New rc calibration channel widget

Left QGCRadioChannelDisplay alone so that I didn’t need to modify all
the other APM board code which uses this control. Also new control only
support horizontal orientation, with no plans to add vertical.

src/ui/designer/RCChannelWidget.cc

+/*=====================================================================
+ 
+ QGroundControl Open Source Ground Control Station
+ 
+ (c) 2009, 2014 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ 
+ This file is part of the QGROUNDCONTROL project
+ 
+ QGROUNDCONTROL 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 3 of the License, or
+ (at your option) any later version.
+ 
+ QGROUNDCONTROL 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 QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+ 
+ ======================================================================*/
+
+/// @file
+///     @author Don Gagne <don@thegagnes.com>
+
+#include "RCChannelWidget.h"
+#include <QPainter>
+
+#define DIMMEST_COLOR   QColor::fromRgb(0,100,0)
+#define MIDBRIGHT_COLOR   QColor::fromRgb(0,180,0)
+#define BRIGHTEST_COLOR   QColor::fromRgb(64,255,0)
+
+RCChannelWidget::RCChannelWidget(QWidget *parent) :
+    QGroupBox(parent),
+    _value(_centerValue),
+    _min(_centerValue),
+    _max(_centerValue),
+    _trim(_centerValue),
+    _showMinMax(false),
+    _showTrim(false)
+{
+
+}
+
+/// @brief Draws the control
+void RCChannelWidget::paintEvent(QPaintEvent *event)
+{
+    // Let the group box draw the outer border
+    QGroupBox::paintEvent(event);
+    
+    // Now we draw the innner contents
+    
+    QPainter painter(this);
+
+    int fontHeight = painter.fontMetrics().height();
+    int rowHeigth = fontHeight + 2;
+
+    painter.setBrush(Qt::Dense4Pattern);
+    painter.setPen(QColor::fromRgb(128,128,64));
+
+    int curVal = _value;
+    if (curVal > _maxRange)  {
+        curVal = _maxRange;
+    }
+    if (curVal < _minRange) {
+        curVal = _minRange;
+    }
+
+    if (isEnabled()) {
+        QLinearGradient hGradientBrush(0, 0, this->width(), this->height());
+        hGradientBrush.setColorAt(0.0,DIMMEST_COLOR);
+        hGradientBrush.setColorAt(0.5,MIDBRIGHT_COLOR);
+        hGradientBrush.setColorAt(1.0, BRIGHTEST_COLOR);
+        
+        // Calculate how much horizontal space we need to show a min/max value. We must be able to display four numeric
+        // digits for the rc value, plus we add another digit for spacing.
+        int minMaxDisplayWidth = painter.fontMetrics().width("00000");
+
+        // Draw the value axis line with center and end point tick marks. We need to leave enough space on the left and the right
+        // for the Min/Max value displays.
+        QRect rcValueAxis(minMaxDisplayWidth, rowHeigth * 2, width() - (minMaxDisplayWidth * 2), rowHeigth);
+        int yLine = rcValueAxis.y() + rcValueAxis.height() / 2;
+        painter.drawLine(rcValueAxis.left(), yLine, rcValueAxis.right(), yLine);
+        painter.drawLine(rcValueAxis.left(), rcValueAxis.top(), rcValueAxis.left(), rcValueAxis.bottom());
+        painter.drawLine(rcValueAxis.right(), rcValueAxis.top(), rcValueAxis.right(), rcValueAxis.bottom());
+        painter.drawLine(rcValueAxis.left() + rcValueAxis.width() / 2, rcValueAxis.top(), rcValueAxis.left() + rcValueAxis.width() / 2, rcValueAxis.bottom());
+        
+        painter.setPen(QColor::fromRgb(50,255,50));
+        painter.setBrush(hGradientBrush);
+
+        if (_showMinMax) {
+            // Draw the Min numeric value display to the left
+            painter.drawText(0, rowHeigth, minMaxDisplayWidth, fontHeight, Qt::AlignHCenter | Qt::AlignBottom, "Min");
+            painter.drawText(0, rowHeigth * 2, minMaxDisplayWidth, fontHeight, Qt::AlignHCenter | Qt::AlignBottom, QString::number(_min));
+
+            // Draw the Max numeric value display to the right
+            painter.drawText(width() - minMaxDisplayWidth, rowHeigth, minMaxDisplayWidth, fontHeight, Qt::AlignHCenter | Qt::AlignBottom, "Max");
+            painter.drawText(width() - minMaxDisplayWidth, rowHeigth * 2, minMaxDisplayWidth, fontHeight, Qt::AlignHCenter | Qt::AlignBottom, QString::number(_max));
+            
+            // Draw the Min/Max tick marks on the axis
+            int xTick = rcValueAxis.left() + (rcValueAxis.width() * ((float)(_min-_minRange) / (_maxRange-_minRange)));
+            painter.drawLine(xTick, rcValueAxis.top(), xTick, rcValueAxis.bottom());
+            xTick = rcValueAxis.left() + (rcValueAxis.width() * ((float)(_max-_minRange) / (_maxRange-_minRange)));
+            painter.drawLine(xTick, rcValueAxis.top(), xTick, rcValueAxis.bottom());
+        }
+        
+        if (_showTrim) {
+            // Draw the Trim value pointer
+            _drawValuePointer(&painter,
+                              rcValueAxis.left() + (rcValueAxis.width() * ((float)(_trim-_minRange) / (_maxRange-_minRange))),      // x position for tip of triangle
+                              (rowHeigth * 2) + (rowHeigth / 2) - 1,                                                                // y position for tip of triangle
+                              rowHeigth / 2,                                                                                        // heigth of triangle
+                              false);                                                                                               // draw upside down
+            
+            // Draw the Trim value label
+            QString trimStr = tr("Trim %1").arg(QString::number(_trim));
+            
+            int trimTextWidth = painter.fontMetrics().width(trimStr);
+            
+            painter.drawText(rcValueAxis.left() + (rcValueAxis.width() * ((float)(_trim-_minRange) / (_maxRange-_minRange))) - (trimTextWidth / 2),
+                             rowHeigth,
+                             trimTextWidth,
+                             fontHeight,
+                             Qt::AlignLeft | Qt::AlignBottom,
+                             trimStr);
+        }
+        
+        // Draw the RC value pointer
+        _drawValuePointer(&painter,
+                          rcValueAxis.left() + (rcValueAxis.width() * ((float)(curVal-_minRange) / (_maxRange-_minRange))),     // x position for tip of triangle
+                          (rowHeigth * 2) + (rowHeigth / 2) + 1,                                                                // y position for tip of triangle
+                          rowHeigth / 2,                                                                                        // heigth of triangle
+                          true);                                                                                                // draw right side up
+
+        // Draw the control value
+        QString valueStr = QString::number(_value);
+        
+        int valueTextWidth = painter.fontMetrics().width(valueStr);
+        
+        painter.drawText(rcValueAxis.left() + (rcValueAxis.width() * ((float)(_value-_minRange) / (_maxRange-_minRange))) - (valueTextWidth / 2),
+                         rowHeigth * 3,
+                         valueTextWidth,
+                         fontHeight,
+                         Qt::AlignLeft | Qt::AlignBottom,
+                         valueStr);
+
+        painter.setPen(QColor::fromRgb(0,128,0));
+        painter.setBrush(hGradientBrush);
+    } else {
+        painter.setPen(QColor(Qt::gray));
+        painter.drawText(0, 0, width(), height(), Qt::AlignHCenter | Qt::AlignVCenter, tr("not available"));
+    }
+}
+
+void RCChannelWidget::setValue(int value)
+{
+    _value = value;
+    update();
+}
+
+void RCChannelWidget::showMinMax(bool show)
+{
+    _showMinMax = show;
+    update();
+}
+
+void RCChannelWidget::showTrim(bool show)
+{
+    _showTrim = show;
+    update();
+}
+
+void RCChannelWidget::setValueAndMinMax(int val, int min, int max)
+{
+    setValue(val);
+    setMinMax(min,max);
+}
+
+void RCChannelWidget::setMinMax(int min, int max)
+{
+    _min = min;
+    _max = max;
+    update();
+}
+
+void RCChannelWidget::setTrim(int value)
+{
+    _trim = value;
+    update();
+}
+
+/// @brief Draw rc value pointer triangle.
+///     @param painter Draw using this painter
+///     @param x X position for tip of triangle
+///     @param y Y position for tip of triangle
+///     @param heigth Height of triangle
+///     @param rightSideUp true: draw triangle right side up, false: draw triangle upside down
+void RCChannelWidget::_drawValuePointer(QPainter* painter, int xTip, int yTip, int height, bool rightSideUp)
+{
+    QPointF trianglePoints[3];
+    
+    // Topmost tip of triangle points to value
+    trianglePoints[0].setX(xTip);
+    trianglePoints[0].setY(yTip);
+    
+    int yBottom;
+    if (rightSideUp) {
+        yBottom = yTip + height;
+    } else {
+        yBottom = yTip - height;
+    }
+    
+    // Right bottom tip of triangle
+    trianglePoints[1].setX(xTip + (height * 0.75));
+    trianglePoints[1].setY(yBottom);
+    
+    // Left bottom tip of triangle
+    trianglePoints[2].setX(xTip - (height * 0.75));
+    trianglePoints[2].setY(yBottom);
+    
+    painter->drawPolygon (trianglePoints, 3);
+}

src/ui/designer/RCChannelWidget.h

+/*=====================================================================
+ 
+ QGroundControl Open Source Ground Control Station
+ 
+ (c) 2009, 2014 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
+ 
+ This file is part of the QGROUNDCONTROL project
+ 
+ QGROUNDCONTROL 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 3 of the License, or
+ (at your option) any later version.
+ 
+ QGROUNDCONTROL 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 QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+ 
+ ======================================================================*/
+
+/// @file
+///     @author Don Gagne <don@thegagnes.com>
+
+#ifndef RCChannelWidget_H
+#define RCChannelWidget_H
+
+#include <QGroupBox>
+
+/// @brief RC Channel Widget - UI Widget based on QGroupBox which displays the current calibration settings
+///         for an RC channel.
+class RCChannelWidget : public QGroupBox
+{
+    Q_OBJECT
+    
+public:
+    explicit RCChannelWidget(QWidget *parent = 0);
+
+    /// @brief Set the current RC value to display
+    void setValue(int value);
+    
+    /// @brief Set the current RC Value, Minimum RC Value and Maximum RC Value
+    void setValueAndMinMax(int val, int min, int max);
+    
+    void setMinMax(int min, int max);
+    
+    /// @brief Sets the Trim value for the channel
+    void setTrim(int value);
+    
+    int value(void) { return _value; }  ///< Returns the current RC Value set in the control
+    int min(void) { return _min; }      ///< Returns the min value set in the control
+    int max(void) { return _max; }      ///< Returns the max values set in the control
+    int trim(void) { return _trim; }    ///< Returns the trim value set in the control
+
+    void showMinMax(bool show);
+    bool isMinMaxShown() { return _showMinMax; }
+    
+    void showTrim(bool show);
+    bool isTrimShown() { return _showTrim; }
+    
+protected:
+    virtual void paintEvent(QPaintEvent *event);
+    
+private:
+    void _drawValuePointer(QPainter* painter, int xTip, int yTip, int height, bool rightSideUp);
+    
+    int _value;         ///< Current RC value
+    int _min;           ///< Min RC value
+    int _max;           ///< Max RC value
+    int _trim;          ///< RC Value for Trim position
+    
+    bool _showMinMax;   ///< true: show min max values on display
+    bool _showTrim;     ///< true: show trim value on display
+    
+    static const int _centerValue = 1500;                           ///< RC Value which is at center
+    static const int _maxDeltaRange = 700;                          ///< Delta around center value which is the max range for widget
+    static const int _minRange = _centerValue - _maxDeltaRange;     ///< Smallest value widget can display
+    static const int _maxRange = _centerValue + _maxDeltaRange;     ///< Largest value widget can display
+};
+
+#endif