is there any way to insert QPixmap object in html?

Question

Simple situation: I have an object, which has a QPixmap member. Object first created (pixmap is null now), then pixmap readed from data base and inserted in object. I need to insert that pixmap in html code () and display that html code in a QLabel but I have no idea how to make it, because pixmap's path is unknown.

I know how to insert images from resource files and from files on my hard-disk, but it isn't that case. I was using QMimeSourceFactory class on qt 3.3.4, but on 4.6.2 it is deprecated. Assistant says: "Use resource system instead". But resource system compiles with app, but it is needed to read images during runtime.

I will be grateful for any help. Thanks.

Answer 1

If you only want to display a QPixmap in a QLabel, you should use QLabel::setPixmap. You can construct the pixmap in memory by using QPixmap::loadFromData.

If you want to display a memory pixmap in HTML, e.g. in a QWebView, you can use

    QByteArray byteArray;
    QBuffer buffer(&byteArray);
    pixmap.save(&buffer, "PNG");
    QString url = QString("<img src=\"data:image/png;base64,") + byteArray.toBase64() + "\"/>";

(untested)

QLabel::setText does not work with HTML but with rich-text. I do not know if the data: protocol is supported by the Qt rich-text implementation.

Another way to insert a pixmap into a QWebView would be to use a subclass of QNetworkAccessManager and reimplement its createRequest() function to check for URLs with your own protocol ("myprot:") and insert the pixmap data there. But this looks like overkill.

Answer 2

I know this is an old question, but here is another option.

I had a similar issue with images in QToolTip. I could reference images from disk fine, but the default scaling behavior is non-smooth and looked terrible. I reimplemented my own tooltip class and used a custom QTextDocument class so that I could override QTextDocument::loadResource().

In your case, you can specify a keyword in the img src attribute. Then in your implementation of loadResource() return the QPixmap identified with the keyword.

Here is the basic code (untested in this context):

class MyTextDocument : public QTextDocument
{
protected:
  virtual QVariant loadResource(int type, const QUrl &name)
  {
    QString t = name.toString();
    if (t == myKeyword)
      return myPixmap;
    return QTextDocument::loadResource(type, name);
  }
};

class MyLabel : public QFrame
{
public:
  MyLabel(QWidget *parent)
  : QFrame(parent)
  , m_doc(new MyTextDocument(this))
  { }

  virtual void paintEvent(QPaintEvent *e)
  {
    QStylePainter p(this);
    // draw the frame if needed

    // draw the contents
    m_doc->drawContents(&p);
  }
};