iOS给图片添加滤镜&使用openGLES动态渲染图片详解及实例

2020-07-26 03:07:31

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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:

//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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