Transparent NSTextView performance

问题

I have a NSWindow with a NSImage and a NSTextView above it with a long text http://www.gutenberg.org/cache/epub/100/pg100.txt and if I draw with a solid background, the text editing is fast.

But if I draw with no background, [self setDrawsBackground:NO] it's very slow.

Any updates? I have also tried

  [self setDrawsBackground:YES];
    [self setBackgroundColor:[NSColor clearColor]];

Maybe with setBackgroundFilters of NSTextView?

Thanks!

回答1:

I found a partial solution. If you disable the smoothed of the font, the performance improves a lot. First you must have a subclass of NSTextView. Then,

- (void)drawRect:(NSRect)dirtyRect
{
    [[NSGraphicsContext currentContext] setShouldAntialias:YES];
    CGContextSetShouldAntialias((CGContextRef)[[NSGraphicsContext currentContext] graphicsPort], YES);
    CGContextSetShouldSmoothFonts((CGContextRef)[[NSGraphicsContext currentContext] graphicsPort], NO);

    [super drawRect:dirtyRect];

    // Drawing code here.
}

Moreover, you can use:

self.textview.layoutManager.allowsNonContiguousLayout = YES;

to improve performance slightly.

This is not the same as having an opaque background, but it helps.

来源：https://stackoverflow.com/questions/35728127/transparent-nstextview-performance