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今天开发一个拍照获取照片的功能的时候, 发现上传之后图片会自动旋转90.
测试发现, 只要是图片大于2m, 系统就会自动翻转照片
相机拍照后直接取出来的uiimage（用uiimagepickercontrolleroriginalimage取出），它本身的imageorientation属性是3，即uiimageorientationright。如果这个图片直接使用则没事，但是如果对它进行裁剪、缩放等操作后，它的这个imageorientation属性会变成0。此时这张图片用在别的地方就会发生旋转。imageorientation是只读的，不能直接修改其值。
解决方法如下:
1. 设置相机的一个属性allowsediting为yes，设了这个值，你拍完照片后会在照片上出现一个框框，这就是对照片的裁剪编辑。在相机的代理方法中取照片的时候就别用uiimagepickercontrolleroriginalimage来取了，要用uiimagepickercontrollereditedimage。用这个key取出来的照片，它的imageorientation是0，所以之后的任何裁剪、缩放操作都不会造成旋转。这是第一种方法。
2. 第一种解决方法基本没用, 开发中基本都会对图片进行裁剪和压缩. 这里有一个专门针对这个事的很好的category
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+ (uiimage *)fixorientation:(uiimage *)aimage {
// no-op if the orientation is already correct
if (aimage.imageorientation ==uiimageorientationup)
return aimage;
// we need to calculate the proper transformation to make the image upright.
// we do it in 2 steps: rotate if left/right/down, and then flip if mirrored.
cgaffinetransform transform =cgaffinetransformidentity;
switch (aimage.imageorientation) {
caseuiimageorientationdown:
caseuiimageorientationdownmirrored:
transform = cgaffinetransformtranslate(transform, aimage.size.width, aimage.size.height);
transform = cgaffinetransformrotate(transform, m_pi);
break;
caseuiimageorientationleft:
caseuiimageorientationleftmirrored:
transform = cgaffinetransformtranslate(transform, aimage.size.width,0);
transform = cgaffinetransformrotate(transform, m_pi_2);
break;
caseuiimageorientationright:
caseuiimageorientationrightmirrored:
transform = cgaffinetransformtranslate(transform, 0, aimage.size.height);
transform = cgaffinetransformrotate(transform, -m_pi_2);
break;
default:
break;
}
switch (aimage.imageorientation) {
caseuiimageorientationupmirrored:
caseuiimageorientationdownmirrored:
transform = cgaffinetransformtranslate(transform, aimage.size.width,0);
transform = cgaffinetransformscale(transform, -1, 1);
break;
caseuiimageorientationleftmirrored:
caseuiimageorientationrightmirrored:
transform = cgaffinetransformtranslate(transform, aimage.size.height,0);
transform = cgaffinetransformscale(transform, -1, 1);
break;
default:
break;
}
// now we draw the underlying cgimage into a new context, applying the transform
// calculated above.
cgcontextref ctx =cgbitmapcontextcreate(null, aimage.size.width, aimage.size.height,
cgimagegetbitspercomponent(aimage.cgimage),0,
cgimagegetcolorspace(aimage.cgimage),
cgimagegetbitmapinfo(aimage.cgimage));
cgcontextconcatctm(ctx, transform);
switch (aimage.imageorientation) {
caseuiimageorientationleft:
caseuiimageorientationleftmirrored:
caseuiimageorientationright:
caseuiimageorientationrightmirrored:
// grr...
cgcontextdrawimage(ctx,cgrectmake(0,0,aimage.size.height,aimage.size.width), aimage.cgimage);
break;
default:
cgcontextdrawimage(ctx,cgrectmake(0,0,aimage.size.width,aimage.size.height), aimage.cgimage);
break;
}
// and now we just create a new uiimage from the drawing context
cgimageref cgimg =cgbitmapcontextcreateimage(ctx);
uiimage *img = [uiimageimagewithcgimage:cgimg];
cgcontextrelease(ctx);
cgimagerelease(cgimg);
return img;
}
以上所述是小编给大家介绍的ios拍照后图片自动旋转90度的完美解决方法，希望对大家有所帮助
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