#27756 [Opn->Bgs]: ImageSetThickness + ImageArc = strange results

ID: 27756 Updated by: iliaa@php.net Reported By: info at silisoftware dot com -Status: Open +Status: Bogus Bug Type: GD related Operating System: Windows XP Pro PHP Version: 4.3.5 New Comment: Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php That is the nature of the arc drawing algorithm inside the GD library. Previous Comments: ------------------------------------------------------------------------ [2004-03-29 10:44:20] info at silisoftware dot com Description: ------------ Drawing an arc with an image thickness of other than 1 produces very strange results. The thicker the line specified, the "hairier" it gets. At 5px it's uneven, 25px quite ragged, at 50px and above it gets very non-round. The best way I can show the problem is with some sample images: http://www.silisoftware.com/temp/imagearc/ Not sure if it's a related issue, but I notice if I use the same code to draw an arc from 1-360 degrees, it looks like a big hairy "+" instead of a "o", but if I draw from 0-360 degrees it becomes a 1px circle, no matter what I specify for ImageSetThickness. Reproduce code: --------------- $imagethickness = 100; $gdimg_output = ImageCreateTrueColor(400, 400); $color_bg = ImageColorAllocate($gdimg_output, 0, 0, 255); $color_fg = ImageColorAllocate($gdimg_output, 255, 0, 0); ImageSetThickness($gdimg_output, $imagethickness); ImageFilledRectangle($gdimg_output, 0, 0, 400, 400, $color_bg); ImageArc($gdimg_output, 200, 200, 200, 200, 90, 360, $color_fg); ImagePNG($gdimg_output); Expected result: ---------------- 100px thick, 270-degree red arc on blue background Actual result: -------------- This: http://www.silisoftware.com/temp/imagearc/100.png 270-degree red arc on blue background, but thickness varies from 1px to 100px, it looks "hairy", with a tendency to elongate into a "+" rather than a "o" (more pronounced the thicker the line is set to). ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=27756&edit=1