Sequential selection among multiple NSTextViews

Question

I have a bunch of NSTextViews that I would like to share a single selection. I basically want this to behave like selecting text on a web page, where there are multiple text views but you can drag to sequentially select text among them.

I found this document which states that it is possible to have multiple NSTextContainer objects sharing a single NSLayoutManager and thus share the selection. This is halfway to what I want, except for the fact that one NSLayoutManager can only have a single NSTextStorage object. I want each text view to have its own NSTextStorage so that each text view can have its own text, but I still want to be able to select text in multiple text views with one drag. Is this possible?

Answer 1

There's no easy way to solve this problem (as I tried to find by asking this question). It involves all the mouse event handling and text selection calculations you'd expect, so I wrote the code and have open sourced it as INDSequentialTextSelectionManager.

Answer 2

To make this separate text containers work, you would calculate the drawn size of each part of the string and limit the NSTextView to that size:

    NSLayoutManager * layout = [[NSLayoutManager alloc] init];
    NSString * storedString = @"A\nquick\nBrown\nFox";
    NSTextStorage * storage = [[NSTextStorage alloc] initWithString:storedString];
    [storage addLayoutManager:layout];

    //I assume you have a parent view to add the text views
    NSView * view;

    //Assuming you want to split up into separate view by line break
    NSArray * paragraphs = [storedString componentsSeparatedByString:@"\n"];
    for (NSString * paragraph in paragraphs)
    {
        NSSize paragraphSize = [paragraph sizeWithAttributes:@{}];
        //Create a text container only big enough for the string to be displayed by the text view
        NSTextContainer * paragraphContainer = [[NSTextContainer alloc] initWithContainerSize:paragraphSize];
        [layout addTextContainer:paragraphContainer];

        //Use autolayout or calculate size/placement as you go along
        NSRect lazyRectWithoutSizeOrPlacement = NSMakeRect(0, 0, 0, 0);
        NSTextView * textView = [[NSTextView alloc] initWithFrame:lazyRectWithoutSizeOrPlacement
                                                    textContainer:paragraphContainer];
        [view addSubview:textView];
    }

You can add a delegate to the NSLayoutManager to watch your text container usage:

- (void)layoutManager:(NSLayoutManager *)aLayoutManager
didCompleteLayoutForTextContainer:(NSTextContainer *)aTextContainer
                    atEnd:(BOOL)flag
{
    if (aTextContainer == nil)
    {
        //All text was unable to be displayed in existing containers. A new NSTextContainer is needed.
    }
}