DialWindow: Scaling font in both dimensions (#4469)

Currently the font in DialWindow is only scaled to make the text fit
into the label vertically. This commit scales the font in both
dimensions and prevents cutting off the content.

The font is rescaled
* If the DialWindow itself is resized
* If the text set and is longer than the previous one
* Every 10 text-changes

src/Train/DialWindow.cpp

@@ -80,7 +80,10 @@ DialWindow::DialWindow(Context *context) :
     QVBoxLayout *layout = new QVBoxLayout;
     layout->setSpacing(0);
     layout->setContentsMargins(3,3,3,3);
-    valueLabel = new QLabel(this);
+    valueLabel = new ScalingLabel(this);
+    QFont vlFont = valueLabel->font();
+    vlFont.setWeight(QFont::Bold);
+    valueLabel->setFont(vlFont);
     valueLabel->setAlignment(Qt::AlignCenter | Qt::AlignVCenter);
     layout->addWidget(valueLabel);
     setChartLayout(layout);
@@ -99,9 +102,6 @@ DialWindow::DialWindow(Context *context) :
     // setup colors
     seriesChanged();
 
-    // setup fontsize etc
-    resizeEvent(NULL);
-
     // set to zero
     resetValues();
 }
@@ -546,21 +546,6 @@ DialWindow::telemetryUpdate(const RealtimeData &rtData)
     }
 }
 
-void DialWindow::resizeEvent(QResizeEvent * )
-{
-    QFont font;
-
-    // set point size within reasonable limits for low dpi screens
-    int size = (geometry().height() - 24) * 72 / logicalDpiY();
-    if (size <= 0) size = 4;
-    if (size >= 64) size = 64;
-
-    font.setPointSize(size);
-
-    font.setWeight(QFont::Bold);
-    valueLabel->setFont(font);
-}
-
 void DialWindow::seriesChanged()
 {
     // we got some!

src/Train/DialWindow.h

@@ -26,6 +26,8 @@
 #include <QLineEdit>
 #include <QFormLayout>
 
+#include "ScalingLabel.h"
+
 #include "Context.h"
 #include "Zones.h" // for data series types
 #include "RideFile.h" // for data series types
@@ -74,9 +76,6 @@ class DialWindow : public GcChartWindow
         int style() const { return _style; }
         int avgSecs() const { return average; }
 
-        // change font as window resizes
-        void resizeEvent(QResizeEvent *);
-
    public slots:
 
         // trap signals
@@ -148,7 +147,7 @@ class DialWindow : public GcChartWindow
         QLineEdit   *averageEdit;
 
         // display
-        QLabel *valueLabel;
+        ScalingLabel *valueLabel;
 
         QColor foreground, background;
 

src/Train/ScalingLabel.cpp

@@ -0,0 +1,194 @@
+/*
+ * Copyright (c) 2022 Joachim Kohlhammer (joachim.kohlhammer@gmx.de)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "ScalingLabel.h"
+
+#include <QDebug>
+
+
+ScalingLabel::ScalingLabel
+(QWidget *parent, Qt::WindowFlags f)
+: ScalingLabel(4, 64, parent, f)
+{
+}
+
+
+
+ScalingLabel::ScalingLabel
+(int minFontPointSize, int maxFontPointSize, QWidget *parent, Qt::WindowFlags f)
+: QLabel(parent, f), minFontPointSize(minFontPointSize), maxFontPointSize(maxFontPointSize)
+{
+    QFont fnt = font();
+    fnt.setPointSize(minFontPointSize);
+    QLabel::setFont(fnt);
+}
+
+
+ScalingLabel::~ScalingLabel
+()
+{
+}
+
+
+void
+ScalingLabel::resizeEvent
+(QResizeEvent *evt)
+{
+    Q_UNUSED(evt);
+    scaleFont(text(), ScalingLabelReason::ResizeEvent);
+}
+
+
+void
+ScalingLabel::setText
+(const QString &text)
+{
+    ++counter;
+    if (text.length() > QLabel::text().length()) {
+        scaleFont(text, ScalingLabelReason::TextLengthChanged);
+    } else if (counter > 10) {
+        scaleFont(text, ScalingLabelReason::CounterExceeded);
+    }
+    QLabel::setText(text);
+}
+
+
+void
+ScalingLabel::setFont
+(const QFont &font)
+{
+    if (! scaleFont(text(), font, ScalingLabelReason::FontChanged)) {
+        QLabel::setFont(font);
+    }
+}
+
+
+int
+ScalingLabel::getMinFontPointSize
+() const
+{
+    return minFontPointSize;
+}
+
+
+void
+ScalingLabel::setMinFontPointSize
+(int size)
+{
+    minFontPointSize = size;
+}
+
+
+int
+ScalingLabel::getMaxFontPointSize
+() const
+{
+    return maxFontPointSize;
+}
+
+
+void
+ScalingLabel::setMaxFontPointSize
+(int size)
+{
+    maxFontPointSize = size;
+}
+
+
+bool
+ScalingLabel::isLinear
+() const
+{
+    return linear;
+}
+
+
+void
+ScalingLabel::setLinear
+(bool linear)
+{
+    this->linear = linear;
+}
+
+
+bool
+ScalingLabel::scaleFont
+(const QString &text, ScalingLabelReason reason)
+{
+    return scaleFont(text, font(), reason);
+}
+
+
+bool
+ScalingLabel::scaleFont
+(const QString &text, const QFont &font, ScalingLabelReason reason)
+{
+    counter = 0;
+    if (linear) {
+        return scaleFontLinear(text, font, reason);
+    } else {
+        return scaleFontExact(text, font, reason);
+    }
+}
+
+
+bool
+ScalingLabel::scaleFontExact
+(const QString &text, const QFont &font, ScalingLabelReason reason)
+{
+    int size = maxFontPointSize + 1;
+    if (reason == ScalingLabelReason::CounterExceeded) {
+        size = font.pointSize() + 1;
+    }
+    QFont f(font);
+    QRect br;
+    do {
+        f.setPointSize(--size);
+        QFontMetrics fm = QFontMetrics(f, this);
+        br = fm.boundingRect(text);
+    } while (size >= minFontPointSize && (br.width() > width() || br.height() > height()));
+    QLabel::setFont(f);
+    return true;
+}
+
+
+bool
+ScalingLabel::scaleFontLinear
+(const QString &text, const QFont &font, ScalingLabelReason reason)
+{
+    if (text.length() == 0 || width() <= 0 || height() <= 0) {
+        return false;
+    }
+    int maxSize = maxFontPointSize;
+    if (reason == ScalingLabelReason::CounterExceeded) {
+        maxSize = font.pointSize();
+    }
+    QFont f(font);
+    f.setPointSize(minFontPointSize);
+    QFontMetrics fmS = QFontMetrics(f, this);
+    f.setPointSize(maxSize);
+    QFontMetrics fmL = QFontMetrics(f, this);
+    QRect brS = fmS.boundingRect(text);
+    QRect brL = fmL.boundingRect(text);
+    int sizeWidth = (maxSize - minFontPointSize) / float(brL.width() - brS.width()) * width();
+    int sizeHeight = (maxSize - minFontPointSize) / float(brL.height() - brS.height()) * height();
+    int calcSize = std::min<int>(sizeWidth, sizeHeight);
+    f.setPointSize(std::max<int>(std::min<int>(calcSize, maxSize), minFontPointSize));
+    QLabel::setFont(f);
+    return true;
+}

src/Train/ScalingLabel.h

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2022 Joachim Kohlhammer (joachim.kohlhammer@gmx.de)
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the Free
+ * Software Foundation; either version 2 of the License, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc., 51
+ * Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#ifndef _GC_ScalingLabel_h
+#define _GC_ScalingLabel_h 1
+
+#include <QLabel>
+
+enum class ScalingLabelReason : uint8_t {
+    TextLengthChanged,
+    FontChanged,
+    ResizeEvent,
+    CounterExceeded
+};
+
+class ScalingLabel : public QLabel
+{
+    Q_OBJECT
+    Q_PROPERTY(int minFontPointSize READ getMinFontPointSize WRITE setMinFontPointSize USER false)
+    Q_PROPERTY(int maxFontPointSize READ getMaxFontPointSize WRITE setMaxFontPointSize USER false)
+    Q_PROPERTY(bool linear READ isLinear WRITE setLinear USER false)
+
+    public:
+        ScalingLabel(QWidget *parent = nullptr, Qt::WindowFlags f = Qt::WindowFlags());
+        ScalingLabel(int minFontPointSize, int maxFontPointSize, QWidget *parent = nullptr, Qt::WindowFlags f = Qt::WindowFlags());
+        virtual ~ScalingLabel();
+
+        virtual void resizeEvent(QResizeEvent *evt);
+        virtual void setFont(const QFont &font);
+
+        int getMinFontPointSize() const;
+        int getMaxFontPointSize() const;
+        bool isLinear() const;
+
+    public slots:
+        void setText(const QString &text);
+        void setMinFontPointSize(int size);
+        void setMaxFontPointSize(int size);
+        void setLinear(bool linear);
+
+    private:
+        bool scaleFont(const QString &text, const QFont &font, ScalingLabelReason reason);
+        bool scaleFont(const QString &text, ScalingLabelReason reason);
+        bool scaleFontExact(const QString &text, const QFont &font, ScalingLabelReason reason);
+        bool scaleFontLinear(const QString &text, const QFont &font, ScalingLabelReason reason);
+
+        int minFontPointSize;
+        int maxFontPointSize;
+        bool linear = true;
+        int counter = 0;
+};
+
+#endif

src/src.pro

@@ -699,7 +699,8 @@ HEADERS += Train/AddDeviceWizard.h Train/CalibrationData.h Train/ComputrainerCon
 HEADERS += Train/TrainBottom.h Train/TrainDB.h Train/TrainSidebar.h \
            Train/VideoLayoutParser.h Train/VideoSyncFile.h Train/WorkoutPlotWindow.h Train/WebPageWindow.h \
            Train/WorkoutWidget.h Train/WorkoutWidgetItems.h Train/WorkoutWindow.h Train/WorkoutWizard.h Train/ZwoParser.h \
-           Train/LiveMapWebPageWindow.h
+           Train/LiveMapWebPageWindow.h \
+           Train/ScalingLabel.h
 
 
 ###=============
@@ -803,7 +804,8 @@ SOURCES += Train/AddDeviceWizard.cpp Train/CalibrationData.cpp Train/Computraine
 SOURCES += Train/TrainBottom.cpp Train/TrainDB.cpp Train/TrainSidebar.cpp \
            Train/VideoLayoutParser.cpp Train/VideoSyncFile.cpp Train/WorkoutPlotWindow.cpp Train/WebPageWindow.cpp \
            Train/WorkoutWidget.cpp Train/WorkoutWidgetItems.cpp Train/WorkoutWindow.cpp Train/WorkoutWizard.cpp Train/ZwoParser.cpp \
-           Train/LiveMapWebPageWindow.cpp
+           Train/LiveMapWebPageWindow.cpp \
+           Train/ScalingLabel.cpp
 
 ## Crash Handling
 win32-msvc* {