I have added 2 QScrollArea-> QLabel in QSplitter. And am displaying video on both of them. And by default, both of them have same size..
So, when I increase the size of one QLabel by adjusting QSplitter handle, the video takes new allocated space and scales accordingly. However, if I then decrease the size of QLabel, the video would still show up at previous bigger scale and scrollbars would appear.
I instead want to display video without scrollbars and with whatever scale factor that fits current size.
How can this be achieved?
Here is screenshot of my dialog.ui:
And this is my code for displaying image on QLabel
multiews[0] = ui->QImageLabel_view0;
multiews[1] = ui->QImageLabel_view1;
multiews[image_view]->setPixmap(QPixmap::fromImage(qImg).scaled(multiews[image_view]->width(),multiews[image_view]->height(),Qt::KeepAspectRatio));
Update:
I tried to manage desired behaviour by managing
void Dialog::on_splitter_2_splitterMoved(int pos, int index)
{
if(m_videos[0].video_playing){
int w= ui->scrollArea_2->width();
int h=ui->scrollArea_2->height();
ui->QImageLabel_view0->setFixedSize(w-20,h-20);
}
if(m_videos[1].video_playing){
int w= ui->scrollArea_1->width();
int h=ui->scrollArea_1->height();
ui->QImageLabel_view1->setFixedSize(w-20,h-20);
}
}
And am setting back policy to expanding when am using zoom out/zoom in.
void Dialog::PausePlayingVideo()
{ ...
m_scrollarea[active_view]->setWidgetResizable(true);
multiews[active_view]->setMaximumSize(10000,10000);
m_scrollarea[active_view]->setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOn);
multiews[active_view]->adjustSize();
multiews[active_view]->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);
}
However, the qLabel size is not expanding with this code. Does anybody know, what am doing wrong?
Related
I have the following hierarchy for layout:
wxMDIChildFrame -> wxNotebook ->
wxScrolledWindow -> wxBoxSizer -> wxStyledTextCtrl
GOAL: The wxStyledTextCtrl (CScriptWnd) resizes itself when user adds or deletes a line or presses Shift+Enter to add another CScriptWnd to the wxScrolledWindow.
The following code is when a line is added:
void CScriptWnd::OnNewLineAdded(wxStyledTextEvent& event)
{
long col, line;
PositionToXY(GetInsertionPoint(), &col, &line);
auto ClientSize = GetClientSize();
int Height = ClientSize.GetHeight();
Height += TextHeight(line);
SetClientSize(ClientSize.GetWidth(), Height);
SetMinSize(wxSize(ClientSize.GetWidth(), Height));
Refresh();
//m_ParentWindow->FitInside(); //CScriptWnd gets smaller rather than larger
//m_ParentWindow->Layout(); //CScriptWnd gets smaller rather than larger
//m_ParentWindow->GetGrandParent()->Layout(); //No effect
event.Skip();
}
Most work well such as the CScriptWnd resizes itself, the new script window added to wxScrolledWindow etc...
The problem is that the update to user interface only properly happens when the wxMDIChildFrame is resized using the mouse.
For example, if there are two CScriptWnd and the top one resizes itself, it overlaps with the bottom one
until the wxMDIChildFrame is resized using the mouse. Similar happens for the visibility of scrollbars such that when CScriptWnd client size gets larger the scrollbars only become visible when top-level window resized using the mouse.
Not sure what I am missing.
You probably need
SetMinSize(GetSize());
GetParent()->Layout();
I'm developing a Qt Application and I'm trying to find a way to use QTextEdit as a label with long text without the scroll bar. In my ui I have a QScrollArea and inside of it I want to place a couple off QTextEdit widgets and I only want use scrolling inside QScrollArea. Problem is that no matter how I try to resize the QTextEdit it seems it has a maximum height and cuts of text, even if I set the size manually and QTextEdit::size returns the correct value.
I did the same thing with QLabel and it works fine, but in this case I need some methods that are only provided in QTextEdit.
I found this post:
Resizing QT's QTextEdit to Match Text Height: maximumViewportSize()
And the answer given was the following:
I have solved this issue. There were 2 things that I had to do to get
it to work:
Walk up the widget hierarchy and make sure all the size policies made
sense to ensure that if any child widget wanted to be big/small, then
the parent widget would want to be the same thing.
This is the main
source of the fix. It turns out that since the QTextEdit is inside a
QFrame that is the main widget in a QScrollArea, the QScrollArea has a
constraint that it will not resize the internal widget unless the
"widgetResizable" property is true. The documentation for that is
here: http://doc.qt.io/qt-4.8/qscrollarea.html#widgetResizable-prop.
The documentation was not clear to me until I played around with this
setting and got it to work. From the docs, it seems that this property
only deals with times where the main scroll area wants to resize a
widget (i.e. from parent to child). It actually means that if the main
widget in the scroll area wants to ever resize (i.e. child to parent),
then this setting has to be set to true. So, the moral of the story is
that the QTextEdit code was correct in overriding sizeHint, but the
QScrollArea was ignoring the value returned from the main frame's
sizeHint.
The problem is that I have no idea how to access the QTextEdit's QScrollArea to enable widgetResizable. Can anyone explain how I can achieve this or suggest a different way of resizing QTextEdit to perfectly fit it's content?
This will allow the height of the text box to change as required. You can edit the code a little to handle the width as well.
connect( m_textField, SIGNAL( textChanged() ), this, SLOT( onTextChanged() ) );
void MyClass::onTextChanged()
{
QSize size = m_textField->document()->size().toSize();
m_textField->setFixedHeight( size.height() + 3 );
}
Try this one :
QTextEdit textEdit;
textEdit.setHtml("<p>test test test test test test</p><p>|||||||||</p>");
textEdit.show();
textEdit.setFixedWidth(textEdit.document()->idealWidth() +
textEdit.contentsMargins().left() +
textEdit.contentsMargins().right());
Without a concrete example it's difficult to judge, but... it sounds as if you simply want a QTextEdit whose sizeHint depends on the current document size.
class text_edit: public QTextEdit {
using super = QTextEdit;
public:
explicit text_edit (QWidget *parent = nullptr)
: super(parent)
{
setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Minimum);
setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
}
virtual QSize sizeHint () const override
{
QSize s(document()->size().toSize());
/*
* Make sure width and height have `usable' values.
*/
s.rwidth() = std::max(100, s.width());
s.rheight() = std::max(100, s.height());
return(s);
}
protected:
virtual void resizeEvent (QResizeEvent *event) override
{
/*
* If the widget has been resized then the size hint will
* also have changed. Call updateGeometry to make sure
* any layouts are notified of the change.
*/
updateGeometry();
super::resizeEvent(event);
}
};
Then use as...
QScrollArea sa;
sa.setWidgetResizable(true);
text_edit te;
te.setPlainText(...);
sa.setWidget(&te);
sa.show();
It appears to work as expected in the few tests I've done.
In ui i defined QTextEdit *textEdit object. I write it as height scalable-content :
int count = 0;
QString str = "";
// set textEdit text
ui->textEdit->setText("hfdsf\ncsad\nfsc\dajkjkjkjhhkdkca\n925");
str = ui->textEdit->toPlainText();
for(int i = 0;i < str.length();i++)
if(str.at(i).cell() == '\n')
count++;
// resize textEdit (width and height)
ui->textEdit->resize(ui->textEdit->fontMetrics().width("this is the max-length line in qlabel")
, ui->textEdit->fontMetrics().height() * (count + 2));
Notice : this work if you change QTextEdit font face or size! just in height scalable (before every thing set your QTextEdit frameShape to BOX).
if you want do width scalable-content, you should do these steps :
read QTextEdit(textEdit object) text as line to line
calculate every line length
select maximum of line length
use of QTextEdit::fontMetrics().width(QString str) for investigate str size in width
I hope this can help you...
I have a QLabel that contains an image. I need to ensure that the image allways takes 100% of the QLabel width, but preserving aspect ration is just as important. This means I also need to increase QLabel height so that the image fits. Like on this image, the height must be fit:
I Qt designer I see no way to specify preferred aspect ratio, so I just tried to override resize event and try to force correct height upon resize:
void QPictureLabel::resizeEvent(QResizeEvent *event)
{
qDebug()<<"Resized.";
// Current image width in pixels
float pw = myPixmap.width();
// current label width in pixels
float my_width = width();
// ratio of label and image width can decide the new required label height
float new_h = (my_width/pw)*myPixmap.height();
// This is an attempt to prevent endless loop... didn't work out
if(new_h!=height()) {
// Force new height (that works)
resize(my_width, new_h);
// Tell the layout to move other elements (that doesn't work at all!)
updateGeometry();
}
}
Before adding the updateGeometry call it just looked like this:
As you can see (I highlighted it with red frame), the label indeed expanded as necessary. But other widgets do not care about that.
I added updateGeometry call, but the result was endless loop for some reason. I need the correct way to inform the layout that QLabel requires more space.
but the result was endless loop for some reason
This is documented, read documentation on resizeEvent(). Shf's solution should work for you.
I am doing a software with a drawing surface that represent a plot (like a sin function) (A child of QWidget) and I would like to have a QScrollBar acting like a QScrollArea. So if my drawing widget show show 750 dots (my plot is made of dots), but there are 1000 dots, I would like the slider of the ScrollBar to fill 75% of the available space.
I can't use a QScrollArea because the scroll is proportionnal with the size of the widget it contains. In my case, the scroll must be proportionnal with the number of dots on the screen. I know how to get my ratio, but I don't know how to setup correctly the QScrollBar
Example: I edited the value of PageStep, but I don't understand how this work. I can set pageStep to 100 with a range of [0,99] and it will fill the half of the QScrollBar.
My interface:
QWidget (Vertical Layout) //Main Widget
Drawing Surface (Child of QWidget)
QScrollBar (Horizontal)
Well, I think I am able to do something with this:
http://harmattan-dev.nokia.com/docs/library/html/qt4/qscrollbar.html
The relationship between a document length, the range of values used in a scroll bar, and the page step is simple in many common situations. The scroll bar's range of values is determined by subtracting a chosen page step from some value representing the length of the document. In such cases, the following equation is useful: document length = maximum() - minimum() + pageStep().
So in my case the length is the number of dots and I can set minimum() to 0. So, as you can see on the picture, to do something like QScrollArea. The proportion is: PercentageVisible = PageStep / Length and another equation is Length = PageStep + Max.
I have two equations, two missing values (PageStep and Maximum) and two known values (PercentageVisible and Length).
Example: I have 1024 dots, but only 75% of them are shown.
0.75 = PageStep / 1024 ----------> PageStep = 768
1024 = Max + 768 ----------------> Max = 256
You can try it in your software and it will works. I know there's not so much people that will needs to reproduce this because QScrollArea will do the job in most of the case.
By example, this code is in a slot reacting from a resize event:
ui.sbarRange->setPageStep(u64SampleCount * dRatio);
ui.sbarRange->setMaximum(u64SampleCount - ui.sbarRange->pageStep());
You can create a new QWidget subclass and reimplement sizeHint and paintEvent. In the paintEvent you can use event->rect() to determine which area is currently exposed and needs to be drawn. Note that paintEvent must be fast if you don't want your window to freeze. Also you need to put created widget in QScrollArea.
Here is a simple example that draws a sinusoid:
class SinWidget : public QWidget {
public:
QSize sizeHint() const {
return QSize(10000, 200);
}
void paintEvent(QPaintEvent* event) {
QPainter painter(this);
for(int x = event->rect().left(); x <= event->rect().right(); x++) {
painter.drawPoint(x, 100.0 + qSin(0.05 * x) * 20.0);
}
}
};
QScrollArea area;
area.setWidget(new SinWidget());
area.show();
This example will work fine with very large widget size (e.g. 100 000 pixels). So full repaint or memory allocation doesn't happen. You only need to keep your paintEvent fast.
I have QGraphicsTextItem objects on a QGraphicsScene. The user can scale the QGraphicsTextItem objects by dragging the corners. (I am using a custom "transformation editor" to do this.) The user can also change the size of the QGraphicsTextItem by changing the font size from a property panel. What I would like to do is unify these so that when the user scales the object by dragging the corner with the mouse, behind the scenes it actually is calculating "What size font is necessary to make the resulting object fit the target size and keep the scale factor at 1.0?"
What I am doing now is letting the object scale as normal using QGraphicsItem::mouseMoveEvent and then triggering a FinalizeMapScale method in QGraphicsItem::mouseReleaseEvent once the mouse scale is complete. This method should then change the font to the appropriate size and set the scale back to 1.0.
I have a solution that appears to be working, but I'm not crazy about it. I'm relatively new to both Qt and C++, so would appreciate any comments or corrections.
Is there a better way to architect this whole thing?
Are there Qt methods that already do this?
Is my method on the right track but has some Qt or C++ errors?
Feel free to comment on my answer below on submit your own preferred solution. Thanks!
[EDIT] As requested in comment, here is the basics of the scaling code. We actually went a different direction with this, so this code (and the code below) is no longer being used. This code is in the mouseMoveEvent method, having previously set a "scaling_" flag to true in mousePressEvent if the mouse was clicked in the bottom-right "hot spot". Note that this code is in a decorator QGraphicsItem that holds a pointer to the target it is scaling. This abstraction was necessary for our project, but is probably overkill for most uses.
void TransformDecorator::mouseMoveEvent(QGraphicsSceneMouseEvent *event) {
...
if (scaling_) {
QGraphicsItem *target_item = target_->AsQGraphicsItem();
target_item->setTransformOriginPoint(0.0, 0.0);
QPointF origin_scene = mapToScene(target_item->transformOriginPoint());
QPointF scale_position_scene = mapToScene(event->pos());
qreal unscaled_width = target_item->boundingRect().width();
qreal scale_x = (scale_position_scene.x() - origin_scene.x()) / unscaled_width;
if (scale_x * unscaled_width < kMinimumSize) {
scale_x = kMinimumSize / unscaled_width;
}
target_item->setScale(scale_x);
} else {
QGraphicsObject::mouseMoveEvent(event);
}
}
Please no holy wars about the loop-with-exit construct. We're comfortable with it.
void MapTextElement::FinalizeMapScale() {
// scene_document_width is the width of the text document as it appears in
// the scene after scaling. After we are finished with this method, we want
// the document to be as close as possible to this width with a scale of 1.0.
qreal scene_document_width = document()->size().width() * scale();
QString text = toPlainText();
// Once the difference between scene_document_width and the calculated width
// is below this value, we accept the new font size.
const qreal acceptable_delta = 1.0;
// If the difference between scene_document_width and the calculated width is
// more than this value, we guess at the new font size by calculating a new
// scale factor. Once it is beneath this value, we creep up (or down) by tiny
// increments. Without this, we would sometimes incur long "back and forth"
// loops when using the scale factor.
const qreal creep_delta = 8.0;
const qreal creep_increment = 0.1;
QScopedPointer<QTextDocument> test_document(document()->clone());
QFont new_font = this->font();
qreal delta = 0.0;
// To prevent infinite loops, we store the font size values that we try.
// Because of the unpredictable (at least to me) relationship between font
// point size and rendering size, this was the only way I could get it to
// work reliably.
QList<qreal> attempted_font_sizes;
while (true) {
test_document->setDefaultFont(new_font);
delta = scene_document_width - test_document->size().width();
if (std::abs(delta) <= acceptable_delta ||
attempted_font_sizes.contains(new_font.pointSizeF())) {
break;
}
attempted_font_sizes.append(new_font.pointSizeF());
qreal new_font_size = 0.0;
if (std::abs(delta) <= creep_delta) {
new_font_size = delta > 0.0 ? new_font.pointSizeF() + creep_increment
: new_font.pointSizeF() - creep_increment;
} else {
new_font_size = new_font.pointSizeF()
* scene_document_width
/ test_document->size().width();
}
new_font.setPointSizeF(new_font_size);
}
this->setFont(new_font);
this->setScale(1.0);
}
Another way to look at the problem is: Qt has scaled the font, what is the effective font size (as it appears to the user, not the font size set in the text item) that I need to display to the user as their choice of new font size? This is just an alternative, you still need a calculation similar to yours.
I have a similar problem. I have a text item that I want to be unit size (one pixel size) like my other unit graphic items (and then the user can scale them.) What font (setPointSize) needs to be set? (Also what setTextWidth and what setDocumentMargin?) The advantage of this design is that you don't need to treat the scaling of text items different than the scaling of any other shape of graphics item. (But I don't have it working yet.)
Also, a user interface issue: if the user changes the font size, does the item change size? Or does it stay the same size and the text wrap differently, leaving more or less blank space at the end of the text? When the user appends new text, does the font size change so all the text fits in the size of the shape, or does the shape size grow to accommodate more text? In other words, is it more like a flowchart app (where the shape size is fixed and the font shrinks), or like a word processor app (where the font size is constant and the shape (number of pages) grows?