Blank Screen Capture

[Phil Pendlebury]

Hi there,

My application relies on capturing screen images. A user complains the application was not working.

Luckily I have a ton of error catching built in which includes a zip file full of the screen grabs made by MS and the images it was looking for at the time.

All his screen captures (taken within the script) are showing nothing but blank white images (all of the correct size). So for example, instead of capturing an image of the application we need to search, MS's capture is just a white solid box.

I searched high and low on this forum and also general google...

He answered:

If I take a manual shot via PrintScrn, it's fine. I see everything. I have no applications running in the background as referenced from the manual. Yes, I am running as an admin. My font size is at 125%. I have no screen saver setup to key shortcuts. No, not running virtual machine.

I had also asked about multiple monitors and some other obvious stuff.

I had to give up and refund him.

I'm interested to know if anyone has any theories on this?

[JRL]

Hi Phil,

If you take a screen capture that is not on the visible desktop you get an all white image. Perhaps the users desktop is located at an odd spot in the coordinate system. Is his upper left hand corner located at 0,0 or is it located at some other point? If it's some other point and you take a screen shot using 0,0 as the upper left base, it might be missing his visible desktop completely.

Just a thought.
Dick

[Phil Pendlebury]

Hi Dick,

Thanks... But...

I am not sure what you mean by that. How would the upper left corner not be located at 0,0? And surely if there was a way of doing that he would know that he had done it?

Can you suggest a way I would check that?

[JRL]

Sorry, I don't know how or why the upper left corner of the desktop would be something other than 0,0, I just know that I've seen it on a virtual desktop. Might be only virtual desktops or might be a display driver or might be a display intensive application like CAD software or a game.

One may or may not know that their desktop coordinate system is non standard. Except for Macro Scheduler, how often do we "see" our mouse coordinates?

Again, this is just a wild-ass-guess as to what the issue might be. You were not getting any other suggestions, plus this serves to bump your question back to the top.

You can easily check by moving the mouse to -32000,-32000 and testing its coordinates when it gets as close to there as it can get.

Code: Select all

GetCursorPos>Curx,CurY
MouseMove>-32000,-32000
GetCursorPos>ULx,ULy
MouseMove>Curx,CurY

MDL>%ULx%,%ULy%

[Phil Pendlebury]

Thanks Dick,

Your input is highly appreciated, I am just at a loss to think of how this could happen. If only I had access to the guy's machine.

I'll try and think of a way to check this accurately using a script I guess...

[mightycpa]

Why not create a script that walks him through some mouseclicking and screenshotting manually, and you take screenshots and record cursor positions too while he follows your instructions? Then save and check the results.

I'd start there.

[Phil Pendlebury]

Hi there,

Yes my application (which has almost a hundred carefully crafted error trapping and tracing routines) already does that to a degree. But sending another script to a customer in this situation is not really an option. Especially as he is now refunded.

I just need to find out if anyone else has come across this bearing in mind that I have tried all the things listed above. And suggestions to what may cause it.

I just want to be able to mail him and say "aha do you by any chance have xxx on your system?"

Thanks again.

[Phil Pendlebury]

Sorry to bump this but just wondered if Marcus may have any thoughts? Anything you may have come across that I haven't checked for? Any suggestions appreciated.

[Marcus Tettmar]

Hi Phil,

No, none, sorry Phil, I've no idea.

If you'd said BLACK screen I'd have suggested it was while locked/logged out. You get a black screen in that situation. I've NEVER seen an all WHITE screen image.

Doesn't help much I know - I wish I had an idea. Maybe screen driver issue?

[Phil Pendlebury]

Thanks Marcus. I will keep trying to repro this and update here if any news.