需求：uiimage根据屏幕宽度按照自己本身比例改变高度
上代码，为uiimage创建一个category
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#import "uiimage+uiimageextras.h" @implementation uiimage (uiimageextras) - (uiimage *)imagebyscalingtosize:(cgsize)targetsize { uiimage *sourceimage = self; uiimage *newimage = nil; cgsize imagesize = sourceimage.size; cgfloat width = imagesize.width; cgfloat height = imagesize.height; cgfloat targetwidth = targetsize.width; cgfloat targetheight = targetsize.height; cgfloat scalefactor = 0.0; cgfloat scaledwidth = targetwidth; cgfloat scaledheight = targetheight; cgpoint thumbnailpoint = cgpointmake(0.0,0.0); if (cgsizeequaltosize(imagesize, targetsize) ==no) { cgfloat widthfactor = targetwidth / width; cgfloat heightfactor = targetheight / height; if (widthfactor < heightfactor) scalefactor = widthfactor; else scalefactor = heightfactor; scaledwidth = width * scalefactor; scaledheight = height * scalefactor; // center the image if (widthfactor < heightfactor) { thumbnailpoint.y = (targetheight - scaledheight) * 0.5; } else if (widthfactor > heightfactor) { thumbnailpoint.x = (targetwidth - scaledwidth) * 0.5; } } // this is actually the interesting part: uigraphicsbeginimagecontext(targetsize); cgrect thumbnailrect = cgrectzero; thumbnailrect.origin = thumbnailpoint; thumbnailrect.size.width = scaledwidth; thumbnailrect.size.height = scaledheight; [sourceimage drawinrect:thumbnailrect]; newimage =uigraphicsgetimagefromcurrentimagecontext(); uigraphicsendimagecontext(); if(newimage == nil) nslog(@"could not scale image"); return newimage ; } @end |
在需要使用的地方import然后使用
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cgsize size = image.size; image = [image imagebyscalingtosize:cgsizemake([uiscreen mainscreen].bounds.size.width,[uiscreen mainscreen].bounds.size.width * (size.height / size.width))]; self.imageview.image = image; |
以上所述是小编给大家介绍的ios uiimage根据屏宽调整size的实例代码，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对服务器之家网站的支持！
原文链接：http://blog.csdn.net/u012265444/article/details/54598873
