Wrong page rotation on Rotate 180 IM: 7.0.4-4

[ZpmFred]

Hello,

I've got a problem when rotating an image by 180°the image effectively rotate by 180°but the Page does not rotate by 180°, instead it rotate by 90°.

After some investigation in the source code I think that I found the source of the problem.
On a rotation of 180° the function that perform the actual rotation is "IntegralRotateImage" MagicCore/shear.c.
A rotation of 180° is transformed in a "rotation" of "2" when passed to "IntegralRotateImage".
In the body of the function there is a switch on the variable "rotation", in the case where "rotation == 2" we find the following code

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case 2:
    {
      register ssize_t
        y;
      /*
        Rotate 180 degrees.
      */

So we are in fact in the right case for our value of "rotation".
Here come the problem at the end of the case we find the following code:

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      Swap(page.width,page.height);
      Swap(page.x,page.y);

But when rotating an image by 180° you don't need to swap the width and the height ... this is right on an 90° rotation.

I hope that this will be able to help you solve the problem

[GeeMack]

I've got a problem when rotating an image by 180°the image effectively rotate by 180°but the Page does not rotate by 180°, instead it rotate by 90°

I'm using IM 7.0.4-4 HDRI on Windows 10 64, and this issue appears here, too. This command creates a 360x240 blue rectangle, then rotates it 180 degrees...

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magick xc:blue[360x240!] -rotate 180 info:

The output of the command shows it rotated the image 180 degrees, while the page info has rotated 90 degrees and shifted w/2 to the left. Here's the output...

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xc:blue[360x240!] XC 360x240 240x360-120+0 16-bit sRGB 0.016u 0:00.016

[magick]

Thanks for the problem report. We can reproduce it and will have a patch to fix it in GIT master branch @ https://github.com/ImageMagick/ImageMagick later today. The patch will be available in the beta releases of ImageMagick @ http://www.imagemagick.org/download/beta/ by sometime tomorrow.

[ZpmFred]

Thanks for the fast reply and fix.