iOS給圖片添加濾鏡&使用openGLES動態渲染圖片
給圖片增加濾鏡有這兩種方式: CoreImage / openGLES
下面先說明如何使用CoreImage給圖片添加濾鏡, 主要為以下步驟:
#1.導入CIImage格式的原始圖片
#2.創建CIFilter濾鏡
#3.用CIContext將濾鏡中的圖片渲染出來
#4.導出渲染后的圖片
參考代碼:
//導入CIImage CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua"]]; //創建出Filter濾鏡 CIFilter *filter = [CIFilter filterWithName:@"CIPixellate"]; [filter setValue:ciImage forKey:kCIInputImageKey]; [filter setDefaults]; CIImage *outImage = [filter valueForKey:kCIOutputImageKey]; //用CIContext將濾鏡中的圖片渲染出來 CIContext *context = [CIContext contextWithOptions:nil]; CGImageRef cgImage = [context createCGImage:outImage fromRect:[outImage extent]]; //導出圖片 UIImage *showImage = [UIImage imageWithCGImage:cgImage]; CGImageRelease(cgImage); UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage]; imageView.center = self.view.center; [self.view addSubview:imageView];
當要設置多個濾鏡的時候, 出了新創建一個CIFilter外還要額外設定kCIInputAngleKey, 代碼如下:
//導入CIImage CIImage *ciImage = [[CIImage alloc] initWithImage:[UIImage imageNamed:@"hua.jpeg"]]; //創建出Filter濾鏡 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]; //如果不增加這行新增的濾鏡不會生效 CIImage *outputImage = [filterTwo valueForKey:kCIOutputImageKey]; //用CIContext將濾鏡中的圖片渲染出來 CIContext *context = [CIContext contextWithOptions:nil]; CGImageRef cgImage = [context createCGImage:outputImage fromRect:[outputImage extent]]; //導出圖片 UIImage *showImage = [UIImage imageWithCGImage:cgImage]; CGImageRelease(cgImage); UIImageView *imageView = [[UIImageView alloc] initWithImage:showImage]; imageView.center = self.view.center; [self.view addSubview:imageView];
下面來介紹怎么用openGLES來使用濾鏡渲染圖片
使用openGlES的步驟大致如下:
#1.導入要渲染的圖片
#2.獲取OpenGLES渲染的上下文
#3.創建出渲染的GLKView buffer
#4.創建CoreImage的上下文
#5.進行CoreImage的相關設置
#6.開始渲染并顯示圖片
參考代碼如下:
//導入要渲染的圖片 UIImage *showImage = [UIImage imageNamed:@"hua.jpeg"]; CGRect rect = CGRectMake(0, 0, showImage.size.width, showImage.size.height); //獲取OpenGLES渲染的上下文 EAGLContext *eagContext = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]; //創建出渲染的buffer GLKView *glkView = [[GLKView alloc] initWithFrame:rect context:eagContext]; [glkView bindDrawable]; [self.view addSubview:glkView]; //創建出CoreImage的上下文 CIContext *ciContext = [CIContext contextWithEAGLContext:eagContext options:@{kCIContextWorkingColorSpace: [NSNull null]}]; //CoreImage相關設置 CIImage *ciImage = [[CIImage alloc] initWithImage:showImage]; CIFilter *filter = [CIFilter filterWithName:@"CISepiaTone"]; [filter setValue:ciImage forKey:kCIInputImageKey]; [filter setValue:@(0) forKey:kCIInputIntensityKey]; //開始渲染 [ciContext drawImage:[filter valueForKey:kCIOutputImageKey] inRect:CGRectMake(0, 0, glkView.drawableWidth, glkView.drawableHeight) fromRect:[ciImage extent]]; [glkView display];如果要動態渲染, 可以通過UISilder動態調整一下代碼的vaule值
[filter setValue:vaule forKey:kCIInputIntensityKey];
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