Full screen dialogs

[plfiorini]

https://material.io/guidelines/components/dialogs.html#dialogs-full-screen-dialogs

(Details of this issue are copied from papyros/qml-material#287)

In the Google Calendar application on Android, you can get an example of full-screen dialog when you create a new event. On a device with a small screen, the full-screen dialog fills the screen:

Nexus 4

But on a device with a larger screen, the dialog does not fill the screen horizontally or vertically (depending on the screen orientation and the screen size):

Nexus 10 (portrait)

Nexus 10 (landscape)

Nexus 7 (portrait)

Nexus 7 (landscape)

We can see that several parameters influence how the screen is filled. After several tests, I got the following results:

• Landscape mode:
  • If parent.width / density < 600 then dialog.width = parent.width else dialog.width = parent.width / 2
  • dialog.height = parent.height
• Portrait mode:
  • If parent.height / density < min_height then dialog.height = parent.height else dialog.height = parent.height / r1
  • If parent.height / density < min_height then dialog.width = parent.width else dialog.width = parent.width / r2

min_height, r1 and r2 have to be defined more precisely.

In my tests, I found min_height = 1280 but it could be lower since there is a big gap between my test devices (between 640 and 1280).
The ratio r1 seems to be around 1.12 but I don't have a clear idea about it. My tests gave me 1.1186833... (quite a strange value).
For r2, I got a "round" value, 1.25, that seems acceptable.

The specs don't talk about these cases but the full-screen dialogs look much better that way on bigger screens.