I am interested in creating a text object type (inheriting QTextObjectInterface) that behaves like a code area:
distinctive background
border
fixed-width font
editable content
the instances need to be identifiable to code, so that content inside them may be extracted (separate code from surrounding content)
saving / loading (from regular html files)
syntax highlighting would be a plus, but is not really required
The other areas of the document would need to behave the usual way (font properties editable, colors editable, etc).
Qt provides an example for implementing custom text objects with QTextEdit. This looks like the hard way, since new text object can't make use of the existing infrastructure inside QTextEdit / QTextDocument.
QTextObject is
a base class for different kinds of objects that can group parts of a QTextDocument together
so inheriting it may be a choice, but neither its source files in Qt SDK package nor Google searches revealed helpful information.
QTextFrame inherits QTextObject so, again, it may be a feasible base class if some hints about this path are to be found.
In an simple HTML file all this (except syntax highlighting) would be easy. QTextEdit takes html as input and is able to export html, but the structure is lost in the process.
<code class="code-sample">
int i = 0;
</code>
QWebView is read-only, by the way. It advertises that:
Parts of HTML documents can be editable for example through the contenteditable attribute on HTML elements.
There may be other platforms where this is readily available, but the text editor needs to be used inside Qt Creator as a plug-in, so using Qt framework makes sense.
Bottom line: how does one implement code areas in a QTextEdit widget?
Later edits:
using Qt sdk from trunk (identifies itself as 4.8.4)
Qt Creator from trunk (Qt Creator 2.6.81)
I have found out that implementing this is possible using QTextEdit / QTextDocument.The most simple implementation that I can think of is presented in this answer for the reference of future seeker.
Notice that saving/loading needs to be customised as regular .toHtml() will not preserve the information needed.
Inserting a code block is simple:
QTextFrame * frame;
frame = cursor.insertFrame( code_block_format_ );
connect( frame, SIGNAL( destroyed() ),
this, SLOT( codeBlockDeleted() ) );
code_blocks_.append( frame );
notice the two variables that you can save in the class:
QTextFrameFormat code_block_format_;
QList<const QTextFrame*> code_blocks_;
We need the format for frame to be consistent and distinctive. It mat be initialised in constructor to something like:
code_block_format_.setBackground( QBrush( Qt::yellow ) );
code_block_format_.setBorder( 1 );
code_block_format_.setBorderStyle( QTextFrameFormat::BorderStyle_Inset);
code_block_format_.setMargin( 10 );
code_block_format_.setPadding( 4 );
We need the list so we can tell if a certain frame is a code box or not. Since all objects inheriting QTextObject need to be created by QTextDocument::createObject() we can't simply subclass the QTextFrame (actually I think we can, but not sure yet).
Now separating the code content from the rest may be done the usual way:
for ( it = frame->begin(); !(it.atEnd()); ++it ) {
child_frame = it.currentFrame();
child_block = it.currentBlock();
if ( child_frame != NULL )
{
if ( code_blocks_.contains( frame ) )
{
/* ... */
}
}
} /* for ( it = frame->begin(); !(it.atEnd()); ++it ) */
but notice that this is over-simplified for the sake of brevity. One needs to take into account nested frames.
If you are interested in a full implementation check out the git repository (work in progress, November 2012).
Related
I've got a pretty old MFC application that's been touched by many people over the years (most of them probably not even CS guys) and it follows, what I like to call the "anarchy design pattern."
Anyway, one of the dialogs has a series of 56 vertical sliders and check boxes. However, there are additional sliders and checkboxes on the dialog as shown below.
Now, the problem is that the additional sliders and checkboxes take on IDs that are in sequence with the slider/checkbox series of the dialog. My task is to add more sliders and checkboxes to the series (in the blank space in the Slider Control group box) Unfortunately, since IDC_SLIDER57 through IDC_SLIDER61 are already in the dialog (same goes for the checkboxes), existing code, such as the snippet below will break:
pVSlider = (CSliderCtrl *)GetDlgItem(IDC_SLIDER1+i);
Is there a better way to modify the resource file without doing it manually? I've seen a third party tool called ResOrg that looks like it'll help do what I want, but the software is a bit pricey, especially since I'll only use it once. I guess I can give the demo a try, but the limitations might restrict me.
FYI, I'm using Visual C++ 6.0 (yes...I know, don't laugh, it's being forced upon me).
Instead of writing:
pVSlider = (CSliderCtrl *)GetDlgItem(IDC_SLIDER1+i);
you could write:
pVSlider = (CSliderCtrl *)GetDlgItem(GetSliderID(i));
where GetSlider is a function that returns the id of slider number i.
GetSlider function
int GetSliderID(int nslider)
{
static int sliderids[] = {IDC_SLIDER1, IDC_SLIDER2, IDC_SLIDER3, .... IDC_SLIDERn};
ASSERT(nslider < _countof(sliderids));
return sliderids[nslider];
}
With this method the IDC_SLIDERn symbols dont need to have sequential values.
Using a QTextEdit, I need to change the font attributes of each paragraph individually. This is similar to how many word processors change the font of a paragraph when the user select a style from a menu (not a specific formatting).
Ideally, I would like to apply a QTextCharFormat (or equivalent) to a block (paragraph) just before it is laid out and rendered, but I would prefer that no font attribute be actually inserted in the text, as I don't want this information in the file but I need to preserve any bold/italic/underline attributes that the user might have set to words within paragraphs (I intend to save the needed information in a QTextBlock::userData). However, I can't figure where I would need to insert a function to perform this task.
I figured I could not change the QTextCharFormat of a paragraph from either QTextBlock nor QTextCursor as this only applies to new blocks, it doesn't affect blocks with existing text.
I checked out QTextLayout but I don't think my answer is there.
I have been looking for a solution to this problem for a few days now. I would be really gracious for any pointer in the right direction.
I have years of experience with C++, but I'm somewhat new to Qt. Using Qt 4.8.
Edit:
I added emphasize (bold) above to an important part of what I'm trying to do. In other word, what I'd really like to do is be able to apply the font attributes to the block of text (perhaps a temporary copy) just before it is displayed. I'm totally comfortable with deriving and modifying (even reimplement) any class that I need to in order to achieve that goal, but I need to be pointed to the right direction as to what I actually need to change. As a last resort, I could also modify some Qt class directly if that is necessary for the task, but again would need to know what class I need to touch. I hope this is clearer. I find it difficult to explain this without being allowed to tell you what the application will do exactly.
[Required Libraries]
#include <QTextEdit> // not needed if using the designer
#include <QTextDocument>
#include <QTextBlock>
#include <QTextCursor>
[Strategy]
QTextDocument
I need it to manage the blocks. The function QTextDocument::findBlockByNumber is quite handy to locate the previous blocks, and I think it is what you are after.
QTextBlock
Container for block texts. A nice and handy class.
QTextCursor
Surprisingly, there is no format-setter in QTextBlock class. Therefore I use QTextCursor as a workaround since there are four format-setters in this class.
[Code for formatting]
// For block management
QTextDocument *doc = new QTextDocument(this);
ui->textEdit->setDocument(doc); // from QTextEdit created by the Designer
//-------------------------------------------------
// Locate the 1st block
QTextBlock block = doc->findBlockByNumber(0);
// Initiate a copy of cursor on the block
// Notice: it won't change any cursor behavior of the text editor, since it
// just another copy of cursor, and it's "invisible" from the editor.
QTextCursor cursor(block);
// Set background color
QTextBlockFormat blockFormat = cursor.blockFormat();
blockFormat.setBackground(QColor(Qt::yellow));
cursor.setBlockFormat(blockFormat);
// Set font
for (QTextBlock::iterator it = cursor.block().begin(); !(it.atEnd()); ++it)
{
QTextCharFormat charFormat = it.fragment().charFormat();
charFormat.setFont(QFont("Times", 15, QFont::Bold));
QTextCursor tempCursor = cursor;
tempCursor.setPosition(it.fragment().position());
tempCursor.setPosition(it.fragment().position() + it.fragment().length(), QTextCursor::KeepAnchor);
tempCursor.setCharFormat(charFormat);
}
Reference:
How to change current line format in QTextEdit without selection?
[DEMO]
Building Environment: Qt 4.8 + MSVC2010 compiler + Windows 7 32 bit
The demo is just for showing the concept of setting the format on a specific block.
Plain text input
Format 1 (notice that it won't bother the current cursor in view)
Format 2
You can use QTextCursor to modify existing blocks.
Just get a cursor and move it to the beginning of the block. Then move it with anchor to create a selection.
Set this cursor to be the current cursor for the text edit and apply your changes.
QTextEdit accepts HTML so all you have to do is to format your paragraphs as HTML. See example below:
QString text = "<p><b>Paragraph 1</b></p><p><i>Paragraph 2</i></p>";
QTextCursor cursor = ui->textEdit->textCursor();
cursor.insertHtml(text);
That will create something like this:
Paragraph 1
Paragraph 2
Having said that, there is only a subset of HTML that is supported in Qt. See Supported HTML Subset
I have created one table by using QTableview and QAbstractTableModel . i have added some vertical header by using QHeaderView . In one of the header cell i want to use delegate ..
I am using the delegate but it does not have any impact ..
Is anywhere i am doing wrong ?
Had this issue myself. The answer from the Qt documentation is simple and annoying:
Note: Each header renders the data for each section itself, and does
not rely on a delegate. As a result, calling a header's
setItemDelegate() function will have no effect.
In other words you cannot use delegates with QHeaderView.
For the record, if you want to style a QHeaderView section, you'll have to do it either via the header data model (changing Qt::FontRole, etc.) or derive your own QHeaderView (don't forget to pass it to your table with "setVerticalHeader()") and overwrite the its paintSection()-function.
i.e.:
void YourCustomHeaderView::paintSection(QPainter* in_p_painter, const QRect& in_rect, int in_section) const
{
if (nullptr == in_p_painter)
return;
// Paint default sections
in_p_painter->save();
QHeaderView::paintSection(in_p_painter, in_rect, in_section);
in_p_painter->restore();
// Paint your custom section content OVER a specific, finished
// default section (identified by index in this case)
if (m_your_custom_section_index == in_section)
{
QPen pen = in_p_painter->pen();
pen.setWidthF(5.5);
pen.setColor(QColor(m_separator_color));
in_p_painter->setPen(pen);
in_p_painter->drawLine(in_rect.right(), in_rect.top(), in_rect.right(), in_rect.bottom());
}
}
This simplified example could of course easily be done via a stylesheet instead, but you could theoretically draw whatever you like using this method.
I am using QT to create a chat messenger client. To display the list of online users, I'm using a QListWidget, as created like this:
listWidget = new QListWidget(horizontalLayoutWidget);
listWidget->setObjectName("userList");
QSizePolicy sizePolicy1(QSizePolicy::Preferred, QSizePolicy::Expanding);
sizePolicy1.setHorizontalStretch(0);
sizePolicy1.setVerticalStretch(0);
sizePolicy1.setHeightForWidth(listWidget->sizePolicy().hasHeightForWidth());
listWidget->setSizePolicy(sizePolicy1);
listWidget->setMinimumSize(QSize(30, 0));
listWidget->setMaximumSize(QSize(150, 16777215));
listWidget->setBaseSize(QSize(100, 0));
listWidget->setContextMenuPolicy(Qt::CustomContextMenu);
Users are shown by constantly refreshing the list, like this: (Note: There are different channels, with different userlists, so refreshing it is the most efficient thing to do, as far as I know.)
void FMessenger::refreshUserlist()
{
if (currentPanel == 0)
return;
listWidget = this->findChild<QListWidget *>(QString("userList"));
listWidget->clear();
QList<FCharacter*> charList = currentPanel->charList();
QListWidgetItem* charitem = 0;
FCharacter* character;
foreach(character, charList)
{
charitem = new QListWidgetItem(character->name());
// charitem->setIcon(QIcon(":/Images/status.png"));
listWidget->addItem(charitem);
}
}
This has always worked perfectly. The line that I commented out is the one I have problems with: my current goal is to be able to display a user's online status with an image, which represents whether they are busy, away, available, etc. Using setIcon() does absolutely nothing though, apparently; the items still show up as they used to, without icons.
I'm aware that this is probably not the way this function needs to be used, but I have found little documentation about it online, and absolutely no useful examples of implementations. My question is, can anybody help me with fixing this problem?
This is how you may conduct your debugging:
Try the constructor that has both icon and text as arguments.
Try to use that icon in another context to ensure it is displayable (construct a QIcon with same argument and use it elsewhere, e.g. QLabel!).
Use icon() from the QListWidgetItem to receive back the icon and then look at that QIcon.
Create a new QListWidget, change nothing, and ordinarily add some stock items in your MainWidget's constructor. See if the icons show up there.
I'm writing a code for a voting machine that will allow user to read in custom XML ballots and then vote on them, however in the current build I have in QtCreator, I don't see an easy way to edit buttons in my GUI directly. In the code snippet below, I assign an element to pull out the names and type of ballot being read in, but I need to append a label on the GUI as well as change buttons to the names of candidates read in. Any ideas on how to do this?
while(!n.isNull()){
QDomNode x = n.firstChildElement();
QDomElement e = n.toElement();
QMessageBox::information(0,
tr( "Loading Element" ),
tr( "Our element is %1" ).arg(e.tagName()) );
QDomElement p = x.firstChildElement();//p finds Races
QMessageBox::information(0,tr("Foo"),tr("p = %1").arg(p.text()));//finds Race and Ballot types
n = n.nextSibling();
}
}
All the widgets you created using the Designer UI are available from your code. How to access them depends on how you linked your UI with the rest of your classes (see http://doc.qt.io/archives/4.6/designer-using-a-ui-file.html) but if you used the multiple inheritance approach your widgets and layouts will be accessible directly from your class using the name under which they appear in Designer. Qt Creator's completion will even work with them.
Having that in mind you can easily use the usual methods to change a widget's name, add a label to a layout, etc.
If this is still unclear, please add the code you use to embed your GUI, as it is needed in order to give you a sensible code example.