New g.drawImage () bug?



I was using g.drawimage () for custom look& fill of knob from png film strip.
i.e. my image try to pain a portion of it only like
g.drawImage (image,0, 0,oneFrameWidth,oneFrameHeight, 0, 0, oneFrameWidth, oneFrameHeight);

But since a few tips, it’s all broken and it’s looks stretched and misplaced.
reverting a few tips back fix it.

Anyone else ?



Thanks, yes - looks like a bug in my new CoreGraphics code. Will get it sorted right away…


Better and faster than fastfood !


This seems to still be an issue. I’m sure your aware and working on it … but just in case it’s useful, I notice that:

Using drawImageAt I get the image properly … the image is 500x500, but using drawImage, I get only a very small corner of the upper right part of the image. Going back a few revisions clears it up.

g.drawImage(captureImageProcessed, 0 , 0, 500 , 500 , 0, 0, 500, 500, false);

g.drawImageAt(captureImageProcessed, 0 , 0, false);

Also … if I replace the 500s with 5000s I get something like the whole image. Could it be that the viewing rectangle is getting scaled incorrectly somewhere?


…nope, there’s no bug there. Are you using the latest tip?


No, I’m using the tip, just downloaded tonight to make sure I was uptodate. Here is a clearer demonstration of the issue …

g.drawImage(captureImageProcessed, 0,0, 1600, 1600, 0, 0, 1600, 1600, false);
works …

g.drawImage(captureImageProcessed, 0,0, 1500, 1600, 0, 0, 1600, 1600, false);
works … rescaling the image

g.drawImage(captureImageProcessed, 0,0, 1600, 1600, 0, 0, 1500, 1600, false);
just blank, no image drawn.

g.drawImage(captureImageProcessed, 0,0, 1600, 1600, 10, 0, 1600, 1600, false);
also blank.

As you can see … I can change the destination x,y,w,h no problem … but any values for the source x,y,w,h other than 0,0, width(), height() … and I just get blank canvas. I’ve tried it with captureImageProcessed()->getWidth() - 100 and it also breaks.

The image is ARGB, not that it matters I suppose.


Are those co-ords actually valid? The source rectangle must lie completely inside the image’s bounds or it should fail (and should throw an assertion - maybe you’re just not seeing that?). But there’s an optimisation that checks whether the dest and source are the same size, and if so uses a faster renderer, so that might just be incorrectly working in the first example, when it really ought to be failing.


Yeah, I had thought that too … it’s definitely not the case though (the bounding box is definitely legal). This error is fairly new, and I noticed it because it broke my app in several places.

Also, taking a closer look … it’s not actually painting nothing: instead, it just paints the top 20 pixels or so … seems odd, so I checked it on several images to make sure I was getting consistent results. I always get just the top strip of the image.

Here is another example:

using drawImageAt or using the following code works as expected:
g.drawImage(beatImage, 10 , 40, 180, 50, 0,0, 180, 50, false); // (the image is 180x50 of course)

but reducing the bounding box:
g.drawImage(beatImage, 10 , 40, 180, 50, 0,0, 170, 50, false); // paints just the top 20 or so pixels … see attachment

Really confused on what’s happening here … so just kicking more grief your way I suppose.

PS - Tinkering with the rectangle in drawImageTransformed has the same effect:
g.drawImageTransformed (captureImageProcessed, Rectangle (0, 0, 170, 50),
AffineTransform::scale ((float)1, (float)1)
.translated ((float)0, (float)0), false);


I tested this myself and it all seemed to be working just fine…


ok, I believe it, thanks. I’ll drop a line when I figure out whats going on over here.


If you can send me an image + test code I’ll have another go. I might just not be doing exactly the same thing.