Tutorial by Examples: ha

Getting started with a simple map

<html> <head> <title>Getting started</title> <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/ol3/3.17.1/ol.css" type="text/css"> <script src="https://cdnjs.cloudflare.com/ajax/libs/ol3/3.17.1/ol...

openlayers-3 • Getting started with openlayers-3

Matching a literal string with a regular expression

Sometimes you need to match a literal (sub-)string with a regular expression despite that substring containing RE metacharacters. While yes, it's possible to write code to insert appropriate backslashes to make that work (using string map) it is easiest to just prefix the pattern with ***=, which ma...

tcl • Regular Expressions

Simple, hard-coded AutoCompleteTextView

Design (layout XML): <AutoCompleteTextView android:id="@+id/autoCompleteTextView1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_alignParentTop="true" android:layout_centerHorizontal="true&...

Android • AutoCompleteTextView

Reading structures with Marshal

Marshal class contains a function named PtrToStructure, this function gives us the ability of reading structures by an unmanaged pointer. PtrToStructure function got many overloads, but they all have the same intention. Generic PtrToStructure: public static T PtrToStructure<T>(IntPtr ptr); ...

C# Language • Interoperability

Handling a CURSOR

Declare the cursor to scan a list of records Open it Fetch current record into variables (this increments position) Use %notfound to detect end of list Don't forget to close the cursor to limit resources consumption in current context -- DECLARE CURSOR curCols IS -- select column name a...

plsql • Cursors

Iterating over the entries of a hash table with loop

The loop macro supports iteration over the keys, the values, or the keys and values of a hash table. The following examples show possibilities, but the full loop syntax allows more combinations and variants. Over keys and values (let ((ht (make-hash-table))) (setf (gethash 'a ht) 1 (g...

common-lisp • Hash tables

Iterating over the entries of a hash table with a hash table iterator

The keys and values of a hash table can be iterated over using the macro with-hash-table-iterator. This may be a bit more complex than maphash or loop, but it could be used to implement the iteration constructs used in those methods. with-hash-table-iterator takes a name and a hash table and binds...

common-lisp • Hash tables

How to tell if you have a JWS or JWE?

From Section 9 of JSON Web Encryption specification (RFC 7516): The JOSE Header for a JWS can be distinguished from the JOSE Header for a JWE by examining the "alg" (algorithm) Header Parameter value. If the value represents a digital signature or MAC algorithm, or is the value "no...

jwt • Getting started with jwt

Changing bytes

Once an object has an effective type, you should not attempt to modify it through a pointer of another type, unless that other type is a character type, char, signed char or unsigned char. #include <inttypes.h> #include <stdio.h> int main(void) { uint32_t a = 57; // conversion...

C Language • Aliasing and effective type

How shapes & images REALLY(!) "move" on the Canvas

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...

html5-canvas • Dragging Path Shapes & Images on Canvas

Dragging irregular shapes around the Canvas

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...

html5-canvas • Dragging Path Shapes & Images on Canvas

Sticker effect using shadows

This code adds outwardly increasing shadows to an image to create a "sticker" version of the image. Notes: In addition to being an ImageObject, the "img" argument can also be a Canvas element. This allows you to stickerize your own custom drawings. If you draw text on the Can...

html5-canvas • Shadows

How to stop further shadowing

Once shadowing is turned on, every new drawing to the canvas will be shadowed. Turn off further shadowing by setting context.shadowColor to a transparent color. // start shadowing context.shadowColor='black'; ... render some shadowed drawings ... // turn off shadowing. context.shadowColor=...

html5-canvas • Shadows

Shadowing is computationally expensive -- Cache that shadow!

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...

html5-canvas • Shadows

Add visual depth with shadows

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...

html5-canvas • Shadows

Inner shadows

Canvas does not have CSS's inner-shadow. Canvas will shadow the outside of a filled shape. Canvas will shadow both inside and outside a stroked shape. But it's easy to create inner-shadows using compositing. Strokes with an inner-shadow To create strokes with an inner-shadow, use destinat...

html5-canvas • Shadows

A password containing at least 1 uppercase, 1 lowercase, 1 digit, 1 special character and have a length of at least of 10

As the characters/digits can be anywhere within the string, we require lookaheads. Lookaheads are of zero width meaning they do not consume any string. In simple words the position of checking resets to the original position after each condition of lookahead is met. Assumption :- Considering non-wo...

Regular Expressions • Password validation regex

Draw Shapes

To start drawing a shape you need to define a pen object The Pen accepts two parameters: Pen Color or Brush Pen Width The Pen Object is used to create an outline of the object you want to draw After Defining the Pen you can set specific Pen Properties Dim pens As New Pen(Color.Purple) ...

Visual Basic .NET Language • GDI+

Fill Shapes

Graphics.FillShapes draws a shape and fills it in with the color given. Fill Shapes can use Brush Tool - to fill shape with a solid color Dim rect As New Rectangle(50, 50, 50, 50) e.Graphics.FillRectangle(Brushes.Green, rect) 'draws a rectangle that is filled with green e.Graphics.FillPie(...

Visual Basic .NET Language • GDI+

Handling QueryClose

The QueryClose event is raised whenever a form is about to be closed, whether it's via user action or programmatically. The CloseMode parameter contains a VbQueryClose enum value that indicates how the form was closed: ConstantDescriptionValuevbFormControlMenuForm is closing in response to user act...

VBA • User Forms