1. 程式人生 > >Web開發之用canvas2image.js將canvas儲存為圖片(實現頁面截圖下載功能)

Web開發之用canvas2image.js將canvas儲存為圖片(實現頁面截圖下載功能)

var canvas, ctx, bMouseIsDown = false, iLastX, iLastY, $save, $imgs, $convert, $imgW, $imgH, $sel; function init () { canvas = document.getElementById('cvs'); ctx = canvas.getContext('2d'); $save = document.getElementById('save'); $convert = document.getElementById('convert'
); $sel = document.getElementById('sel'); $imgs = document.getElementById('imgs'); $imgW = document.getElementById('imgW'); $imgH = document.getElementById('imgH'); $imgFileName =document.getElementById('imgFileName'); bind(); draw(); } function
bind () {
canvas.onmousedown = function(e) { bMouseIsDown = true; iLastX = e.clientX - canvas.offsetLeft + (window.pageXOffset||document.body.scrollLeft||document.documentElement.scrollLeft); iLastY = e.clientY - canvas.offsetTop + (window.pageYOffset||document.body.scrollTop||document.documentElement.scrollTop); } canvas.onmouseup = function
() {
bMouseIsDown = false; iLastX = -1; iLastY = -1; } canvas.onmousemove = function(e) { if (bMouseIsDown) { var iX = e.clientX - canvas.offsetLeft + (window.pageXOffset||document.body.scrollLeft||document.documentElement.scrollLeft); var iY = e.clientY - canvas.offsetTop + (window.pageYOffset||document.body.scrollTop||document.documentElement.scrollTop); ctx.moveTo(iLastX, iLastY); ctx.lineTo(iX, iY); ctx.stroke(); iLastX = iX; iLastY = iY; } }; $save.onclick = function (e) { var type = $sel.value, w = $imgW.value, h = $imgH.value; f = $imgFileName.value; Canvas2Image.saveAsImage(canvas, w, h, type,f); } $convert.onclick = function (e) { var type = $sel.value, w = $imgW.value, h = $imgH.value; $imgs.appendChild(Canvas2Image.convertToImage(canvas, w, h, type)) } } function draw () { ctx.fillStyle = '#ffffff'; ctx.fillRect(0, 0, 600, 400); ctx.fillStyle = 'red'; ctx.fillRect(100, 100, 50, 50); } onload = init;