Manual stop capture (#62)

* Stop capture (#56) * adds a `config.stopFunctionName` and `--stop-function-name` which allows the user to specify a function that can be called to stop capture * updated cli.js and README.md for stopFunctionName Co-authored-by: RhinoW <[email protected]> Co-authored-by: user <[email protected]>
tungs · Jun 14, 2021 · b0fe2e8 · b0fe2e8
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diff --git a/README.md b/README.md
@@ -170,6 +170,8 @@ Opens https://breathejs.org/examples/Drawing-US-Counties.html, sets the viewport
     * Suppresses console logging.
 * <a name="cli-options-output-stdout" href="#cli-options-output-stdout">#</a> Output stdout: `--output-stdout`
     * Outputs images to stdout. Useful for piping.
+* <a name="cli-options-stop-function-name" href="#cli-options-stop-function-name">#</a> Stop Function Name: `--stop-function-name` *function name*
+    * Creates a function with *function name* that the client web page can call to stop capturing. For instance, `--stop-function-name=stopCapture` could be called in the client, via `stopCapture()`.
 * <a name="cli-options-version" href="#cli-options-version">#</a> Version: `-v`, `--version`
     * Displays version information. Immediately exits.
 * <a name="cli-options-help" href="#cli-options-help">#</a> Help: `-h`, `--help`
@@ -282,6 +284,7 @@ The Node API is structured similarly to the command line options, but there are
         * <a name="js-config-should-skip-frame-frame-count" href="#js-config-should-skip-frame-frame-count">#</a> `frameCount` &lt;[number][]&gt; The current frame count, starting at 1.
         * <a name="js-config-should-skip-frame-frames-to-capture" href="#js-config-should-skip-frame-frames-to-capture">#</a> `framesToCapture` &lt;[number][]&gt; The total number of frames to be captured.
         * <a name="js-config-should-skip-frame-page" href="#js-config-should-skip-frame-page">#</a> `page` &lt;[Page][]&gt; the puppeteer page.
+    * <a name="js-config-stop-function-name" href="#js-config-stop-function-name">#</a> `stopFunctionName` &lt;[string][]&gt; *function name* that the client web page can call to stop capturing. For instance, `'stopCapture'` could be called in the client, via `stopCapture()`.
     * <a name="js-config-frame-processor" href="#js-config-frame-processor">#</a> `frameProcessor` &lt;[function][]([Buffer][], [number][], [number][])&gt; A function that will be called after capturing each frame. If `config.outputDirectory` and `config.outputPattern` aren't specified, enabling this suppresses automatic file output. After capturing each frame, `config.frameProcessor` is called with three arguments, and if it returns a promise, capture will be paused until the promise resolves:
         * `screenshotData` &lt;[Buffer][]&gt; A buffer of the screenshot data.
         * `frameNumber` &lt;[number][]&gt; The current frame number (1 based).

diff --git a/cli.js b/cli.js
@@ -95,6 +95,7 @@ commander
     // TODO: make a more sophisticated parser for options that can handle quote marks
     return str.split(' ');
   })
+  .option('--stop-function-name <function name>', 'Allows client page to call function name to stop capture')
   .option('--no-headless', 'Chromium/Chrome runs in a window instead of headless mode')
   .option('--screenshot-type <type>', 'Output image format for screenshots, either png or jpeg')
   .option('--screenshot-quality <level>', 'The quality level for lossy screenshots', parseFloat)

diff --git a/index.js b/index.js
@@ -47,6 +47,7 @@ module.exports = function (config) {
   var unrandom = config.unrandomize;
   var fps = config.fps, frameDuration;
   var framesToCapture;
+  var requestStopCapture = false;
   var outputPath = path.resolve(process.cwd(), (config.outputDirectory || './'));
 
   if (!url.includes('://')) {
@@ -168,6 +169,11 @@ module.exports = function (config) {
         return overwriteRandom(page, unrandom, log);
       }).then(function () {
         return timeHandler.overwriteTime(page);
+      }).then(function () {
+        // page can call the function with config.stopFunctionName to stop capture before --duration is up
+        if (config.stopFunctionName) {
+          return page.exposeFunction(config.stopFunctionName, () => requestStopCapture = true);
+        }
       }).then(function () {
         if (typeof config.navigatePageToURL === 'function') {
           return config.navigatePageToURL({ page, url, log });
@@ -248,7 +254,7 @@ module.exports = function (config) {
         var startCaptureTime = new Date().getTime();
         var markerIndex = 0;
         return promiseLoop(function () {
-          return markerIndex < markers.length;
+          return markerIndex < markers.length && !requestStopCapture;
         }, function () {
           var marker = markers[markerIndex];
           var p;