qwt_dial_needle.cpp

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/* -*- mode: C++ ; c-file-style: "stroustrup" -*- *****************************
 * Qwt Widget Library
 * Copyright (C) 1997   Josef Wilgen
 * Copyright (C) 2002   Uwe Rathmann
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the Qwt License, Version 1.0
 *****************************************************************************/

#include "qwt_dial_needle.h"
#include "qwt_global.h"
#include "qwt_math.h"
#include "qwt_painter.h"
#include <qapplication.h>
#include <qpainter.h>

#if QT_VERSION < 0x040601
#define qFastSin(x) qSin(x)
#define qFastCos(x) qCos(x)
#endif

static void qwtDrawStyle1Needle( QPainter *painter,
    const QPalette &palette, QPalette::ColorGroup colorGroup,
    double length )
{
    const double r[] = { 0.4, 0.3, 1, 0.8, 1, 0.3, 0.4 };
    const double a[] = { -45, -20, -15, 0, 15, 20, 45 };

    QPainterPath path;
    for ( int i = 0; i < 7; i++ )
    {
        const double angle = a[i] / 180.0 * M_PI;
        const double radius = r[i] * length;

        const double x = radius * qFastCos( angle );
        const double y = radius * qFastSin( angle );

        path.lineTo( x, -y );
    }

    painter->setPen( Qt::NoPen );
    painter->setBrush( palette.brush( colorGroup, QPalette::Light ) );
    painter->drawPath( path );
}

static void qwtDrawStyle2Needle( QPainter *painter,
    const QPalette &palette, QPalette::ColorGroup colorGroup, double length )
{
    const double ratioX = 0.7;
    const double ratioY = 0.3;

    QPainterPath path1;
    path1.lineTo( ratioX * length, 0.0 );
    path1.lineTo( length, ratioY * length );

    QPainterPath path2;
    path2.lineTo( ratioX * length, 0.0 );
    path2.lineTo( length, -ratioY * length );

    painter->setPen( Qt::NoPen );

    painter->setBrush( palette.brush( colorGroup, QPalette::Light ) );
    painter->drawPath( path1 );

    painter->setBrush( palette.brush( colorGroup, QPalette::Dark ) );
    painter->drawPath( path2 );
}

static void qwtDrawShadedPointer( QPainter *painter, 
    const QColor &lightColor, const QColor &darkColor,
    double length, double width )
{
    const double peak = qMax( length / 10.0, 5.0 );

    const double knobWidth = width + 8;
    QRectF knobRect( 0, 0, knobWidth, knobWidth );
    knobRect.moveCenter( QPointF(0, 0) );

    QPainterPath path1;
    path1.lineTo( 0.0, 0.5 * width );
    path1.lineTo( length - peak, 0.5 * width );
    path1.lineTo( length, 0.0 );
    path1.lineTo( 0.0, 0.0 );

    QPainterPath arcPath1;
    arcPath1.arcTo( knobRect, 0.0, -90.0 );

    path1 = path1.united( arcPath1 );

    QPainterPath path2;
    path2.lineTo( 0.0, -0.5 * width );
    path2.lineTo( length - peak, -0.5 * width );
    path2.lineTo( length, 0.0 );
    path2.lineTo( 0.0, 0.0 );

    QPainterPath arcPath2;
    arcPath2.arcTo( knobRect, 0.0, 90.0 );

    path2 = path2.united( arcPath2 );

    painter->setPen( Qt::NoPen );

    painter->setBrush( lightColor );
    painter->drawPath( path1 );

    painter->setBrush( darkColor );
    painter->drawPath( path2 );
}

static void qwtDrawArrowNeedle( QPainter *painter,
    const QPalette &palette, QPalette::ColorGroup colorGroup,
    double length, double width )
{
    if ( width <= 0 )
        width = qMax( length * 0.06, 9.0 );

    const double peak = qMax( 2.0, 0.4 * width );

    QPainterPath path;
    path.moveTo( 0.0, 0.5 * width );
    path.lineTo( length - peak, 0.3 * width );
    path.lineTo( length, 0.0 );
    path.lineTo( length - peak, -0.3 * width );
    path.lineTo( 0.0, -0.5 * width );

    QRectF br = path.boundingRect();

    QPalette pal( palette.color( QPalette::Mid ) );
    QColor c1 = pal.color( QPalette::Light );
    QColor c2 = pal.color( QPalette::Dark );

    QLinearGradient gradient( br.topLeft(), br.bottomLeft() );
    gradient.setColorAt( 0.0, c1 );
    gradient.setColorAt( 0.5, c1 );
    gradient.setColorAt( 0.5001, c2 );
    gradient.setColorAt( 1.0, c2 );

    QPen pen( gradient, 1 );
    pen.setJoinStyle( Qt::MiterJoin );

    painter->setPen( pen );
    painter->setBrush( palette.brush( colorGroup, QPalette::Mid ) );

    painter->drawPath( path );
}

static void qwtDrawTriangleNeedle( QPainter *painter,
    const QPalette &palette, QPalette::ColorGroup colorGroup,
    double length )
{
    const double width = qRound( length / 3.0 );

    QPainterPath path[4];

    path[0].lineTo( length, 0.0 );
    path[0].lineTo( 0.0, width / 2 );

    path[1].lineTo( length, 0.0 );
    path[1].lineTo( 0.0, -width / 2 );

    path[2].lineTo( -length, 0.0 );
    path[2].lineTo( 0.0, width / 2 );

    path[3].lineTo( -length, 0.0 );
    path[3].lineTo( 0.0, -width / 2 );


    const int colorOffset =  10;
    const QColor darkColor = palette.color( colorGroup, QPalette::Dark );
    const QColor lightColor = palette.color( colorGroup, QPalette::Light );

    QColor color[4];
    color[0] = darkColor.light( 100 + colorOffset );
    color[1] = darkColor.dark( 100 + colorOffset );
    color[2] = lightColor.light( 100 + colorOffset );
    color[3] = lightColor.dark( 100 + colorOffset );

    painter->setPen( Qt::NoPen );

    for ( int i = 0; i < 4; i++ )
    {
        painter->setBrush( color[i] );
        painter->drawPath( path[i] );
    }
}

QwtDialNeedle::QwtDialNeedle():
    d_palette( QApplication::palette() )
{
}

QwtDialNeedle::~QwtDialNeedle()
{
}

void QwtDialNeedle::setPalette( const QPalette &palette )
{
    d_palette = palette;
}

const QPalette &QwtDialNeedle::palette() const
{
    return d_palette;
}

void QwtDialNeedle::draw( QPainter *painter, 
    const QPointF &center, double length, double direction, 
    QPalette::ColorGroup colorGroup ) const
{
    painter->save();

    painter->translate( center );
    painter->rotate( -direction );

    drawNeedle( painter, length, colorGroup );

    painter->restore();
}

void QwtDialNeedle::drawKnob( QPainter *painter,
    double width, const QBrush &brush, bool sunken ) const
{
    QPalette palette( brush.color() );

    QColor c1 = palette.color( QPalette::Light );
    QColor c2 = palette.color( QPalette::Dark );

    if ( sunken )
        qSwap( c1, c2 );

    QRectF rect( 0.0, 0.0, width, width );
    rect.moveCenter( painter->combinedTransform().map( QPointF() ) );

    QLinearGradient gradient( rect.topLeft(), rect.bottomRight() );
    gradient.setColorAt( 0.0, c1 );
    gradient.setColorAt( 0.3, c1 );
    gradient.setColorAt( 0.7, c2 );
    gradient.setColorAt( 1.0, c2 );

    painter->save();

    painter->resetTransform();

    painter->setPen( QPen( gradient, 1 ) );
    painter->setBrush( brush );
    painter->drawEllipse( rect );

    painter->restore();
}

QwtDialSimpleNeedle::QwtDialSimpleNeedle( Style style, bool hasKnob,
        const QColor &mid, const QColor &base ):
    d_style( style ),
    d_hasKnob( hasKnob ),
    d_width( -1 )
{
    QPalette palette;
    palette.setColor( QPalette::Mid, mid );
    palette.setColor( QPalette::Base, base );

    setPalette( palette );
}

void QwtDialSimpleNeedle::setWidth( double width )
{
    d_width = width;
}

double QwtDialSimpleNeedle::width() const
{
    return d_width;
}

void QwtDialSimpleNeedle::drawNeedle( QPainter *painter, 
    double length, QPalette::ColorGroup colorGroup ) const
{
    double knobWidth = 0.0;
    double width = d_width;

    if ( d_style == Arrow )
    {
        if ( width <= 0.0 )
            width = qMax(length * 0.06, 6.0);

        qwtDrawArrowNeedle( painter, 
            palette(), colorGroup, length, width );

        knobWidth = qMin( width * 2.0, 0.2 * length );
    }
    else
    {
        if ( width <= 0.0 )
            width = 5.0;
        
        QPen pen ( palette().brush( colorGroup, QPalette::Mid ), width );
        pen.setCapStyle( Qt::FlatCap );
    
        painter->setPen( pen );
        painter->drawLine( QPointF( 0.0, 0.0 ), QPointF( length, 0.0 ) );

        knobWidth = qMax( width * 3.0, 5.0 );
    }

    if ( d_hasKnob && knobWidth > 0.0 )
    {
        drawKnob( painter, knobWidth,
            palette().brush( colorGroup, QPalette::Base ), false );
    }
}

QwtCompassMagnetNeedle::QwtCompassMagnetNeedle( Style style,
        const QColor &light, const QColor &dark ):
    d_style( style )
{
    QPalette palette;
    palette.setColor( QPalette::Light, light );
    palette.setColor( QPalette::Dark, dark );
    palette.setColor( QPalette::Base, Qt::gray );

    setPalette( palette );
}

void QwtCompassMagnetNeedle::drawNeedle( QPainter *painter, 
    double length, QPalette::ColorGroup colorGroup ) const
{
    if ( d_style == ThinStyle )
    {
        const double width = qMax( length / 6.0, 3.0 );

        const int colorOffset = 10;

        const QColor light = palette().color( colorGroup, QPalette::Light );
        const QColor dark = palette().color( colorGroup, QPalette::Dark );

        qwtDrawShadedPointer( painter,
            dark.light( 100 + colorOffset ),
            dark.dark( 100 + colorOffset ),
            length, width );
        
        painter->rotate( 180.0 );
    
        qwtDrawShadedPointer( painter,
            light.light( 100 + colorOffset ),
            light.dark( 100 + colorOffset ),
            length, width );
        
        const QBrush baseBrush = palette().brush( colorGroup, QPalette::Base );
        drawKnob( painter, width, baseBrush, true );
    }
    else
    {
        qwtDrawTriangleNeedle( painter, palette(), colorGroup, length );
    }
}

QwtCompassWindArrow::QwtCompassWindArrow( Style style,
        const QColor &light, const QColor &dark ):
    d_style( style )
{
    QPalette palette;
    palette.setColor( QPalette::Light, light );
    palette.setColor( QPalette::Dark, dark );

    setPalette( palette );
}

void QwtCompassWindArrow::drawNeedle( QPainter *painter, 
    double length, QPalette::ColorGroup colorGroup ) const
{
    if ( d_style == Style1 )
        qwtDrawStyle1Needle( painter, palette(), colorGroup, length );
    else
        qwtDrawStyle2Needle( painter, palette(), colorGroup, length );
}