ios给图片添加滤镜&使用opengles动态渲染图片
给图片增加滤镜有这两种方式: coreimage / opengles
下面先说明如何使用coreimage给图片添加滤镜, 主要为以下步骤:
#1.导入ciimage格式的原始图片
#2.创建cifilter滤镜
#3.用cicontext将滤镜中的图片渲染出来
#4.导出渲染后的图片
参考代码:
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//导入ciimage
ciimage *ciimage = [[ciimage alloc] initwithimage:[uiimage imagenamed:@"hua"]];
//创建出filter滤镜
cifilter *filter = [cifilter filterwithname:@"cipixellate"];
[filter setvalue:ciimage forkey:kciinputimagekey];
[filter setdefaults];
ciimage *outimage = [filter valueforkey:kcioutputimagekey];
//用cicontext将滤镜中的图片渲染出来
cicontext *context = [cicontext contextwithoptions:nil];
cgimageref cgimage = [context createcgimage:outimage
fromrect:[outimage extent]];
//导出图片
uiimage *showimage = [uiimage imagewithcgimage:cgimage];
cgimagerelease(cgimage);
uiimageview *imageview = [[uiimageview alloc] initwithimage:showimage];
imageview.center = self.view.center;
[self.view addsubview:imageview];
当要设置多个滤镜的时候, 出了新创建一个cifilter外还要额外设定kciinputanglekey, 代码如下:
//导入ciimage
ciimage *ciimage = [[ciimage alloc] initwithimage:[uiimage imagenamed:@"hua.jpeg"]];
//创建出filter滤镜
cifilter *filter = [cifilter filterwithname:@"cipixellate"];
[filter setvalue:ciimage forkey:kciinputimagekey];
[filter setdefaults];
ciimage *outimage = [filter valueforkey:kcioutputimagekey];
cifilter *filtertwo = [cifilter filterwithname:@"cihueadjust"];
[filtertwo setvalue:outimage forkey:kciinputimagekey];
[filtertwo setdefaults];
[filtertwo setvalue:@(1.0f) forkey:kciinputanglekey]; //如果不增加这行新增的滤镜不会生效
ciimage *outputimage = [filtertwo valueforkey:kcioutputimagekey];
//用cicontext将滤镜中的图片渲染出来
cicontext *context = [cicontext contextwithoptions:nil];
cgimageref cgimage = [context createcgimage:outputimage
fromrect:[outputimage extent]];
//导出图片
uiimage *showimage = [uiimage imagewithcgimage:cgimage];
cgimagerelease(cgimage);
uiimageview *imageview = [[uiimageview alloc] initwithimage:showimage];
imageview.center = self.view.center;
[self.view addsubview:imageview];
下面来介绍怎么用opengles来使用滤镜渲染图片
使用opengles的步骤大致如下:
#1.导入要渲染的图片
#2.获取opengles渲染的上下文
#3.创建出渲染的glkview buffer
#4.创建coreimage的上下文
#5.进行coreimage的相关设置
#6.开始渲染并显示图片
参考代码如下:
//导入要渲染的图片
uiimage *showimage = [uiimage imagenamed:@"hua.jpeg"];
cgrect rect = cgrectmake(0, 0, showimage.size.width, showimage.size.height);
//获取opengles渲染的上下文
eaglcontext *eagcontext = [[eaglcontext alloc] initwithapi:keaglrenderingapiopengles2];
//创建出渲染的buffer
glkview *glkview = [[glkview alloc] initwithframe:rect
context:eagcontext];
[glkview binddrawable];
[self.view addsubview:glkview];
//创建出coreimage的上下文
cicontext *cicontext = [cicontext contextwitheaglcontext:eagcontext
options:@{kcicontextworkingcolorspace: [nsnull null]}];
//coreimage相关设置
ciimage *ciimage = [[ciimage alloc] initwithimage:showimage];
cifilter *filter = [cifilter filterwithname:@"cisepiatone"];
[filter setvalue:ciimage forkey:kciinputimagekey];
[filter setvalue:@(0) forkey:kciinputintensitykey];
//开始渲染
[cicontext drawimage:[filter valueforkey:kcioutputimagekey]
inrect:cgrectmake(0, 0, glkview.drawablewidth, glkview.drawableheight)
fromrect:[ciimage extent]];
[glkview display];
如果要动态渲染, 可以通过uisilder动态调整一下代码的vaule值
[filter setvalue:vaule forkey:kciinputintensitykey];
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