CKEditor 5 copy selected content from one editor to another - ckeditor5

Question

I have two editors on the screen, one read-only. What I want to do is allow the user to select content from the read-only editor and paste it into the current position of the other by clicking a button. (the logic may manipulate the text which is one reason I don't want to use the system's clipboard.)
So far I have the function that is able to paste the text like as follows. (I am using the Angular wrapper which explains the presence of the CKEditorComponent reference.
doPaste(pasteEvent: PasteEvent, editorComponent: CKEditorComponent) {
const editor = editorComponent.editorInstance;
editor.model.change(writer => {
writer.insertText(pasteEvent.text, editor.model.document.selection.getFirstPosition() );
});
}
What I can't find from the documentation is how to extract the selected text. What I have so far is:
clickPasteSelectedPlain(editorComponent: CKEditorComponent) {
const editor = editorComponent.editorInstance;
const selection = editor.model.document.selection;
console.log('clickPasteAll selection', selection);
console.log('clickPasteAll selectedcontent', editor.model.document.getSelectedContent);
}
The selection appears to change depending on what is selected in the editor's view. The getSelectedContent function is undefined. How do I get the content?

Answer 1

With a bit of poking around I figured out how to do this. I'll document it here on the chance that it will help someone down the road avoid the process of discovery that I went through.
On the source document I have a ckeditor element like this:
<div *ngIf="document">
<ckeditor #ckEditor
[editor]="Editor" [config]="ckconfig" [disabled]="true"
[(ngModel)]="document.text"></ckeditor>
<button mat-flat-button (click)="clickPasteSelectedPlain(ckEditor)">Paste Selected Text Plain</button>
</div>
In the component the function called on the click event is like this:
#Output() paste = new EventEmitter<PasteEvent>();
...
clickPasteSelectedPlain(editorComponent: CKEditorComponent) {
const editor = editorComponent.editorInstance;
this.paste.emit({
content: editor.model.getSelectedContent(editor.model.document.selection),
obj: this.document,
quote: false
});
}
The PasteEvent is defined as an exported interface which I will omit here to save space. The content key will refer to a DocumentFragment.
Note that I am passing the CKEditorComponent as a parameter. You could also access it via an Angular #ViewChild declaration but note that my ckeditor is inside an *ngIf structure. I think that works well in Angular 6 but in the past I have had difficulty with #ViewChild references when the target was conditionally in the DOM. This method always works but use whatever method you want.
The event fired by the emit is processed with a method that looks like this:
doPaste(pasteEvent: PasteEvent, editorComponent: CKEditorComponent) {
const editor = editorComponent.editorInstance;
editor.model.insertContent(pasteEvent.content);
}
Because the content is a DocumentFragment the paste operation will include all formatting and text attributes contained in the selected source. But that's all there is to it.