MatrixDecoder is fully JavaScript object with a couple of methods which you can use to compute the dimensions of HTML elements' corners. You can use getBoundingClientRect method or offsetWidth, offsetHeight property, to get the 2d box dimensions, but it's not effective, if you transform your HTML object with CSS transform property and want to get proper dimensions of transformed 3d box. MatrixDecoder gets matrix() and matrix3d() values of transform CSS property and convert it's 6 or 16 values into proper box dimensions. MatrixDecoder computes the x and y coordinates of four element corners toward the chosen element.
- better control of transforming
- easier manipulation with CANVAS
- when you use
event.clientXevent.clientYto calculate the proper position of the mouse cursor on the transformed element - to stick outer elements to the edges of transformed element
- when you know the position of each corner, you can calculate, alike using CANVAS method
isPointInPath(), whether the 2d or 3d transformed element overlaps another one. - to transform the element till it's corners reach specified positions
The generator of DIV element transformed with transform, transform-style, transform-origin and perspective properties:
- https://devrafalko.github.io/matrixDecoder/samp/
- the four small boxes with blue border and x, y, z coordinates use the matrixDecoder to get sticked to the corners of transforming box.
- You can manipulate transform values and examine, how matrixDecoder works in the flow
- You can select Value Type from the select element to change the dimensions returned in four corner boxes. Use the
top,leftandrotateslider to understand the differences between returned values.
| Chrome | Firefox | IE | Safari | Opera | iOS Safari | Opera Mini |
|---|---|---|---|---|---|---|
| 11+ | 4+ | 9-11 | 5+ | 10.6+ | 3.2+ | 5+ |
| name | description | syntax | parameters | parameters description |
|---|---|---|---|---|
| decode | The decode() method returns the rounded x and y px coordinates of four corners of the chosen HTML element. It returns the full numbers of pixels, eg. 4, 100, 1500 |
matrixDecoder.decode(elem) |
elem | The HTML element, which dimensions you want to get. |
| decodePrecise | The decodePrecise() method returns the accurate computed values for x and y px coordinates of four corners of the chosen HTML element. It returns the numbers with decimal fractions (if exists) of pixels, eg. 4, 100.234523, 1500.2354634346 |
matrixDecoder.decodePrecise(elem) |
elem | The HTML element, which dimensions you want to get. |
{fixed:
{A: {x:number,y:number},
B: {x:number,y:number},
C: {x:number,y:number},
D: {x:number,y:number}},
parent:{
{A: {x:number,y:number},
B: {x:number,y:number},
C: {x:number,y:number},
D: {x:number,y:number}},
element{
{A: {x:number,y:number},
B: {x:number,y:number},
C: {x:number,y:number},
D: {x:number,y:number}}}The decode() method and decodePrecise() method return the object with 3 types of values:
fixed- returns the coordinates (topandleftproperties) of four corners relative to the screen top-left cornerparent- returns the coordinates (topandleftproperties) of four corners relative to the element's parent top-left cornerelement- returns the coordinates (topandleftproperties) of four corners relative to itself top-left corner, as if the element would be set totransform:none
Each type of value contains A B C D objects related to 4 corners of element (going clockwise from top-left):
A- returns the coordinates (topandleftproperties) of top-left cornerB- returns the coordinates (topandleftproperties) of top-right cornerC- returns the coordinates (topandleftproperties) of bottom-right cornerD- returns the coordinates (topandleftproperties) of bottom-left corner
Each corner contains x and y properties:
xdefine left numerical value of pixelsydefine top numerical value of pixels
//find HTML element
var getElement = document.getElementById('htmlDivContainer');
//return the object with all coordinates
var getCoorinates = matrixDecoder.decode(getElement);
//get the top (y) and left (x) position of top-left corner (A), relative to the element's parent (parent)
console.log(getCoordinates.parent.A.x,
getCoordinates.parent.A.y);
//get the left (x) positions of top-right (B) and bottom-right (C) corners, relative to the BODY (fixed)
console.log(getCoordinates.fixed.B.x,
getCoordinates.fixed.C.x);
//get the new top (y) and left (x) position of bottom-right (C) corner of transformed element (element)
//relative to it's non-transformed position
console.log(getCoordinates.element.C.x,
getCoordinates.element.C.y);
});<script src="matrixDecoder.js"></script>Any outer libraries needed. It is a fully JavaScript project.
<div id="container"></div>#container {
transform: rotateX(50deg) rotateY(25deg) skewX(10deg);
}var getElement = document.getElementById('container');
var getCoorinates = matrixDecoder.decode(getElement);Released under the MIT license.
Copyright (c) 2016 Paweł Rafałko dev.rafalko@gmail.com
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 furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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