I have used the (void)drawRect:(NSRect)dirtyRect to draw triangles, which is displayed in a NSWindow. My triangles are drawn, but the problem is removing them from the window. I have to figure out how to remove/clear the lines that are drawn from the strokeLineFromPoint:toPoint using a simple method.
Thanks in advance!
You have to create a view and set it to the view property of the NSWindow. Then, draw using the view's drawRect method. The NSWindow does not have a drawRect method. Also, If you want to change the drawing, you have to redraw the part or the entire view.
You need to use the setNeedsDisplay method to redraw the view. So, you'd need something like this:
-(void) deleteStuff{
removeTriangles = YES; //Boolean value
[myView setNeedsDisplay];
}
Then, inside the drawRect function, simply put all your drawing code inside an if statement.
(void)drawRect:(NSRect)dirtyRect{
if(!removeTriangles){
//Rest of drawing code
}
}
Don't forget to set removeTriangles to NO originally so you can draw the triangles!
Hope this helps.
Related
I am working on a small application on Mac that I need to create customed cursor and move it. I used NSImageView to implement it. However when I call setFrameOrigin (the same to setFrame) it will leaves images on the previous place.
Here is my code:
#property (nonatomic, strong) NSImageView *eraserView;
this is the define
_eraserView = [[NSImageView alloc] initWithFrame:CGRectMake(100, 100, 32, 32)];
_eraserView.image = [NSImage imageNamed:#"EraserCursor"];
[self.view addSubview:_eraserView];
[_eraserView setHidden:YES];
here is the initialization. Everything goes well until now but:
- (void)setImageatPoint:(NSPoint)point
{
[_eraserView setFrameOrigin:point];
}
- (void)hidePenImage
{
[_eraserView setHidden:YES];
}
- (void)unhidePenImage: (BOOL)isEraser
{
[_eraserView setHidden:NO];
}
These are methods I use to change the state of the NSImageView. They will be called by another class using delegate when corresponding events of trackpad occurs.
However every time I change the state of the NSImageView, it seems like it is drawn on the superview.
I debugged it and found there was no extra subviews. And when I use setHidden it has no effect on those tracks. I think it somehow did something to the CALayer, but I have no idea how to fix it.
Screenshots would help but in general if you move a view or change the area of the view that is drawn, you need to redraw.
To do this it kind of depends on how your drawing happens. Calling setNeedsDisplay may not be enough if your implementation of drawRect only draws a sub rect of the view bounds. Cocoa only draws what it is told to draw.
You can erase sections of the view that should be empty by drawing (filling) where it should be empty. That means drawing a color ( NSColor clearColor if nothing else) in the area that was previously drawn.
I want to change background color for many nsview. I override drawRect: on subclass NSview but i don't know how to set background color for myview( is reference IBOUTLET). please help me. Thanks so much
Code for CustomView.h
#import <Cocoa/Cocoa.h>
#interface CustomView : NSView
#end
Code for CustomView.m
#import "CustomView.h"
#implementation CustomView
- (void) drawRect:(NSRect)dirtyRect {
[[NSColor whiteColor] setFill];
NSRectFill(dirtyRect);
[super drawRect:dirtyRect];
}
#end
And in main class, i added #import "CustomView.h" but i don't know how to set background for myview.
Welcome to Cocoa drawing.
Cocoa drawing uses Quartz which is a PDF model.
Drawing in this occurs in a back to front procedural order.
In Quartz drawing there is a drawing environment state object called the Graphics Context.
This is an implicit object in many of the drawing ops in AppKit.
(in Core Graphics or other APIs it could need to be explicitly called)
You tell the Graphics Context what the current color and other parameters are, then draw something, then change parameters and draw more, etc...
In AppKit, you do this by sending a message to the NSColor object, which is weird. but that's how it works.
In your drawRect: method you should call super first usually, because you probably want your drawing on top of that...
- (void) drawRect:(NSRect)dirtyRect {
[super drawRect:dirtyRect];
// This next line sets the the current fill color parameter of the Graphics Context
[[NSColor whiteColor] setFill];
// This next function fills a rect the same as dirtyRect with the current fill color of the Graphics Context.
NSRectFill(dirtyRect);
// You might want to use _bounds or self.bounds if you want to be sure to fill the entire bounds rect of the view.
}
If you want to change the color, you'll need an #property NSColor
You might need more than one for your drawing.
That allows you to set the color.
You might want the view to use KVO and observe its own color property then draw itself if the color property changes.
You could do a lot of different things to set the color. (a button or pallette elsewhere) But all of them would eventually result in sending a message to set the color of a property of your view for drawing.
Finally, if you want to update the drawing, you need to call [myView setNeedsDisplay:YES]; where myView is a reference to an instance of the NSView subclass.
There is also display but that's forceful.
setNeedsDisplay: says to schedule it on the next run of the event loop (runLoop). display kind of makes everything jump to that right away.
The event loop comes back around fast enough you shouldn't force it.
Of note, setNeedsDisplay: is the entire view.
In a fancy ideal world with complex views, you might want to more appropriately optimize things by calling setNeedsDisplayInRect: where you designate a specific CG/NSRect of the view as needing to be redrawn.
This allows the system to focus redrawing to the smallest union rect possible in the window.
I'm super late, but this is how I do it - there's no need to sub class:
NSView *myview = [NSView new];
[view setWantsLayer:YES];
view.layer.backgroundColor = [NSColor greenColor].CGColor;
Everywhere on the internet I can read that to change the background color of a NSView you can just override its method drawRect like this:
- (void)drawRect:(NSRect)rect
{
[[NSColor yellowColor] set];
NSRectFill(rect);
}
For example here.
However, in my case, the color is drawn on top of the view (I can't see anymore the content), which is quite logical to me. DrawRect is supposed to draw the view, not just its background.
what am I missing?
You should call [super drawRect:rect] after filling the background. Otherwise, you're simply replacing everything that would be drawn by the superclass's implementation.
The examples you refer to are displaying the subviews of the view above the background.
I have a UIView that contains another UIView. The outer UIView draws a border around the inner UIView via drawRect. (The border is too complicated to be drawn via CALayer properties.)
At present, when I animate the resizing of the outer UIView, its drawRect method is called once at the beginning of the animation and the result is stretched or shrunk. This does not look good.
I am looking for a way to either redraw the content at every step of the animation, or find a way to achieve the same visual effect. (The result should be similar to the resizing of a stretchable UIImage.)
You should change view's content type to:
your_view.contentMode = UIViewContentModeRedraw;
And it will redraw each time its frame changes.
I ended up adding subviews with autoresizing masks that kept them positioned correctly during the animation.
You need to send a [UIView setNeedsToDisplay] to the view for every time the frame size is changed, you could try overriding the setFrame: method like
- (void)setFrame:(CGRect)r
{
[super setFrame:r];
[self setNeedsToDisplay];
}
I have a UIImageView in a UIScrollView in another UIScrollView (based on Apple's
PhotoScroller sample code). When the UIScrollView calls back to its controller to dismiss itself, it calls this method:
- (void)dismiss {
[scrollView removeFromSuperview];
ImageScrollView *isv = [self currentImageScrollView];
UIImage *image = isv.imageView;
image.frame = [self.view convertRect:image.frame fromView:isv];
[self.view insertSubview:image belowSubview:captionView];
[(NSObject *)delegate performSelector:#selector(scrollViewDidClose:)
withObject:self
afterDelay:2.0];
}
Now here's the weird part: the image view jumps to a different position right after this method executes, but before the scollViewDidClose method gets called on the delegate. If the image is larger than its new super view, it jumps so that its left edge is aligned with the left edge of its super view. If it's smaller than its new super view, it jumps to the very center of the view. There is no animation to this change.
So my question is, how do I prevent it from doing that? I've tweaked both the super view (self.view) class and the image view class to see what methods might be called. Neither the frame nor the center is set on the image view after this method is called, and while the layoutSubviews method is called on the super view, that is not what jumps the image to the center or left side of the superview. I've also tried turning off autoResizesSubviews in the super view, and setting the autoresizingMask of the image view to UIViewAutoresizingNone, with no change in behavior.
So where is this happening, and why? And more importantly, how do I make it stop?
I've been beating my head on this for days. Any pointers or guidance would be greatly appreciated.
ImageScrollView is the one centering your UIImageView. Set a breakpoint in ImageScrollView layoutSubviews and you'll see how your UIImageView is being centered.
You're taking ImageScrollView's internal imageView and placing it into another view. That's not going to work because ImageScrollView still retains ownership of that UIImageView instance and is still managing its layout.
You'll either need to copy the image into another UIImageView instance, or you'll need to change ImageScrollView to allow it to relinquish ownership of its imageView.
You're not setting up the frame of the 'image' view when you insert it as a subview. You probably want to do that explicitly if you want the view to appear at a particular position in the scroll view.