todataurl

问题 I want to get the data of an image of a fabric.Image object to loop through each pixel and change its color if it's a given color to another given color. But I don't want to get the data of the entire canvas , only of that specific object. Something like this - changeColor = (object, targetColor, replacementColor) => { data = object.getData(); for(var i = 0, n = data.length; i<n; i+=4){ let r = data[i]; let g = data[i + 1]; let b = data[i + 2]; if(r === targetColor.r && g === targetColor.g &&

问题 The code below should convert html to pdf using html2canvas library and then download it, but it's showing this error: Failed to execute 'toDataURL' on 'HTMLCanvasElement': Tainted canvases may not be exported The issue is still present after allowing cross-origin on the S3 bucket. html2canvas(document.getElementById('compare'), { scale: window.devicePixelRatio, logging: true, allowTaint:true, onrendered: function (canvas) { var data = canvas.toDataURL(); var docDefinition = { content: [{

问题 Use canvas.toDataURL('image/jpeg', 1) in Chrome, the image is lose a little seriously, but in Firefox, It's ok, almost lossless, even use default quality value 0.92. It seems does not working by setting the quality in Chrome. 回答1: It's a known issue and it's due to how chroma subsampling is handled. Chrome do this differently than Firefox and Safari. The latter ones uses 4:4:4 at 1.0 setting while current Chrome doesn't. However, it seem as the latest Canary (version 33) do the same as the

问题 Use canvas.toDataURL('image/jpeg', 1) in Chrome, the image is lose a little seriously, but in Firefox, It's ok, almost lossless, even use default quality value 0.92. It seems does not working by setting the quality in Chrome. 回答1: It's a known issue and it's due to how chroma subsampling is handled. Chrome do this differently than Firefox and Safari. The latter ones uses 4:4:4 at 1.0 setting while current Chrome doesn't. However, it seem as the latest Canary (version 33) do the same as the

问题 Okay, I know that canvas.toDataUrl() will produce an image in png format. However, when I try to get the image from http://threejs.org/examples/#webgl_lines_sphere. All I see is a black image on chrome. To replicate the steps - 1) Open dev console and select the canvas element. 2) canvas = $0 3) context = canvas.getContext('webgl', {preserveDrawingBuffer: true}) 4) img = canvas.toDataUrl() 5) document.write('<img src="'+img+'"/>') The image is blank. However, I tried with a different canvas

问题 Here is how I send data from the client (coffeescript & dajaxice): imageData = canvas.toDataURL("image/png") Dajaxice.draw.saveImage( @saveImage_callback, {'image': imageData } ) Here is how I save my image on the server (taken from this answer) @dajaxice_register def saveImage(request, image): imageData = re.search(r'base64,(.*)', image).group(1) output = open('image.png', 'wb') output.write(imageData.decode('base64')) output.close() I would like to load the image and send it like so:

问题 Here is how I send data from the client (coffeescript & dajaxice): imageData = canvas.toDataURL("image/png") Dajaxice.draw.saveImage( @saveImage_callback, {'image': imageData } ) Here is how I save my image on the server (taken from this answer) @dajaxice_register def saveImage(request, image): imageData = re.search(r'base64,(.*)', image).group(1) output = open('image.png', 'wb') output.write(imageData.decode('base64')) output.close() I would like to load the image and send it like so:

问题 I'm using glfx.js to edit my image but when I'm trying to get that image's data using the toDataURL() function I get a blank image (width the same size as the original image). The strange thing is that in Chrome the script works perfect. What I want to mention is that the image is loaded in canvas using the onload event: img.onload = function(){ try { canvas = fx.canvas(); } catch (e) { alert(e); return; } // convert the image to a texture texture = canvas.texture(img); // draw and update

问题 I'm aware that this question was answered in this forum (Unable to get values in POST php web serivce), but both the question and the answer used jQuery and, in my case, I can't use it (no matter why)... So, I have a Javascript file that is intended to make a canvas' "screen capture" (using the "toDataURL()" function) and send it to a PHP file using AJAX. As the data to be sent is really long, I can't use the "GET" method (AJAX returns a 414 error: "URL TOO LONG"), so I need to use "POST". I

问题 Here is doc for toDataURL : Syntax canvas.toDataURL(type, encoderOptions); Parameters type Optional A DOMString indicating the image format. The default type is image/png. encoderOptions Optional A Number between 0 and 1 indicating image quality if the requested type is image/jpeg or image/webp. If this argument is anything else, the default value for image quality is used. Other arguments are ignored. If this argument is anything else, the default value for image quality is used. Other