call-capture
v0.2.1
Published
Capture calls and property assignments on an object
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capture
Wrap around an object and capture sets on its properties and calls on its methods.
usage
node
const capture = require("call-capture");browser
<html>
<head>
<meta charset="UTF-8">
<script src="src/capture.js"></script>
</head>
<body>
<script>
// capture is in the global scope
</script>
</body>
</html>deferring
// assume we have a canvas on a webpage
var ctx = capture(canvas.getContext("2d"));
// call and set on the capture object, will not execute immediately
ctx.beginPath();
ctx.lineWidth = 5;
ctx.moveTo(5, 10);
ctx.lineTo(70, 60);
ctx.stroke();
// examine queued commands
console.log(ctx.queue[1]);
// modify queued command arguments
ctx.queue[1].args[1] += 10; // now becomes ctx.moveTo(5, 20)
// execute all queued commands
ctx.executeAll();
// execute a specific one in the queue
ctx.queue[3].execute();
// clear queued commands (won't clear automatically after executing)
ctx.clearQueue();indirect wrapping
If you don't have access to object creation (for example if it's done in a library), then you can patch its creation function.
// wrap around with canvas drawing
var oldGetContext = HTMLCanvasElement.prototype.getContext;
HTMLCanvasElement.prototype.getContext = function () {
return capture(oldGetContext.apply(this, arguments));
};It's not recommended to try wrapping the CanvasRenderingContext2D's prototype directly because it contains native calls.
immediate execution
If you don't actually to defer anything, but instead capture them, then that is available via the immediatelyExecute option:
var ctx = capture(canvas.getContext("2d"), {immediatelyExecute: true});This and other options can be configured by directly modifying the captured object:
ctx.opts.executeImmediately = false;pause/start capturing
You can suspend capture and execute commands immediately by calling
ctx.pauseCapture();
// immediately executed commands on ctx...
ctx.resumeCapture();