On 12/04/2013 11:47 AM, Sletta Gunnar wrote:
> QWidget has the exact opposite problem. Layouts, styles and rendering happens
> in pixel units while fonts are sized in point size. This is also a problem
> when moving between platfoms as the pixelsize of a point has a different
> definition on each platform. When running widgets on a hidpi screen, the
> fonts are usually huge compared to spacing, lines and icons. In addition to
> looking quite ugly it easily breaks the layout scheme set up by the
> application because the text takes up too much space.
>
> As long as one sticks to one unit type through the application everything is
> fine. Mixing leads to problems.
>
> Just thinking out loud:
>
> Sticking to pixels makes it possible for the application developer to make
> the right decision based on what he/she wants to achieve. Layout out relative
> to millimeters can quite easily be done by providing supporting logic in Qt.
>
> If we added conversion functions for inch(), cm(), mm(), points() to
> QQuickItem, it could look up its current window/screen object and figure out
> the relationship between each unit for the screen the item is on and just set
> that. The app can then layout in the unit space it prefers with information
> readily available.
>
> Text {
> font.pixelSize: cm(0.5);
> anchors.left: parent.left
> anchors.margins: cm(0.25);
> }
>
>
> Making them functions makes it impossible to listen for screen changes which
> in turn trigger dpi changes so they would have to be properties...
>
> Text {
> font.pixelSize: 0.5 * cm;
> anchors.left: parent.left
> anchors.margins: 0.25 * cm;
> }
>
> The properties would look up the item's window and then the screen and do the
> calculation from there so no extra memory for each item to store the
> properties. And since they don't change all that often, the added calculation
> is a negligible overhead. When the item is not associated with a window, it
> will have to use the OS definition of a point instead, usually 72 or 96.
>
> Just an idea.
>
> -
> Gunnar
>
That's a pretty cool idea! It would make it so painless to design stuff
for different screens' DPIs.
> ________________________________________
> Fra: [email protected]
> [[email protected]] på vegne av
> Thiago Macieira [[email protected]]
> Sendt: 3. desember 2013 18:09
> To: [email protected]
> Emne: Re: [Development] OpenGL drivers
>
> On terça-feira, 3 de dezembro de 2013 10:27:24, Thomas Hartmann wrote:
>> Hi,
>>
>> we really should think about introducing em or percent for font sizes.
>>
>> But non pixel size fonts create a lot of problems for complex layouts.
>
> QWidget has worked with that for 15 years, so I don't accept that as an
> excuse. We have anchor layouts in Qt Quick, which are a lot more powerful than
> the grids and spacers that we used in QWidget.
>
> Desktop support does not require pixel perfection. It does require scaling
> over widely different resolutions and DPIs, though -- from 1366x768 to
> 3200x1800, for example.
>
> --
> Thiago Macieira - thiago.macieira (AT) intel.com
> Software Architect - Intel Open Source Technology Center
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