Archive for category: Random Stories

Original Source: https://www.sitepoint.com/building-ethereum-dapps-cross-contract-communication-token-selling/

In part 4 of this tutorial series on building DApps with Ethereum, we started building and testing our DAO contract. Now let’s go one step further and handle adding content and tokens to the story, as per our introduction.

Adding Tokens

For a contract to be able to interact with another contract, it needs to be aware of that other contract’s interface — the functions available to it. Since our TNS token has a fairly straightforward interface, we can include it as such in the contract of our DAO, above the contract StoryDao declaration and under our import statements:

contract LockableToken is Ownable {
function totalSupply() public view returns (uint256);
function balanceOf(address who) public view returns (uint256);
function transfer(address to, uint256 value) public returns (bool);
event Transfer(address indexed from, address indexed to, uint256 value);
function allowance(address owner, address spender) public view returns (uint256);
function transferFrom(address from, address to, uint256 value) public returns (bool);
function approve(address spender, uint256 value) public returns (bool);
event Approval(address indexed owner, address indexed spender, uint256 value);
function approveAndCall(address _spender, uint256 _value, bytes _data) public payable returns (bool);
function transferAndCall(address _to, uint256 _value, bytes _data) public payable returns (bool);
function transferFromAndCall(address _from, address _to, uint256 _value, bytes _data) public payable returns (bool);

function increaseLockedAmount(address _owner, uint256 _amount) public returns (uint256);
function decreaseLockedAmount(address _owner, uint256 _amount) public returns (uint256);
function getLockedAmount(address _owner) view public returns (uint256);
function getUnlockedAmount(address _owner) view public returns (uint256);
}

Notice that we don’t need to paste in the “meat” of the functions, but only their signatures (skeletons). This is all that’s needed to interact between contracts.

Now we can use these functions in the DAO contract. The plan is as follows:

launch the token (we already did this)
launch the DAO from the same address
send all tokens from the token-launcher to the DAO, then transfer ownership over the contract to the DAO itself
at this point the DAO owns all tokens and can sell them to people using the transfer function, or can reserve them for spending using the approve function (useful during votes), etc.

But how does the DAO know which address the token is deployed on? We tell it.

First, we add a new variable at the top of the DAO contract:

LockableToken public token;

Then, we add some functions:

constructor(address _token) public {
require(_token != address(0), “Token address cannot be null-address”);
token = LockableToken(_token);
}

The constructor is the function which gets called automatically when a contract is deployed. It’s useful for initializing values like linked contracts, default values, etc. In our case, we’ll use it to consume and save the address of the TNS token. The require check is there to make sure the token’s address is valid.

While we’re at it, let’s add a function that lets users check how many tokens remain for sale in the DAO, and the ability to change to another token should something go wrong and such a change be required. This change deserves an event, too, so let’s add that in as well.

event TokenAddressChange(address token);

function daoTokenBalance() public view returns (uint256) {
return token.balanceOf(address(this));
}

function changeTokenAddress(address _token) onlyOwner public {
require(_token != address(0), “Token address cannot be null-address”);
token = LockableToken(_token);
emit TokenAddressChange(_token);
}

The first function is set to view because it doesn’t change the state of the blockchain; it doesn’t alter any values. This means it’s a free, read-only function call to the blockchain: it doesn’t need a paid transaction. It also returns the balance of tokens as a number, so this needs to be declared on the function’s signature with returns (uint256). The token has a balanceOf function (see the interface we pasted in above) and it accepts one parameter — the address whose balance to check. We’re checking our (this) DAO’s balance, so “this”, and we turn “this” into an address with address().

The token address changing function allows the owner (admin) to change the token contract. It’s identical to the logic of the constructor.

Let’s see how we can let people buy the tokens now.

Buying Tokens

As per the previous part of the series, users can buy tokens by:

Using the fallback function if already whitelisted. In other words, just sending ether to the DAO contract.
Using the whitelistAddress function by sending more than the fee required for whitelisting.
Calling the buyTokens function directly.

There is a caveat, however. When someone calls the buyTokens function from the outside, we want it to fail if there aren’t enough tokens in the DAO to sell. But when someone buys tokens via the whitelist function by sending in too much in the first whitelisting attempt, we don’t want it to fail, because then the whitelisting process will get canceled as everything fails at once. Transactions in Ethereum are atomic: either everything has to succeed, or nothing. So we’ll make two buyTokens functions.

// This goes at the top of the contract with other properties
uint256 public tokenToWeiRatio = 10000;

function buyTokensThrow(address _buyer, uint256 _wei) external {

require(whitelist[_buyer], “Candidate must be whitelisted.”);
require(!blacklist[_buyer], “Candidate must not be blacklisted.”);

uint256 tokens = _wei * tokenToWeiRatio;
require(daoTokenBalance() >= tokens, “DAO must have enough tokens for sale”);
token.transfer(_buyer, tokens);
}

function buyTokensInternal(address _buyer, uint256 _wei) internal {
require(!blacklist[_buyer], “Candidate must not be blacklisted.”);
uint256 tokens = _wei * tokenToWeiRatio;
if (daoTokenBalance() < tokens) {
msg.sender.transfer(_wei);
} else {
token.transfer(_buyer, tokens);
}
}

So, 100 million TNS tokens exist. If we set a price of 10000 tokens per one ether, that comes down to around 4–5 cents per token, which is acceptable.

The functions do some calculations after doing sanity checks against banned users and other factors, and immediately send the tokens out to the buyer, who can start using them as they see fit — either for voting, or for selling on exchanges. If there’s fewer tokens in the DAO than the buyer is trying to buy, the buyer is refunded.

The part token.transfer(_buyer, tokens) is us using the TNS token contract to initiate a transfer from the current location (the DAO) to the destination _buyer for amount tokens.

Now that we know people can get their hands on the tokens, let’s see if we can implement submissions.

The post Ethereum DApps: Cross-contract Communication & Token Selling appeared first on SitePoint.

Original Source: http://feedproxy.google.com/~r/Designrfix/~3/NDhN2b4t5f8/tips-to-design-a-good-logo-for-a-client-or-yourself

Before entering your field of choice, you must understand that a good logo reflects the values of the brand by using forms, colors, and typographies. Its objective is to inspire confidence and recognition of your brand and help the company to stand out from the competition. When it comes to logo design, you get out of […]

The post Tips to Design a Good Logo for A Client or Yourself appeared first on designrfix.com.

Original Source: http://feedproxy.google.com/~r/CreativeBloq/~3/3whUD8CCERI/google-chrome-extensions-21410570

Chrome's DevTools are great, but it's possible to add even more exciting features to your internet browser to make web design and development easier. Here are 29 of our favourite Chrome extensions for web designers and developers.

01. Sizzy

An easy way to test your site across multiple viewports

Responsive web design's a given these days, and it you want a straightforward way to check your designs across multiple viewports, Sizzy's worth a look. It'll show you an interactive view of your page rendered on a number of different device screen sizes, and you can also show and hide a simulated device keyboard, and switch between portrait and landscape modes.

02. Site Palette

If a colour scheme takes your fancy, Site Palette will help you borrow it

The next time you see a site that makes great use of colour, here's a simple way to take advantage of it. Site Palette extracts the main colours from a website and generates a shareable palette that you can easily show to collaborators. You can also download a Sketch template, and there's Adobe Swatch support, too. 

03. Checkbot

Sort out all those broken links and get a free SEO boost

Making sure that all the links on your site actually work is an instant usability win and it's a good way to improve your SEO, too. Checkbot is a Chrome extension that checks for broken links, duplicate titles, redirect chains, invalid HTML/JS/CSS and more, so you can quickly audit your site for bad links and get them fixed.

04. Toby

Turn all those unruly tabs into useful collections of bookmarks

It is a truth universally acknowledged that by the time you've had Chrome open for a couple of hours it'll be a confusing nest of tabs the width of your little finger. Toby's a great way to tame them; with it you can organise all those tabs into collections of links as an alternative to loads of individual bookmarks, making them much easier to manage.

05. DomFlags

A new way to work with DevTools

Radically speed up the processes of styling elements with DomFlags, a truly great extension that lets you create keyboard shortcuts for DOM elements. It's like having bookmarks for navigating the DOM; this will change the way you work with DevTools. 

06. Highly Highlighter

Highly, a new way to participate in industry conversation

Here's an interesting way to bring people into a discussion: Highly lets you share highlights from articles on the web, so you can draw attention to the most significant bits of writing. 

07. Booom

Get a better Dribbble experience with Booom

Booom makes Dribbble better by showing larger shots in lists; putting Like and Add to Bucket buttons in lists; making GIFs autoplay and bringing infinite scroll. 

08. CSS-Shack

This Chrome extension enables you to create layer styles and export them into a CSS file

This powerful Chrome extension enables you to create designs then export them into a CSS file for use on your site. It supports layers and contains a plethora of the tools that you're used to from your regular photo editor.

09. Marmoset

With Marmoset you can create gorgeous code snapshots within seconds

This brilliant extension will take your code and output snapshots for your demos and mockups. You can also add themes and effects to create images for promo and your online portfolio.

10. iMacros for Chrome

iMacros Chrome extension enables you to record actions and save them

As a web developer, you may be required to test your webpages. Repeating the same actions over and over again can be a tiresome process. iMacros is a handy Chrome extension that lets you record your actions and save them so you only need to do them once. After that you can test your pages over and over again, repeating the action with a click of a button. It saves valuable time, freeing up your time so you can concentrate on more pressing matters.

Next: 10 more Chrome extensions

11. Window Resizer

This Chrome extension re-sizes the browser window in order to emulate various resolutions

This Chrome extension is a useful tool that does exactly as it says on the tin – resizes your browser window to help you with your responsive website designs. Choose from a list of popular monitor dimensions or add custom sizes and resolutions for increased accuracy.

12. Project Naptha

With Naptha you can highlight, copy, edit, and translate text from any image on the web

If you ever find yourself working from a mockup image with embedded text, Project Naptha could save you a world of mild irritation. Thanks to some smart OCR trickery it enables you to highlight, copy and paste text from any image; it can even translate it for you.

13. WhatFont

What font are they using? The WhatFont Chrome extension can tell you!

A very useful Google Chrome extension, WhatFont allows developers and designers to identify the fonts being used on a webpage. So, if you stumble upon a fancy-looking web font that you want to use in one of your future projects, just hover over it and find out instantly which font it is.

14. Web Developer

The Web Developer Chrome extension provides a range of useful dev tools

As a web developer, you might ask yourself how you have lived without this extension. It adds a toolbar button to Chrome with a plethora of useful web developer tools. It's the official port of the Web Developer extension for Firefox.

15. Web Developer Checklist

Fix issues quickly with this handy Chrome extension

This tool allows you check if all of your webpages are following best practice when it comes to SEO, usability, accessibility and performance (page speed). So if, for example, you don't have an H1 tag on a webpage or if a webpage is missing its meta title or meta description, it will notify you so that you can fix the issue quickly. If you click the 'more info and help' link at the bottom of the extension, you will find a more in-depth checklist.

16. DevTools Autosave

Automatically save any changes to a page’s CSS and JS to its source file

A true gem for all web developers out there, DevTools AutoSave allows you to automatically save any changes that you make to a webpage's CSS and JS via the Chrome Dev Tools environment to its source file. It's easy to set up and use and it will save you lots of time and stress.

17. Instant Wireframe

View live webpages with a wireframe overlay

Turn any webpage into a wireframe with just one click. This Google Chrome extension helps web developers and designers view webpages, whether local or live on the web, with a wireframe overlay.

18. ColorZilla

With ColorZilla you can get a colour reading from any point in your browser

The ColorZilla Chrome extension is an advanced eyedropper, colour picker, gradient generator and useful colour tool that will help you in your design – right there in your browser window.

19. Streak CRM for Gmail

Turn an email conversation into a trackable, assignable ticket

Streak is the ultimate tool for managing CRM and support emails within Gmail. It allows you to turn a single email or an entire conversation into a trackable, assignable, organised ticket that you can manage yourself or share with others.

20. Search Stackoverflow

Get your questions answered quickly with this must-have extension

If you're a web developer then you've probably heard about Stack Overflow, the go-to place for any development related issues. If not, then you definitely need to check it out. The community is thriving and it covers a wide range of topics from C# and Java to PHP and jQuery. This fantastic extension adds a search box directly into your browser, allowing you to search the vast resources of Stack Overflow.

Next: more Chrome extensions

21. PerfectPixel

This extension helps you ensure your site matches the design pixel for pixel

Designers hate it when their stunning design doesn't match up perfectly when it's coded. Perfect Pixel really is the perfect extension for web developers who are striving to develop sites that are accurate representations of designs. This easy-to-use extension enables you to put a semi-transparent image overlay over the top of your webpage and perform a per pixel comparison between them to ensure it is 100% accurate.

22. Code Cola

Edit your webpages’ CSS on the spot

Not only does this tool allow you to view the source code of what you've been working on, but it also functions as a CSS editor. This means you can edit your webpages' CSS style on the spot and see the changes instantly.

23. IE tab

Test webpages with different versions of IE

One of the most popular and useful IE emulators available on the web, IE tab enables web developers to test webpages with different versions of IE directly in their Chrome browser.

24. PicMonkey

Grab every image from a webpage with a click of a button

This is an easy-to-use free online photo editor that allows you to edit webpage images and screenshots. But that's not what makes it so good. PicMonkey also lets you grab every image and a screenshot of the entire page with a click of a button. Once you select an image you can edit it in any way you wish, from applying effects to changing exposure.

25. Chrome Daltonize

Create images more suitable for viewing by those with Colour Vision Deficiency

Colour Vision Deficiency (CVD) or colour blindness affects millions of people across the globe. This ingenious extension uses Daltonization, a technique that allows the creation of images more suitable for viewing by those with CVD. This fantastic extension can be used to simulate how images appear to people with CVD and to help you design a more accessible web app.

26. Check My Links

Check My Links crawls through your webpage and looks for broken links

Finished building a site? Ah, but have you been through and checked all the links? No matter how careful you are, it's inevitable that you'll have overlooked one or two, and checking them all is a tedious chore. Unless…. With the Check My Links extension you can simply put it to work and it'll comb through all the links on any page, highlighting valid ones in green and broken ones in red.

27. Flickr Tab

Smarten up your Chome tabs with beautiful Flickr images

Are you tired of your Chrome tabs looking dull when you open a new one? The answer to your prayers has arrived in the form of Flickr Tab. It's a simple little Extension that displays a popular Fickr photograph each time you open up a window. Click the photo to view it in Flickr, or click the username to see more photos from the photographer.

28. Google Art Project

Make each new Chrome tab an adventure in art and discovery with the Google Art Project

Similar to Flickr Tab's glossy photos, Google's Art Project extension treats you to a high-res masterpiece from the likes of van Gogh and Monet in each new tab you open. If an image sparks your interest, click on it to go to the Google Cultural Institute website, which is full of information about the work and its creator.

29. Data Saver

Save cash when viewing designs on your mobile with Google’s compression based Data Saver

So, your latest bill from your mobile provider was rather toe curling? Don't panic. You need Data Saver, from Google. The extension does what it says on the tin: it reduces the amount of data used when browsing the web. When enabled, Chrome will use Google servers to compress pages before you download them. There's only one caveat: SSL and incognito pages won't be included.

Read more:

13 best pieces of user testing software30 web design tools to speed up your workflow23 steps to the perfect website layout

Original Source: http://feedproxy.google.com/~r/CreativeBloq/~3/7XgLkLMtibs/adobe-shares-pantones-summer-trending-colours

Adobe has teamed up with the Pantone Colour Institute to reveal which colours are trending this summer. Compiling its findings into the Pantone Colour Me Social gallery, Adobe suggests bold, saturated tones are big at the moment. And while this won't change colour theory, colour trends do affect the decisions of designers and brands.

The colours in question include Lime Green, Hawaiian Ocean, Flame Orange, Fuchsia Purple, Cherry Tomato, Blazing Yellow and Dazzling Blue. According to Laurie Pressman, the Institute's vice president, these tones mark a sea change in colour trends.

"Following years of essentialist and pared-down aesthetics, the thirst for vivid, rich colour is taking centre stage as people want to spark a new kind of joy and create playful paradises," she explains.

Get 15% off Adobe Creative Cloud with our exclusive deal

One of the key drivers behind this change is social media. Pressman reasons that these online platforms give users the freedom to experiment with colours and intense experiences, which in turn leads to people gravitating towards richer hues.

Given that social media is a relentlessly noisy world, it makes sense that brighter, bolder images have been on the rise as users attempt to stand out from the crowd. With colour seen as a form of self-expression on social media, vibrant colours lead to more interaction.

You can explore these vibrant colours below; use the left and right arrows to click through the gallery.

Despite this trend having its roots in social media, saturated colours have spilled over into the worlds of retail and fashion. This is an interesting inversion of traditional design, which usually saw fashion industries shaping the colour trends for everyone else to follow.

"While all of the shades highlighted are being seen on the street and the catwalk," says Pressman, "we are seeing these colours show up in other areas as well, from travel to food. Some of the newest sources for colour inspiration are home furnishings, lifestyle and beauty."

Brands, museums and exhibitions can all take advantage from these trending colours to connect with audiences. Pressman goes on to add that even if saturated colours don't immediately appear suitable for your brand or company, "even a small accent or a bright shade in the background could do the trick."

And with the Institute predicting the current colour trend to continue right the way through until the summer of 2020, there's plenty of time to get on board with this eye-popping palette.

Related articles:

Pantone launches super-sized colour chipsIf celebrities were Pantone coloursPrince gets his own Pantone colour – what could it be?