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• Please check if the PR fulfills these requirements
• The commit message follows our guidelines: https://github.com/angular/angular/blob/master/CONTRIBUTING.md#commit-message-format
• What kind of change does this PR introduce? (Bug fix, feature, docs update, ...)
  This PR enables the overriding of Hammer default thresholds when using gestures.
• What is the current behavior? (You can also link to an open issue here)
  If you want to listen to Hammer gestures, you have to either keep the existing configuration or create your own Hammer event plugin with the configuration you want. This requires quite a bit of extra work if you just want to tweak a distance threshold.
• What is the new behavior (if this is a feature change)?
  You can now override the default Hammer config by defining your own HammerGestureConfig and adding it as a provider.

main.ts

bootstrap(MyApp, [
   provide(HAMMER_GESTURE_CONFIG, {useClass: MyHammerConfig})
])

Then, in your class, set an overrides object with the event names and your changes:

MyHammerConfig.ts

export class MyHammerConfig extends HammerGestureConfig  {
   overrides = {
      'pan': {threshold: 5},
      'swipe': {velocity: 0.5}
   }
}

If you want more control, you can instantiate Hammer any way you like by defining a buildHammer method that returns a Hammer instance instead (ignoring overrides object):

MyHammerConfig.ts

export class MyHammerConfig {
   buildHammer(element: HTMLElement): Object {
      var mc = new Hammer(element);

      // custom configuration
      mc.get('pan').set({threshold: 5});

      return mc;
   }
}

• Does this PR introduce a breaking change?

No, existing code should not have to change.