Re: [JAVA2D] Copying a portion of an Image?

2008-08-25 Thread Ken Warner 

uhhh

Maybe you meant:

BufferedImage snap = new BufferedImage(subw, subh, TYPE_INT_RGB);
>>> Graphics2D g2d = snap.createGraphics();


Jim Graham wrote:

Yes, if you want alpha you should pass in TYPE_INT_ARGB.

Note that the default compositing mode of the freshly retrieved graphics 
object is SRC_OVER.  The code sample still works fine since the newly 
constructed image is all 0's (transparent pixels) so copying your source 
image "over" the fully transparent image works just fine.


But, if you try to reuse the image and copy a different section of the 
source image into it at a later stage then you might want to do the 
image copy using "g2d.setComposite(AlphaComposite.SRC)"...


...jim

[EMAIL PROTECTED] wrote:


// assuming:
Image src;
int subx, suby, subw, subh;
// then execute:
BufferedImage snap =
new BufferedImage(subw, subh, TYPE_INT_RGB);
Graphics2D g2d = snap.createImage();
g2d.drawImage(src, -subx, -suby, null);
g2d.dispose();
// snap is now a snapshot of subx,y,w,h of src



OK; thanks.


If you didn't want a snapshot, I can outline other
ways, but I'm guessing that this is probably what you wanted...?



Yep.  What allowed you to know that TYPE_INT_RGB was the correct 
parameter to pass in the BufferedImage constructor?  If it helps, I 
know that the source image often has an alpha value set.  Would I use 
TYPE_INT_RGBA in this case?


Thanks again for helping this newbie out.

Best,
Laird
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Re: [JAVA2D] Copying a portion of an Image?

2008-08-25 Thread Jim Graham 

Yes, if you want alpha you should pass in TYPE_INT_ARGB.

Note that the default compositing mode of the freshly retrieved graphics 
object is SRC_OVER.  The code sample still works fine since the newly 
constructed image is all 0's (transparent pixels) so copying your source 
image "over" the fully transparent image works just fine.


But, if you try to reuse the image and copy a different section of the 
source image into it at a later stage then you might want to do the 
image copy using "g2d.setComposite(AlphaComposite.SRC)"...


...jim

[EMAIL PROTECTED] wrote:

// assuming:
Image src;
int subx, suby, subw, subh;
// then execute:
BufferedImage snap =
new BufferedImage(subw, subh, TYPE_INT_RGB);
Graphics2D g2d = snap.createImage();
g2d.drawImage(src, -subx, -suby, null);
g2d.dispose();
// snap is now a snapshot of subx,y,w,h of src


OK; thanks.


If you didn't want a snapshot, I can outline other
ways, but I'm 
guessing that this is probably what you wanted...?


Yep.  What allowed you to know that TYPE_INT_RGB was the correct parameter to 
pass in the BufferedImage constructor?  If it helps, I know that the source 
image often has an alpha value set.  Would I use TYPE_INT_RGBA in this case?

Thanks again for helping this newbie out.

Best,
Laird
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Re: [JAVA2D] Copying a portion of an Image?

2008-08-25 Thread java2d 
>   // assuming:
>   Image src;
>   int subx, suby, subw, subh;
>   // then execute:
>   BufferedImage snap =
>   new BufferedImage(subw, subh, TYPE_INT_RGB);
>   Graphics2D g2d = snap.createImage();
>   g2d.drawImage(src, -subx, -suby, null);
>   g2d.dispose();
>   // snap is now a snapshot of subx,y,w,h of src

OK; thanks.

> If you didn't want a snapshot, I can outline other
> ways, but I'm 
> guessing that this is probably what you wanted...?

Yep.  What allowed you to know that TYPE_INT_RGB was the correct parameter to 
pass in the BufferedImage constructor?  If it helps, I know that the source 
image often has an alpha value set.  Would I use TYPE_INT_RGBA in this case?

Thanks again for helping this newbie out.

Best,
Laird
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Re: [JAVA2D] Copying a portion of an Image?

2008-08-25 Thread Jim Graham 

It depends on your definition of the term "from the contents of".

The simplest way to get a snapshot of a subrectangle of an existing 
image is to simply create a new image and draw the original into the new 
one, as in:


// assuming:
Image src;
int subx, suby, subw, subh;
// then execute:
BufferedImage snap =
new BufferedImage(subw, subh, TYPE_INT_RGB);
Graphics2D g2d = snap.createImage();
g2d.drawImage(src, -subx, -suby, null);
g2d.dispose();
// snap is now a snapshot of subx,y,w,h of src

and the "snap" image will now be a snapshot of the contents in that 
rectangle (subxywh) of the original "src" image, and it will be a 
BufferedImage as you requested.  Further rendering on the "src" image 
will not affect the contents of the "view" image and vice versa.


If you didn't want a snapshot, I can outline other ways, but I'm 
guessing that this is probably what you wanted...?


...jim

[EMAIL PROTECTED] wrote:

I feel fairly stupid asking this question, as it seems like an operation that 
should be pretty simple, and it probably is, but for whatever reason I can't 
figure out the best way to do it.  So I'm sorry in advance.  :-)

I'd like to create a new BufferedImage from the contents of a subregion of an 
existing java.awt.Image.  What is the best, least bloated, least convoluted way 
to do this?

Thanks in advance,
Laird
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Re: [JAVA2D] Copying a portion of an Image?

2008-08-25 Thread Ken Warner 

I'd suggest starting with a BufferedImage rather than an Image.
They don't play well together...

[EMAIL PROTECTED] wrote:

I feel fairly stupid asking this question, as it seems like an operation that 
should be pretty simple, and it probably is, but for whatever reason I can't 
figure out the best way to do it.  So I'm sorry in advance.  :-)

I'd like to create a new BufferedImage from the contents of a subregion of an 
existing java.awt.Image.  What is the best, least bloated, least convoluted way 
to do this?

Thanks in advance,
Laird
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[JAVA2D] Copying a portion of an Image?

2008-08-25 Thread java2d 
I feel fairly stupid asking this question, as it seems like an operation that 
should be pretty simple, and it probably is, but for whatever reason I can't 
figure out the best way to do it.  So I'm sorry in advance.  :-)

I'd like to create a new BufferedImage from the contents of a subregion of an 
existing java.awt.Image.  What is the best, least bloated, least convoluted way 
to do this?

Thanks in advance,
Laird
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