Stabilize tst_qquickwindow and tst_scenegraph.

Change-Id: I6f1b6c0ed86869149658e3ce07545217ce9797a7
Reviewed-by: Lars Knoll <lars.knoll@digia.com>

2 files changed, 39 insertions, 3 deletions

diff --git a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
index 28945c4cb5..fcab0c7ef2 100644
--- a/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
+++ b/tests/auto/quick/qquickwindow/tst_qquickwindow.cpp
@@ -1112,6 +1112,43 @@ void tst_qquickwindow::animationsWhileHidden()
     QTRY_VERIFY(window->isVisible());
 }
 
+// When running on native Nvidia graphics cards on linux, the
+// distance field glyph pixels have a measurable, but not visible
+// pixel error. Use a custom compare function to avoid
+//
+// This was GT-216 with the ubuntu "nvidia-319" driver package.
+// llvmpipe does not show the same issue.
+//
+bool compareImages(const QImage &ia, const QImage &ib)
+{
+    if (ia.size() != ib.size())
+        qDebug() << "images are of different size" << ia.size() << ib.size();
+    Q_ASSERT(ia.size() == ib.size());
+    Q_ASSERT(ia.format() == ib.format());
+
+    int w = ia.width();
+    int h = ia.height();
+    const int tolerance = 5;
+    for (int y=0; y<h; ++y) {
+        const uint *as= (const uint *) ia.constScanLine(y);
+        const uint *bs= (const uint *) ib.constScanLine(y);
+        for (int x=0; x<w; ++x) {
+            uint a = as[x];
+            uint b = bs[x];
+
+            // No tolerance for error in the alpha.
+            if ((a & 0xff000000) != (b & 0xff000000))
+                return false;
+            if (qAbs(qRed(a) - qRed(b)) > tolerance)
+                return false;
+            if (qAbs(qRed(a) - qRed(b)) > tolerance)
+                return false;
+            if (qAbs(qRed(a) - qRed(b)) > tolerance)
+                return false;
+        }
+    }
+    return true;
+}
 
 void tst_qquickwindow::headless()
 {
@@ -1159,8 +1196,7 @@ void tst_qquickwindow::headless()
 
     // Verify that the visual output is the same
     QImage newContent = window->grabWindow();
-
-    QCOMPARE(originalContent, newContent);
+    QVERIFY(compareImages(newContent, originalContent));
 }
 
 void tst_qquickwindow::noUpdateWhenNothingChanges()
diff --git a/tests/auto/quick/scenegraph/tst_scenegraph.cpp b/tests/auto/quick/scenegraph/tst_scenegraph.cpp
index 5d393fedb5..c3d237a806 100644
--- a/tests/auto/quick/scenegraph/tst_scenegraph.cpp
+++ b/tests/auto/quick/scenegraph/tst_scenegraph.cpp
@@ -119,7 +119,7 @@ bool compareImages(const QImage &ia, const QImage &ib)
 
     int w = ia.width();
     int h = ia.height();
-    const int tolerance = 1;
+    const int tolerance = 5;
     for (int y=0; y<h; ++y) {
         const uint *as= (const uint *) ia.constScanLine(y);
         const uint *bs= (const uint *) ib.constScanLine(y);