is there any way to insert QPixmap object in html?
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开发者_开发问答.
I will be grateful for any help. Thanks.
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.
I put this in another answer to be able to format the code. I wrote the following program and it works as intended:
#include <QtGui>
int main(int argc, char *argv[])
{
QApplication app(argc, argv);
QWidget window;
window.resize(320, 240);
window.show();
window.setWindowTitle(
QApplication::translate("toplevel", "Top-level widget"));
QLabel* label = new QLabel(&window);
label->setTextFormat(Qt::RichText);
QString text = "<html><h1>Test</h1>here is an image: ";
QPixmap pixmap("testicon.jpg");
QByteArray byteArray;
QBuffer buffer(&byteArray);
pixmap.save(&buffer, "PNG");
QString url = QString("<img src=\"data:image/png;base64,") + byteArray.toBase64() + "\"/>";
text += url;
text += "</html>";
label->setText(text);
label->move(100, 100);
label->show();
return app.exec();
}
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);
}
};
This is my two cents about serializing/deserializing QPixmap to/from Base64 e strings. I've included methods to load/save the image as a text file but also two simple toBase64() and fromBase64() that help with HTML, SQL or JSON encoding.
#include "b64utils.h"
#include <QBuffer>
#include <QFile>
#include <QTextStream>
/**
* Serializes a QPixmap object into a Base64 string
*/
QString B64Utils::toBase64(QPixmap *pixmap) {
// Convert the pixel map into a base64 byte array
QBuffer *buffer = new QBuffer;
pixmap->save(buffer, "png");
QByteArray b64 = buffer->data().toBase64();
QString *b64Str = new QString(b64);
return *b64Str;
}
/**
* Serializes a QPixmap object into a Base64 string and save it to a file
*/
bool B64Utils::savePixmapToBase64(QPixmap *pixmap, QString filePath) {
// Opens a file for writing text
QFile file(filePath);
if (!file.open(QIODevice::WriteOnly | QFile::Text)) return false;
// Write the Base64 string into the file
QTextStream stream(&file);
stream << toBase64(pixmap);
file.close();
return true;
}
/**
* Deserializes a Base64 string, representing an image, into a QPixmap
*/
QPixmap* B64Utils::fromBase64(QString b64Str) {
QPixmap *pixmap = new QPixmap;
pixmap->loadFromData(QByteArray::fromBase64(b64Str.toUtf8()));
return pixmap;
}
/**
* Retrieves a Base64 string, representing an image, from a file and deserializes it into a QPixmap
*/
QPixmap* B64Utils::loadPixmapFromBase64(QString filePath) {
// Opens a file for reading text
QFile file(filePath);
if (!file.open(QFile::ReadOnly | QFile::Text)) return nullptr;
// Reads the contents of the file into a string
QTextStream in(&file);
QString b64Str = in.readAll();
file.close();
return fromBase64(b64Str);
}
加载中,请稍侯......
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