如何绘制与NSTextView中的文本完全相同的文本

Question

I used NSTextView for text editing, setting font color and size, without set NSParagraphStyle . Now I want to hide NStextView and take out NSString or NSAttributedString from NSTextView and draw it on the NSView behind the NSTextView object. I want the rendered text to be exactly the same as in NSTextView , including fonts, word spacing, line height, line spacing.

What methods should be used to do this?

My current approach is as follows, but the effect is not good. Line height is not consistent with that in NSTextView . There is also a problem with other details.

NSTextView* textView = [[NSTextView alloc]init];
        [[self contentView] addSubview:textView positioned:NSWindowAbove relativeTo:myView];
        [textView setAutoresizingMask:NSViewWidthSizable];
        [textView setMinSize:NSMakeSize(25, 25)];
        [textView setMaxSize:NSMakeSize(FLT_MAX, FLT_MAX)];
        [textView setDrawsBackground:NO];

    [[textView textContainer] setContainerSize:NSMakeSize(FLT_MAX, FLT_MAX)];
    [[textView textContainer] setWidthTracksTextView:NO];

    [textView setVerticallyResizable:YES];
    [textView setHorizontallyResizable:YES];
    [textView setTextColor:[NSColor redColor]]; 
    [textView setFrame: NSMakeRect(200, 200, 25, 25)];  //the textView will auto resize when typing
    [textView setFont:[NSFont fontWithName:@"Arial" size:16.0f];
    [textView setHidden:NO];

//after typing, i will hide the textView and draw the attributedString in myView's drawInRect function.

    NSRect rct = textView.frame;
    [textView setHidden: YES];
    NSMutableAttributedString *textDraw = [[NSMutableAttributedString alloc] initWithAttributedString: textView.attributedString];
    //i get the defaultParagraphStyle to set to NSMutableAttributedString
    [textDraw setAttributes:textView.defaultParagraphStyle range:NSMakeRange(0, textDraw.length)];

    NSMutableDictionary *md = [NSMutableDictionary dictionary];
    [md setObject:[NSColor redColor] forKey:NSForegroundColorAttributeName];            
    [textDraw setAttributes:md range:NSMakeRange(0, textDraw.length)];

    [textDraw drawInRect:rct];

Answer 1

i have found the answer.
[string drawAtPoint:point] - uses NSTypesetterBehavior_10_2_WithCompatibility, but NSTextView uses NSTypesetterLatestBehavior by default.

i use the code bellow to solve the problem:

[[textView layoutManager] setTypesetterBehavior:NSTypesetterBehavior_10_2_WithCompatibility];

set the TypesetterBehavier the same as NSString draw functions, then the problem disapears.

the origin link is here:

https://zachwaugh.com/posts/nstextview-and-nsstring-differences-in-text-rendering

so the last code is:

    NSTextView* textView = [[NSTextView alloc]init];
    [[self contentView] addSubview:textView positioned:NSWindowAbove relativeTo:myView];
    [textView setAutoresizingMask:NSViewWidthSizable];
    [textView setMinSize:NSMakeSize(25, 25)];
    [textView setMaxSize:NSMakeSize(FLT_MAX, FLT_MAX)];
    [textView setDrawsBackground:NO];

    [[textView textContainer] setContainerSize:NSMakeSize(FLT_MAX, FLT_MAX)];
    [[textView textContainer] setWidthTracksTextView:NO];

    [textView setVerticallyResizable:YES];
    [textView setHorizontallyResizable:YES];
    [textView setTextColor:[NSColor redColor]]; 
    [textView setFrame: NSMakeRect(200, 200, 25, 25)];  //the textView will auto resize when typing
    [textView setFont:[NSFont fontWithName:@"Arial" size:16.0f];
    [textView setHidden:NO];
    [[textView layoutManager] setTypesetterBehavior:NSTypesetterBehavior_10_2_WithCompatibility];

and drawing code:

    NSRect rct = textView.frame;
    [textView setHidden: YES];
    NSAttributedString textDraw = textView.attributedString;        
    [textDraw drawInRect:rct];