String Rotation

[Saj]

Is it possible to rotate a string on the device using the ImageLixEx library? I've had a look the help but it didn't quite click.

 

[agraham]

Yes. Haven't you tried running the demo? Look at the DrawString Sub.

 

[Saj]

Sorry for being a pain, but I can't find the DrawString sub in any of the examples included in ImageLibEx2.2.zip?

 

[agraham]

It's at line 60 in ImageLibExDemo.sbp.

 

[mjcoon]

Thanks agraham for answering my question about loading bitmaps. I hope that my renewed interest in graphics excuses using your mention of ImageLibExDemo.sbp triggering me to have a play with it (maybe not for the 1st time).

Playfully, I tried multiple rotations by 45 degrees (since that was the default that appeared) to see if the image steadily degraded as I expected it to do. Probably it did, but my PC also slowed down alarmingly (I was running under the PC IDE). And eventually I got OOM as per attached pop-up.

(After a while I got a virtual memory warning too, but I have been getting those sporadically lately.)

So maybe this demo source is not a good example of how to avoid memory leaks per the explanation of memory use in the ImageLibEx Help file.

Regards, Mike.

 

[agraham]

So maybe this demo source is not a good example of how to avoid memory leaks per the explanation of memory use in the ImageLibEx Help file.

That's not the reason for this observed behaviour. From the help for Rotate -

Rotating a bitmap increases its' size by an amount necessary to accomodate the complete rotated image and the blank space created is filled with the fillcolor specified.

The image gets too big after multiple rotates.

 

[mjcoon]

That's not the reason for this observed behaviour.
The image gets too big after multiple rotates.

Ah, I understand the principle. And no doubt the increase will be geometric (appropriately enough!). But I'm amazed that it was so quickly crippling for my PC. I should do some instrumentation...

Mike.

 

[Saj]

When rotating a string using a RotatedFont object, the string seems to progressively move away from being aligned with the centre of rotation as the angle increases. See attached JPG - black dot is the centre. Any suggestions for getting around this as i'd like the string to still be aligned regardless of the angle?

 

[agraham]

I'm afraid not other than to try to characterise the bahaviour and compensate for it.

 

[mjcoon]

Ah, I understand the principle. And no doubt the increase will be geometric (appropriately enough!). But I'm amazed that it was so quickly crippling for my PC. I should do some instrumentation...

Although I have not done any instrumentation, it occured to me that I should not have to. If the increase in size of a single bitmap is causing the problem it should be very apparent. This is because the original image will steadily shrink in the centre of the display as if it were being over-zoomed. It will then be obvious how much the number of pixels has been increased and therefore what the memory overhead is becoming. But the shrinkage I observed was not that great. So I still do not understand why a Win-XP PC should have had a problem.

So maybe instrumentation is still needed...

Mike.

 

[klaus]

If you rotate an image, the size of the new birmap will be the size of the surrounding rectangle. For example, if you rotate a square image by 45° the new bitmap will double in size.

Best regards.

 

[agraham]

This is because the original image will steadily shrink in the centre of the display as if it were being over-zoomed.

No it won't. The mode of the Image control is cCenterImage. If you don't believe me put a Msgbox in showing the Bitmap Width and Height after each rotation.