Add a note in the QScreen documentation about logical vs physical DPI.

Change-Id: I1d536711cbbc0ea8a21c6917e5e0066c1ad4ccae
Reviewed-by: Alan Alpert <alan.alpert@nokia.com>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/gui/kernel/qscreen.cpp b/src/gui/kernel/qscreen.cpp
index 7d83cebd2b..682e42ad4c 100644
--- a/src/gui/kernel/qscreen.cpp
+++ b/src/gui/kernel/qscreen.cpp
@@ -61,6 +61,17 @@ public:
     \class QScreen
     \brief The QScreen class is used to query screen properties.
 
+    A note on logical vs physical dots per inch: physical DPI is based on the
+    actual physical pixel sizes when available, and is useful for print preview
+    and other cases where it's desirable to know the exact physical dimensions
+    of screen displayed contents.
+
+    Logical dots per inch are used to convert font and user interface elements
+    from point sizes to pixel sizes, and might be different from the physical
+    dots per inch. The logical dots per inch are sometimes user-settable in the
+    desktop environment's settings panel, to let the user globally control UI
+    and font sizes in different applications.
+
     \inmodule QtGui
 */