Qt 4.7 - 使用Paintevent使用动态反馈的2个点线
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12-12-2019 - |
题
所以我试图在两点之间画一条线。左鼠标单击开始行,然后我希望通过动态绘制为鼠标移动(几乎像行的预览)的线路。左鼠标再次单击,线将永久绘制。我知道有很多关于QPaintevents的帖子,我已经组合了一些使用的技术,但由于某种原因没有任何东西被绘制到画布上。以下是代码:
void Main::mousePressEvent(QMouseEvent * event)
{
if (event->button() == Qt::LeftButton) {
QPointF pos = event->pos();
if( mStartPoint.isNull() ) {
if(josh.contains(pos))
mStartPoint = pos;
} else {
canvas.addLine(mStartPoint.x(),mStartPoint.y(),pos.x(),pos.y());
mStartPoint = QPointF();
}
}
}
bool Main::eventFilter(QObject *obj, QEvent *event)
{
if (event->type() == QEvent::MouseMove)
{
QMouseEvent *mouseEvent = static_cast<QMouseEvent*>(event);
if (!mStartPoint.isNull()) {
m_targetImage = QImage(canvas.width(),canvas.height(),QImage::Format_ARGB32);
QPainter p;
p.begin(&m_targetImage);
p.drawLine(mStartPoint, mouseEvent->pos());
p.end();
}
statusBar()->showMessage(QString("Mouse move (%1,%2)").arg(mouseEvent->pos().x()).arg(mouseEvent->pos().y()));
}
return false;
}
void Main::paintEvent(QPaintEvent *pe)
{
QPainter painter(this);
QPen pen(Qt::red);
pen.setWidth(10);
painter.setPen(pen);
painter.drawImage(0, 0, m_targetImage);
}
.
任何帮助都得到了赞赏!谢谢!Josh
解决方案
我认为这是你想要的。根据您的要求更改参数。
//In your constructor
m_nInitialX = 0;
m_nInitialY = 0;
m_nFinalX = 0;
m_nFinalY = 0;
m_nPTargetPixmap = 0;
m_nPTargetPixmap = new QPixmap(400,400);
m_nbMousePressed = false;
void Main::mousePressEvent(QMouseEvent* event)
{
m_nbMousePressed = true;
m_nInitialX = event->pos().x();
m_nInitialY = event->pos().y();
}
void Main::mouseReleaseEvent(QMouseEvent *event)
{
m_nbMousePressed = false;
}
void Main::paintEvent(QPaintEvent *e)
{
if(m_nbMousePressed)
{
QPainter PixmapPainter(m_nPTargetPixmap);
QPen pen(Qt::green);
PixmapPainter.setPen(pen);
PixmapPainter.drawLine(m_nInitialX, m_nInitialY, m_nFinalX, m_nFinalY);
}
QPainter painter(this);
painter.drawPixmap(0, 0, *m_nPTargetPixmap);
}
void Main::mouseMoveEvent(QMouseEvent *event)
{
if (event->type() == QEvent::MouseMove)
{
QPainter PixmapPainter(m_nPTargetPixmap);
QPen pen(Qt::black);
PixmapPainter.setPen(pen);
PixmapPainter.drawLine(m_nInitialX, m_nInitialY, m_nFinalX, m_nFinalY);
update(); // update your view
m_nFinalX = event->pos().x();
m_nFinalY = event->pos().y();
}
update(); // update your view
}
.
这段代码将绘制一个所需的世代odicetagcode。
其他提示
这是我如何直接在窗口小部件上绘制线条的示例。
声明:
private:
void drawLines(QPainter *p);
QPoint startPos;
QPoint endPos;
bool inDrawing;
QVector<QLine> lines;
.
在构造函数中设置初始值:
Widget::Widget(QWidget *parent)
: QWidget(parent)
{
startPos = QPoint();
endPos = QPoint();
inDrawing = false;
setMouseTracking(true);
}
.
启动或结束行图:
void Widget::mousePressEvent(QMouseEvent *event)
{
if (event->buttons() & Qt::LeftButton)
{
if (!inDrawing)
{
startPos = event->pos();
}
else
{
endPos = event->pos();
QLine line = QLine(startPos, event->pos());
lines.append(line);
}
inDrawing = !inDrawing;
}
}
void Widget::mouseMoveEvent(QMouseEvent *event)
{
if (inDrawing)
{
endPos = event->pos();
update();
}
}
.
绘制电流和保存的线条:
void Widget::drawLines(QPainter *p)
{
if (!startPos.isNull() && !endPos.isNull())
{
p->drawLine(startPos, endPos);
}
p->drawLines(lines);
}
.
绘图:
void Widget::paintEvent(QPaintEvent *event)
{
QPainter p(this);
QPen pen;
pen.setColor(Qt::red);
pen.setWidth(4);
p.setPen(pen);
drawLines(&p);
}
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