table in QLabel

[Pan Wojtas]

QLabel *label = new QLabel(0);
label->setFrameStyle(QFrame::Plain);
label->setBackgroundMode(Qt::FixedColor);
label->setPaletteBackgroundColor(QColor("red"));
label->setText("<table bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");
label->show();

QLabel *label = new QLabel(0);
label->setFrameStyle(QFrame::Plain);
label->setBackgroundMode(Qt::FixedColor);
label->setPaletteBackgroundColor(QColor("red"));
label->setText("<table bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");
label->show();

To copy to clipboard, switch view to plain text mode 

and effect:


What can I do to avoid this red border above, under and on the right of the table?
I'd like to have a QLabel that consist ONLY the table - and nothing else (no margins).

(I've made red and white colors only to show you this margins)

[jacek]

Did you try:

label->setScaledContents( true );

label->setScaledContents( true );

To copy to clipboard, switch view to plain text mode 

and/or

label->setAlignment( Qt::AlignCenter );

label->setAlignment( Qt::AlignCenter );

To copy to clipboard, switch view to plain text mode 

[Pan Wojtas]

setScaledContents doesn't change anything;
setAlignment only moves this table to the center of QLabel (makes another margin on the left side).

[jacek]

Then try:

label->setText("<table width=\"100%\" bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");

label->setText("<table width=\"100%\" bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");

To copy to clipboard, switch view to plain text mode 

[Pan Wojtas]

It looks like this:


So it removes left and right margins, but QLabel is a way too wide.
For me more serious issue are margins above and below table. "height=100%" doesn't work.

[jacek]

For me more serious issue are margins above and below table. "height=100%" doesn't work.

Then make the QLabel smaller --- there isn't enough content to fill it.

[Pan Wojtas]

Then make the QLabel smaller --- there isn't enough content to fill it.

I don't understand...
I've made larger QLabel:

but there is still the same margin

I've noticed, that it is always 16px at the bottom and 2px at the top...

[wysota]

Maybe you should just find some other way to place your table?

[piotrpsz]

Can you try:

label->layout()->setSpacing( ... ),
label->layout()->setMargin( ... ),

[Pan Wojtas]

label->layout()->setSpacing( ... ),
label->layout()->setMargin( ... ),

But it makes "segmentation fault"...

[wysota]

QLabel is not a container, thus it doesn't have a layout (unless you provide one, but I don't know what will happen then... QLabel is not supposed to have a layout).

[Everall]

What can I do to avoid this red border above, below

i did some testing on QT4. I know you're on QT3, but i wanted to see the behaviour here also.

QT4 doesn't provide the left and right margins, but you get top and bottom margins. So this is better than QT3.

But the margins on top and bottom arestill there.
I noticed I could drag the dialogbox to a minimum size = sizehint of the textlabel. I couldn't drag it smaller. (because of QT's wonderfull sizehint functionality)

So here is my dirty trick :
label->resize(1,1);//resize it to 1 by 1 pixel, which QT won't allow.

and in QT4 the dialogbox is the size you want without the margins.

I hope it will work for QT3 also.

Cheers

[Pan Wojtas]

So here is my dirty trick :
label->resize(1,1);//resize it to 1 by 1 pixel, which QT won't allow.

It resize this QLabel ALWAYS to minimal size, so the table is without margins, but Qt doesn't show the whole table...

QLabel *label = new QLabel(0);
label->resize(1,1);
label->setFrameStyle(QFrame::Plain);
label->setBackgroundMode(Qt::FixedColor);
label->setPaletteBackgroundColor(QColor("red"));
label->setText("<table width=\"100%\" bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");
label->show();

QLabel *label = new QLabel(0);
label->resize(1,1);
label->setFrameStyle(QFrame::Plain);
label->setBackgroundMode(Qt::FixedColor);
label->setPaletteBackgroundColor(QColor("red"));
label->setText("<table width=\"100%\" bgcolor=white border=0 cellspacing=0 cellpadding=0><tr><td>aaa<br>ccc<br>ddd</td><td>bbb</td></tr></table>");
label->show();

To copy to clipboard, switch view to plain text mode 

gives:

How does it look on Qt4?

I've seen in some sources this trick with resize(1,1), but I don't remember exacly where it was... I'll look for it.

[Everall]

How does it look on Qt4?

it looks like :

Cheers

[piotrpsz]

QLabel is not a container, thus it doesn't have a layout (unless you provide one, but I don't know what will happen then... QLabel is not supposed to have a layout).

QLabel is a QWidget.
Every QWidget have a layout (QWidget have a function member QLayout* layout()).
Maybe is not used, but have layout.

Piotr

[piotrpsz]

But it makes "segmentation fault"...

That's right.
For label function layout() returns 0 (NULL).

But try this code:

QLabel* lbl = new QLabel( "cos_niecos", this );
QHBoxLayout* lbl_layout = new QHBoxLayout( lbl );
QLayout* lay = lbl->layout();
 
if( 0 == lay ) qWarning( "lay is 0" );
else qWarning( "OK" );
 
lbl->layout()->setMargin( 0 );
lbl->layout()->setSpacing( 0 );

QLabel* lbl = new QLabel( "cos_niecos", this );
QHBoxLayout* lbl_layout = new QHBoxLayout( lbl );
QLayout* lay = lbl->layout();
	
if( 0 == lay ) qWarning( "lay is 0" );
else qWarning( "OK" );

lbl->layout()->setMargin( 0 );
lbl->layout()->setSpacing( 0 );

To copy to clipboard, switch view to plain text mode 

This code functioning.
Piotr

[wysota]

QLabel is a QWidget.
Every QWidget have a layout (QWidget have a function member QLayout* layout()).
Maybe is not used, but have layout.

Eeem.... no.

#include <qwidget.h>
#include <qlayout.h>
#include <qapplication.h>
 
int main(int argc, char **argv){
  QApplication app(argc, argv);
  QWidget *w = new QWidget();
  w->layout()->setMargin(5);
  delete w;
  return 0;
}

#include <qwidget.h>
#include <qlayout.h>
#include <qapplication.h>

int main(int argc, char **argv){
  QApplication app(argc, argv);
  QWidget *w = new QWidget();
  w->layout()->setMargin(5);
  delete w;
  return 0;
}

To copy to clipboard, switch view to plain text mode 

On my system it crashes on "w->layout()->setMargin()" call, meaning there is no layout in the widget. A class may have methods to get or set a layout, but it doesn't mean it uses them. If you take a look at QWidget sources, you'll notice, that it only references "layout" while dealing with "height for width".

[piotrpsz]

Eeem.... no.

#include <qwidget.h>
#include <qlayout.h>
#include <qapplication.h>
 
int main(int argc, char **argv){
  QApplication app(argc, argv);
  QWidget *w = new QWidget();
  w->layout()->setMargin(5);
  delete w;
  return 0;
}

#include <qwidget.h>
#include <qlayout.h>
#include <qapplication.h>

int main(int argc, char **argv){
  QApplication app(argc, argv);
  QWidget *w = new QWidget();
  w->layout()->setMargin(5);
  delete w;
  return 0;
}

To copy to clipboard, switch view to plain text mode 

On my system it crashes on "w->layout()->setMargin()" call, meaning there is no layout in the widget. A class may have methods to get or set a layout, but it doesn't mean it uses them. If you take a look at QWidget sources, you'll notice, that it only references "layout" while dealing with "height for width".

OK
Sorry, I should tell, that every widget CAN have a layout.
Look a previous my post.

Best regards
Piotr

[wysota]

So set a layout for QWidget and try to do anything meaningfull with it...

[Pan Wojtas]

I've noticed, that this extra margin on the bottom is always equal
to "fontMetrics().height()", so it seems that Qt adds one empty line below
each table...