Differing DPI [font sizes] in QWebView compared to all other QWidgets?

Question

I have a QWebView which displays some HTML content and I used CSS to style the text:

body { font-size: 10pt; }

The window with the QWebView also has a QTextEdit field, for which I have set the font like this:

QFont newFont;
newfont.setPointSize(10);
myEditField->setFont(newFont);

Unfortunately, the text displayed in the QWebView is slightly larger than the text displayed in the QTextEdit. I have a feeling that this has something to do with DPI settings being different in the QWebView.

Is there a way to get the same font sizes displayed for both the QWebView and the QTextEdit?

Thanks!

Answer 1

Explanation of this behavior has been given on the bugreports:

It appears to be true that WebKit assumes 96 dpi as a fixed resolution. If this is how web content is designed then we have a problem changing that, because there are other people that expect WebKit to render web content like in web browsers. See also https://www.webkit.org/blog/57/css-units/

They suggested two solutions:

QWebView provides setZoomFactor and setTextMultiplier which I believe could be used to get the desired behaviour (matching the QWidget ).

You can calculate zoom factor and text multiplier using current DPI:

QWidget* window = QApplication::desktop()->screen();
const int horizontalDpi = window->logicalDpiX(); 
m_view->setZoomFactor(horizontalDpi / 96.0);

Using QWebSettings::ZoomTextOnly you can apply zooming to the text only.

Answer 2

This is a little tricky. I found a good way to get accurate DPI measurements is from QApplication, example:

QWidget* window = QApplication::desktop()->screen();
int horizontalDpi = window->logicalDpiX(); 

As far as font goes, you can use QWidget::fontMetrics() to get a good font metrics information.

I think a combination of both will give you some consistency between your web view and text edit.

Good luck.