originell

Analysis of Apple’s rubber band scrolling

January 6, 2013

I recently saw a post on Twitter from @chpwn that described the alogorithm that Apple uses for its “rubber band” or “bungee” scrolling.

b = (1.0 – (1.0 / ((x * c / d) + 1.0))) * d

paul-delange

/*
 *  TGDFileHash.c
 *  TagAdA: Tagging Advanced Application
 *  
 *  Copyright © 2008-2010 The TagAdA Team. All rights reserved.
 * 
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  

steipete

// Taken from http://PSPDFKit.com. This snippet is under public domain.
#define UIKitVersionNumber_iOS_7_0 0xB57
BOOL PSPDFIsUIKitFlatMode(void) {
    static BOOL isUIKitFlatMode = NO;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        // We get the modern UIKit if system is running >= iOS 7 and we were linked with >= SDK 7.
        if (kCFCoreFoundationVersionNumber >= kCFCoreFoundationVersionNumber_iOS_7_0) {
            isUIKitFlatMode = (NSVersionOfLinkTimeLibrary("UIKit") >> 16) >= UIKitVersionNumber_iOS_7_0;
        }

aras-p

// Just before switching jobs:
// Add one of these.
// Preferably into the same commit where you do a large merge.
//
// This started as a tweet with a joke of "C++ pro-tip: #define private public",
// and then it quickly escalated into more and more evil suggestions.
// I've tried to capture interesting suggestions here.
//
// Contributors: @r2d2rigo, @joeldevahl, @msinilo, @_Humus_,
// @YuriyODonnell, @rygorous, @cmuratori, @mike_acton, @grumpygiant,

ashfurrow

1.3MB png 640x1136

• Accelerate 179ms every time
• CoreImage 298ms first time 147ms subsequent times @1x scale
• CoreImage 262ms first time 126ms subsequent times @0.5x scale
• CoreImage 260ms first time 118ms subsequent times @0.25x scale

(Lower on 0.5x probably because of whole number for blur radius)

niw

/*
 * A simple libpng example program
 * http://zarb.org/~gc/html/libpng.html
 *
 * Modified by Yoshimasa Niwa to make it much simpler
 * and support all defined color_type.
 *
 * To build, use the next instruction on OS X.
 * $ brew install libpng
 * $ clang -lz -lpng16 libpng_test.c

steipete

//
// PSPDFThreadSafeMutableDictionary.m
//
// Copyright (c) 2013 Peter Steinberger, PSPDFKit GmbH. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is

christianroman

#! /bin/bash

# build the environment
mkdir tessenv; cd tessenv 
TROOT=`pwd` 
mkdir $TROOT/stockfonts; mkdir $TROOT/build; mkdir $TROOT/build/eng 
echo "Environment built"
# Get the stock english fonts from Google (old, but they work)
cd $TROOT/stockfonts
GET http://tesseract-ocr.googlecode.com/files/boxtiff-2.01.eng.tar.gz > boxtiff-2.01.eng.tar.gz

boredzo

//
//  PRHAngleGradientFilter.h
//
//  Created by Peter Hosey on 2013-01-30.
//  Copyright (c) 2013 Peter Hosey. All rights reserved.
//

#import <QuartzCore/QuartzCore.h>

@interface PRHAngleGradientFilter : CIFilter

oliland

- (void)viewDidLoad
{
    [super viewDidLoad];
    
    // Great tutorial: http://www.raywenderlich.com/22167/beginning-core-image-in-ios-6
    // Official docs: https://developer.apple.com/library/ios/#documentation/GraphicsImaging/Conceptual/CoreImaging/ci_intro/ci_intro.html#//apple_ref/doc/uid/TP30001185-CH1-TPXREF101
    // Alt-click on function names for more!
    
    // Make any old label, with our frame set to the view so we know it's there.
    UILabel *label = [[UILabel alloc] initWithFrame:self.view.frame];