iv: Add min/max/avg and sizing to pixel closeup view (AcademySoftwareFoundation#4807)

This changeset has bunch of improvements for pixel closeup window
feature:
- Min/max/avg values
- RGB channels are colored with respective color
- Pixel colors in preview window are showing actual colors (previously
there was semi-dimming overlay on top of them)
- Center pixel is now marked including corner cases when close to the
edge
- During follow cursor mode window switches the the left from the cursor
when too close to right edge, and at the top when too close to bottom
edge
- Number of previeable pixels is configurable
- Number of pixels in a preview used for averaging is configurable
-- When avg subset is smaller then main closeup window there is an
indicator showing are that being averaged

---------

Signed-off-by: Aleksandr Motsjonov <soswow@gmail.com>

Author: soswow

src/iv/imageviewer.cpp

@@ -497,6 +497,40 @@ ImageViewer::createActions()
     toggleAreaSampleAct->setShortcut(tr("Ctrl+A"));
     connect(toggleAreaSampleAct, SIGNAL(triggered()), this,
             SLOT(toggleAreaSample()));
+
+    closeupPixelsLabel = new QLabel(tr("# closeup pixels:"));
+    closeupPixelsBox   = new QSpinBox();
+    closeupPixelsBox->setRange(9, 25);
+    closeupPixelsBox->setValue(13);
+    closeupPixelsBox->setSingleStep(2);
+
+    QString closeupPixelsTooltip = tr(
+        "Number of pixels to show in the closeup view.");
+    closeupPixelsBox->setToolTip(closeupPixelsTooltip);
+    closeupPixelsLabel->setToolTip(closeupPixelsTooltip);
+
+    closeupAvgPixelsLabel = new QLabel(tr("# closeup avg pixels:"));
+    closeupAvgPixelsBox   = new QSpinBox();
+    closeupAvgPixelsBox->setRange(3, 25);
+    closeupAvgPixelsBox->setValue(11);
+    closeupAvgPixelsBox->setSingleStep(2);
+
+    QString closeupAvgPixelsTooltip = tr(
+        "Number of pixels to use for averaging in the closeup view.");
+    closeupAvgPixelsBox->setToolTip(closeupAvgPixelsTooltip);
+    closeupAvgPixelsLabel->setToolTip(closeupAvgPixelsTooltip);
+
+    // Connect signals to ensure closeupAvgPixelsBox value is always <= closeupPixelsBox value
+    connect(closeupPixelsBox, QOverload<int>::of(&QSpinBox::valueChanged),
+            [this](int value) {
+                if (closeupAvgPixelsBox->value() > value)
+                    closeupAvgPixelsBox->setValue(value);
+            });
+    connect(closeupAvgPixelsBox, QOverload<int>::of(&QSpinBox::valueChanged),
+            [this](int value) {
+                if (value > closeupPixelsBox->value())
+                    closeupAvgPixelsBox->setValue(closeupPixelsBox->value());
+            });
 }
 
 
@@ -833,6 +867,7 @@ ImageViewer::readSettings(bool ui_is_set_up)
         maxMemoryIC->setValue(settings.value("maxMemoryIC", 2048).toInt());
     slideShowDuration->setValue(
         settings.value("slideShowDuration", 10).toInt());
+    closeupPixelsBox->setValue(settings.value("closeupPixels", 13).toInt());
 
     OIIO::attribute("imagebuf:use_imagecache", 1);
 
@@ -855,6 +890,7 @@ ImageViewer::writeSettings()
     settings.setValue("autoMipmap", autoMipmap->isChecked());
     settings.setValue("maxMemoryIC", maxMemoryIC->value());
     settings.setValue("slideShowDuration", slideShowDuration->value());
+    settings.setValue("closeupPixels", closeupPixelsBox->value());
     QStringList recent;
     for (auto&& s : m_recent_files)
         recent.push_front(QString(s.c_str()));

src/iv/imageviewer.h

@@ -26,6 +26,7 @@
 #include <QDialog>
 #include <QMainWindow>
 #include <QMimeData>
+#include <QSpinBox>
 
 #if OIIO_QT_MAJOR < 6
 #    include <QGLWidget>
@@ -50,7 +51,6 @@ class QMenu;
 class QMenuBar;
 class QProgressBar;
 class QPushButton;
-class QSpinBox;
 class QScrollArea;
 class QStatusBar;
 class QVBoxLayout;
@@ -245,6 +245,16 @@ class ImageViewer final : public QMainWindow {
         return linearInterpolationBox && linearInterpolationBox->isChecked();
     }
 
+    int closeupPixels(void) const
+    {
+        return closeupPixelsBox ? closeupPixelsBox->value() : 13;
+    }
+
+    int closeupAvgPixels(void) const
+    {
+        return closeupAvgPixelsBox ? closeupAvgPixelsBox->value() : 11;
+    }
+
     bool darkPalette(void) const
     {
         return darkPaletteBox ? darkPaletteBox->isChecked() : m_darkPalette;
@@ -416,6 +426,10 @@ private slots:
     QSpinBox* maxMemoryIC;
     QLabel* slideShowDurationLabel;
     QSpinBox* slideShowDuration;
+    QLabel* closeupPixelsLabel;
+    QSpinBox* closeupPixelsBox;
+    QLabel* closeupAvgPixelsLabel;
+    QSpinBox* closeupAvgPixelsBox;
 
     std::vector<IvImage*> m_images;  // List of images
     int m_current_image;             // Index of current image, -1 if none