canvas

问题 I am doing a Ajax call to Server for a Jpeg file. I have the data returned as Array buffer. Now how can I render this Array buffer on the canvas. Now please dont suggest any answer like setting the source url to the image. I want to hold the image data on memory for some processing. 回答1: If you don't want to use the buffer as an image source, the only option left is to parse the raw buffer yourself. Just have in mind that this buffer contains the unprocessed (raw) file, so by parsing it means

问题 I am doing a Ajax call to Server for a Jpeg file. I have the data returned as Array buffer. Now how can I render this Array buffer on the canvas. Now please dont suggest any answer like setting the source url to the image. I want to hold the image data on memory for some processing. 回答1: If you don't want to use the buffer as an image source, the only option left is to parse the raw buffer yourself. Just have in mind that this buffer contains the unprocessed (raw) file, so by parsing it means

问题 I have a HTML canvas (using KineticJS, however canvas aficionados should still chime in) that loads an image from another domain, places it onto the canvas and overlays some other information to product a final image. When I try to use canvas.toDataURL () to output the file, I receive the message "The operation is insecure.", obviously due to cross-domain restrictions. I was wondering if anyone knows of any methods to work around this error (preferably cross-browser compatible). I was

问题 I have a HTML canvas (using KineticJS, however canvas aficionados should still chime in) that loads an image from another domain, places it onto the canvas and overlays some other information to product a final image. When I try to use canvas.toDataURL () to output the file, I receive the message "The operation is insecure.", obviously due to cross-domain restrictions. I was wondering if anyone knows of any methods to work around this error (preferably cross-browser compatible). I was

问题 How I dynamically add an id value for a canvas object in jQuery? HTML <div id="obj"> <canvas></canvas> <canvas></canvas> </div> How do I change the second canvas object value with somename ? Expected result: <canvas id="somename"></canvas> 回答1: The $() function returns an array of matching DOM elements so you can just assign to the id property of the second element: $('#obj canvas')[1].id = 'somename'; 回答2: Try this: $("#obj canvas").slice(1).attr("id","somename"); 来源： https://stackoverflow

问题 How just move image in canvas? There are no x\y coordinates which I can change by += or -=. 回答1: Canvas is an immedate drawing surface. When you make a call like drawImage the canvas renders the bitmap to the context and then forgets that anything ever happened. It keeps track of nothing. That means you need to keep track of everything. If you want the image you move, you need to clear the canvas and redraw the image (and everything else in the scene) at a different location than before. This

问题 I'm trying to draw a donut chart, and so far I've been successful. The problem is that when trying to animate the arc by combining stroke() with setInterval() , it works, but it does not look smooth, and produces jagged edges. I tried using clearRect() to clear the canvas after the animation was done and re-add the final version of the animation, but I must have been using clearRect() wrong, because it did nothing. If you have any ideas on how to get this looking good, I'd really appreciate

问题 how can I display a programmatically created ImageView on top of a previously created View Canvas? I tried using bringToFront(), but without success. Code: RelativeLayout root = findViewById(R.id.layout); ImageView img = new ImageView(GameGuessActivity.context); img.setImageResource(R.drawable.image); RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(width, height); params.leftMargin = x; params.topMargin = y; root.addView(img, params); img.bringToFront(); The Image is

问题 Here i am trying to make circle using multiple arc shape. like following: var startAngle = 0; var arc = Math.PI / 6; var ctx; var leftValue=275; var topValue=300; var wheelImg = "http://i.stack.imgur.com/wwXlF.png"; function drawWheelImg() { var canvas = document.getElementById("canvas"); if(canvas.getContext) { var outsideRadius = 260; var textRadius = 217; var insideRadius = 202; ctx = canvas.getContext("2d"); for(var i = 0; i < 12; i++) { var angle = startAngle + i * arc; ctx.beginPath();

问题 How can I make a Facebook app that doesn't require users to log in/authorize my app? Is it even possible for canvas apps? The conversion in auth dialog is quite poor (39%) for my app, even though I ask for the basic information only. Hence the question. Thanks for advice! 回答1: There are no special actions necessary to run a canvas app in Facebook without authentication. Simply set the Canvas URL and Secure Canvas URL in your app's settings ( https://developers.facebook.com/apps/<app_id>