feat(iOS): screensharing support

The Jitsi team would like to thank @AliKarpuzoglu, @linuxpi and The Hopp Foundation for the initial effort and help throughout.

react/features/toolbox/components/native/ScreenSharingAndroidButton.js

@@ -0,0 +1,74 @@
+// @flow
+
+import { translate } from '../../../base/i18n';
+import { IconShareDesktop } from '../../../base/icons';
+import { connect } from '../../../base/redux';
+import { AbstractButton, type AbstractButtonProps } from '../../../base/toolbox/components';
+import { toggleScreensharing, isLocalVideoTrackDesktop } from '../../../base/tracks';
+
+/**
+ * The type of the React {@code Component} props of {@link ScreenSharingAndroidButton}.
+ */
+type Props = AbstractButtonProps & {
+
+    /**
+     * Whether video is currently muted or not.
+     */
+    _screensharing: boolean,
+
+    /**
+     * The redux {@code dispatch} function.
+     */
+    dispatch: Function
+};
+
+/**
+ * An implementation of a button for toggling screen sharing.
+ */
+class ScreenSharingAndroidButton extends AbstractButton<Props, *> {
+    accessibilityLabel = 'toolbar.accessibilityLabel.shareYourScreen';
+    icon = IconShareDesktop;
+    label = 'toolbar.startScreenSharing';
+    toggledLabel = 'toolbar.stopScreenSharing';
+
+    /**
+     * Handles clicking / pressing the button.
+     *
+     * @override
+     * @protected
+     * @returns {void}
+     */
+    _handleClick() {
+        this.props.dispatch(toggleScreensharing());
+    }
+
+    /**
+     * Indicates whether this button is in toggled state or not.
+     *
+     * @override
+     * @protected
+     * @returns {boolean}
+     */
+    _isToggled() {
+        return this.props._screensharing;
+    }
+}
+
+/**
+ * Maps (parts of) the redux state to the associated props for the
+ * {@code ToggleCameraButton} component.
+ *
+ * @param {Object} state - The Redux state.
+ * @private
+ * @returns {{
+ *     _disabled: boolean,
+ *     _screensharing: boolean
+ * }}
+ */
+function _mapStateToProps(state): Object {
+    return {
+        _screensharing: isLocalVideoTrackDesktop(state)
+    };
+}
+
+export default translate(connect(_mapStateToProps)(ScreenSharingAndroidButton));