ppm/pgm image formats: fix reading 16bit and limited range

The color values of ppm and pgm images can be either 8 or 16 bits.
They can also be scaled to a smaller max value, and they can be
expressed either binary or ascii. For some of these permutations, Qt's
image handler lacked implementation or would decode the wrong color
value. This commit fixes that.

Task-number: QTBUG-18262
Task-number: QTBUG-35990
Change-Id: I7cf11c2366244f3a9b31c1a565a81e2658bc6a51
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 76 insertions, 0 deletions

diff --git a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
index bd02dc6255..18649b3de5 100644
--- a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
+++ b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp
@@ -133,6 +133,9 @@ private slots:
     void gifImageCount();
     void gifLoopCount();
 
+    void ppmMaxval_data();
+    void ppmMaxval();
+
     void readCorruptImage_data();
     void readCorruptImage();
     void readCorruptBmp();
@@ -956,6 +959,79 @@ void tst_QImageReader::gifLoopCount()
     }
 }
 
+void tst_QImageReader::ppmMaxval_data()
+{
+    QTest::addColumn<bool>("hasColor");
+    QTest::addColumn<QByteArray>("bytes");
+
+    QTest::newRow("PGM plain  8bit full") << false << QByteArray("P2 3 1   255   255 0   127\n");
+    QTest::newRow("PGM plain  8bit lim.") << false << QByteArray("P2 3 1    50    50 0    25\n");
+    QTest::newRow("PGM plain 16bit full") << false << QByteArray("P2 3 1 65535 65535 0 32767\n");
+    QTest::newRow("PGM plain 16bit lim.") << false << QByteArray("P2 3 1  5000  5000 0  2500\n");
+    QTest::newRow("PGM raw    8bit full") << false << QByteArray("P5 3 1   255 \xff\x00\x7f", 13 + 3);
+    QTest::newRow("PGM raw    8bit lim.") << false << QByteArray("P5 3 1    50 \x32\x00\x19", 13 + 3);
+    QTest::newRow("PGM raw   16bit full") << false << QByteArray("P5 3 1 65535 \xff\xff\x00\x00\x7f\xff", 13 + 3 * 2);
+    QTest::newRow("PGM raw   16bit lim.") << false << QByteArray("P5 3 1  5000 \x13\x88\x00\x00\x09\xc4", 13 + 3 * 2);
+
+    QTest::newRow("PPM plain  8bit full") << true  << QByteArray("P3 3 2   255 "
+                                                                 "255 255 255   0   0   0 127 127 127 "
+                                                                 "255   0   0   0 255   0   0   0 255\n");
+
+    QTest::newRow("PPM plain  8bit lim.") << true  << QByteArray("P3 3 2    50 "
+                                                                 " 50  50  50   0   0   0  25  25  25 "
+                                                                 " 50   0   0   0  50   0   0   0  50\n");
+
+    QTest::newRow("PPM plain 16bit full") << true  << QByteArray("P3 3 2 65535 "
+                                                                 "65535 65535 65535     0     0     0 32767 32767 32767 "
+                                                                 "65535     0     0     0 65535     0     0     0 65535\n");
+
+    QTest::newRow("PPM plain 16bit lim.") << true  << QByteArray("P3 3 2  5000 "
+                                                                 " 5000  5000  5000     0     0     0  2500  2500  2500 "
+                                                                 " 5000     0     0     0  5000     0     0     0  5000\n");
+
+    QTest::newRow("PPM raw    8bit full") << true  << QByteArray("P6 3 2   255 "
+                                                                 "\xff\xff\xff\x00\x00\x00\x7f\x7f\x7f"
+                                                                 "\xff\x00\x00\x00\xff\x00\x00\x00\xff", 13 + 6 * 3);
+
+    QTest::newRow("PPM raw    8bit lim.") << true  << QByteArray("P6 3 2    50 "
+                                                                 "\x32\x32\x32\x00\x00\x00\x19\x19\x19"
+                                                                 "\x32\x00\x00\x00\x32\x00\x00\x00\x32", 13 + 6 * 3);
+
+    QTest::newRow("PPM raw   16bit full") << true  << QByteArray("P6 3 2 65535 "
+                                                                 "\xff\xff\xff\xff\xff\xff\x00\x00\x00\x00\x00\x00\x7f\xff\x7f\xff\x7f\xff"
+                                                                 "\xff\xff\x00\x00\x00\x00\x00\x00\xff\xff\x00\x00\x00\x00\x00\x00\xff\xff", 13 + 6 * 3 * 2);
+
+    QTest::newRow("PPM raw   16bit lim.") << true  << QByteArray("P6 3 2  5000 "
+                                                                 "\x13\x88\x13\x88\x13\x88\x00\x00\x00\x00\x00\x00\x09\xc4\x09\xc4\x09\xc4"
+                                                                 "\x13\x88\x00\x00\x00\x00\x00\x00\x13\x88\x00\x00\x00\x00\x00\x00\x13\x88", 13 + 6 * 3 * 2);
+}
+
+void tst_QImageReader::ppmMaxval()
+{
+    SKIP_IF_UNSUPPORTED("ppm");
+
+    QFETCH(bool, hasColor);
+    QFETCH(QByteArray, bytes);
+
+    QImage img;
+    img.loadFromData(bytes);
+    QVERIFY(!img.isNull());
+    QCOMPARE(img.width(), 3);
+    QCOMPARE(img.height(), hasColor ? 2 : 1);
+
+    QCOMPARE(img.pixel(0,0), qRgb(0xff, 0xff, 0xff));
+    QCOMPARE(img.pixel(1,0), qRgb(0, 0, 0));
+    QRgb gray = img.pixel(2,0);
+    QVERIFY(qIsGray(gray));
+    QVERIFY(qRed(gray) > 0x70 && qRed(gray) < 0x90 );
+
+    if (hasColor) {
+        QCOMPARE(img.pixel(0,1), qRgb(0xff, 0, 0));
+        QCOMPARE(img.pixel(1,1), qRgb(0, 0xff, 0));
+        QCOMPARE(img.pixel(2,1), qRgb(0, 0, 0xff));
+    }
+}
+
 class Server : public QObject
 {
     Q_OBJECT