSize; ++i)
-        fixedPointPositions.append(QFixedPoint::fromPointF(glyphPositions.at(i)));
+        fixedPointPositions.append(QFixedPoint::fromPointF(position + glyphPositions.at(i)));
 
     QTextureGlyphCache *cache = glyphCache();
 
@@ -815,18 +816,16 @@
     Q_ASSERT(geometry->sizeOfVertex() == sizeof(QVector4D));
     ushort *ip = geometry->indexDataAsUShort();
 
-    QPointF position(p.x(), p.y() - m_font.ascent());
     bool supportsSubPixelPositions = fontD->fontEngine->supportsSubPixelPositions();
     for (int i=0; i<glyphIndexes.size(); ++i) {
+         QPointF glyphPosition = glyphPositions.at(i) + position;
          QFixed subPixelPosition;
          if (supportsSubPixelPositions)
-             subPixelPosition = fontD->fontEngine->subPixelPositionForX(QFixed::fromReal(glyphPositions.at(i).x()));
+             subPixelPosition = fontD->fontEngine->subPixelPositionForX(QFixed::fromReal(glyphPosition.x()));
 
          QTextureGlyphCache::GlyphAndSubPixelPosition glyph(glyphIndexes.at(i), subPixelPosition);
          const QTextureGlyphCache::Coord &c = cache->coords.value(glyph);
 
-         QPointF glyphPosition = glyphPositions.at(i) + position;
-
          // On a retina screen the glyph positions are not pre-scaled (as opposed to
          // eg. the raster paint engine). To ensure that we get the same behavior as
          // the raster engine (and CoreText itself) when it comes to rounding of the

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File fix-subpixel-positioned-text.patch of Package libqt5-qtdeclarative.19402

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