<div>I still wonder how kind of google earth rotate image very fast</div><div>anyway, thank you for your advice~!</div><div><br><br><div class="gmail_quote">2010/10/10 Stephen Bloch <span dir="ltr"><<a href="mailto:sbloch@adelphi.edu">sbloch@adelphi.edu</a>></span><br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;"><div class="im">On Oct 10, 2010, at 4:17 AM, 김태윤 <<a href="mailto:kty1104@gmail.com">kty1104@gmail.com</a>> wrote:<br> <br> > there is little images(16x16) that cropped from other chipset<br> > and I gether them and make an image which size is about 320 x 320<br> ><br> > and I rotate it, but it is very very slow and blink alot<br> <br> </div>This is because it really does take a lot of processing to rotate a bitmap image by an arbitrary angle. I bet it's really fast if you rotate by exactly 90 degrees....<br> <div class="im"><br> > so I test basic polygon<br> > it works perfectly, no delay, no blinking, even if when it grows big<br> <br> </div>Yes, that's because a polygon is determined by just a few points, so there's a lot less processing to be done.<br> <br> If it makes you feel better, in the old image library the polygon would have been just as slow as the bitmap :-)<br> <br> I don't know enough about the internals of the image library to tell you how to speed up operations on the former picture.<br> <font color="#888888"><br> Stephen Bloch</font></blockquote></div><br></div>