QGroupBox's child restricts shrink the form - c++

Question

I have a multiple screen video player, and I just want to keep 16:9 ratio. There is a qgroupbox as a container of a qwidget which plays video in it. I also use qgroupbox to show selected frame by painting border to green. I can't do this on qwidget because rendered video overlaps that. When I have done with resize, I emit a signal with mouseup event to be able to informed about the resize operation completed. Then I calculate new bounds for qwidget to keep 16:9 ratio and apply this values for qwidget. Here is the image to show you how my app looks like:
And here is the code that I use to resize qwidgets:
void playBack::OnWindowResized()
{
float ratio = 16.0f / 9.0f;
float w = playBackplayer_contList.at(0)->size().width(); //qgroupbox's width
float h = playBackplayer_contList.at(0)->size().height();//qgroupbox's height
float currentRatio = w / h;
float newW = 0;
float newH = 0;
if (currentRatio > ratio)
{
newH = h;
newW = h*ratio;
}
else if (currentRatio < ratio)
{
newW = w;
newH = w / ratio;
}
qDebug() << "NEW WIDGET SIZE: " << (int)newW << " x " << (int)newH;
for (int i = 0; i < playBackplayer_widgtList.count(); i++)
{
playBackplayer_widgtList.at(i)->setMinimumSize(newW, newH);
//playBackplayer_widgtList.at(i)->resize(newW, newH);
}
}
This code works perfectly when I enlarge form, but When I want to shrink, It doesn't allow me to do that. Because I set a minimum value for qwidgets. If I don't use setMinimumSize, use resize(w,h) instead, than orientation problems occur. And here is a example for this issue:
This code below shows ctor and this is where I set the layout:
playBack::playBack()
{
playback_player_1_widget = new QWidget;
playback_player_2_widget = new QWidget;
playback_player_3_widget = new QWidget;
playback_player_4_widget = new QWidget;
playback_player_1_widget_cont = new QGroupBox;
playback_player_2_widget_cont = new QGroupBox;
playback_player_3_widget_cont = new QGroupBox;
playback_player_4_widget_cont = new QGroupBox;
playBackplayer_widgtList.append(playback_player_1_widget);
playBackplayer_widgtList.append(playback_player_2_widget);
playBackplayer_widgtList.append(playback_player_3_widget);
playBackplayer_widgtList.append(playback_player_4_widget);
playBackplayer_contList.append(playback_player_1_widget_cont);
playBackplayer_contList.append(playback_player_2_widget_cont);
playBackplayer_contList.append(playback_player_3_widget_cont);
playBackplayer_contList.append(playback_player_4_widget_cont);
int rowcnt = 0;
int colcnt = 0;
for (int i = 0; i < 4; i++)
{
playBackplayer_contList.at(i)->setStyleSheet(QString("border:1px solid #000;background-color:#000;"));
playBackplayer_widgtList.at(i)->setStyleSheet(QString("background-color:#f00;"));
QGridLayout* layout = new QGridLayout;
layout->setRowStretch(0, 1);
layout->setColumnStretch(0, 1);
layout->setRowStretch(2, 1);
layout->setColumnStretch(2, 1);
playBackplayer_widgtList.at(i)->setMinimumWidth(100);
playBackplayer_widgtList.at(i)->setMinimumHeight(100);
playBackplayer_widgtList.at(i)->setMaximumWidth(10000);
playBackplayer_widgtList.at(i)->setMaximumHeight(10000);
layout->addWidget(playBackplayer_widgtList.at(i),1,1);
layout->setMargin(0);
layout->setSpacing(0);
playBackplayer_contList.at(i)->setLayout(layout);
mainLayout->addWidget(playBackplayer_contList.at(i), colcnt, rowcnt);
rowcnt++;
if (rowcnt % 2 == 0)
{
rowcnt = 0;
colcnt++;
}
playBackplayer_widgtList.at(i)->setAcceptDrops(true);
}
}
I have tried various things, I have tried to set size 0 for qwidget before resize, (in mousedownevent) that didn't work, I have tried deleting layout for qgroupbox, after resize happens, create new layout and set it for groupbox, that didn't work, I have tried layout()->adjustSize(), update(), repaint(), all that stuff didn't work. What am I missing? I need helps from you. Any help would be appreciated. Thank you in advance.

Answer 1

Do away with the grid layout inside the container group boxes. Instead, align and resize the video widget with setGeometry
Here is a simple subclass of QGroupBox I made that keeps your desired ratio and always stays in the center:
class RatioGroupBox : public QGroupBox{
Q_OBJECT
public:
RatioGroupBox(QWidget *parent = nullptr) : QGroupBox (parent){
setFlat(true);
setStyleSheet("border:1px solid #000;background-color:#000;");
setMinimumSize(100, 100);
setMaximumSize(10000, 10000);
ratio = 16.0f/9.0f;
ratioWidget = new QWidget(this);
ratioWidget->setStyleSheet("background: #f00;");
ratioWidget->setAcceptDrops(true);
}
protected:
void resizeEvent(QResizeEvent *){//or you can use your own resize slot
float w = width();
float h = height();
float currentRatio = w/h;
float newW(0);
float newH(0);
if (currentRatio > ratio){
newH = h;
newW = h*ratio;
}
else if (currentRatio < ratio){
newW = w;
newH = w / ratio;
}
ratioWidget->setGeometry((w-newW)/2, (h-newH)/2, newW, newH);
}
private:
QWidget *ratioWidget;
float ratio;
};
Your entire ctor will become something like:
playBack::playBack()
{
for(int r=0; r<2; r++){
for(int c=0; c<2; c++){
RatioGroupBox* playback_player_cont = new RatioGroupBox;
mainLayout->addWidget(playback_player_cont, c, r);
playBackplayer_contList.append(playback_player_cont);
}
}
}
You can of course access your video widgets by exposing ratioWidget any way you like. Either by making it public or creating a getter function.