Programming a chart... scroll problem

[kea_]

Hello together,

I like to write a little Chart for my program.
This should work in this way.
Left must be a legend that must be fixed.
And on the right hand site there should be the scrollable area.
I like just to scroll on the horizontal direction.

If I start scrolling everything works fine.
But if I resize the scrollarea it has a strange behavior and the scrollarea works in a wrong way.

Has any body a solution for my problem.

Thanks an I hope you can follow my bad english.
Heiko

chart.jpg

UChart.h

#ifndef UCHART_H
#define UCHART_H
 
#include <QtGui>
 
 
class UChart : public QScrollArea
{
    public:
        UChart();
        ~UChart();
 
    protected:
 
    private:
        int m_width;
        int m_fixed;
 
        void paintEvent(QPaintEvent *event);
        void scrollContentsBy(int dx, int dy);
        void resizeEvent(QResizeEvent *event);
        void setScrollBars();
};
 
#endif // UCHART_H

#ifndef UCHART_H
#define UCHART_H

#include <QtGui>


class UChart : public QScrollArea
{
    public:
        UChart();
        ~UChart();

    protected:

    private:
        int m_width;
        int m_fixed;

        void paintEvent(QPaintEvent *event);
        void scrollContentsBy(int dx, int dy);
        void resizeEvent(QResizeEvent *event);
        void setScrollBars();
};

#endif // UCHART_H

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UChart.cpp

#include "UChart.h"
 
UChart::UChart()
        : QScrollArea(){
 
    setObjectName("UChart");
    setStyleSheet(" #UChart { background: white } ");
    setFrameStyle(QFrame::NoFrame);
 
    horizontalScrollBar()->setRange(0, 1);
}
 
 
UChart::~UChart(){}
 
 
void UChart::paintEvent(QPaintEvent *event){
    int dx = horizontalScrollBar()->value();
    int dy = verticalScrollBar()->value();
    m_fixed = 100;
    m_width = 300;
 
    QPainter painter(viewport());
    painter.translate(-dx, 0);
 
    painter.setPen("#8e520c");
    painter.setBrush(QBrush("#fbf2a3"));
    painter.drawRect(-1, -1, m_fixed, size().height()+1);
 
 
    painter.setPen("#000000");
    painter.drawText(m_fixed + 5, 50, "Hello World!");
 
    setScrollBars();
}
 
 
void UChart::scrollContentsBy(int dx, int dy){
    viewport()->scroll(dx, dy, QRect(m_fixed, 0, m_width, size().height()));
}
 
 
void UChart::resizeEvent(QResizeEvent *event){
    //viewport()->scroll(dx, dy, QRect(m_fixed, 0, m_width, size().height()));
}
 
 
void UChart::setScrollBars(){
    if(m_width > size().width()){
        horizontalScrollBar()->setRange(0, m_width-size().width());
        horizontalScrollBar()->setPageStep(m_width);
    }else horizontalScrollBar()->setRange(0, 0);
}

#include "UChart.h"

UChart::UChart()
        : QScrollArea(){

    setObjectName("UChart");
    setStyleSheet(" #UChart { background: white } ");
    setFrameStyle(QFrame::NoFrame);

    horizontalScrollBar()->setRange(0, 1);
}


UChart::~UChart(){}


void UChart::paintEvent(QPaintEvent *event){
    int dx = horizontalScrollBar()->value();
    int dy = verticalScrollBar()->value();
    m_fixed = 100;
    m_width = 300;

    QPainter painter(viewport());
    painter.translate(-dx, 0);

    painter.setPen("#8e520c");
    painter.setBrush(QBrush("#fbf2a3"));
    painter.drawRect(-1, -1, m_fixed, size().height()+1);


    painter.setPen("#000000");
    painter.drawText(m_fixed + 5, 50, "Hello World!");

    setScrollBars();
}


void UChart::scrollContentsBy(int dx, int dy){
    viewport()->scroll(dx, dy, QRect(m_fixed, 0, m_width, size().height()));
}


void UChart::resizeEvent(QResizeEvent *event){
    //viewport()->scroll(dx, dy, QRect(m_fixed, 0, m_width, size().height()));
}


void UChart::setScrollBars(){
    if(m_width > size().width()){
        horizontalScrollBar()->setRange(0, m_width-size().width());
        horizontalScrollBar()->setPageStep(m_width);
    }else horizontalScrollBar()->setRange(0, 0);
}

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[FelixB]

do you want the legend to be always visible? Then you shouldn't derive UChart from QScrollArea. Create a horizontal layout with the legend as first element and a scrollarea as second. You could also use a Splitter if you want the legend to be resizeable...

hth
Felix

[kea_]

Ok, I hoped I could resolve this problem width more elegant.
But then this is the way.

Thank you very much for your anwer.
Heiko