如果我提供了不必要的详细信息,我深表歉意。我有一个Canvas
看起来像这样的类:
class Canvas : public QWidget
{
Q_OBJECT
public:
explicit Canvas(int width = 700, int height = 700, QWidget *parent = 0);
void setDelegate(CanvasDelegate *delegate);
private:
CanvasDelegate *delegate;
void paintEvent(QPaintEvent *event);
void resizeEvent(QResizeEvent *resizeEvent);
[...]
};
该Canvas::paintEvent(QPaintEvent *)
功能是这样实现的:
void Canvas::paintEvent(QPaintEvent *)
{
delegate->redrawBuffer();
QPainter canvas_painter(this);
canvas_painter.drawImage(0, 0, *(delegate->getImage()));
}
所以这个类CanvasDelegate
看起来像这样:
class CanvasDelegate
{
friend class Canvas;
public:
CanvasDelegate(const Canvas *canvas);
~CanvasDelegate();
const QImage * getImage() const;
void drawPoint(const Complex &z, const QColor &color = "black", int width = 3);
[...]
virtual void redrawBuffer(const H2Isometry &mobius = H2Isometry::identity()) = 0;
virtual void mousePress(QMouseEvent * mouseEvent) = 0;
[...]
protected:
const Canvas *canvas;
int sizeX, sizeY;
[...]
QPen *pen;
QImage *image;
QPainter *painter;
void rescale(int sizeX, int sizeY);
};
CanvasDelegate 的构造函数如下:
CanvasDelegate::CanvasDelegate(const Canvas *canvas) : canvas(canvas)
{
pen = new QPen;
image = new QImage(canvas->width(), canvas->height(), QImage::Format_RGB32);
painter = new QPainter(image);
[...]
}
我不确定这是有史以来最好的设计,但这不是我的问题(尽管欢迎任何评论)。Canvas
我的问题是调整窗口 ( ) 大小时会发生什么。这是我的代码的样子:
void Canvas::resizeEvent(QResizeEvent *resizeEvent)
{
QSize newSize = resizeEvent->size();
delegate->rescale(newSize.width(), newSize.height());
//update();
}
void CanvasDelegate::rescale(int sizeX, int sizeY)
{
*image = QImage(sizeX, sizeY, QImage::Format_RGB32);
painter->eraseRect(0, 0, sizeX, sizeY);
this->sizeX = sizeX;
this->sizeY = sizeY;
[...]
}
问题是当我运行程序时,它崩溃了。显然在painter->eraseRect(0, 0, sizeX, sizeY);
调用时存在分段错误void CanvasDelegate::rescale(int sizeX, int sizeY)
。我不明白为什么,我不明白问题是什么。
在以前的版本中,我编写了以下内容(现在在我看来,这比必要的更复杂):
void CanvasDelegate::rescale(int sizeX, int sizeY)
{
QImage * oldImage = image;
QImage * newImage = new QImage(sizeX, sizeY, QImage::Format_RGB32);
QPainter * oldPainter = painter;
QPainter * newPainter = new QPainter(newImage);
newPainter->eraseRect(0, 0, sizeX, sizeY);
newPainter->setPen(*pen);
image = newImage;
painter = newPainter;
delete oldImage;
delete oldPainter;
this->sizeX = sizeX;
this->sizeY = sizeY;
[...]
}
但这不起作用:我收到 Qt 错误QPaintDevice: Cannot destroy paint device that is beingpainting。如果我删除delete oldImage;
and delete oldPainter;
,一切正常,但这是一个令人作呕的内存泄漏,不是吗。
有人明白为什么我写的东西不起作用,我需要做什么吗?
非常感谢您的关注。