How to make checkbox tri-state?

Hi I am developing web application in Angular 5. I have tree view with checkbox. Whenever data is loaded onto page, based on the property I am making checkbox checked or not checked. I am accepting little different behavior here. Whenever property is false i want to add cross mark in checkbox by default. Below is my code which will render tree view with checkbox.

<tree-root #tree [options]="options" [nodes]="nodes">
    <ng-template #treeNodeTemplate let-node="node" let-index="index">
        <input (change)="check(node, !node.data.checked)"
               type="checkbox"
               [indeterminate]="node.data.indeterminate"
               [checked]="node.data.checked" class="css-checkbox">
        
</ng-template>
</tree-root>  

In the above code snippet whenever node.data.checked is true then I am making checkbox checked b default. Whenever node.data.checked comes false I want to display cross mark in checkbox. I have searched over the net but did not get any use full links. Can some one help me to make this work? Any help would be greatly appreciated. Thank you.