Tutorial by Examples: v

To add a value to a WeakSet, use the .add() method. This method is chainable. const obj1 = {}, obj2 = {}; const weakset = new WeakSet(); weakset.add(obj1).add(obj2);

To check if a value exits in a WeakSet, use the .has() method. const obj1 = {}, obj2 = {}; const weakset = new WeakSet([obj1]); console.log(weakset.has(obj1)); // true console.log(weakset.has(obj2)); // false

To remove a value from a WeakSet, use the .delete() method. This method returns true if the value existed and has been removed, otherwise false. const obj1 = {}, obj2 = {}; const weakset = new WeakSet([obj1]); console.log(weakset.delete(obj1)); // true console.log(weakset.delete(obj2));...

import java.util.stream.IntStream; public class Concurrent { public static void printAndWait(String s) { System.out.println(s); try { Thread.sleep(1000); } catch (Exception e) {} } public static void main(String[] args) { Threa...

Our server object is given an 'application' parameter which can be any callable application object (see other examples). It writes first the headers, then the body of data returned by our application to the system standard output. import os, sys def run(application): environ['wsgi.inpu...

A problem: Canvas only remembers pixels, not shapes or images This is an image of a circular beach ball, and of course, you can't drag the ball around the image. It may surprise you that just like an image, if you draw a circle on a Canvas you cannot drag that circle around the canvas. That's be...

What is a "Shape"? You typically save your shapes by creating a JavaScript "shape" object representing each shape. var myCircle = { x:30, y:20, radius:15 }; Of course, you're not really saving shapes. Instead, you're saving the definition of how to draw the shapes. Then put...

Most Canvas drawings are either rectangular (rectangles, images, text-blocks) or circular (circles). Circles & rectangles have mathematical tests to check if the mouse is inside them. This makes testing circles and rectangles easy, quick and efficient. You can "hit-test" hundreds of c...

See this Example for a general explanation of dragging Shapes around the Canvas. This annotated example shows how to drag images around the Canvas // canvas related vars var canvas=document.createElement("canvas"); var ctx=canvas.getContext("2d"); canvas.width=378; canvas.h...

Here is an example of an IntentService that pretends to load images in the background. All you need to do to implement an IntentService is to provide a constructor that calls the super(String) constructor, and you need to implement the onHandleIntent(Intent) method. public class ImageLoaderIntentSe...

Given the 3 points of a quadratic curve the following function returns the length. function quadraticBezierLength(x1,y1,x2,y2,x3,y3) var a, e, c, d, u, a1, e1, c1, d1, u1, v1x, v1y; v1x = x2 * 2; v1y = y2 * 2; d = x1 - v1x + x3; d1 = y1 - v1y + y3; e = v1x - 2 * x1; ...

VB_Name specifies the class or module name. Attribute VB_Name = "Class1" A new instance of this class would be created with Dim myClass As Class1 myClass = new Class1

In VBA, this attribute is ignored. It was not ported over from VB6. In VB6, it creates a Default Global Instance of the class (a "shortcut") so that class members can be accessed without using the class name. For example, DateTime (as in DateTime.Now) is actually part of the VBA.Conversio...

This attribute is ignored. It was not ported over from VB6. In VB6, it was used in combination with the VB_Exposed attribute to control accessibility of classes outside of the current project. VB_Exposed=True VB_Creatable=True Would result in a Public Class, that could be accessed from other ...

Creates a Global Default Instance of a class. The default instance is accessed via the name of the class. Declaration VERSION 1.0 CLASS BEGIN MultiUse = -1 'True END Attribute VB_Name = "Class1" Attribute VB_GlobalNameSpace = False Attribute VB_Creatable = False Attribute VB_Pr...

Controls the instancing characteristics of a class. Attribute VB_Exposed = False Makes the class Private. It cannot be accessed outside of the current project. Attribute VB_Exposed = True Exposes the class Publicly, outside of the project. However, since VB_Createable is ignored in VBA, inst...

Adds a text description to a class or module member that becomes visible in the Object Explorer. Ideally, all public members of a public interface / API should have a description. Public Function GiveMeATwo() As Integer Attribute GiveMeATwo.VB_Description = "Returns a two!" ...

VB_VarUserMemId (for module-scope variables) and VB_UserMemId (for procedures) attributes are used in VBA mostly for two things. Specifying the default member of a class A List class that would encapsulate a Collection would want to have an Item property, so the client code can do this: For i = 1...

Warning! Apply shadows sparingly! Applying shadowing is expensive and is multiplicatively expensive if you apply shadowing inside an animation loop. Instead, cache a shadowed version of your image (or other drawing): At the start of your app, create a shadowed version of your image in a secon...

The traditional use of shadowing is to give 2-dimensional drawings the illusion of 3D depth. This example shows the same "button" with and without shadowing var canvas=document.createElement("canvas"); var ctx=canvas.getContext("2d"); document.body.appendChild(can...