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Topic: A quick way to sample pixels in Windows 7? (Read 4038 times) |
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sbracken
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Re: A quick way to sample pixels in Windows 7?
« Reply #4 on: Mar 10th, 2014, 4:47pm » |
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Hi Richard,
Even better - the translated code looks much more friendly! Thanks again for your help.
I have now had a chance to try the original code you posted with LBB and it does indeed work well on Windows 7.
Simon
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admin
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Re: A quick way to sample pixels in Windows 7?
« Reply #5 on: Mar 10th, 2014, 6:03pm » |
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on Mar 10th, 2014, 4:47pm, sbracken wrote:| I have now had a chance to try the original code you posted with LBB and it does indeed work well on Windows 7. |
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Windows 7 isn't too much of a challenge - my Magnifying Glass program runs acceptably by virtue of temporarily disabling the Desktop Window Manager (magglass.exe here); you're welcome to have the source code of that. But Windows 8/8.1 is a different matter; you can't disable the DWM and the magnifying glass program doesn't work at all. 
The LB program doesn't attempt to be so ambitious, so runs OK on all versions of Windows.
Richard.
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sbracken
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Re: A quick way to sample pixels in Windows 7?
« Reply #6 on: Mar 10th, 2014, 7:57pm » |
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Quote:| ...my Magnifying Glass program runs acceptably by virtue of temporarily disabling the Desktop Window Manager... |
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I had tried your Magnifying Glass program before, but I somehow failed to notice the change in the desktop, and the warning that accompanies it!
Thank you for the offer of the source code. I may take you up on this, but I will have a go at using StretchBlt first.
Simon
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admin
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Re: A quick way to sample pixels in Windows 7?
« Reply #7 on: Mar 11th, 2014, 11:59am » |
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on Mar 10th, 2014, 7:57pm, sbracken wrote:| I had tried your Magnifying Glass program before |
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I was looking at the 'Magnification API' as a possible way of making the Magnifying Glass program work in Windows 8/8.1, when I found this on MSDN:
"The Magnification API is not supported under WOW64; that is, a 32-bit magnifier application will not run correctly on 64-bit Windows."
That is very bad; I wonder how Microsoft can justify it.
Edit: Further Googling reveals that it's a bug in the Magnification DLL (an internal handle being declared as signed rather than unsigned), which - rather than being fixed - Microsoft have decided to 'document away' by means of the above caveat. I'm not a Microsoft hater - far from it - but I can understand the anger caused when they do something so idiotic.
Richard.
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| « Last Edit: Mar 11th, 2014, 12:10pm by admin » |
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sbracken
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Re: A quick way to sample pixels in Windows 7?
« Reply #8 on: Mar 11th, 2014, 3:17pm » |
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I have now managed to get StretchBlt to work, and much to my own amazement it proved to be pretty staight forward. It would certainly have taken longer if I only had the Liberty BASIC original to work form, so many thanks again, Richard.
Code:
VDU 23,22,228;156;8,16,16,0
OFF
COLOUR 15,236,233,216
COLOUR 1,236,233,216
GCOL0,128+1:CLG
DIM pt{x%,y%}
oldx%=0
oldy%=0
r%=0
g%=0
b%=0
step%=11
side%=24
GCOL0,0
RECTANGLE FILL side%-4,side%-6,(side%*step%)+8,(side%*step%)+8
RECTANGLE FILL 304,160,132,132
SYS "GetDesktopWindow" TO dtw%
SYS "GetDC", dtw% TO hdc%
SYS "GetDC", @hwnd% TO mag%
ON CLOSE SYS "ReleaseDC", hdc%:SYS "ReleaseDC", mag%:QUIT
REPEAT
WAIT 1
MOUSE X%,Y%,B%
IF (X%<>oldx% OR Y%<>oldy%) THEN
SYS "GetCursorPos", pt{}
SYS "GetPixel", hdc%, pt.x%, pt.y% TO rgb%
r%=rgb% AND 255
g%=(rgb% >> 8) AND 255
b%=(rgb% >> 16) AND 255
COLOUR1,r%,g%,b%
GCOL0,1
RECTANGLE FILL 308,164,124,124
SYS "SetWindowText", @hwnd%, STRING$(3-LEN(STR$(r%))," ")+STR$(r%)+" "+STRING$(3-LEN(STR$(g%))," ")+STR$(g%)+" "+STRING$(3-LEN(STR$(b%))," ")+STR$(b%)
magX%=pt.x%-INT(step%/2)
magY%=pt.y%-INT(step%/2)
SYS "StretchBlt", mag%, side%/2, side%/2, (side%*step%)/2, (side%*step%)/2, hdc%, magX%, magY%, step%, step%, 13369376, @memhdc% TO r%
GCOL4,0
RECTANGLE side%*(INT(step%/2)+1)-2,side%*(INT(step%/2)+1)-2,side%+2,side%+2
oldx%=X%
oldy%=Y%
ENDIF
UNTIL FALSE
QUIT
The only issue remaining is the inversely plotted rectangle that is supposed to frame the central pixel in the magnification box. It does not work properly, presumably because BB4W doesn't know what has been put there by the call to StretchBlt. My solution has been to simply draw a filled rectangle in the centre of the magnification box myself and then invert its edge, replacing
Code:
GCOL4,0
RECTANGLE side%*(INT(step%/2)+1)-2,side%*(INT(step%/2)+1)-2,side%+2,side%+2
with
Code:
GCOL0,1
RECTANGLE side%*(INT(step%/2)+1),side%*(INT(step%/2)+1),side%,side%
GCOL4,0
RECTANGLE side%*(INT(step%/2)+1),side%*(INT(step%/2)+1),side%,side%
but is there a better way?
Simon
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admin
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Re: A quick way to sample pixels in Windows 7?
« Reply #9 on: Mar 11th, 2014, 4:05pm » |
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on Mar 11th, 2014, 3:17pm, sbracken wrote:| I have now managed to get StretchBlt to work, and much to my own amazement it proved to be pretty staight forward. |
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It's not working properly. You are plotting directly to the screen, not to BB4W's output bitmap, which means the two will be fighting each other! The most obvious symptom is the failure of your 'inverse' rectangle, but it's the wrong way to go about things.
Effectively you have tried to reproduce the way the Liberty BASIC program works in 'real' LB 4.04, not the way it works in LB Booster. If you look at the LBB translation you will see that the code doesn't actually call the Windows GetDC API function at all, but the function FN_getdc in LBLIB (which returns the DC of the output bitmap).
To fix this you need to get rid of all references to mag%, which is the screen DC and therefore something that you should not be touching, and replace it with @memhdc% as follows:
Code: VDU 23,22,228;156;8,16,16,0
OFF
COLOUR 15,236,233,216
COLOUR 1,236,233,216
GCOL0,128+1:CLG
DIM pt{x%,y%}
oldx%=0
oldy%=0
r%=0
g%=0
b%=0
step%=11
side%=24
GCOL0,0
RECTANGLE FILL side%-4,side%-6,(side%*step%)+8,(side%*step%)+8
RECTANGLE FILL 304,160,132,132
SYS "GetDesktopWindow" TO dtw%
SYS "GetDC", dtw% TO hdc%
ON CLOSE SYS "ReleaseDC", hdc%:QUIT
REPEAT
WAIT 1
MOUSE X%,Y%,B%
IF (X%<>oldx% OR Y%<>oldy%) THEN
SYS "GetCursorPos", pt{}
SYS "GetPixel", hdc%, pt.x%, pt.y% TO rgb%
r%=rgb% AND 255
g%=(rgb% >> 8) AND 255
b%=(rgb% >> 16) AND 255
COLOUR1,r%,g%,b%
GCOL0,1
RECTANGLE FILL 308,164,124,124
SYS "SetWindowText", @hwnd%, STRING$(3-LEN(STR$(r%))," ")+STR$(r%)+" "+STRING$(3-LEN(STR$(g%))," ")+STR$(g%)+" "+STRING$(3-LEN(STR$(b%))," ")+STR$(b%)
magX%=pt.x%-INT(step%/2)
magY%=pt.y%-INT(step%/2)
SYS "StretchBlt", @memhdc%, side%/2, side%/2, (side%*step%)/2, (side%*step%)/2, hdc%, magX%, magY%, step%, step%, 13369376, @memhdc% TO r%
SYS "InvalidateRect", @hwnd%, 0, 0
GCOL4,0
RECTANGLE side%*(INT(step%/2)+1)-2,side%*(INT(step%/2)+1)-2,side%+2,side%+2
oldx%=X%
oldy%=Y%
ENDIF
UNTIL FALSE
QUIT
Richard.
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sbracken
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Re: A quick way to sample pixels in Windows 7?
« Reply #10 on: Mar 11th, 2014, 5:24pm » |
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Thanks for the correction. I tried to find LBLIB to better understand the translation, but all my searching came up blank. It is not in the Files area of the Yahoo group, for example, although LBprompt.tpl is.
Although it is not relevant for my program, I was curious about another aspect of the translation: Zoom$(15) is dimensioned by a call to PROC_dim1d$ rather than a DIM statement. Is there another BB4W/LB difference here?
Simon
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admin
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Re: A quick way to sample pixels in Windows 7?
« Reply #11 on: Mar 11th, 2014, 5:59pm » |
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on Mar 11th, 2014, 5:24pm, sbracken wrote:| I tried to find LBLIB to better understand the translation, but all my searching came up blank. It is not in the Files area of the Yahoo group |
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It is in the Files area of the LBB Yahoo group, but it's called LBLIB.BBCC (note the unusual extension):
https://groups.yahoo.com/neo/groups/lbb/files
But since it's a 'crunched' library it's hard to read and I wouldn't necessarily have expected you to look at it. I probably should have drawn your attention to the fact that you would need to use @memhdc% as the 'destination' DC. It's the old problem of not knowing what you don't know!
Quote:| Is there another BB4W/LB difference here? |
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Not in that particular program, no; if you were to trace through PROC_dim1d$ you would find that in fact it just does a conventional DIM.
The issue arises if a program DIMs (or REDIMs; in LB they are synonymous) that same array again. In BBC BASIC that would simply give rise to a 'Bad DIM' error so the procedure in LBLIB checks to see if the array was previously defined and if so avoids generating the error.
Richard.
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sbracken
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Re: A quick way to sample pixels in Windows 7?
« Reply #12 on: Mar 11th, 2014, 7:49pm » |
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on Mar 11th, 2014, 5:59pm, Richard Russell wrote:It's the old problem of not knowing what you don't know!
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Indeed, I often don't know what I don't know!
Thanks again for the help. Now to update the full version of my program to work with StretchBlt...
Simon
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RNBW
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Re: A quick way to sample pixels in Windows 7?
« Reply #13 on: Jan 7th, 2015, 4:21pm » |
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I've tried finding LBLIB.BBCC in the files area and I can't find it either. It might be a mystery to me, but I'd like to have a look at it.
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rtr2
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Re: A quick way to sample pixels in Windows 7?
« Reply #14 on: Jan 7th, 2015, 5:18pm » |
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on Jan 7th, 2015, 4:21pm, RNBW wrote:| I've tried finding LBLIB.BBCC in the files area and I can't find it either. |
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I'm mystified by that. I just clicked on the link I published in my earlier reply, and there was LBLIB.bbcc as the very first file listed!
Of course you'll need to be a member of that group before you can see the contents of its Files area; is it possible you neglected to join the group before looking there?
Richard.
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RNBW
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Re: A quick way to sample pixels in Windows 7?
« Reply #15 on: Jan 12th, 2015, 4:57pm » |
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Hi Richard
I've gone back to the link and it does say that I have to be a member to access the LBB area. I can get into the BB4W files area. Do I need to have a separate membership for the LBB area? If so, how do I go about it?
Regards
Ray
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rtr2
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Re: A quick way to sample pixels in Windows 7?
« Reply #16 on: Jan 12th, 2015, 5:34pm » |
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on Jan 12th, 2015, 4:57pm, RNBW wrote:| Do I need to have a separate membership for the LBB area? If so, how do I go about it? |
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It's not an "LBB area", it's a completely different Yahoo group! You must join, just as you needed to join the BB4W group before you could access the files there. I don't know exactly what the process is, subsequent to the introduction of the awful Neo interface, but it should hopefully be obvious.
Richard.
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RNBW
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Re: A quick way to sample pixels in Windows 7?
« Reply #17 on: Jan 12th, 2015, 9:46pm » |
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Richard
Thanks, I've found out how to join and I've submitted my application for membership to the LBB group. Awaiting a response.
Regards
Ray
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rtr2
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Re: A quick way to sample pixels in Windows 7?
« Reply #18 on: Jan 31st, 2015, 09:36am » |
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on Mar 11th, 2014, 5:59pm, admin wrote:| It is in the Files area of the LBB Yahoo group, but it's called LBLIB.BBCC (note the unusual extension) |
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For those who may be using LBLIB, or may have downloaded it just for interest, please note that it has been updated to version 2.86:
https://groups.yahoo.com/neo/groups/lbb/files
You must be a member of that group to access its Files area.
Richard.
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| « Last Edit: Jan 31st, 2015, 12:56pm by rtr2 » |
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