How to invoke QBrush.setTexture() with QPixmap on QGraphicsRectItem?
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- One more questions, How can I update the png after the item status changed?
You make the class know which image to draw via variable
**NEW** const int StartImage=1; ( or use enum) const int StopImage=2; class MyItem :public QGraphicsRectItem ( OR QGraphicsItem ) { int Status=StartImage; // some flag to tell if start or stop **NEW** public: void SetStatus(int newStatus) { Status=newStatus; update(); /* this makes it redraw ( i hope) */ } **NEW** ... // overriding paint() void paint(QPainter * painter, const QStyleOptionGraphicsItem * option, QWidget * widget) { // draw pixmap QPixmap pixStart(":/images/h_startdown.png"); // could be loaded in constructor so we dont do each draw QPixmap pixStop(":/images/h_shutdown.png"); // draw one or the other if (Status == StartImage ) painter->drawPixmap(pixStart); else painter->drawPixmap(pixStop); // draw normally QGraphicsRectItem::paint(painter, option, widget); ( or QGraphicsItem::paint) } };Then from outside, you can do
myitem->SetStatus(StartImage);
or
myitem->SetStatus(StopImage);I try to update the png for the item when some status changed.
But every time I need to trigger the ui to repaint, it seems that it never repaint the ui unless there are some change in the UI, such as move cursor or focus on the UI.
Is there any way to update the UI automatically?
BRs
Kevin -
Calling update() on the item should do the trick.
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I try to update the png for the item when some status changed.
But every time I need to trigger the ui to repaint, it seems that it never repaint the ui unless there are some change in the UI, such as move cursor or focus on the UI.
Is there any way to update the UI automatically?
BRs
Kevin@Kevin-Zhong
Hi
Did you call the
void SetStatus(int newStatus) {
Status=newStatus;
update(); /* this makes it redraw ( i hope) */ << this should make it draw the other bitmap?
} -
@Kevin-Zhong
Hi
Did you call the
void SetStatus(int newStatus) {
Status=newStatus;
update(); /* this makes it redraw ( i hope) */ << this should make it draw the other bitmap?
} -
The behavior is the same as I mentioned before whatever I use update or repaint. Actually, I prefer to use repaint because I need to refresh the item secondly.
BRs
Kevin@Kevin-Zhong
Ok, im not sure why.
maybe update() dont trigger painter.
Would need to debug to know.
Normally it just works. -
@Kevin-Zhong
Ok, im not sure why.
maybe update() dont trigger painter.
Would need to debug to know.
Normally it just works.I try to overload the paintEvent in my own code.
But after I call item.repaint() the paintEvent was not invoked.But this is the interface description for Qt 5.6.
[slot] void QWidget::repaint()
Repaints the widget directly by calling paintEvent() immediately, unless updates are disabled or the widget is hidden.
We suggest only using repaint() if you need an immediate repaint, for example during animation. In almost all circumstances update() is better, as it permits Qt to optimize for speed and minimize flicker.
Warning: If you call repaint() in a function which may itself be called from paintEvent(), you may get infinite recursion. The update() function never causes recursion.
See also update(), paintEvent(), and setUpdatesEnabled(). -
Hi
are we still talking about the QGraphicsItem ?
As far as I know they do not have paintEvent only
void paint(QPainter * painter,xx)So item.update() should trigger it ?
Maybe show full code of what you are doing ?
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Hi
are we still talking about the QGraphicsItem ?
As far as I know they do not have paintEvent only
void paint(QPainter * painter,xx)So item.update() should trigger it ?
Maybe show full code of what you are doing ?
My code is a little bit complex.
Let's recap my original purpose.
At the beginning, I just want to use a png as background at the GraphicsRectItem.
I tried to use code below:QImage mage = (QImage(":/images/h_" + filename + ".png")); brush.setTextureImage(image.scaled(70,30,Qt::KeepAspectRatio, Qt::FastTransformation));The result is not what I want.
So, I try to follow your guys' suggestion.map = QPixmap(":/images/h_" + statusStr + ".png"); painter->drawPixmap((int)x, (int)y, 40, 50, map);It's really works, the png can be shown correctly, not collage.
But the png cannot be redraw immediately only I move the cursor or focus the window.
So, is it possible to show the png in the GraphicsRectItem? Because I need to show lots of triangle, rectangle and cricle on the QGraphsicsView with hoverEvent and click Event.BRs
Kevin -
- But the png cannot be redraw immediately only I move the cursor or focus the window.
That is the part i dont understand.
It should trigger paint()!?!- So, is it possible to show the png in the GraphicsRectItem?
Yes , same as with QGraphicsItem , but i be surprised if that alters anything.
When calling update() it should draw the png. Else there is a bug in the code. or something im not aware of.
You should looking to this. Using break points. etc.item->update() should trigger paint() , else i have no idea what is going on.
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Do not confuse paintEvent with paint.
paintEvent is for Widgets
paint is for GraphicsItems -
Hi all,
Finally, I solved this problems.
@mrjj, as you mentioned that useitem->update()WORKs.
My code is a little bit complex, all the item were originated from a template:
template <typename T, typename Event> class DeviceEventHandler : public Event, public QObjectAt the beginning, I try to update the from the template, it doesn't work.
Then I move theupdate()method in the all the subclass, then the pixmap can be updated automatically.
So, really thanks for your patience and kindly support.
Have a nice weekend.
PS: Be honest, I am newbie in Qt area and I got so kindly support. I really appreciate your kindness. :)
BRs
Kevin -
Hi all,
Finally, I solved this problems.
@mrjj, as you mentioned that useitem->update()WORKs.
My code is a little bit complex, all the item were originated from a template:
template <typename T, typename Event> class DeviceEventHandler : public Event, public QObjectAt the beginning, I try to update the from the template, it doesn't work.
Then I move theupdate()method in the all the subclass, then the pixmap can be updated automatically.
So, really thanks for your patience and kindly support.
Have a nice weekend.
PS: Be honest, I am newbie in Qt area and I got so kindly support. I really appreciate your kindness. :)
BRs
KevinHi
You are most welcome. we do like Qt newbies here :)It was a bit odd with update() but good you found the solution.
Still not sure why it didn't trigger inside SetStatus :)
Good weekend to you too
