Re: Screen Resolution and Screen Size
Re: Screen Resolution and Screen Size
- Subject: Re: Screen Resolution and Screen Size
- From: Lance Saleme <email@hidden>
- Date: Tue, 22 Nov 2005 13:32:17 -0800
As is sometimes the case... I didn't read deeper than the title...
I don't have help to offer in finding the physical screen size to
calibrate the pixel counts to a "real size" value. In a fleeting
attempt a few years ago we discovered that even when it was possible
to determine the size of a screen in inches it was never accurate to
the inch during display due to user calibration changes on non-LCD
screens. Even on LCD screens the DPI varies (as you obviously
already know) and you wind up resorting to user input to complete the
calibration.
eBeam (virtual whiteboard solution) solves the issue by projecting
calibration points that you have to "touch" to verify. It works.
Sorry to divert the topic below,
Lance
On Nov 22, 2005, at 1:13 PM, Lance Saleme wrote:
// SAMPLE CODE FOR EXTRACTING MONITOR SIZES
NSArray *screenArray = [NSScreen screens];
NSScreen *mainScreen = [NSScreen mainScreen];
unsigned screenCount = [screenArray count];
unsigned index = 0;
for (index; index < screenCount; index++)
{
NSScreen *screen = [screenArray objectAtIndex: index];
NSRect screenRect = [screen visibleFrame];
NSString *mString = ((mainScreen == screen) ? @"Main" : @"not-
main");
NSLog(@"Screen #%d (%@) Frame: %@", index, mString,
NSStringFromRect(screenRect));
}
Enjoy,
Lance
On Nov 22, 2005, at 1:02 PM, Gerd Knops wrote:
On Tue, Nov 22, at 1:27 AM, j o a r wrote:
On 22 nov 2005, at 08.20, m wrote:
Docs say that NSScreen's displayDescription method returns a
dictionary that is supposed to have an entry (key:
NSDeviceResolution) that describes the device's pixel density.
You should be able to back calculate the screen's physical
dimensions from that and the pixel dimensions.
Yes, if it weren't for the fact (?) that it _always_ returns 72
dpi [*].
I think that the bottom line is that Apple _can't_ provide this
information, because it _can't_ get it from the monitor. At least
I'm pretty sure that it wouldn't be possible for CRT and VGA
monitors. Perhaps it would be possible using LCD+DVI, I don't
know enough to say for sure.
When we needed it way back then for OneVision on NeXTSTEP we ended
up adding a calibration preference screen that would show a box
of a certain pixel size, had the user measure it with a ruler and
enter the result...
Gerd
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