Clean up logical dpi for QImage.

Revert to the pre highdpi-patch behaviour.

Before, both physical and logical DPI would be based
on the dpmx/dpmy variables, which could be changed
with setDotsPerMeter(). The highdpi patch introduced
separate ldpmx/ldpmy variables, which were not
changed by setDotsPerMeter().

This broke when loading images: setDotsPerMeter
would be called but the logical dpi would not change.

Remove ldpmx/ldpmy. Keep scaling the physical dpi
by the devicePixelRatio, which will be set to 1 by
default.

Task-number: QTBUG-29187
Change-Id: I0d6f5f3b8efae5fb1adc0a50b22a5da78324a282
Reviewed-by: Gunnar Sletta <gunnar.sletta@digia.com>

1 files changed, 22 insertions, 0 deletions

diff --git a/tests/auto/gui/image/qimage/tst_qimage.cpp b/tests/auto/gui/image/qimage/tst_qimage.cpp
index 6f372b0160..b668f57909 100644
--- a/tests/auto/gui/image/qimage/tst_qimage.cpp
+++ b/tests/auto/gui/image/qimage/tst_qimage.cpp
@@ -86,6 +86,7 @@ private slots:
 #endif
 
     void dotsPerMeterZero();
+    void dotsPerMeterAndDpi();
 
     void convertToFormatPreserveDotsPrMeter();
     void convertToFormatPreserveText();
@@ -899,6 +900,27 @@ void tst_QImage::dotsPerMeterZero()
 
     QCOMPARE(img.dotsPerMeterX(), defaultDpmX);
     QCOMPARE(img.dotsPerMeterY(), defaultDpmY);
+
+}
+
+// verify that setting dotsPerMeter has an effect on the dpi.
+void tst_QImage::dotsPerMeterAndDpi()
+{
+    QImage img(100, 100, QImage::Format_RGB32);
+    QVERIFY(!img.isNull());
+
+    QPoint defaultLogicalDpi(img.logicalDpiX(), img.logicalDpiY());
+    QPoint defaultPhysicalDpi(img.physicalDpiX(), img.physicalDpiY());
+
+    img.setDotsPerMeterX(100);  // set x
+    QCOMPARE(img.logicalDpiY(), defaultLogicalDpi.y()); // no effect on y
+    QCOMPARE(img.physicalDpiY(), defaultPhysicalDpi.y());
+    QVERIFY(img.logicalDpiX() != defaultLogicalDpi.x()); // x changed
+    QVERIFY(img.physicalDpiX() != defaultPhysicalDpi.x());
+
+    img.setDotsPerMeterY(200);  // set y
+    QVERIFY(img.logicalDpiY() != defaultLogicalDpi.y()); // y changed
+    QVERIFY(img.physicalDpiY() != defaultPhysicalDpi.y());
 }
 
 void tst_QImage::rotate_data()