image orientation

src/mainwindow.cpp

@@ -5,6 +5,8 @@
 #include <QBitmap>
 #include <QKeyEvent>
 #include <QGraphicsBlurEffect>
+#include <libexif/exif-data.h>
+#include <iostream>
 
 MainWindow::MainWindow(QWidget *parent) :
     QMainWindow(parent),
@@ -18,7 +20,7 @@ MainWindow::MainWindow(QWidget *parent) :
     QApplication::setOverrideCursor(Qt::BlankCursor);
     QLabel *label = this->findChild<QLabel*>("image");
     setCentralWidget(label);
-    label->setStyleSheet("QLabel {  background-color: rgba(0, 0, 0, 230);}");
+    label->setStyleSheet("QLabel {  background-color: rgba(0, 0, 0, 180);}");
     label->setAlignment(Qt::AlignHCenter | Qt::AlignVCenter);
     update();
 
@@ -51,32 +53,84 @@ void MainWindow::setImage(std::string path)
     updateImage();
 }
 
+int MainWindow::getImageRotation()
+{
+    if (currentImage == "")
+        return 0;
+
+    int orientation = 0;
+    ExifData *exifData = exif_data_new_from_file(currentImage.c_str());
+    if (exifData)
+    {
+      ExifByteOrder byteOrder = exif_data_get_byte_order(exifData);
+      ExifEntry *exifEntry = exif_data_get_entry(exifData, EXIF_TAG_ORIENTATION);
+
+      if (exifEntry)
+      {
+        orientation = exif_get_short(exifEntry->data, byteOrder);
+      }
+      exif_data_free(exifData);
+    }
+
+    int degrees = 0;
+    switch(orientation) {
+        case 8:
+        degrees = 270;
+        break;
+        case 3:
+        degrees = 180;
+        break;
+        case 6:
+        degrees = 90;
+        break;
+    }
+
+    return degrees;
+}
+
 void MainWindow::updateImage()
 {
     if (currentImage == "")
-    {
         return;
-    }
-    QLabel *label = this->findChild<QLabel*>("image");
+
     QPixmap p( currentImage.c_str() );
-    int w = label->width();
-    int h = label->height();
-    QPixmap scaled = p.scaled(w,h,Qt::KeepAspectRatio);
+    QPixmap rotated = getRotatedPixmap(p);
+    QPixmap scaled = getScaledPixmap(rotated);
+
+    QLabel *label = this->findChild<QLabel*>("image");
     label->setPixmap(scaled);
 
+    drawBackground(rotated, scaled);
+    update();
+}
 
+QPixmap MainWindow::getRotatedPixmap(const QPixmap& p)
+{
+    QMatrix matrix;
+    matrix.rotate(getImageRotation());
+    return p.transformed(matrix);
+}
+
+QPixmap MainWindow::getScaledPixmap(const QPixmap& p)
+{
+    int w = width();
+    int h = height();
+    return p.scaled(w, h, Qt::KeepAspectRatio);
+}
+
+void MainWindow::drawBackground(const QPixmap& originalSize, const QPixmap& scaled)
+{
     QPalette palette;
     if (scaled.width() < width()) {
-        QPixmap background = p.scaledToWidth(width());
+        QPixmap background = originalSize.scaledToWidth(width());
         QRect rect(0, (background.height() - height())/2, width(), height());
         background = background.copy(rect);
         palette.setBrush(QPalette::Background, background);
     } else {
-        QPixmap background = p.scaledToHeight(height());
+        QPixmap background = originalSize.scaledToHeight(height());
         QRect rect((background.width() - width())/2, 0, width(), height());
         background = background.copy(rect);
         palette.setBrush(QPalette::Background, background);
     }
     this->setPalette(palette);
-    update();
 }