Cover Browser: Add an option to show covers with their original aspect ratio instead of resizing them all to have the same width and height. Option is in Preferences->Look & Feel->Cover Browser. Fixes #1295902 [[Enhancement Request] Allow cover browser to show book covers in actual dimensions/orientation](https://bugs.launchpad.net/calibre/+bug/1295902)

src/calibre/gui2/__init__.py

@@ -123,6 +123,7 @@ defs['cover_grid_texture'] = None
 defs['show_vl_tabs'] = False
 defs['show_highlight_toggle_button'] = False
 defs['add_comments_to_email'] = False
+defs['cb_preserve_aspect_ratio'] = False
 del defs
 # }}}
 

src/calibre/gui2/cover_flow.py

@@ -21,6 +21,7 @@ pictureflow, pictureflowerror = plugins['pictureflow']
 if pictureflow is not None:
 
     class EmptyImageList(pictureflow.FlowImages):
+
         def __init__(self):
             pictureflow.FlowImages.__init__(self)
 
@@ -108,7 +109,6 @@ if pictureflow is not None:
         def image(self, index):
             return self.model.cover(index)
 
-
     class CoverFlow(pictureflow.PictureFlow):
 
         dc_signal = pyqtSignal()
@@ -125,6 +125,10 @@ if pictureflow is not None:
                     type=Qt.QueuedConnection)
             self.context_menu = None
             self.setContextMenuPolicy(Qt.DefaultContextMenu)
+            try:
+                self.setPreserveAspectRatio(gprefs['cb_preserve_aspect_ratio'])
+            except AttributeError:
+                pass  # source checkout without updated binary
             if hasattr(self, 'setSubtitleFont'):
                 self.setSubtitleFont(QFont(rating_font()))
             if not gprefs['cover_browser_reflections']:
@@ -290,7 +294,6 @@ class CoverFlowMixin(object):
                 self.library_view.setCurrentIndex(idx)
                 self.library_view.scroll_to_row(idx.row())
 
-
     def show_cover_browser(self):
         d = CBDialog(self, self.cover_flow)
         d.addAction(self.cb_splitter.action_toggle)
@@ -313,7 +316,6 @@ class CoverFlowMixin(object):
             self.cb_dialog = None
         self.cb_splitter.button.set_state_to_show()
 
-
     def sync_cf_to_listview(self, current, previous):
         if self.cover_flow_sync_flag and self.cover_flow.isVisible() and \
                 self.cover_flow.currentSlide() != current.row():

src/calibre/gui2/pictureflow/pictureflow.cpp

@@ -318,6 +318,9 @@ struct SlideInfo
   PFreal cy;
 };
 
+static const QString OFFSET_KEY("offset");
+static const QString WIDTH_KEY("width");
+
 // PicturePlowPrivate {{{
 
 class PictureFlowPrivate
@@ -367,6 +370,7 @@ public:
   QTime  previousPosTimestamp;
   int    pixelDistanceMoved;
   int    pixelsToMovePerSlide;
+  bool   preserveAspectRatio;
   QFont subtitleFont;
 
   void setImages(FlowImages *images);
@@ -421,6 +425,7 @@ PictureFlowPrivate::PictureFlowPrivate(PictureFlow* w, int queueLength_)
   slideHeight = 200;
   fontSize = 10;
   doReflections = true;
+  preserveAspectRatio = false;
 
   centerIndex = 0;
   queueLength = queueLength_;
@@ -598,36 +603,53 @@ void PictureFlowPrivate::resetSlides()
   }
 }
 
-static QImage prepareSurface(QImage img, int w, int h, bool doReflections)
+static QImage prepareSurface(QImage srcimg, int w, int h, bool doReflections, bool preserveAspectRatio)
 {
-  img = img.scaled(w, h, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
-
     // slightly larger, to accommodate for the reflection
-  int hs = int(h * REFLECTION_FACTOR);
+    int hs = int(h * REFLECTION_FACTOR), left = 0, top = 0, a = 0, r = 0, g = 0, b = 0, ht, x, y, bpp;
+    QImage img = (preserveAspectRatio) ? QImage(w, h, srcimg.format()) : srcimg.scaled(w, h, Qt::IgnoreAspectRatio, Qt::SmoothTransformation);
+    QRgb color;
 
     // offscreen buffer: black is sweet
     QImage result(hs, w, QImage::Format_RGB16);  
     result.fill(0);
 
+    if (preserveAspectRatio) {
+        QImage temp = srcimg.scaled(w, h, Qt::KeepAspectRatio, Qt::SmoothTransformation);
+        img = QImage(w, h, temp.format());  
+        img.fill(0);
+        left = (w - temp.width()) / 2;
+        top = h - temp.height();
+        bpp = img.bytesPerLine() / img.width();
+        x = temp.width() * bpp;
+        result.setText(OFFSET_KEY, QString::number(left));
+        result.setText(WIDTH_KEY, QString::number(temp.width()));
+        for (y = 0; y < temp.height(); y++) {
+            const uchar *src = temp.scanLine(y);
+            uchar *dest = img.scanLine(top + y) + (bpp * left);
+            memcpy(dest, src, x);
+        }
+    }
+
     // transpose the image, this is to speed-up the rendering
     // because we process one column at a time
     // (and much better and faster to work row-wise, i.e in one scanline)
-  for(int x = 0; x < w; x++)
+    for(x = 0; x < w; x++)
-    for(int y = 0; y < h; y++)
+        for(y = 0; y < h; y++)
             result.setPixel(y, x, img.pixel(x, y));
 
     if (doReflections) {
         // create the reflection
-    int ht = hs - h;
+        ht = hs - h;
-    for(int x = 0; x < w; x++)
+        for(x = 0; x < w; x++)
-        for(int y = 0; y < ht; y++)
+            for(y = 0; y < ht; y++)
             {
-        QRgb color = img.pixel(x, img.height()-y-1);
+                color = img.pixel(x, img.height()-y-1);
                 //QRgb565 color = img.scanLine(img.height()-y-1) + x*sizeof(QRgb565); //img.pixel(x, img.height()-y-1);
-        int a = qAlpha(color);
+                a = qAlpha(color);
-        int r = qRed(color)   * a / 256 * (ht - y) / ht * 3/5;
+                r = qRed(color)   * a / 256 * (ht - y) / ht * 3/5;
-        int g = qGreen(color) * a / 256 * (ht - y) / ht * 3/5;
+                g = qGreen(color) * a / 256 * (ht - y) / ht * 3/5;
-        int b = qBlue(color)  * a / 256 * (ht - y) / ht * 3/5;
+                b = qBlue(color)  * a / 256 * (ht - y) / ht * 3/5;
                 result.setPixel(h+y, x, qRgb(r, g, b));
             }
     }
@@ -668,12 +690,12 @@ QImage* PictureFlowPrivate::surface(int slideIndex)
       painter.setBrush(QBrush());
       painter.drawRect(2, 2, slideWidth-3, slideHeight-3);
       painter.end();
-      blankSurface = prepareSurface(blankSurface, slideWidth, slideHeight, doReflections);
+      blankSurface = prepareSurface(blankSurface, slideWidth, slideHeight, doReflections, preserveAspectRatio);
     }
     return &blankSurface;
   }
 
-  surfaceCache.insert(slideIndex, new QImage(prepareSurface(img, slideWidth, slideHeight, doReflections)));
+  surfaceCache.insert(slideIndex, new QImage(prepareSurface(img, slideWidth, slideHeight, doReflections, preserveAspectRatio)));
   return surfaceCache[slideIndex];
 }
 
@@ -874,8 +896,7 @@ QRect PictureFlowPrivate::renderCenterSlide(const SlideInfo &slide) {
 // Renders a slide to offscreen buffer. Returns a rect of the rendered area.
 // alpha=256 means normal, alpha=0 is fully black, alpha=128 half transparent
 // col1 and col2 limit the column for rendering.
-QRect PictureFlowPrivate::renderSlide(const SlideInfo &slide, int alpha, 
+QRect PictureFlowPrivate::renderSlide(const SlideInfo &slide, int alpha, int col1, int col2)
-int col1, int col2)
 {
   QImage* src = surface(slide.slideIndex);
   if(!src)
@@ -913,6 +934,13 @@ int col1, int col2)
 
   bool flag = false;
   rect.setLeft(xi);
+  int img_offset = 0, img_width = 0;
+  bool slide_moving_to_center = false;
+  if (preserveAspectRatio) {
+      img_offset = src->text(OFFSET_KEY).toInt();
+      img_width = src->text(WIDTH_KEY).toInt();
+      slide_moving_to_center = slide.slideIndex == target && target != centerIndex;
+  }
   for(int x = qMax(xi, col1); x <= col2; x++)
   {
     PFreal hity = 0;
@@ -935,6 +963,17 @@ int col1, int col2)
       break;
     if(column < 0)
       continue;
+    if (preserveAspectRatio && !slide_moving_to_center) {
+        // We dont want a black border at the edge of narrow images when the images are in the left or right stacks
+        if (slide.slideIndex < centerIndex) {
+            column = qMin(column + img_offset, sw - 1);
+        } else if (slide.slideIndex == centerIndex) {
+            if (target > centerIndex) column = qMin(column + img_offset, sw - 1);
+            else if (target < centerIndex) column = qMax(column - sw + img_offset + img_width, 0);
+        } else {
+            column = qMax(column - sw + img_offset + img_width, 0);
+        }
+    }
 
     rect.setRight(x);  
     if(!flag)
@@ -1196,6 +1235,17 @@ void PictureFlow::setSlideSize(QSize size)
   d->setSlideSize(size);
 }
 
+bool PictureFlow::preserveAspectRatio() const
+{
+  return d->preserveAspectRatio;
+}
+
+void PictureFlow::setPreserveAspectRatio(bool preserve)
+{
+  d->preserveAspectRatio = preserve;
+  clearCaches();
+}
+
 void PictureFlow::setSubtitleFont(QFont font)
 {
   d->subtitleFont = font;

src/calibre/gui2/pictureflow/pictureflow.h

@@ -93,6 +93,7 @@ Q_OBJECT
   Q_PROPERTY(int currentSlide READ currentSlide WRITE setCurrentSlide)
   Q_PROPERTY(QSize slideSize READ slideSize WRITE setSlideSize)
   Q_PROPERTY(QFont subtitleFont READ subtitleFont WRITE setSubtitleFont)
+  Q_PROPERTY(bool preserveAspectRatio READ preserveAspectRatio WRITE setPreserveAspectRatio)
 
 public:
   /*!
@@ -121,6 +122,16 @@ public:
   */  
   void setSlideSize(QSize size);
 
+  /*!
+    Returns whether aspect ration is preserved when scaling images
+  */  
+  bool preserveAspectRatio() const;
+
+  /*!
+    Whether to preserve aspect ration when scaling images
+  */  
+  void setPreserveAspectRatio(bool preserve);
+
   /*!
     Turn the reflections on/off.
   */  

src/calibre/gui2/pictureflow/pictureflow.sip

@@ -41,6 +41,10 @@ public :
 
   void setSlideSize(QSize size);
 
+  bool preserveAspectRatio() const;
+
+  void setPreserveAspectRatio(bool preserve);
+
   QFont subtitleFont() const;
 
   void setSubtitleFont(QFont font);

src/calibre/gui2/preferences/look_feel.py

@@ -183,6 +183,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         r('use_roman_numerals_for_series_number', config)
         r('separate_cover_flow', config, restart_required=True)
         r('cb_fullscreen', gprefs)
+        r('cb_preserve_aspect_ratio', gprefs)
 
         choices = [(_('Off'), 'off'), (_('Small'), 'small'),
             (_('Medium'), 'medium'), (_('Large'), 'large')]
@@ -461,6 +462,7 @@ class ConfigWidget(ConfigWidgetBase, Ui_Form):
         gui.library_view.refresh_book_details()
         if hasattr(gui.cover_flow, 'setShowReflections'):
             gui.cover_flow.setShowReflections(gprefs['cover_browser_reflections'])
+            gui.cover_flow.setPreserveAspectRatio(gprefs['cb_preserve_aspect_ratio'])
         gui.library_view.refresh_row_sizing()
         gui.grid_view.refresh_settings()
 

src/calibre/gui2/preferences/look_feel.ui

@@ -897,7 +897,7 @@ a few top-level elements.</string>
          </property>
         </widget>
        </item>
-       <item row="5" column="0" colspan="2">
+       <item row="6" column="0" colspan="2">
         <spacer name="verticalSpacer_4">
          <property name="orientation">
           <enum>Qt::Vertical</enum>
@@ -913,14 +913,14 @@ a few top-level elements.</string>
        <item row="1" column="1">
         <widget class="QSpinBox" name="opt_cover_flow_queue_length"/>
        </item>
-       <item row="3" column="0" colspan="2">
+       <item row="4" column="0" colspan="2">
         <widget class="QCheckBox" name="opt_cb_fullscreen">
          <property name="text">
           <string>When showing cover browser in separate window, show it &amp;fullscreen</string>
          </property>
         </widget>
        </item>
-       <item row="4" column="0" colspan="2">
+       <item row="5" column="0" colspan="2">
         <widget class="QLabel" name="fs_help_msg">
          <property name="styleSheet">
           <string notr="true">margin-left: 1.5em</string>
@@ -940,6 +940,17 @@ a few top-level elements.</string>
          </property>
         </widget>
        </item>
+       <item row="3" column="0" colspan="2">
+        <widget class="QCheckBox" name="opt_cb_preserve_aspect_ratio">
+         <property name="toolTip">
+          <string>Show covers in their original aspect ratio instead of resizing
+them to all have the same width and height</string>
+         </property>
+         <property name="text">
+          <string>Preserve &amp;aspect ratio of covers displayed in the cover browser</string>
+         </property>
+        </widget>
+       </item>
       </layout>
      </widget>
     </widget>