I have rich text items implemented using QGraphicsTextItem
To set font size, for example:
void set (int fontSize) {
QTextCursor _cursor = textCursor();
QTextCharFormat _format;
_format.setFontPointSize(fontSize);
_cursor.mergeCharFormat(_format);
setTextCursor(_cursor); }
A lot more complicated is to read the font size.
Assuming I have a selection, I must iterate through the document, through all QTextBlock, QTextFragment, reading the QTextCharFormat ...
But the simple option, if there is no selection, just reading the font size at cursor:
int get () {
return textCursor().charFormat().fontPointSize(); }
This works, but I found 3 issues:
1) Setting font size by QGraphicsTextItem properties:
QFont f = font();
f.setPointSize(20);
setFont(f);
this returns 0 by my get function above. To set the font size for the entire item, I have to use the same method as in the set function.
Shouldn't the setFont method set a font that can be read from the QTextCursor ?
2) setHtml can set formatting - but I don't see any way to read that formatting
How can I read the rich text formatting from an html fragment ? Is the only posiblity, parsing the html ?
3) (my current stumbling block)
Copy formatted text from an outside source and paste in the QGraphicsTextItem seems to maintain the formatting of the source - but how can I read that formatting ?
The get method above reads font size 0 if the text was pasted from outside.
font().pointSize() always returns 8. (I have not set it so I imagine that is a default)
Is there another method to read the text format ?
is the clipboard text formatted using html ?
How can I find the font size (or any other formatting) from the pasted text ?
(The same questions apply to block formatting, like alignment).
I think most of your problems could be solved by getting the QTextDocument for your QGraphicsTextItem object and work with it. QTextDocument and its methods (like QTextFormat::property(int propertyId)) can help you to get a lot of properties for your text.
1) If you set the size using the QFont object, you should get the size using the same way.
2) When you set the text using html, QGraphicsTextItem::font() is not useful so you need to get the QTextDocument and use their functions instead.
3) Same as 2. I think... because I don't have your code to test it :)
Well, here you have a code as an example. I hope this answer helps you.
#include <QApplication>
#include <QGraphicsScene>
#include <QGraphicsView>
#include <QGraphicsTextItem>
#include <QTextCursor>
#include <QTextCharFormat>
#include <QFont>
#include <QDebug>
#include <QTextDocument>
#include <QTextBlock>
int main(int argc, char *argv[])
{
QApplication a(argc, argv);
QGraphicsScene scene;
QGraphicsView view(&scene);
/* ITEM 1 */
QGraphicsTextItem* item_1 = new QGraphicsTextItem("QGraphicsTextItem 1");
item_1->setTextInteractionFlags(Qt::TextEditorInteraction);
QFont f = item_1->font();
f.setPointSize(30);
item_1->setFont(f);
qDebug() << "textCursor().position() (returns 0): " <<
item_1->textCursor().position();
qDebug() << "textCursor().charFormat().fontPointSize() (returns 0): " <<
item_1->textCursor().charFormat().fontPointSize();
qDebug() << "font().pointSize() (returns 30 - OK!): " <<
item_1->font().pointSize();
QTextDocument* doc = item_1->document();
f = doc->defaultFont();
qDebug() << "pointSize (returns 30 - OK!): " << f.pointSize();
scene.addItem(item_1);
/* ITEM 2 */
QGraphicsTextItem* item_2 = new QGraphicsTextItem();
item_2->setPos(0, 50);
item_2->setHtml("<html><head/><body><p>"
"<span style=\"font-size:14pt; font-weight:600;\">QGraphics</span>"
"<span style=\"font-size:24pt; font-weight:600;\">TextItem 2</span>"
"</p></body></html>");
qDebug() << "font().pointSize() (returns 8, the default value): "
<< item_2->font().pointSize();
doc = item_2->document();
f = doc->defaultFont();
qDebug() << "pointSize (returns 8, the default value): " << f.pointSize();
QVector<QTextFormat> formats = doc->allFormats();
QVectorIterator<QTextFormat> i(formats);
while (i.hasNext()) {
QTextFormat format = i.next();
if (format.property(QTextFormat::FontPointSize).isValid())
qDebug() << "format.property (returns 14 or 24): " <<
format.property(QTextFormat::FontPointSize).toInt();
}
/*
* Get the block of text. In this example, we only have one block, but
* two text fragments (see below)
*/
QTextBlock text_block = item_2->document()->findBlock(1);
QTextBlock::iterator it;
for (it = text_block.begin(); !(it.atEnd()); ++it) {
QTextFragment currentFragment = it.fragment();
if (currentFragment.isValid())
qDebug() << "currentFragment.text(): " << currentFragment.text();
qDebug() << "currentFragment.charFormat().font().pointSize() "
"(returns 14 or 24, depending on"
"the current text fragment): " <<
currentFragment.charFormat().font().pointSize();
}
scene.addItem(item_2);
view.setFixedSize(640, 480);
view.show();
return a.exec();
}
Related
I have inherited a virtual keyboard system with an array of buttons, one for each key. The label for each button is a single QChar. When showing the "symbols" keyboard, the code uses an '&' QChar for a key label, but the key shows as blank. I'm sure Qt is processing the '&' as a shortcut key prefix. Similarly, the entered text is shown on another, longer, button label; this label, as well, handles '&' character as an accelerator. Entering "ABC&DEF" is shown as "ABCDEF" with the 'D' underlined.
I have tried building with QT_NO_SHORTCUT #defined, but that made no difference.
Does anyone know of an easy way to disable this special handling of '&'?
The answer is found in Qt doc. QAbstractButton::text:
If the text contains an ampersand character ('&'), a shortcut is automatically created for it. The character that follows the '&' will be used as the shortcut key. Any previous shortcut will be overwritten or cleared if no shortcut is defined by the text. See the QShortcut documentation for details. To display an actual ampersand, use '&&'.
(Emphasize by me.)
QPushButton is derived from QAbstractButton inheriting this behavior.
Sample testQPushButtonAmp.cc:
#include <QtWidgets>
int main(int argc, char **argv)
{
qDebug() << "Qt Version:" << QT_VERSION_STR;
QApplication app(argc, argv);
QPushButton qBtn("Text with &&");
qBtn.show();
return app.exec();
}
testQPushButtonAmp.pro:
SOURCES = testQPushButtonAmp.cc
QT = widgets
Compiled and tested on cygwin64 on Windows 10:
$ qmake-qt5 testQPushButtonAmp.pro
$ make
$ ./testQPushButtonAmp
Qt Version: 5.9.4
Concerning how to disable this default behavior:
I had a look at woboq.org QAbstractButton::setText().
void QAbstractButton::setText(const QString &text)
{
Q_D(QAbstractButton);
if (d->text == text)
return;
d->text = text;
#ifndef QT_NO_SHORTCUT
QKeySequence newMnemonic = QKeySequence::mnemonic(text);
setShortcut(newMnemonic);
#endif
d->sizeHint = QSize();
update();
updateGeometry();
#ifndef QT_NO_ACCESSIBILITY
QAccessibleEvent event(this, QAccessible::NameChanged);
QAccessible::updateAccessibility(&event);
#endif
}
So, QT_NO_SHORTCUT disables to retrieve the shortcut out of text but it has to be defined when Qt library is built from source. Actually, I'm afraid even with disabled shortcuts, the single & will still become invisible in output.
I digged deeper in woboq.org and found some promising candidates e.g.:
qt_set_sequence_auto_menmonic()
Specifies whether mnemonics for menu items, labels, etc., should be honored or not. On Windows and X11, this feature is on by default; on macOS, it is off. When this feature is off (that is, when b is false), QKeySequence::mnemonic() always returns an empty string.
Note: This function is not declared in any of Qt's header files. To use it in your application, declare the function prototype before calling it.
and a sample in QProxyStyle
#include "textedit.h"
#include <QApplication>
#include <QProxyStyle>
class MyProxyStyle : public QProxyStyle
{
public:
int styleHint(StyleHint hint, const QStyleOption *option = 0,
const QWidget *widget = 0, QStyleHintReturn *returnData = 0) const override
{
if (hint == QStyle::SH_UnderlineShortcut)
return 0;
return QProxyStyle::styleHint(hint, option, widget, returnData);
}
};
int main(int argc, char **argv)
{
Q_INIT_RESOURCE(textedit);
QApplication a(argc, argv);
a.setStyle(new MyProxyStyle);
TextEdit mw;
mw.resize(700, 800);
mw.show();
//...
}
which I tried in my sample.
Finally, nothing of them achieved the desired effect, i.e. only "&&" was rendered as & but "&" never.
__
I have a problem with QPainter on QImage in Qt 5.4.
The image has Format_ARGB32. I want to set a given RGBA value on pixels in the image using a QPainter draw function and later read the value back using QImage::pixel.
Yet the value painted and the value read back are different. What am I doing wrong?
Sample code:
QImage image(100, 100, QImage::Format_ARGB32);
uint value = 0x44fa112b; //some value..
QPainter painter(&image);
painter.setCompositionMode(QPainter::CompositionMo de_Source);
QColor color(qRed(value), qGreen(value), qBlue(value), qAlpha(value));
QBrush brush(color);
painter.setBrush(brush);
painter.drawRect(0,0,image.width(), image.height());
uint value1 = image.pixel(50,50);
// value1 IS NOT EQUAL TO value. Why??
This works fine in Qt 5.7. Perhaps earlier Qt versions need the painter.end() call.
#include <QtGui>
int main(int argc, char ** argv) {
QGuiApplication app{argc, argv};
QImage image{100, 100, QImage::Format_ARGB32};
auto const set = 0x44fa112b;
QPainter painter(&image);
painter.setCompositionMode(QPainter::CompositionMode_Source);
painter.setBrush({{qRed(set), qGreen(set), qBlue(set), qAlpha(set)}});
painter.drawRect(image.rect());
if (false) painter.end(); //<< try with true here
auto readback = image.pixel(50,50);
qDebug() << hex << set << readback;
Q_ASSERT(readback == set);
}
Problem solved!!
Working properly when I tried with Qt 5.8
Looks like a bug with Qt 5.4.
Thanks to all :)
I've looked around a little bit but couldn't find an answer to this.
I have a function returning a pair of pointers to objects, the situation can be simplified to:
#include <iostream>
#include <utility>
#include <memory>
std::pair<int *, int *> shallow_copy()
{
int *i = new int;
int *j = new int;
*i = 5;
*j = 7;
return std::make_pair(i, j);
}
int main(int argc, char *argv[])
{
std::pair<int *, int *> my_pair = shallow_copy();
std::cout << "a = " << my_pair.first << " b = " << *my_pair.second << std::endl;
// This is just creating a newpointer:
std::unique_ptr<int> up(my_pair.first);
std::cout << "a = " << &up << std::endl;
delete my_pair.first;
delete my_pair.second;
return 0;
}
I cannot change the return value of the function. From std::cout << "a = " << &up << std::endl; I can see that the address of the smart pointer is different from the address of the raw pointer.
Is there a way to capture tha std::pair returned by the function in a std::unique_ptr and prevent memory leaks without calling delete explicitly?
NB: The question have been edited to better state the problem and make me look smarter!
You're doing it the right way, but testing it the wrong one. You're comparing the address in first with the address of up. If you print up.get() instead (the address stored in up), you'll find they're equal.
In addition, your code has a double-delete problem. You do delete my_pair.first;, which deallocates the memory block pointed to by my_pair.first and also by up. Then, the destructor of up will deallocate it again when up goes out of scope, resulting in a double delete.
You also asked how to capture both pointers in smart pointers. Since the constructor of std::unique_ptr taking a raw pointer is explicit, you cannot directly do this with a simple std::pair<std::unique_ptr<int>, std::unique_ptr<int>>. You can use a helper function, though:
std::pair<std::unique_ptr<int>, std::unique_ptr<int>> wrapped_shallow_copy()
{
auto orig = shallow_copy();
std::pair<std::unique_ptr<int>, std::unique_ptr<int>> result;
result.first.reset(orig.first);
result.second.reset(orig.second);
return result;
}
Now, use wrapped_shallow_copy() instead of shallow_copy() and you will never leak memory from the call.
I have to write a small QT program that reads in 3 mark percentages separated by commas and then do some further calculations on the marks... I have to use QInputDialog to do this but it seems like it's only possible to read in one value at a time.
at this stage I am only trying to read in and display the three marks.
When I run this code QTCreator stops working and I have to end the process in task manager.
Any idea how I can approach this would be much appreciated. Should I read in a string and then convert that to double values or is there a simpler way?
Thanks in advance.
Code:
#include <QTGui>
#include <QApplication>
#include <QString>
#include <QTextStream>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QTextStream cin(stdin, QIODevice::ReadOnly);
QTextStream cout(stdout, QIODevice::WriteOnly);
double mark1, mark2, mark3;
double passMarkNeeded = 0;
QInputDialog::getDouble(0, "Enter marks", "Marks", 1);
cin >> mark1 >> mark2 >> mark3;
cout << "User entered " << mark1 << mark2 << mark3;
return EXIT_SUCCESS;
}
Obviously you cannot use QInputDialog::getDouble because it won't allow you to input 3 values separated by commas. You should use QInputDialog::getText, QString::split and QString::toDouble:
QStringList list = QInputDialog::getText(0, "Input values", "Input values:").split(",");
if (list.count() == 3) {
double a = list[0].toDouble(),
b = list[1].toDouble(),
c = list[2].toDouble();
qDebug() << "Values:" << a << b << c;
}
I'm not sure why you use QInputDialog and the standard input (cin). QInputDialog is for GUI apps, and cin is console apps. It's strange and pointless to use them together in such a way.
Are the iterators pointed to elements of QList still valid after there are any remove operation from QList?
I need to remove some element from QList, so I store an iterators for those elements to another container and than take this saved iterators and use to remove necessary elements from QList.
It looks like this:
// inside a loop for 'list'
QList<type>::iterator it = list.begin() + j;
removing.append(it);
// end of loop for 'list'
...
while(removing.empty() == false)
{
list.erase(removing.takeFirst());
}
So, when removing container contains more than 1 element, app crash occurs (SEGMENTATION FAULT) when attempting to erase second element, whereas first was erased successfully.
What is the reason and is there any way to remove elements with iterators?
If for some reason you would like to remove elements from a container in that way then you could try to use QLinkedList instead of QList because Iterators pointing to an item in a QLinkedList remain valid as long as the item exists, whereas iterators to a QList can become invalid after any insertion or removal. I copied this quotation from Qt's documentation: Container Classes.
No, the iterators will not be valid. If you just want to remove all the elements, use QList::clear(). You can call qDeleteAll() on the QList first if you need to delete the items.
If you want to selectively remove elements using iterators, you can do something like the following. You may need to modify it for memory management.
#include <QtCore>
#include <QtDebug>
int main(int argc, char **argv) {
QCoreApplication app(argc, argv);
QList<int> items;
items << 0 << 1 << 1 << 2 << 3 << 5 << 8 << 13 << 21 << 34 << 55 << 89 << 144;
QList<int>::iterator i = items.begin();
while (i != items.end()) {
if ((*i) % 2 == 0) {
// i->DoSomething(); // Not with ints, obviously, but in general.
i = items.erase(i); // i points to the next item.
} else {
++i;
}
}
qDebug() << items;
return app.exec();
}