NSTextView not drawing text onto NSImage

Question

I'm attempting to draw some text onto an NSImage, but I've run into some issues.
Originally I was just drawing an attributed string onto the NSImage, but if the string was too long it would run off the image and I couldn't find a way to wrap the text to a newline.

To solve this I figured that I could just make an NSTextView, place the text in there, and then draw it onto the NSImage.

Unfortunately, when I attempt to draw the NSTextView to the NSImage, the text does not appear. The NSTextView's background color does show up though.

When I set a breakpoint before I lock focus on the NSImage, and preview the NSTextView, the text view has text. After I draw the text view onto the NSImage, it looks like the NSTextView is drawn, just without the text.

If there is a better way to throw text onto an NSImage that has the ability to have multiple lines, please let me know how.

Here's the code I've written for reference:

NSTextView *textToDraw = [[NSTextView alloc] initWithFrame:NSMakeRect(0, 0, input.size.width - 16, 243)];
textToDraw.backgroundColor = [NSColor blueColor];
[textToDraw setAlignment:NSTextAlignmentCenter];
[textToDraw setEditable:YES];
// textOnImage is a regular NSString  
[textToDraw insertText:textOnImage replacementRange:NSMakeRange(0, textOnImage.length)];
[textToDraw setTextColor:[NSColor blackColor]];
[textToDraw setFont:font];
[textToDraw setEditable:NO];

// input is an NSImage
[input lockFocus];
[textToDraw drawRect:NSMakeRect(8, inputImage.size.height - textToDraw.frame.size.height - 8, textToDraw.frame.size.width, textToDraw.frame.size.height)];
[input unlockFocus];

duplicate ; stackoverflow.com/questions/13873764/cocoa-draw-text-on-nsimage — john elemans
@johnelemans That question, although similar, is not a duplicate of mine, nor does it answer my question. — tww0003
I don't think you can just call the textview's drawRect method like that. Before such objects are drawn there is a lot of graphic context setup done normally by its superview. Why don't you add the textview to the superview of the imageview, covering the image and then just let the app trigger the drawing? — Rudi Angela
Sorry about my last post. To make things more complex, I just copied your code into one of my apps and it works fine. The text is drawn on the image exactly as it should. — john elemans
@johnelemans Thanks for the reply. I'm calling drawRect solely because that is how I've seen it done elsewhere when searching around, I'm normally an iOS developer and I usually don't mess around with drawing things. It's interesting that it works for you. Even with cleaning the project, and reseting my computer, I can't get it to work. I ended up just drawing the Bitmap image representation of the NSTextView to a new NSImage, then drawing the new image onto the original one. It seems messy, but for my purposes it'll work fine. Thanks. — tww0003

sanket nagar sanket nagar · Accepted Answer · 2016-04-06T12:42:28

Instead of drawing textview on image you can provide the bounded rect in which text should be drawn. If the string is too long it wouldn't run off the image and will automatically enter in new line.

Here is code where inputImage is the image on which you want to draw text

NSImage *newImage = [[NSImage alloc] initWithSize:inputImage.size];  
[newImage lockFocus];  
[inputImage drawAtPoint:NSZeroPoint fromRect:NSZeroRect operation:NSCompositeSourceOver fraction:1.0];  
[textStr drawInRect:boundedRect withAttributes:attrsDictionary];  
[newImage unlockFocus];

NSTextView not drawing text onto NSImage

1 Answers