Hi Richard,
On Jan 12, 6:54 pm, Richard Schilling <[email protected]>
wrote:
> Did you try fetching the scale that will allow you to convert from DPI
> to actual screen pixels? I found this very reliable:
>
> final scale =
> getContext().getResources().getDisplayMetrics().density;
The description of that says:
"on a 160dpi screen this density value will be 1; on a 120 dpi
screen
it would be .75; etc."
> Then multiply scale by one inch of pixels in DPI resolution (depending
> on the screen you're on) - 120, 160, 240, 320.
>
> This API call ...
>
> int densityDpi =
> getContext().getResources().getDisplayMetrics().densityDpi;
>
> will tell you the density of the screen you're on.
Approximately.
> So, this will tell you how many screen pixels equate to an inch.
I'm not at all sure that it does.
> Then
> you can use that to lay out your ruler markings:
> int pxPerInch = 340; // default value - note it's a new density
> in API version 9.
>
> switch(densityDpi){
> case DisplayMetrics.DENSITY_LOW:
> pxPerInch = 120 * scale;
> break;
> case DisplayMetrics.DENSITY_MEDIUM:
> pxPerInch = 160 * scale;
> break;
> case DisplayMetrics.DENSITY_HIGH:
> pxPerInch = 240 * scale;
> break;
> }
Note that the values of those constants DENSITY_* are their numeric
values, so there is no need for the case statement; you can just
write:
pxPerInch = densityDpi * scale;
However, I really don't think that does what you believe it does. I
think that densityDpi reliably gives the approximate dpi, and density
just gives densityDpi/160. Multiplying them together doesn't do
anything useful. But I could be wrong!
Thanks, Phil.
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