Merge from 3.x: PR #4738

Fixes #4734

spyder/widgets/panels/linenumber.py

@@ -8,13 +8,19 @@
 """
 import sys
 
+from qtpy import QT_VERSION
 from qtpy.QtCore import QSize, Qt
 from qtpy.QtGui import QPainter, QColor
 
 from spyder.py3compat import to_text_string
 from spyder.utils import icon_manager as ima
+from spyder.utils.programs import check_version
 from spyder.api.panel import Panel
 
+
+QT55_VERSION = check_version(QT_VERSION, "5.5", ">=")
+
+
 class LineNumberArea(Panel):
     """Line number area (on the left side of the text editor widget)"""
 
@@ -67,7 +73,12 @@ def paintEvent(self, event):
         active_line_number = active_block.blockNumber() + 1
 
         def draw_pixmap(ytop, pixmap):
-            painter.drawPixmap(0, ytop + (font_height-pixmap.height()) / 2,
+            if not QT55_VERSION:
+                pixmap_height = pixmap.height()
+            else:
+                # scale pixmap height to device independent pixels
+                pixmap_height = pixmap.height() / pixmap.devicePixelRatio()
+            painter.drawPixmap(0, ytop + (font_height-pixmap_height) / 2,
                                pixmap)
 
         for top, line_number, block in self.editor.visible_blocks: