[Interest] Text rendering problem.

[william.crocker at analog.com]

On 07/21/2015 01:31 PM, william.crocker at analog.com wrote:
> On 07/18/2015 08:02 PM, william.crocker at analog.com wrote:
>>
>>>>>
>>>>> I am having a text rendering problem.
>>>>
>>>> What you can do in your example is
>>>>
>>>>        scene_font.setHintingPreference(QFont::PreferNoHinting);
>>>>
>
> It appears that one needs to use the DirectWrite text rendering
> system on Windows.
>

I have this working with DirectWrite on Windows,
but it only appears to work when my app is built with debug mode.
If I build it in release mode then it does *not* work
and the text appears badly kerned.

In debug mode I see Visual Studio loading DWrite.dll
I do not see that when built and run in release mode.

I tried copying DWrite.dll to the Qt.../bin dir (where
the app finds all of the Qt DLLs) but that did not help.

In all cases I have the font hinting preference
set to QFont::PreferNoHinting and a scan of the Qt source
shows that as the condition under which direct write is used.

Bill

When I say it does not work, I mean that
text is badly kerned at the smaller point sizes.
I can see this by zooming in on a QGraphicsScene
with text items.

>
>>> I forgot the most import rule of software engineering in the 21st century:
>>>
>>> "No matter how obscure the problem, you are not the first to encounter it.
>>>      Others have come before you, solved the problem and those solutions are
>>>      there for all to see if you Google the right subject."
>>>
>>> Bill
>>>
>>>>> Bill
>>>>>
>>>>> -------------------------
>>>>> int
>>>>> main( int argc, char **argv ) {
>>>>>          QApplication app(argc,argv);
>>>>>
>>>>>          int sz = 6, scale = 10;
>>>>>          QString text = QString("Impedance");
>>>>>
>>>>>          // Text size is 60.
>>>>>          // This text renders well.
>>>>>          QFont label_font = QFont("Arial",scale*sz,QFont::Bold);
>>>>>          QLabel *label = new QLabel(text);
>>>>>          label->setFont(label_font);
>>>>>
>>>>>          // Text size is 6, then the view is zoomed in x10.
>>>>>          // This text is not properly kerned.
>>>>>          QFont scene_font = QFont("Arial",sz,QFont::Bold);
>>>>>          QTextDocument *html = new QTextDocument;
>>>>>          html->setDefaultFont(scene_font);
>>>>>          html->setHtml(text);
>>>>>          QGraphicsTextItem *gi = new QGraphicsTextItem;
>>>>>          gi->setDocument(html);
>>>>>          QGraphicsScene *sp = new QGraphicsScene;
>>>>>          sp->addItem(gi);
>>>>>          QGraphicsView *view = new QGraphicsView;
>>>>>          view->setScene(sp);
>>>>>          view->scale(scale,scale);
>>>>>
>>>>>          QHBoxLayout *hbox = new QHBoxLayout;
>>>>>          hbox->addWidget(label);
>>>>>          hbox->addWidget(view);
>>>>>
>>>>>          QWidget *wp = new QWidget;
>>>>>          wp->setLayout(hbox);
>>>>>          wp->show();
>>>>>
>>>>>          app.exec();
>>>>> }
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