drawimage

来源： https://stackoverflow.com/questions/63138513/canvas-drawimage-slow-first-time-another-canvas-is-used-as-the-source-argument

来源： https://stackoverflow.com/questions/63138513/canvas-drawimage-slow-first-time-another-canvas-is-used-as-the-source-argument

来源： https://stackoverflow.com/questions/63138513/canvas-drawimage-slow-first-time-another-canvas-is-used-as-the-source-argument

问题 Here's the code: window.onload = function() { var c = document.getElementById("myCanvas"); var ctx = c.getContext("2d"); var img = document.getElementById("scream"); ctx.drawImage(img, 0, 0, img.height, img.width, 0, 0, 100, 100); }; Here's the picture: I set it to get the whole image by setting img.height and img.width. But still I see that no whole picture is there, only part: bottom part is getting cut. How can I get it? Am I entering wrong value? Refer here 回答1: Arguments of function

问题 I have a pdf document with one or more pages A4 paper. The resulting pdf document should be A3 paper where each page contains two from the first one (odd on the left, even on the right side). I already got it to render the A4 pages into images and the odd pages are successfully placed on the first parts of a new A3 pages but I cannot get the even pages to be placed. public class CreateLandscapePDF { public void renderPDF(File inputFile, String output) { PDDocument docIn = null; PDDocument

问题 I have a pdf document with one or more pages A4 paper. The resulting pdf document should be A3 paper where each page contains two from the first one (odd on the left, even on the right side). I already got it to render the A4 pages into images and the odd pages are successfully placed on the first parts of a new A3 pages but I cannot get the even pages to be placed. public class CreateLandscapePDF { public void renderPDF(File inputFile, String output) { PDDocument docIn = null; PDDocument

问题 I'm drawing an image to a canvas element. I then have code that depends on this process to be finished. My code looks like this: var myContext = myCanvasElement.getContext('2d'), myImg = new Image(); myImg.onload = function() { myContext.drawImage(containerImg, 0, 0, 300, 300); }; myImg.src = "someImage.png"; So now, I would like to be notified when drawImage is done. I checked the spec but I couldn't find either an event or the possibility to pass a callback function. So far I just set a

问题 (I'll show the pure javascript below) I've got these two lines of code that are, in my mind, doing the exact same thing but one of them reports an error. This appears in a file named "Rendering.coffee". Here are the two lines (in coffeescript): ... ctx.drawImage(document.getElementById("bg"), 0, 0) #this works ctx.drawImage(root.resources.bg, 0, 0) #TypeError: Value could not be converted to any of: HTMLImageElement, HTMLCanvasElement, HTMLVideoElement. ... I assign root.resources.bg in

问题 I am using a GDI+ Graphic to draw a 4000*3000 image to screen, but it is really slow. It takes about 300ms. I wish it just occupy less than 10ms. Bitmap *bitmap = Bitmap::FromFile("XXXX",...); //-------------------------------------------- // this part takes about 300ms, terrible! int width = bitmap->GetWidth(); int height = bitmap->GetHeight(); DrawImage(bitmap,0,0,width,height); //------------------------------------------ I cannot use CachedBitmap, because I want to edit the bitmap later.

问题 I'm using this script: var canvas = new fabric.Canvas('game_canvas', { selection: false }); fabric.Image.fromURL('images/bg.jpg', function(img) { img.set('left', 1024/2).set('top', 600/2).set('zindex', 0); canvas.add(img); }); fabric.Image.fromURL('images/panel-2-bg-l-r.png', function(img) { img.set('left', 262/2).set('top', (390/2)+110).set('zindex', 1); canvas.add(img); }); fabric.Image.fromURL('images/player-board.png', function(img) { img.set('left', 254/2).set('top', (122/2)).set('zindex