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js canvas filtercanvasfilter
<!DOCTYPE html> <html> <body> <p>Image to use:</p> <img id="scream" width="220" height="277" src="img_the_scream.jpg" alt="The Scream"> <p>Canvas:</p> <canvas id="myCanvas" width="340" height="397" style="border:1px solid #d3d3d3;"> Your browser does not support the HTML5 canvas tag. </canvas> <script> window.onload = function() { var c = document.getElementById("myCanvas"); var ctx = c.getContext("2d"); // 合成模式 ctx.filter = 'blur(4px) grayscale(50%)'; // 分别设置,后面会把前面内容覆盖 // ctx.filter = 'blur(4px)'; // ctx.filter = 'grayscale(50%)' var img = document.getElementById("scream"); ctx.drawImage(img, 10, 10); // 这里设置 filter 无效 // ctx.filter = 'grayscale(1)'; } </script> <p><strong>Note:</strong> The canvas tag is not supported in Internet Explorer 8 and earlier versions.</p> </body> </html>
