CODEWITHSUNDEEP
c++qtqt5
Dr. Weiss
Dr. Weiss

Reputation: 81

Qt, resizeEvent in "Paint"

I am trying to implement two options; First when changing a window size my drawing is filling in white color, and I got it.

#include "drawPlace.h"
#include "QDebug"
#include "QFile"
#include "QFileDialog"
#include "QString"
#include "QPen"
#include "QPainter"

drawPlace::drawPlace(QWidget *parent) : QWidget(parent)
{

 }

void drawPlace::drawBlue()
{
    qDebug("blue");
    mColour = Qt::blue;
}

void drawPlace::drawRed()
{
    qDebug("red");
    mColour = Qt::red;
}

void drawPlace::drawYellow()
{
    qDebug("yellow");
    mColour = Qt::yellow;
}

void drawPlace::drawGreen()
{
    qDebug("green");
    mColour = Qt::green;
}

void drawPlace::clearScreen()
{
    qDebug("CLEAR");
    QImage bitMap(this->size(), QImage::Format_RGB32);
    bitMap.fill(Qt::white);
    mDraw = bitMap;
    this->update();
}

bool drawPlace::saveFile()
{
    qDebug("SAVING");
    mDraw.save(QFileDialog::getSaveFileName(this, ("Save File"), "/home/jana/untitled.png", "Pictures (*.PNG)"));
    return true;
}

void drawPlace::mousePressEvent(QMouseEvent *event)
{
    if (event->button() == Qt::LeftButton)
    {
        qDebug("Drawing started");
        mDrawing = true;
        oldPos = event->pos();
    }
}

void drawPlace::mouseMoveEvent(QMouseEvent *event)
{
    if(mDrawing)
    {
       QPen newPen(mColour, 3);
       QPainter drawing(&mDraw);
       drawing.setPen(newPen);
       newPos = event->pos();
       drawing.drawLine(oldPos, newPos);
       oldPos = newPos;
       this->update();
    }
}

void drawPlace::mouseReleaseEvent(QMouseEvent *event)
{
   if(event->button() == Qt::LeftButton)
   {
       qDebug("Drawing ended");
       mDrawing = false;
   }
}

void drawPlace::paintEvent(QPaintEvent *event)
{
    QPainter drawing(this);
    drawing.drawImage(0, 0, mDraw);
}
void drawPlace::resizeEvent(QResizeEvent *event)
{
    QImage newDraw(event>size(),      QImage::Format_RGB32);
    newDraw.fill(Qt::white);
    mDraw = newDraw;
    this->update();
}

it's my drawplace.cpp @eyllanesc

and it works, but the second option is that my drawing can't disappear and stay in the same place, but window is changing its size... I got no idea how to do it.

I tried with drawImage and others, but it don't work.

Upvotes: 1

Views: 1153

Answers (1)

eyllanesc
eyllanesc

Reputation: 244301

According to what you say, I understand that you are erasing the lines you draw with the mouse, and that happens because you are placing an image with a white background and replacing the previous image in the resizeEvent method, what you must do is also copy the drawing. The solution that I propose is only to paint if the new size is bigger in some of its dimensions and repaint.

void drawPlace::resizeEvent(QResizeEvent *event)
{
    if(event->size().width() > mDraw.size().width() || event->size().height() > mDraw.size().height()){
        QSize size;
        size.setWidth(event->size().width() > mDraw.size().width()? event->size().width(): mDraw.size().width());
        size.setHeight(event->size().height() > mDraw.size().height()? event->size().height(): mDraw.size().height());
        QImage newDraw(size, QImage::Format_RGB32);
        newDraw.fill(Qt::white);

        QPainter painter(&newDraw);
        painter.drawImage(QPoint(), mDraw);
        painter.end();
        mDraw = newDraw;
        update();
    }
}

Upvotes: 1

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