I'm facing a strange issue in my Qt application... I have a Widget inheriting QLabel with the following stylesheet:
QLabel { padding: 10px ; }
QLabel[current-player=true] { background: blue ; }
QLabel:disabled { background: #eee ; }
And a method:
void MyWidget::updateInformation () {
this->setEnabled (m_player->isEnable ());
if (m_player->isCurrentPlayer ()) {
qDebug () << "Setting current player to true: " << PlayerInfo::toString (m_player->player ()) ;
this->setProperty ("current-player", true);
}
// this->setProperty ("current-player", true);
qDebug () << "Property current player: " << this->property ("current-player") ;
}
As you can see, I want to set the background of my widget to blue when the current-player property is true, so I have the conditions m_player->isCurrentPlayer().
I have a line commented, which was used to test if the property worked, and it did. When I uncomment the line, the background becomes blue.
What is strange is that my debug output is (when the line is commented):
Setting current player to true: "Player1"
Property current player: QVariant(bool, true)
Setting current player to true: "Player1"
Property current player: QVariant(bool, true)
As you can see, the execution goes inside the if statement because I see the Setting current player... output, and the current-player property is true, but the background stay white...
I don't understand my the code works when I set the property all the time and doesn't work if I set the property in a if statement which is taken.
If anyone as an idea, it'll help me a lot!
Thanks!
It's OK. Stylesheets are not recomputed when you change custom properties. Because of performance issues.
Solution: Call polish() and unpolish() to a widget with stylesheet.
P.S. I want to note, that usage of custom properties for such style customization is bad practice, because in case of complex styles it will cause UI lags.
Related
I am using TextEditor from the example provided with Qt (https://doc.qt.io/qt-5/qtquickcontrols1-texteditor-example.html). Here is the complete code https://code.qt.io/cgit/qt/qtquickcontrols.git/tree/examples/quickcontrols/controls/texteditor?h=5.15
I have created a custom method void DocumentHandler::setBackgroundColor(const QColor &color) to change the background color of the overall HTML document.
My problem is whenever I call a method to change the background color of QTextDocument using setDefaultStyleSheet, it is executed only once. ie, my document background changes only once. For the next calls, I can see the qDebug printing correctly, but the setDefaultStyleSheet doesn't work. However, everything works perfectly with normal text, only not with m_doc->toHtml().
How do I fix this?
If I change m_doc->setHtml("some random text"), it works as required
...
QColor DocumentHandler::backgroundColor() const
{
return m_backgroundColor;
}
void DocumentHandler::setBackgroundColor(const QColor &color)
{
m_backgroundColor = color.name(); // QColor variable
m_doc->setDefaultStyleSheet("body{background-color: '"+ color.name() +"'}"); // m_doc is QTextDocument *
m_doc->setHtml(m_doc->toHtml());
qDebug() << "BACKGROUND COLOR CHANGED" << color.name() ;
emit backgroundColorChanged();
}
In the QML, I have called it like this
...
DocumentHandlerModel {
id: document
target: textArea
cursorPosition: textArea.cursorPosition
selectionStart: textArea.selectionStart
selectionEnd: textArea.selectionEnd
backgroundColor: colorDialog2.color
onFontFamilyChanged: {
var index = Qt.fontFamilies().indexOf(document.fontFamily)
if (index === -1) {
fontFamilyComboBox.currentIndex = 0
fontFamilyComboBox.special = true
} else {
fontFamilyComboBox.currentIndex = index
fontFamilyComboBox.special = false
}
}
onError: {
errorDialog.text = message
errorDialog.visible = true
}
}
Cause
The documentation of QTextDocument::setDefaultStyleSheet says:
Note: Changing the default style sheet does not have any effect to the existing content of the document.
You try to overcome this by calling setHtml after setDefaultStyleSheet like that:
m_doc->setHtml(m_doc->toHtml());
However, this does not produce the desired result, because setDefaultStyleSheet actually embeds the background color in the HTML through the bgcolor CSS property.
To test this, add
m_doc->setHtml("<html><body><p>Test</p></body></html>");
qDebug() << m_doc->toHtml();
after
m_doc->setHtml(m_doc->toHtml());
The HTML content of m_doc from <html><body><p>Test</p></body></html>, when tested with #FF00FF, becames:
"<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.0//EN\" \"http://www.w3.org/TR/REC-html40/strict.dtd\">\n<html><head><meta name=\"qrichtext\" content=\"1\" /><style type=\"text/css\">\np, li { white-space: pre-wrap; }\n</style></head><body style=\" font-family:'MS Shell Dlg 2'; font-size:8.25pt; font-weight:400; font-style:normal;\" bgcolor=\"#ff00ff\">\n<p style=\" margin-top:12px; margin-bottom:12px; margin-left:0px; margin-right:0px; -qt-block-indent:0; text-indent:0px;\">Test</p></body></html>"
Note: Please, notice that assignment: bgcolor=\"#ff00ff\.
So, by writing m_doc->setHtml(m_doc->toHtml()); you effectively return the old color. That is why the color changes only the first time.
By the way, the widget now changes its color, but has lost its content.
Solution
It is hard to find an elegant solution, because in this case markup and styles are not kept separate, as in real HTML and CSS, but the style is embedded by Qt in the markup. The one thing which comes to my mind, is to parse the content of m_doc manually.
Note: Such a solution would be extremely fragile and I advise strongly against it. Maybe instead of using a stylesheet, change the background color by setting up the palette of the widget, which renders the content of the QTextDocument on the screen.
Note: In any case this does not seem like the intended behavior, at least it does not match the description in the documentation, so I would have reported it as a bug to Qt, if I were you.
Example
Here is an example I wrote for you in order to demonstrate the proposed solution:
void DocumentHandler::setBackgroundColor(const QColor &color)
{
const QString &bgcolor("bgcolor=\"");
QString html(m_doc->toHtml());
int n = html.indexOf(bgcolor, html.indexOf("<body"));
int k = n + bgcolor.length();
m_doc->setDefaultStyleSheet("body { background-color: '" + color.name() + "' }");
if (n >= 0)
html.replace(n + bgcolor.length(), html.mid(k, html.indexOf("\"", n + bgcolor.length()) - k).length(), color.name());
m_doc->setHtml(html);
m_backgroundColor = color.name(); // QColor variable
emit backgroundColorChanged();
}
I have some problems with QTabWidget. In case of the missing Hide functionality I have to build my own. According to the documentation I use removeTab and insertTab, but with insert Tab I have a problem to show the Tab page that is removed.
I use to add
RibbonTabContent *ribbonTabContent = new RibbonTabContent;
QTabWidget::addTab(ribbonTabContent, tabIcon, tabName);
To remove is use:
void Ribbon::hideTab(const QString &tabName)
{
// Find ribbon tab
for (int i = 0; i < count(); i++)
{
if (tabText(i).toLower() == tabName.toLower())
{
QTabWidget::removeTab(i);
break;
}
}
}
Both functions are working, pWidget is always null. But now the insert function do not work well. I think there I have a problem, but do not understand my problem.
void Ribbon::showTab(const QString &tabName){
// Find ribbon tab
QWidget* pWidget= QTabWidget::findChild<RibbonTabContent *>(tabName);
if(pWidget){
QTabWidget::insertTab(2,pWidget, tabName);
}
}
Maybe someone can help me out?
If you call QTabWidget::removeTab you remove the tab at the specified index from the children tree of your QTabWidget, the tab instance is not actually deleted though, so when you search for that same tab with QTabWidget::findChild you can't find it because it's not a child of your QTabWidget anymore. From the code you show I think you probably would not find it anyway since findChild searches for a widget with the specified objectName but you never set it for your tab.
A solution would be to store the removed tabs and then restore them when you please.
Assuming m_hiddenTabs is a QHash<QString, QWidget*> or QMap<QString, QWidget*> you could try something like this.
void Ribbon::hideTab(const QString &tabName)
{
// Find ribbon tab
for (int i = 0; i < count(); i++)
{
if (tabText(i).toLower() == tabName.toLower())
{
m_hiddenTabs.insert(tabName.toLower(), QTabWidget::widget(i));
QTabWidget::removeTab(i);
break;
}
}
}
void Ribbon::showTab(const QString &tabName){
// Find ribbon tab
auto tab = m_hiddenTabs.take(tabName.toLower());
if(tab){
QTabWidget::insertTab(2, tab, tabName);
}
}
Since Qt 5.15 it is also possible to use setTabVisible:
void QTabWidget::setTabVisible(int index, bool visible)
If visible is true, the page at position index is visible; otherwise the page at position index is hidden. The page's tab is redrawn appropriately.If visible is true, the page at position index is visible; otherwise the page at position index is hidden. The page's tab is redrawn appropriately.
It is unfortunate that QTabBar is unable to 'hide' a tab.
Here is my very easy work-around: mark the tabs 'disabled' instead (e.g. ui->tabWidget->setTabEnabled(tabIndex, false);).
Then, use stylesheets to style the "disabled" tab as entirely invisible and taking up no space:
QTabBar::tab:disabled
{
min-width: 0px;
max-width: 0px;
color: rgba(0,0,0,0);
background-color: rgba(0,0,0,0);
}
This works near-perfectly for me, with the only downside being that you can't have both disabled and "hidden" tabs in the same tabbar. However, usually I want one or the other, not both in the same bar.
I need to create a button which has three states:
unclicked
intermediate
clicked
The logic I want to implement with this button is that whenever this button is clicked, I want the system to go to the intermediate state and wait for an event.
In other way when the state transition is unclicked --> intermediate -- > clicked and then clicked --> intermediate -->unclicked.
Does Qt support implementing this kind of button? If so, how?
The nearest you have is QCheckBox. It already has a property for it: QCheckBox::setTristate:
auto yourCheckBoxButton = new QCheckBox("Tristate button");
yourCheckBoxButton->setTristate(true);
You can do it on the Designer too (it is at the end of the properties list).
If you don't want to use a QCheckBox, a stylesheet and a custom property that is modified each time the button is pressed can do it:
auto pushButton = new QPushButton("Tristate button");
pushButton->setProperty("state", 0);
pushButton->setProperty("state-step", 1); // change to next state, 1 or -1
pushButton->setStyleSheet("QPushButton[state=\"0\"] { background: red; }"
"QPushButton[state=\"1\"] { background: grey; }"
"QPushButton[state=\"2\"] { background: blue; }");
connect(pushButton, &QPushButton::clicked, [ = ](bool) {
const int state = pushButton->property("state").toInt();
const int step = state == 0 ? 1 :
state == 2 ? -1 : pushButton->property("state-step").toInt();
pushButton->setProperty("state", state + step);
pushButton->setProperty("state-step", step); // update in case it changed
// Changing the property is not enough to choose a new style from the stylesheet,
// it is necessary to force a re-evaluation
pushButton->style()->unpolish(pushButton);
pushButton->style()->polish(pushButton);
});
Other more elaborated options would be to use a QProxyStyle or to re-implement the QPushButton class itself.
What I'm trying to do
I am trying to create a subclass of QWizardPage that looks somewhat like this,but has a slight tweak. I want to disable the next button when a counter variable is more than 0. (It can't be 0 from the get-go due to some functionality that requires it to go x..x-1...0).
What I've tried
Reimplement isComplete() and emit completeChanged() in the constructor
bool DemoWizardPage::isComplete()
{
return ! (counter > 0); //Also tried just return false;
}
Reimplement initializePage and disable the next button from there
void DemoWizardPage::initializePage()
{
qDebug() << "QWizardPage:: initialize page";
if (!this->isComplete())
{
qDebug() << "try to turn off next button";
wizard()->button(QWizard::NextButton)->setDisabled(true);
qDebug() << "next button enabled? "
<< wizard()->button(QWizard::NextButton)->isEnabled();
}
}
Results so far
From stepping through the code I can see that the next button is disabled when the page loads. But then it is enabled again due to these 2 lines in QWizardPrivate (taken from qwizard.cpp)
bool complete = page && page->isComplete();
btn.next->setEnabled(canContinue && complete);
I am quite baffled as to why isComplete() is returning true here. I mean, I set my counter to be 2 at the beginning and I never decrease it. (And yes, I do emit a completeChanged() whenever I set the counter).
Any ideas?
QWizard automatically manages the state of Next button based on the QWizardPage::isComplete(), you should not implement that functionality yourself in initializePage(). The reason your isComplete() is not being called is that it doesn't actually overwrite QWizardPage::isComplete const from QWizardPage. Declare your function const and it will properly overwrite the original function.
I'd like to know more about how this system works, specifically when and how the framework actually decides to update a UI element.
My application has a 'tools' system where a single tool can be active at a time. I used the "ON_UPDATE_COMMAND_UI" message to 'check' the tool's icon/button in the UI, which affected both the application menu and the toolbars. Anyway, this was all working great until some point in the last couple of days, when the toolbar icons stopped getting highlighted properly.
I investigated a little and found that the update command was only being received when the icon was actually clicked. What's strange is this is only affecting the toolbars, not the menu, which is still working fine. Even when the buttons in the menu are updated the toolbar icon stays the same.
Obviously I've done something to break it - any ideas?
EDIT:
Never mind. I'd overwritten the Application's OnIdle() method and hadn't called the original base class method - that is, CWinApp::OnIdle() - which I guess is where the update gets called most of the time. This code snippet from https://msdn.microsoft.com/en-us/library/3e077sxt.aspx illustrates:
BOOL CMyApp::OnIdle(LONG lCount)
{
// CWinApp's original method is involved in the update message handling!
// Removing this call will break things
BOOL bMore = CWinApp::OnIdle(lCount);
if (lCount == 0)
{
TRACE(_T("App idle for short period of time\n"));
bMore = TRUE;
}
// ... do work
return bMore;
// return TRUE as long as there are any more idle tasks
}
Here's a good article that kinda explains how to do it. Don't use his code example with WM_KICKIDLE though, instead scroll down to the comments section. There are two code samples that explain how to do it better. I quote:
//Override WM_INITMENUPOPUP
void CDialog::OnInitMenuPopup(CMenu* pPopupMenu, UINT nIndex, BOOL bSysMenu)
{
CDialog::OnInitMenuPopup(pPopupMenu, nIndex, bSysMenu);
// TODO: Add your message handler code here
if(pPopupMenu &&
!bSysMenu)
{
CCmdUI CmdUI;
CmdUI.m_nIndexMax = pPopupMenu->GetMenuItemCount();
for(UINT i = 0; i < CmdUI.m_nIndexMax; i++)
{
CmdUI.m_nIndex = i;
CmdUI.m_nID = pPopupMenu->GetMenuItemID(i);
CmdUI.m_pMenu = pPopupMenu;
// There are two options:
// Option 1. All handlers are in dialog
CmdUI.DoUpdate(this, FALSE);
// Option 2. There are handlers in dialog and controls
/*
CmdUI.DoUpdate( this, FALSE );
// If dialog handler doesn't change state route update
// request to child controls. The last DoUpdate will
// disable menu item with no handler
if( FALSE == CmdUI.m_bEnableChanged )
CmdUI.DoUpdate( m_pControl_1, FALSE );
...
if( FALSE == CmdUI.m_bEnableChanged )
CmdUI.DoUpdate( m_pControl_Last, TRUE );
*/
}
}
}
See if this helps - http://msdn.microsoft.com/en-us/library/essk9ab2(v=vs.80).aspx