mirror of
https://github.com/adriancooney/console.snapshot.git
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49 lines
2.2 KiB
Markdown
49 lines
2.2 KiB
Markdown
# console.snapshot( _canvas_ )
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### A simple canvas profiler
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`console.snapshot` takes and inputted _<canvas>_ element and outputs a snapshot of it into the console. It makes debugging the canvas a little less dramatic. See [this demo](http://adriancooney.github.io/console.snapshot). `console.snapshot` is a fork of the [`console.image`](http://github.com/adriancooney/console.image) and actually does something useful.
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## Usage
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### console.snapshot( _<canvas>_ )
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`console.snapshot` profiles a canvas for 1 iteration in the browser render loop or for one `requestAnimationFrame` tick and outputs the canvas context call stack and state changes to the console.
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```js
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var canvas = document.getElementById("canvas");
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console.snapshot(canvas);
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```
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;
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### console.screenshot( _<canvas>_ [, _<scale>_ ] )
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`console.screenshot` takes in a `HTMLCanvasElement`, base64 encodes it using `toDataURL` and then outputs it to the canvas using `console.image`. You can also pass along an optional scale factor to scale down the outputted image for better viewing within the Dev tools.
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```js
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var canvas = document.createElement("canvas"),
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ctx = canvas.getContext("2d");
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// ...
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//draw
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// ...
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console.screenshot(canvas);
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console.screenshot(canvas, 0.8); //Snapshot it and scale the output to 80% of the original size
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```
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### console.image( _<url>_ )
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`console.image` outputs an image from a url into the console. See [console.image](http://github.com/adriancooney/console.image).
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```js
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console.image("http://i.imgur.com/wWPQK.gif");
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```
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## Troubleshooting
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##### I'm getting "Uncaught Error: SecurityError: DOM Exception 18" when I try to snapshot the canvas.
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This is caused by printing a non CORS-enabled image on the canvas. The browser blocks the `toDataURL` function which is what `console.image` depends on to print the canvas. To fix this, see [this tutorial on HTML5Rocks](http://www.html5rocks.com/en/tutorials/cors/) or consider passing your image through a CORS proxy such as [corsproxy.com](http://corsproxy.com).
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License: MIT
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