Fixed loading of 8-bit grayscale TIFF files.

The PHOTOMETRIC_MINISBLACK and PHOTOMETRIC_MINISWHITE settings also
apply to 8-bit grayscale, so we need to check the bit depth of the image
as well. For convenience we also try to write the images using
PHOTOMETRIC_MINISBLACK and PHOTOMETRIC_MINISWHITE as opposed to
PHOTOMETRIC_PALETTE when we detect that the color table is grayscale.

Task-number: QTBUG-5459
Reviewed-by: Benjamin Poulain

4 files changed, 23 insertions, 3 deletions

diff --git a/tests/auto/qimagereader/images/grayscale-ref.tif b/tests/auto/qimagereader/images/grayscale-ref.tif
new file mode 100644
index 0000000..960531e
--- /dev/null
+++ b/tests/auto/qimagereader/images/grayscale-ref.tif
diff --git a/tests/auto/qimagereader/images/grayscale.tif b/tests/auto/qimagereader/images/grayscale.tif
new file mode 100644
index 0000000..5f4e114
--- /dev/null
+++ b/tests/auto/qimagereader/images/grayscale.tif
diff --git a/tests/auto/qimagereader/tst_qimagereader.cpp b/tests/auto/qimagereader/tst_qimagereader.cpp
index 05b506c..15b1c1c 100644
--- a/tests/auto/qimagereader/tst_qimagereader.cpp
+++ b/tests/auto/qimagereader/tst_qimagereader.cpp
@@ -157,6 +157,8 @@ private slots:
 
     void tiffOrientation_data();
     void tiffOrientation();
+
+    void tiffGrayscale();
 #endif
 
     void autoDetectImageFormat();
@@ -1376,6 +1378,13 @@ void tst_QImageReader::tiffOrientation()
     QCOMPARE(expectedImage, orientedImage);
 }
 
+void tst_QImageReader::tiffGrayscale()
+{
+    QImage actualImage(prefix + "grayscale.tif");
+    QImage expectedImage(prefix + "grayscale-ref.tif");
+
+    QCOMPARE(expectedImage, actualImage.convertToFormat(expectedImage.format()));
+}
 #endif
 
 void tst_QImageReader::dotsPerMeter_data()
diff --git a/tests/auto/qimagewriter/tst_qimagewriter.cpp b/tests/auto/qimagewriter/tst_qimagewriter.cpp
index 584a060..5ec287d3 100644
--- a/tests/auto/qimagewriter/tst_qimagewriter.cpp
+++ b/tests/auto/qimagewriter/tst_qimagewriter.cpp
@@ -391,16 +391,27 @@ void tst_QImageWriter::readWriteNonDestructive_data()
 {
     QTest::addColumn<QImage::Format>("format");
     QTest::addColumn<QImage::Format>("expectedFormat");
-    QTest::newRow("tiff mono") << QImage::Format_Mono << QImage::Format_Mono;
-    QTest::newRow("tiff indexed") << QImage::Format_Indexed8 << QImage::Format_Indexed8;
-    QTest::newRow("tiff rgb32") << QImage::Format_ARGB32 << QImage::Format_ARGB32;
+    QTest::addColumn<bool>("grayscale");
+    QTest::newRow("tiff mono") << QImage::Format_Mono << QImage::Format_Mono << false;
+    QTest::newRow("tiff indexed") << QImage::Format_Indexed8 << QImage::Format_Indexed8 << false;
+    QTest::newRow("tiff rgb32") << QImage::Format_ARGB32 << QImage::Format_ARGB32 << false;
+    QTest::newRow("tiff grayscale") << QImage::Format_Indexed8 << QImage::Format_Indexed8 << true;
 }
 
 void tst_QImageWriter::readWriteNonDestructive()
 {
     QFETCH(QImage::Format, format);
     QFETCH(QImage::Format, expectedFormat);
+    QFETCH(bool, grayscale);
     QImage image = QImage(prefix + "colorful.bmp").convertToFormat(format);
+
+    if (grayscale) {
+        QVector<QRgb> colors;
+        for (int i = 0; i < 256; ++i)
+            colors << qRgb(i, i, i);
+        image.setColorTable(colors);
+    }
+
     QVERIFY(image.save(prefix + "gen-readWriteNonDestructive.tiff"));
 
     QImage image2 = QImage(prefix + "gen-readWriteNonDestructive.tiff");