66// Copyright (c) 2015 Twitter. All rights reserved.
77//
88
9+ #import < Accelerate/Accelerate.h>
910#import < TwitterImagePipeline/TwitterImagePipeline.h>
1011
1112#import " TIPTestImageFetchDownloadInternalWithStubbing.h"
2728 { @" public.png" " PNG" " twitterfied.png" NO , NO },
2829 { @" public.tiff" " TIFF" " twitterfied.tiff" NO , NO },
2930 { @" com.compuserve.gif" " GIF" " fireworks_original.gif" NO , YES },
31+ { @" com.google.webp" " WEBP" " twitterfied.webp" NO , NO },
32+ { @" public.jpeg" " Small-PJPEG" " twitterfied.small.pjpg" YES , NO },
3033};
3134
35+ static const NSUInteger kBitrateDribble = 4 * 1000 ;
36+ static const NSUInteger kBitrate80sModem = 16 * 1000 ;
37+ static const NSUInteger kBitrateBad2G = 56 * 1000 ;
3238static const NSUInteger kBitrate2G = 128 * 1000 ; // 2G
3339static const NSUInteger kBitrate2GPlus = kBitrate2G * 2 ; // 2.5G
3440static const NSUInteger kBitrate3G = kBitrate2GPlus * 2 ; // 3G
3743static const NSUInteger kBitrate4GPlus = kBitrate4G * 2 ; // ~LTE
3844
3945static const NSUInteger sBitrates [] = {
46+ kBitrateDribble , kBitrate80sModem , kBitrateBad2G ,
4047 kBitrate2G , kBitrate2GPlus ,
4148 kBitrate3G , kBitrate3GPlus ,
4249 kBitrate4G , kBitrate4GPlus
4350};
4451
45- static const NSUInteger kDefaultBitrateIndex = 2 ;
52+ static const NSUInteger kDefaultBitrateIndex = 5 ;
4653
47- @interface ViewController () <UIPickerViewDataSource, UIPickerViewDelegate, TIPImageFetchRequest, TIPImageFetchDelegate>
54+ @interface ViewController () <UIPickerViewDataSource, UIPickerViewDelegate, TIPImageFetchRequest, TIPImageFetchDelegate, TIPImageFetchTransformer >
4855@end
4956
5057@implementation ViewController
@@ -56,6 +63,7 @@ @implementation ViewController
5663 IBOutlet UIButton *_startButton;
5764 IBOutlet UIPickerView *_pickerView;
5865 IBOutlet UILabel *_resultsLabel;
66+ IBOutlet UISwitch *_blurSwitch;
5967
6068 BOOL _selectingSpeed;
6169 UITapGestureRecognizer *_tapper;
@@ -314,6 +322,148 @@ - (UIViewContentMode)targetContentMode
314322 return _imageView.contentMode ;
315323}
316324
325+ - (id <TIPImageFetchTransformer>)transformer
326+ {
327+ return _blurSwitch.on ? self : nil ;
328+ }
329+
330+ - (UIImage *)tip_transformImage : (UIImage *)image withProgress : (float )progress hintTargetDimensions : (CGSize )targetDimensions hintTargetContentMode : (UIViewContentMode)targetContentMode forImageFetchOperation : (TIPImageFetchOperation *)op
331+ {
332+ if (!image.CGImage ) {
333+ return nil ;
334+ }
335+
336+ BOOL shouldScaleFirst = NO ;
337+ const CGSize imageDimension = [image tip_dimensions ];
338+ CGFloat blurRadius = 0 ;
339+ if (progress < 0 || progress >= 1 .f ) {
340+ // placeholder?
341+ id <TIPImageFetchRequest> request = op.request ;
342+ if (![request respondsToSelector: @selector (options )]) {
343+ return nil ;
344+ }
345+ if ((request.options & TIPImageFetchTreatAsPlaceholder) == 0 ) {
346+ return nil ;
347+ }
348+ if (targetDimensions.width <= imageDimension.width && targetDimensions.height <= imageDimension.height ) {
349+ return nil ;
350+ }
351+ blurRadius = log2 (MAX (targetDimensions.height / imageDimension.height , targetDimensions.width / targetDimensions.width ));
352+ shouldScaleFirst = YES ;
353+ } else {
354+ // progressive
355+ if (progress > .65f ) {
356+ return nil ;
357+ }
358+ const CGFloat divisor = (1 .f + progress) * 2 .f ;
359+ blurRadius = log2 (MAX (imageDimension.width , imageDimension.height )) / divisor;
360+ blurRadius *= 1 .f - progress;
361+ }
362+
363+ if (blurRadius < 0.5 ) {
364+ return nil ;
365+ }
366+
367+ // TRANSFORM!
368+ if (shouldScaleFirst) {
369+ image = [image tip_scaledImageWithTargetDimensions: targetDimensions contentMode: targetContentMode];
370+ }
371+ UIImage *transformed = [self applyBlurToImage: image withRadius: blurRadius];
372+ NSAssert (CGSizeEqualToSize([image tip_dimensions ], [transformed tip_dimensions ]), @"sizing missmatch!");
373+ return transformed;
374+ }
375+
376+ // This is a modified version of Apple's 2013 WWDC sample code for UIImage(ImageEffects)
377+ // https://developer.apple.com/library/content/samplecode/UIImageEffects/Listings/UIImageEffects_UIImageEffects_m.html
378+ - (UIImage *)applyBlurToImage : (UIImage *)image withRadius : (CGFloat )blurRadius
379+ {
380+ // Check pre-conditions
381+ if (image.size .width < 1 || image.size .height < 1 ) {
382+ return nil ;
383+ }
384+ if (!image.CGImage ) {
385+ return nil ;
386+ }
387+
388+ CGRect imageRect = { CGPointZero , image.size };
389+ UIImage *effectImage = image;
390+
391+ const BOOL hasBlur = blurRadius > __FLT_EPSILON__;
392+ if (hasBlur) {
393+ UIGraphicsBeginImageContextWithOptions (image.size , NO , [[UIScreen mainScreen ] scale ]);
394+ CGContextRef effectInContext = UIGraphicsGetCurrentContext ();
395+ CGContextScaleCTM (effectInContext, 1.0 , -1.0 );
396+ CGContextTranslateCTM (effectInContext, 0 , -image.size .height );
397+ CGContextDrawImage (effectInContext, imageRect, image.CGImage );
398+
399+ vImage_Buffer effectInBuffer;
400+ effectInBuffer.data = CGBitmapContextGetData (effectInContext);
401+ effectInBuffer.width = CGBitmapContextGetWidth (effectInContext);
402+ effectInBuffer.height = CGBitmapContextGetHeight (effectInContext);
403+ effectInBuffer.rowBytes = CGBitmapContextGetBytesPerRow (effectInContext);
404+
405+ UIGraphicsBeginImageContextWithOptions (image.size , NO , [[UIScreen mainScreen ] scale ]);
406+ CGContextRef effectOutContext = UIGraphicsGetCurrentContext ();
407+ vImage_Buffer effectOutBuffer;
408+ effectOutBuffer.data = CGBitmapContextGetData (effectOutContext);
409+ effectOutBuffer.width = CGBitmapContextGetWidth (effectOutContext);
410+ effectOutBuffer.height = CGBitmapContextGetHeight (effectOutContext);
411+ effectOutBuffer.rowBytes = CGBitmapContextGetBytesPerRow (effectOutContext);
412+
413+ // A description of how to compute the box kernel width from the Gaussian
414+ // radius (aka standard deviation) appears in the SVG spec:
415+ // http://www.w3.org/TR/SVG/filters.html#feGaussianBlurElement
416+ //
417+ // For larger values of 's' (s >= 2.0), an approximation can be used: Three
418+ // successive box-blurs build a piece-wise quadratic convolution kernel, which
419+ // approximates the Gaussian kernel to within roughly 3%.
420+ //
421+ // let d = floor(s * 3*sqrt(2*pi)/4 + 0.5)
422+ //
423+ // ... if d is odd, use three box-blurs of size 'd', centered on the output pixel.
424+ //
425+ const CGFloat inputRadius = blurRadius * [[UIScreen mainScreen ] scale ];
426+ uint32_t radius = (uint32_t )floor (inputRadius * 3 . * sqrt (2 * M_PI) / 4 + 0.5 );
427+ if (radius % 2 != 1 ) {
428+ radius += 1 ; // force radius to be odd so that the three box-blur methodology works.
429+ }
430+ vImageBoxConvolve_ARGB8888 (&effectInBuffer, &effectOutBuffer, NULL , 0 , 0 , radius, radius, 0 , kvImageEdgeExtend);
431+ vImageBoxConvolve_ARGB8888 (&effectOutBuffer, &effectInBuffer, NULL , 0 , 0 , radius, radius, 0 , kvImageEdgeExtend);
432+ vImageBoxConvolve_ARGB8888 (&effectInBuffer, &effectOutBuffer, NULL , 0 , 0 , radius, radius, 0 , kvImageEdgeExtend);
433+
434+ effectImage = UIGraphicsGetImageFromCurrentImageContext ();
435+ UIGraphicsEndImageContext ();
436+ UIGraphicsEndImageContext ();
437+ }
438+
439+ // Set up output context.
440+ UIGraphicsBeginImageContextWithOptions (image.size , NO , [[UIScreen mainScreen ] scale ]);
441+ CGContextRef outputContext = UIGraphicsGetCurrentContext ();
442+ CGContextScaleCTM (outputContext, 1.0 , -1.0 );
443+ CGContextTranslateCTM (outputContext, 0 , -image.size .height );
444+
445+ // Draw base image.
446+ CGContextDrawImage (outputContext, imageRect, image.CGImage );
447+
448+ // Draw effect image.
449+ if (hasBlur) {
450+ CGContextSaveGState (outputContext);
451+ CGContextDrawImage (outputContext, imageRect, effectImage.CGImage );
452+ CGContextRestoreGState (outputContext);
453+ }
454+
455+ // Output image is ready.
456+ UIImage *outputImage = UIGraphicsGetImageFromCurrentImageContext ();
457+ UIGraphicsEndImageContext ();
458+
459+ return outputImage;
460+ }
461+
462+ // - (NSDictionary *)progressiveLoadingPolicies
463+ // {
464+ // return @{ TIPImageTypeJPEG : [[TIPGreedyProgressiveLoadingPolicy alloc] init] };
465+ // }
466+
317467// - (NSDictionary *)progressiveLoadingPolicies
318468// {
319469// if ([sImageTypes[_imageTypeIndex].type isEqualToString:TIPImageTypeJPEG2000] || [sImageTypes[_imageTypeIndex].type isEqualToString:TIPImageTypePNG]) {
0 commit comments