iOS CoreImage图片处理动态渲染(滤镜)

//
//  ViewController.m
//  CoreImageOfDong
//
//  Created by Dong on 15/6/30.
//  Copyright (c) 2015年 xindong. All rights reserved.
//
#import "ViewController.h"
#import <GLKit/GLKit.h>
// 需要导入此库
@interface ViewController ()

@property (nonatomic,
strong)
GLKView *glkView;
//渲染用的buffer视图(类似流媒体,实时改变)
@property (nonatomic, strong) CIFilter *filter;
@property (nonatomic, strong) CIImage *ciImage;
@property (nonatomic, strong) CIContext *ciContext;
@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
        
    UIImage *showImage = [UIImage imageNamed:@"demo1.jpg"];
    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
    self.glkView = [[GLKView alloc] initWithFrame:rect context:eagContext];
    [self.glkView bindDrawable];
// 绑定绘制,否则刚开始会黑屏
    [self.view addSubview:self.glkView];

    
   
// 创建出CoreImage用的上下文
    self.ciContext = [CIContext contextWithEAGLContext:eagContext options:@{kCIContextWorkingColorSpace : [NSNull null]}];

    
   
// CoreImage相关设置
    self.ciImage = [[CIImage alloc] initWithImage:showImage];
    self.filter = [CIFilter filterWithName:@"CISepiaTone"];
    [self.filter setValue:self.ciImage forKey:kCIInputImageKey];
    [self.filter setValue:@(0) forKey:kCIInputIntensityKey];

    
   
// 开始渲染
    [self.ciContext drawImage:[self.filter valueForKey:kCIOutputImageKey] inRect:CGRectMake(0, 0, self.glkView.drawableWidth, self.glkView.drawableHeight) fromRect:[self.ciImage
extent]];
    [self.glkView display];

    
    //
动态渲染
    UISlider *slider = [[UISlider alloc] initWithFrame:CGRectMake(30, 500, 200, 10)];
    slider.minimumValue = 0.f;
    slider.maximumValue = 10.f;
    [slider addTarget:self action:@selector(changeColorValue:) forControlEvents:UIControlEventValueChanged];
    [self.view addSubview:slider];
}
- (void)changeColorValue:(UISlider *)slider
{
    [self.filter setValue:self.ciImage forKey:kCIInputImageKey];
    [self.filter setValue:@(slider.value) forKey:kCIInputIntensityKey];
   
// 开始渲染
    [self.ciContext drawImage:[self.filter valueForKey:kCIOutputImageKey] inRect:CGRectMake(0, 0, self.glkView.drawableWidth, self.glkView.drawableHeight) fromRect:[self.ciImage
extent]];
    [self.glkView display];
}