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Topic: Fading away (Read 677 times) |
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KenDown
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Fading away
« Thread started on: Sep 29th, 2015, 10:04am » |
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Some time ago I copied, from somewhere, a short program written by Richard which faded from one picture to another. I have used it sparingly in my "Display" program - perhaps one or two fades per presentation.
I am working on a different program and this time use lots of fades. I was horrified to discover that after 7 full-screen fades (and my screens are 1920x1080) the fade function just stopped working!
Eventually I tracked the problem down to a missing command. Whether I missed it out when I copied the program or it is missing for some other reason, once it was inserted the fade program appears - as far as I have tested it - to be fixed.
After the line SYS"DeleteObject",himage%TOdelete% you must insert SYS"DeleteDC",hdc%
Apparently DeleteObject on its own will not delete an object that has been turned into a DC (whatever a DC is).
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DDRM
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Re: Fading away
« Reply #1 on: Sep 29th, 2015, 11:47am » |
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Hi Ken,
DC is a device context - "a structure that defines a set of graphic objects and their associated attributes, as well as the graphic modes that affect output", according MSDN
https://msdn.microsoft.com/en-us/library/windows/desktop/dd183553%28v=vs.85%29.aspx
I can imagine that if you don't delete such a structure once you have finished using it, you may eventually run out of space, but I don't know if that is the problem in your case.
Is it possible to use the same DC for successive fades, by selecting a new bitmap into it?
Best wishes,
D
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KenDown
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Re: Fading away
« Reply #2 on: Sep 29th, 2015, 6:19pm » |
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Thanks for the explanation.
My experience would seem to indicate that you can't. Without the deletion the fade stopped working. I mentioned that it stopped after 7 full-screen fades. With the program I'm working on the screens were a mere 9th of the full-screen, so I got up to 74 fades before it stopped. I ran it several times and it always stopped at the same number, so yes, I think it was a memory problem.
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DDRM
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Re: Fading away
« Reply #3 on: Sep 30th, 2015, 4:06pm » |
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Hi Ken,
Here's some basic, if working, code, showing that you can re-use the same device context/bitmap for successive images. I hope I've annotated it enough to make sense.
Basically, you choose the first jpeg from a folder full of them, and it will then plough through the rest, fading from one to the next. First we set up a device context (and associated bitmap) to match the BB4W output window, then we load the images into it. AlphaBlend does the actual magic, copying the image from the "spare" copy into the output window, at ever increasing alpha values (0 = transparent, 255 = solid).
Most of the code is just clumsy ways of getting the file names - so if you have these already you can ditch it.
Does that help with what you want to do?
Best wishes,
D
Edit: Note that I haven't included routines to tidy up by releasing the bitmap and DC when the program finishes, which I should have done - I think it will automatically get released when the program exits, but might not if you ran it repeatedly without restarting.
Code:
MODE 21 :REM 800 x 600
xpos%=0
ypos%=0
xsize%=@vdu%!208
ysize%=@vdu%!212
REM We make a "spare" device context and bitmap the same size as the display
PROCMakeSpareBitmap(xsize%,ysize%)
REM AlphaBlend isn't one of the functions we can get by name, so need to find and load it
SYS "LoadLibrary", "Msimg32.DLL" TO msim%
SYS "GetProcAddress", msim%, "AlphaBlend" TO alphablend%
IF alphablend%=0 ERROR 100, "Could not get address of AlphaBlend"
REM Choose the first jpeg in a folder manually
picture$=FNGetFileName
IF picture$<>"" THEN
REPEAT
REM We load the chosen picture into our "spare" DC and bitmap
PROCLoadPictoNewDC(picture$,xpos%,ypos%,xsize%,ysize%)
FOR x%=1 TO 8
REM Now we are going to blend it into the screen, at ever increasing densities (range 0-255)
density%=((2^x%)-1)<<16
SYS alphablend%,@memhdc%,0,0,xsize%,ysize%,newdc%,0,0,xsize%,ysize%,density%
REM Tell windows to update the picture
SYS "InvalidateRect", @hwnd%, 0, 0
SYS "UpdateWindow", @hwnd%
WAIT 5 :REM Adjust to give the speed of fade you want
NEXT x%
ENDIF
WAIT 20
REM Now we'll look automatically for the next jpeg in that folder, and start the whole thing again
picture$=FNlistdirectory
UNTIL picture$=""
ENDIF
END
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DEFPROCMakeSpareBitmap(xsize%,ysize%)
SYS "CreateCompatibleDC",@memhdc% TO newdc%
IF newdc%=0 THEN PRINT "Failed to make DC":END
SYS "CreateCompatibleBitmap",@memhdc%,xsize%,ysize% TO newbmp%
IF newbmp%=0 THEN PRINT "Failed to make bmp":END
SYS "SelectObject",newdc%,newbmp%
ENDPROC
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DEF PROCLoadPictoNewDC(picture$,xpos%,ypos%,xsize%,ysize%)
REM This is just PROCdisplay from the manual, adapted to load the image into the spare device context/bitmap
LOCAL oleaut32%, olpp%, iid%, gpp%, hmw%, hmh%, picture%, res%
SYS "LoadLibrary", "OLEAUT32.DLL" TO oleaut32%
SYS "GetProcAddress", oleaut32%, "OleLoadPicturePath" TO olpp%
IF olpp%=0 ERROR 100, "Could not get address of OleLoadPicturePath"
DIM iid% LOCAL 15, picture% LOCAL 513
SYS "MultiByteToWideChar", 0, 0, picture$, -1, picture%, 256
iid%!0 = &7BF80980
iid%!4 = &101ABF32
iid%!8 = &AA00BB8B
iid%!12 = &AB0C3000
SYS olpp%, picture%, 0, 0, 0, iid%, ^gpp%
IF gpp% = 0 ERROR 100, "OleLoadPicturePath failed"
SYS !(!gpp%+24), gpp%, ^hmw% : REM. IPicture::get_Width
SYS !(!gpp%+28), gpp%, ^hmh% : REM. IPicture::get_Height
SYS !(!gpp%+32), gpp%, newdc%, xpos%, ypos%, xsize%, ysize%, 0, \
\ hmh%, hmw%, -hmh%, 0 TO res%
IF res% ERROR 100, "IPicture::Render failed"
SYS !(!gpp%+8), gpp% : REM. IPicture::Release
ENDPROC
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DEFFNGetFileName
REM Basically the routine from the manual made into a function returning the filename
LOCAL fs{},fp,ff$,filename$
DIM fs{lStructSize%, hwndOwner%, hInstance%, lpstrFilter%, \
\ lpstrCustomFilter%, nMaxCustFilter%, nFilterIndex%, \
\ lpstrFile%, nMaxFile%, lpstrFileTitle%, \
\ nMaxFileTitle%, lpstrInitialDir%, lpstrTitle%, \
\ flags%, nFileOffset{l&,h&}, nFileExtension{l&,h&}, \
\ lpstrDefExt%, lCustData%, lpfnHook%, lpTemplateName%}
DIM fp{t&(260)}
REM ff$ = "BMP files"+CHR$0+"*.BMP"+CHR$0+CHR$0
fs.lStructSize% = DIM(fs{})
fs.hwndOwner% = @hwnd%
fs.lpstrFilter% = !^ff$
fs.lpstrFile% = fp{}
fs.nMaxFile% = 260
fs.flags% = 6
SYS "GetOpenFileName", fs{} TO result%
IF result% filename$ = $$fp{} ELSE filename$=""
=filename$
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DEF FNlistdirectory
REM Basically the routine in the manual, adapted to give the next jpeg in the directory
PRIVATE dir%, res%,cdir$,cdirbuff%
PRIVATE sh%
IF sh%=0 THEN
DIM dir% LOCAL 317
DIM cdirbuff% LOCAL 300
SYS "GetCurrentDirectory",300,cdirbuff%
cdir$=$$cdirbuff%+"\"
SYS "FindFirstFile", "*.jpg", dir% TO sh%
= cdir$+$$(dir%+44)
ELSE
SYS "FindNextFile", sh%, dir% TO res%
IF res%=0 THEN =""
= cdir$+$$(dir%+44)
ENDIF
=""
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« Last Edit: Sep 30th, 2015, 9:21pm by DDRM » |
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