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Trouble with Pixmaps

BlitzMax Forums/BlitzMax Beginners Area/Trouble with Pixmaps

Mordax_Praetorian(Posted 2006) [#1]
Graphics 800,600
Local Image = LoadImage ("Images/Cursor.png")
DrawImage(Image, 0,0)
Local Cheese:tpixmap = LockImage(Image)
DrawPixmap(Cheese, 64, 0)
Flip
Delay 5000

The image "Cursor.png" is an arrow with a pixel thin orange outline, in the image from the Pixmap this outline is now 2 pixels thick


Cheese = ColourSub(Cheese,0,0,128,200,140,0,32,19)


Function ColourSub:Tpixmap(Image:Tpixmap,OldR,OldG,OldB,NewR,NewG,NewB,w,h)
	MaskPixmap:Tpixmap(Image, OldR,OldG,OldB)
	SetClsColor NewR,NewG,NewB
	Cls
	DrawPixmap Image:TPixmap, 0, 0
	Image = GrabPixmap:TPixmap (0,0,w,h)
	SetClsColor 0,0,0
	Return Image
End Function

The function seems not to modify the pixmap at all, when I draw it out again after calling the function, it looks just like it did when it went in

I have checked the colour codes in MS Paint, 0,0,128 does indeed make up the main body of the arrow


Beaker(Posted 2006) [#2]
I'm not surprised it doesn't look different. Masks don't have any effect on pixmaps.

I'm guessing (cos I'm not entirely sure what you are tryin to do), but I think you may need to draw the image using DrawImage instead of DrawPixmap, before you grab it using GrabPixmap.


Mordax_Praetorian(Posted 2006) [#3]
ok, Changing

MaskPixmap:Tpixmap(Image, OldR,OldG,OldB)


to:

Image = MaskPixmap:Tpixmap(Image, OldR,OldG,OldB)


Did have some affect, unfortunatly it wasnt what I was hoping for

it created a transparent area, and the colours around it all advanced 1 pixel further into the transparent area

MaskPixmap returns a new Pixmap with pixels of the specified colour made transparent

There are good reasons I cant use Images here, you cant mask them directly anymore, only upon load or when modified, which is very unhelpful indeed


REDi(Posted 2006) [#4]


But IMO it would be better to readpixel/writepixel to do this sort of thing.


Mordax_Praetorian(Posted 2006) [#5]
Wow, I am such an atrocious programmer

Not only have I been unable to solve a single problem I've had with max on my own so far, but every document I've found on Alpha Blending in response to reading that post has either been irrelevant or just gone way over my head

-Edit: Nevermind, figured the above out, that could be very useful later-

I dont understand how I would handle the output of ReadPixel, or construct input for Write pixel either


REDi(Posted 2006) [#6]
I dont understand how I would handle the output of ReadPixel, or construct input for Write pixel either 

Strict
Graphics 800,600,0
Local Image:Timage = LoadImage ("Cursor.bmp")
DrawImage(Image, 0,0)
ColourSub(Image,0,0,128, 200,140,0)
DrawImage(Image, 64, 0)
Flip
Delay 5000

Function ColourSub(Image:TImage,OldR,OldG,OldB,NewR,NewG,NewB)
	Local Pix:TPixmap = LockImage(Image)
	Local x:Int, y:Int
	Local OldColour:Int = (255 Shl 24)|(OldR Shl 16)|(OldG Shl 8)|OldB 
	Local NewColour:Int = (255 Shl 24)|(NewR Shl 16)|(NewG Shl 8)|NewB 
	For x=0 Until PixmapWidth(Pix)
		For y=0 Until PixmapHeight(Pix)
			If ReadPixel(Pix,x,y) = OldColour
				WritePixel(Pix,x,y,NewColour)
			EndIf
		Next
	Next
	UnlockImage(Image)
End Function



Mordax_Praetorian(Posted 2006) [#7]
Ok, General question, do Pixmaps always store things as these argb values?

If so I imagine that this would vastly restrict the number of shades you can have, the difference between 0->7 for R, G or B, and 0->255 for R, G, and B is pretty huge

Edit: Please, dont write code for me, I'm not asking for that, I thank you for the effort, but I'd rather just have some hints in the right direction so I can figure it out for myself, I'm never going to get anywhere if people are just writing my code for me


REDi(Posted 2006) [#8]
0->7? dont panic its still stored as 0->255, its just all packed into one int.

http://en.wikipedia.org/wiki/ARGB


Mordax_Praetorian(Posted 2006) [#9]
Aha, its in Hex, that explains it

ty very much, I think I can write a working function now