Improve conversion of bytes to human readable string

Fixes issues like showing 0 MiB when the value is just slightly less then 1 MiB.

pglab/util/PgLabItemDelegate.cpp

@@ -5,6 +5,7 @@
 #include "ResultTableModelUtil.h"
 #include "CustomDataRole.h"
 #include "AbstractEditorFactory.h"
+#include "utils/HumanReadableBytes.h"
 
 PgLabItemDelegate::PgLabItemDelegate(QObject *parent)
 	: QStyledItemDelegate(parent)
@@ -111,37 +112,11 @@ void PgLabItemDelegate::initStyleOption(QStyleOptionViewItem *option,
 		else {
             forground_color = GetDefaultColorForType(oid);
             if (meaning == DataMeaning::Bytes) {
-                QString suffix;
-                auto s = value.toLongLong();
-                double val;
-                if (s > 1024 * 1024 * 1000) {
-                    val = s / (1024 * 1024 * 1024);
-                    suffix = "GiB";
-                    forground_color = QColorConstants::Svg::darkorange;
-                    option->font.setBold(true);
-                }
-                else if (s > 1024 * 1000) {
-                    val = s / (1024 * 1024);
-                    suffix = "MiB";
-                    forground_color = QColorConstants::Svg::darkgoldenrod;
-                }
-                else if (s > 1000) {
-                    val = s / 1024;
-                    suffix = "KiB";
-                    forground_color = QColorConstants::Svg::darkgreen;
-                }
-                else {
-                    val = s;
-                    suffix = "B";
-                    forground_color = QColorConstants::Svg::darkblue;
-                }
-                option->text = QString{ "%1 %2" }.arg(val, 0, 'g', 3).arg(suffix)   ;
+                option->text = HandleBytes(value.toLongLong(), forground_color);
             }
             else {
                 auto str = value.toString();
                 auto s = str.left(100);
-    //			auto f = s.indexOf('\n');
-    //			option->text = ((f > 0) ? s.left(f) : s).toString();
                 option->text = s;
             }
         }
@@ -161,30 +136,48 @@ void PgLabItemDelegate::initStyleOption(QStyleOptionViewItem *option,
 	option->styleObject = nullptr;
 }
 
-void PgLabItemDelegate::paint(QPainter *painter,
-		const QStyleOptionViewItem &option, const QModelIndex &index) const
+QString PgLabItemDelegate::HandleBytes(qlonglong s, QColor &forground_color) const
 {
-	Q_ASSERT(index.isValid());
+    auto str = HumanReadableBytes(s);
+    if (s > 1024 * 1024 * 1024) {
+        forground_color = QColorConstants::Svg::darkorange;
+    }
+    else if (s > 1024 * 1024) {
+        forground_color = QColorConstants::Svg::darkgoldenrod;
+    }
+    else if (s > 1024) {
+        forground_color = QColorConstants::Svg::darkgreen;
+    }
+    else {
+        forground_color = QColorConstants::Svg::darkblue;
+    }
+    return QString::fromStdString(str);
+}
 
-	QStyleOptionViewItem opt = option;
-	initStyleOption(&opt, index);
+void PgLabItemDelegate::paint(QPainter *painter,
+                              const QStyleOptionViewItem &option, const QModelIndex &index) const
+{
+    Q_ASSERT(index.isValid());
 
-	const QWidget *widget = option.widget; // QStyledItemDelegatePrivate::widget(option);
-	QStyle *style = widget ? widget->style() : QApplication::style();
-	style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
+    QStyleOptionViewItem opt = option;
+    initStyleOption(&opt, index);
+
+    const QWidget *widget = option.widget; // QStyledItemDelegatePrivate::widget(option);
+    QStyle *style = widget ? widget->style() : QApplication::style();
+    style->drawControl(QStyle::CE_ItemViewItem, &opt, painter, widget);
 }
 
 QWidget *PgLabItemDelegate::createEditor(QWidget *parent, const QStyleOptionViewItem &option, const QModelIndex &index) const
 {
-	if (m_editorFactory)
-		return m_editorFactory->createEditor(parent, option, index);
-	return QStyledItemDelegate::createEditor(parent, option, index);
+    if (m_editorFactory)
+        return m_editorFactory->createEditor(parent, option, index);
+    return QStyledItemDelegate::createEditor(parent, option, index);
 }
 
 void PgLabItemDelegate::setEditorData(QWidget *editor, const QModelIndex &index) const
 {
-	if (m_editorFactory)
-		m_editorFactory->setEditorData(editor, index);
+    if (m_editorFactory)
+        m_editorFactory->setEditorData(editor, index);
 	else
 		QStyledItemDelegate::setEditorData(editor, index);
 }

pglab/util/PgLabItemDelegate.h

@@ -29,7 +29,8 @@ protected:
 	virtual void initStyleOption(QStyleOptionViewItem *option, const QModelIndex &index) const override;
 
 private:
-	AbstractEditorFactory *m_editorFactory = nullptr;
+    AbstractEditorFactory *m_editorFactory = nullptr;
+    QString HandleBytes(qlonglong s, QColor &forground_color) const;
 };
 
 #endif // PGLABITEMDELEGATE_H

pglablib/pglablib.pro

@@ -87,7 +87,8 @@ SOURCES += \
     catalog/PgLanguage.cpp \
     catalog/PgAcl.cpp \
     catalog/PgSequence.cpp \
-    catalog/PgSequenceContainer.cpp
+    catalog/PgSequenceContainer.cpp \
+    utils/HumanReadableBytes.cpp
 
 HEADERS += \
         Pglablib.h \
@@ -162,7 +163,8 @@ HEADERS += \
     catalog/PgLanguage.h \
     catalog/PgAcl.h \
     catalog/PgSequence.h \
-    catalog/PgSequenceContainer.h
+    catalog/PgSequenceContainer.h \
+    utils/HumanReadableBytes.h
 
 unix {
     target.path = /usr/lib

pglablib/utils/HumanReadableBytes.cpp

@@ -0,0 +1,56 @@
+#include "HumanReadableBytes.h"
+#include <iomanip>
+#include <sstream>
+
+using namespace std;
+
+namespace {
+
+struct scale {
+    int64_t scale;
+    const char* prefix;
+};
+
+void fmt(std::ostringstream &o, double d)
+{
+    ;
+    if (d < 10.0)
+    {
+        o << fixed << setprecision(2) << d;
+        //return std::format("{:.3g}", d);
+    }
+    else if (d < 100.0)
+    {
+        o << fixed << setprecision(1) << d;
+        //return std::format("{:.3g}", d);
+    }
+    else
+    {
+        o << fixed << setprecision(0) << d;
+    }
+}
+
+}
+
+std::string HumanReadableBytes(uint64_t bytes)
+{
+    static scale scales[] = {
+                             { 1024ll * 1024 * 1024 * 1024, "Ti" },
+                             { 1024ll * 1024 * 1024, "Gi" },
+                             { 1024ll * 1024, "Mi" },
+                             { 1024ll, "ki" },
+                             };
+
+    std::ostringstream out;
+    for (int i = 0; i < (sizeof(scales) / sizeof(scale)); ++i)
+    {
+        if (bytes >= scales[i].scale)
+        {
+            fmt(out, bytes / double(scales[i].scale));
+            out << " " << scales[i].prefix << "B";
+            return out.str();
+        }
+    }
+    out << bytes << " B";
+    return out.str();
+}

pglablib/utils/HumanReadableBytes.h

@@ -0,0 +1,5 @@
+#pragma once
+
+#include <string>
+
+std::string HumanReadableBytes(uint64_t bytes);

tests/pglabtests/pglabtests.pro

@@ -18,6 +18,7 @@ SOURCES +=     main.cpp \
     tst_ConvertLangToSqlString.cpp \
     tst_ConvertToMultiLineCString.cpp \
     tst_ExplainJsonParser.cpp \
+    tst_HumanReadableBytes.cpp \
     tst_escapeConnectionStringValue.cpp \
     tst_expected.cpp \
     tst_SqlLexer.cpp \

tests/pglabtests/tst_HumanReadableBytes.cpp

@@ -0,0 +1,23 @@
+#include <gtest/gtest.h>
+#include <gmock/gmock-matchers.h>
+#include "PrintTo_Qt.h"
+
+#include "utils/HumanReadableBytes.h"
+
+TEST(HumanReadableBytesTest, bytes7)
+{
+    auto s = HumanReadableBytes(7);
+    ASSERT_EQ("7 B", s);
+}
+
+TEST(HumanReadableBytesTest, bytes1023)
+{
+    auto s = HumanReadableBytes(1023);
+    ASSERT_EQ("1023 B", s);
+}
+
+TEST(HumanReadableBytesTest, bytes1k)
+{
+    auto s = HumanReadableBytes(1024);
+    ASSERT_EQ("1.00 kiB", s);
+}