Created
September 30, 2016 10:59
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An example about how to draw a region by using mouse gestures
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| <!doctype html> | |
| <html> | |
| <head> | |
| <style> | |
| .fullwindow { | |
| position: absolute; | |
| height: 100%; | |
| width: 100%; | |
| top: 0px; | |
| left: 0px; | |
| } | |
| .select-region { | |
| background-color: red; | |
| position: absolute; | |
| } | |
| </style> | |
| </head> | |
| <body> | |
| <div class="fullwindow"></div> | |
| <div class="select-region"></div> | |
| <script> | |
| 'use strict'; | |
| var mousePressed = false; | |
| var start = { clientX: 0, clientY: 0 }; | |
| var body = document.querySelector('body'); | |
| var selection = document.querySelector('.select-region'); | |
| body.addEventListener('mousedown', e => { | |
| mousePressed = true; | |
| start.clientX = e.clientX; | |
| start.clientY = e.clientY; | |
| selection.style.width = '0px'; | |
| selection.style.height = '0px'; | |
| selection.style.top = start.clientY + 'px'; | |
| selection.style.left = start.clientX + 'px'; | |
| }); | |
| body.addEventListener('mousemove', e => { | |
| if (mousePressed) { | |
| selection.style.width = Math.abs(e.clientX - start.clientX) + 'px'; | |
| selection.style.height = Math.abs(e.clientY - start.clientY) + 'px'; | |
| if (e.clientX < start.clientX) { | |
| selection.style.left = e.clientX + 'px'; | |
| } | |
| if (e.clientY < start.clientY) { | |
| selection.style.top = e.clientY + 'px'; | |
| } | |
| } | |
| }); | |
| body.addEventListener('mouseup', e => { | |
| mousePressed = false; | |
| }); | |
| </script> | |
| </body> | |
| </html> |
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