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Resizing and Freeing Images

BlitzMax Forums/BlitzMax Beginners Area/Resizing and Freeing Images

Clyde(Posted 2005) [#1]
This is not a TPixmap question, regular LoadImages.

Is there a way to resize, and also release any images that arent needed by BMAX? Equivelant commands to ResizeImage and FreeImage?

Thanks,
THUMBZ


xlsior(Posted 2005) [#2]
images are stored in the videoram on your actual video card.

you can -draw- them are a different size by changing the scale with SetScale, but the only way to truly resize the image bitmap itself is by copying it back into regular RAM, resize it, and abck to video ram: by converting to a pixmap, resize it, and back to an image when you're done.

You can release an image though:

myimg:timage=loadimage("whatever.jpg")
myimg:timage=null ' mark for deletion
flushmem ' remove unused objects from memory


Clyde(Posted 2005) [#3]
The resizing sounds complicated, thanks for the freeimages tip.


tonyg(Posted 2005) [#4]
Graphics 640,480
image = LoadImage("max.png",dynamicimage)
DrawImage image,0,0
DrawText "Original : " ,0,0
Flip
WaitKey()
my_pixmap = LockImage(image)
my_new_pixmap = ResizePixmap (my_pixmap,100,100)
UnlockImage(image)
image=LoadImage(my_new_pixmap)
WaitKey()
Cls
DrawImage image,0,0
DrawText "Resized : ",0,0
Flip
WaitKey()



Clyde(Posted 2005) [#5]
Wonderfull, I'll have a stab at that.
Thanks man.


ImaginaryHuman(Posted 2005) [#6]
Isn't it faster to write the image to the backbuffer then grab it back into a new image, rather than move it to a pixmap, change it, move it back from a pixmap?


tonyg(Posted 2005) [#7]
It's close.
290ms Pixmap vs 360 Images with debug.
180ms Pixmap vs 220 Images without debug
The pixmap results in a cleaner image though. 
Graphics 640,480
image = LoadImage("max.png",dynamicimage)
start_time=MilliSecs()
my_pixmap = LockImage(image)
xscale# = 1.5
yscale# = 1.5
my_new_pixmap = ResizePixmap (my_pixmap,ImageWidth(image)*xscale,ImageHeight(image)*yscale)
UnlockImage(image)
image=LoadImage(my_new_pixmap)
Cls
DrawImage image,0,0
DrawText "Resized : ",0,0
end_time=MilliSecs()
total_time = end_time - start_time
DrawText "Total_time : " + total_time,0,10
Flip
WaitKey()


Graphics 640,480
image = LoadImage("max.png",dynamicimage)
start_time=MilliSecs()
xscale# = 1.5
yscale# = 1.5
SetScale xscale,yscale
DrawImage image,0,0
my_image = CreateImage(ImageWidth(image)*xscale,ImageHeight(image)*yscale)
GrabImage(my_image,0,0)
Cls
SetScale 1.0,1.0
DrawImage my_image,0,0
DrawText "Resized : ",0,0
end_time=MilliSecs()
total_time = end_time - start_time
DrawText "Total_time : " + total_time,0,10
Flip
WaitKey()

Any mistake spotting or optimisations most welcome


Emmett(Posted 2005) [#8]
Using the pixmap method I did this to get an image to pump. Image size is 64x64
Graphics 640,480
Repeat
	If MouseX()>0 And MouseX()<60 And MouseY()<60 blink()
	image = LoadImage("media/tiles/first.png",dynamicimage)
	DrawImage image,0,0
	Flip
	Cls
	FlushMem
Until KeyHit(1)

Function blink()
	For count=1 To 4
	image = LoadImage("media/tiles/first.png",dynamicimage)
	DrawImage image,0,0
	Flip
	Delay 100
	my_pixmap = LockImage(image)
	my_new_pixmap = ResizePixmap (my_pixmap,66,66)
	UnlockImage(image)
	image=LoadImage(my_new_pixmap)
	Cls
	DrawImage image,0,0
	Flip
	Delay 100
	Next
End Function

Will this cause any problems? Is there another way to pump an image?
So if CreateImage is the method used on the backbuffer where is the pixmap operation happening?
I'm learning folks - please excuse my ignorance.


Curtastic(Posted 2005) [#9]
DrawImageRect draws the entire image into a rectangle at whetever size you want


tonyg(Posted 2005) [#10]
Very good to know. The image looks a bit pixelly.
For the 'pump' I would probably use Set Scale rather than using pixmaps.


FlameDuck(Posted 2005) [#11]
Isn't it faster to write the image to the backbuffer then grab it back into a new image, rather than move it to a pixmap, change it, move it back from a pixmap?
The problem with doing it this way is that any transforms and filtering (probably tri-linear) will be passed on to the new image. For resizeing, it's probably not a big deal since you'd want some sort of filtering anyway.

However, it would generally be faster to do it all in realtime ala. SetRotation.

As for how to free images, that ones real simple. Stop using it. And don't forget to call flushmem once in a while (from as "global" a scope as possible).