I have an application I'm writing in which I'm drawing into an NSView. In mouseDown I am saving the location in my data model and then drawing a graphic at that location within the drawRect method of the view. It all works fine.
At the end of my mouseDown I was calling [self setNeedsDisplay:YES]; to force a redraw. The only thing is that the dirtyRect is always the full size of the view. I wanted to optimize this as much as possible so that I'm not redrawing the entire window for just a few changed pixels.
So now I'm calling [self drawRect:...] instead and specifying the rectangle.
Now in my drawRect I am comparing every graphic I have to see if it falls in the dirtyRect. It seems like I've traded work of drawing for work of bounds checking everything. I'm not sure I've made it any more or less efficient.
So what is the standard practice? Is it common to just redraw everything in the view and ignore the dirtyRect? Is there a nice function I can use as a test to see whether my object is in the dirtyRect?
You should never call -drawRect: yourself if you're trying to draw to the screen. Let AppKit call it for you. What you should do is call -setNeedsDisplayInRect: at the end of your -mouseDown:.
Then, in -drawRect:, only draw stuff contained in the dirtyRect. You can test to see if a point is inside the dirtyRect with NSPointInRect(). There are lots of other useful functions for working with NSRect. See the documentation for the point functions and the rectangle functions.
I'm placing a few buttons in a simple rectangular NSview which acts as a custom toolbar. On first render the buttons/views come out as expected, but every time a button is pressed (and sometimes with no mouse interaction at all) artefacts start appearing.
Before
After
I can eliminate the artefacts by calling a [self.toolbarView setNeedsDisplay:YES] in all the action and focus methods but this seems like a hack, is there any clean way to deal with this?
It was a beginner's problem. In the drawRect method
- (void)drawRect:(NSRect)dirtyRect
I was using the param dirtyRect for drawing an outline of my view, assuming it was the view's bounds, where in fact it was only the area around the buttons that became dirty when they were pressed. The 'artefacts' were actually my outline being drawn in the wrong place.
By correctly using the bounds of the view
NSRect drawingRect = [self bounds];
the 'artefacts' no longer appeared.
You just try to set focus ring for a buttons to 'none' in IB.
I have a NSView as the documentView for a NSScrollView. I also have a NSImageView as a subview of the NSView. The image dynamically changes size so the scroll bars become active/inactive at various times. Once the image has changed, I'd like to scroll to a certain point on the image. From within the NSView's drawRect: method, I call
[[myScrollView contentView] scrollToPoint: myPoint];
The scroll bars update and the image appears as I'd like, but as soon as the image is scrolled, a double image appears or parts of the image get cut off. Any help would be appreciated. Thank you.
Sounds like you might want to turn off the "Copy On Scroll" behavior option of the NSScrollView either in Interface Builder or programmatically.
From Scroll View Programming Guide for Mac OS X: How Scrolling Works:
The NSClipView class provides low-level scrolling support through the
scrollToPoint: method. This method translates the origin of the
content view’s bounds rectangle and optimizes redisplay by copying as
much of the rendered document view as remains visible, only asking the
document view to draw newly exposed regions. This usually improves
scrolling performance but may not always be appropriate. You can turn
this behavior off using the NSClipView method setCopiesOnScroll:
passing NO as the parameter. If you do leave copy-on-scroll active, be
sure to scroll the document view programmatically using the NSView
method scrollPoint: method rather than translateOriginToPoint:.
I've got my custom NSView with a bunch of custom buttons in it, the buttons are added as a subView in the NSView's drawRect method.
Now I'm finding that after pressing a button the drawRect of the parent view is repeatedly called. Sometimes it only stops when I quit the app - I know this from a simple log statement in drawRect.
Now I know there are probably bigger architectural issues in my app causing this, where do I go to begin tracking down what's causing this view to be repeatedly redrawn?
Thanks!
First of all you shouldn't be adding subviews in drawRect:.
Are you doing any custom drawing or are you just adding subviews? If you're not doing any drawing, you should not implement drawRect:.
You want to add the subviews in initWithFrame: and then you want to set the frames of the subviews in layoutSubviews based on self.bounds.
If you have any questions, feel free to ask.
EDIT: Just realized that you were asking about NSView and not UIView. I've never used NSView, but perhaps they work similarly.
EDIT 2: I read a bit about NSView and it doesn't seem to have layoutSubviews. Perhaps you should set the frames in drawRect:? I'm still pretty sure you don't want to add subviews in drawRect:.
I have made a window with an NSOpenGLView that I am rendering openGL content into.
I want to add some buttons and text fields to the view: I can add NSTextFields and NSButtons using interface builder (or code) but they do not appear.
NSOpenGLView is documented as not being able to have sub views, so I then made my own CustomGLView by deriving directly from NSView and implementing the code to create and use a NSOpenGLContext in it. But the subviews are still not appearing :- the OpenGL context paints over them.
On Windows this problem does not exist:- Windows used to host OpenGL MUST have the WS_CLIPCHILDREN and WS_CHIPSIBLINGS styles set ensuring that any peer, or sub children (views) will not be obscured by the OpenGL surface.
How do I get subviews to display over a NSView thats drawing using OpenGL ?
You have 2 choices:
Create a window just for the text field. Add as a child window of the one hosting the OpenGL view. Major downside is you have to manage positioning it correctly if the Open GL view is moved.
Set up your view hierarchy like so:
Layer-backed view
Layer-hosting view whose layer contains an OpenGL layer
Text field
Simply call -setWantsLayer:YES on the subviews of the NSOpenGLView.
NSOpenGLView cannot have subviews according to the documentation. Even if you subclass the NSOpenGLView, that will change nothing.
What you can do is to create a NSView that will hold both the NSOpenGLView and the NSTextField. You then overlap them in the right order to make one draw atop the other.
I'm not heavily into OpenGL yet, but it's my understanding that you can accomplish the visual effect of subviews with Quartz Extreme using layer-backed views; however, those may be problematic. Since subviews are not supported directly, any solution is liable to be a hack.
Indeed, the solution in that link actually hacks a second window to appear over your OpenGL display, the second window displaying the Cocoa views you desire.
The following code (from the above link) is something I've not tested (again not being an OpenGL guy by nature -- yet), but appears like a fairly clever approach:
// This is the GL Window and view you already have
glWindow = [[GLWindow alloc] initWithContentRect:windowRect];
glView = [[[GLView alloc] initWithFrame:NSMakeRect(0, 0, windowRect.size.width, windowRect.size.height)] autorelease];
[glView translateOriginToPoint:NSMakePoint(glView.bounds.size.width/2, glView.bounds.size.height/2)];
[glWindow setContentView:glView];
// And here's your transparent UI window
uiWindow = [[TransparentWindow alloc] initWithContentRect:windowRect];
uiView = [[[NSView alloc] initWithFrame:NSMakeRect(0, 0, windowRect.size.width, windowRect.size.height)] autorelease];
[uiView translateOriginToPoint:NSMakePoint(uiView.bounds.size.width/2, uiView.bounds.size.height/2)];
uiView.wantsLayer = YES;
[uiWindow setContentView:uiView];
[glWindow addChildWindow:uiWindow ordered:NSWindowAbove];
Again, I've not tested this, but it looks like it will get you the visual effect you desire.
The text can be rendered into a texture -- I just used this for a project, did a lot of looking for sample code, and ultimately found Apple's GLString demo code, which was an absolute trove of how-to:
http://developer.apple.com/library/mac/#samplecode/CocoaGL/Listings/GLString_m.html
I haven't tried adding buttons, but you can, of course, draw your own and comparing the positions of click events with those of your buttons...
This was my solution:
1) Create a parent NSView (let's call it parentView).
2) Add an NSOpenGLView Child to parentView.
3) Add an additional NSView Child to parentView (make sure this is after the OpenGLView within the hierarchy). You can add additional TextFields, etc. to this view.
4) In the ViewController for the parent make sure you call [parentView setWantsLayer: TRUE]; I did this within -(void) viewWillAppear
1) The NSOpenGLView can have a subview. It can have plenty even.
2) The reason some views, controls and other elements are being bullied by NSOpenGLView is due to the loading process when the Application launches. I.e If you add a slider or textfield above and into the content view of the window where the NSOpenGLView also resides, upon Application-Launch that textfield will most likely wind up beneath the NSOpenGLView.
This is an Apple Bug. And they know about it.
You can solve it quite easily even without adding a subview to NSOpenGLView...
In Interface Builder drag i.e. a CustomView into the canvas (Not the view). And set it the way you want it with sliders, text and what not. Then create an outlet (Call it i.e topView) in your view controller. Then somewhere in your code... Perhaps (applicationDidFinishLaunching) add this line...
[_window.contentView addSubview:_topView];
(Do your positioning & layout)
This will do the exact same thing as if you had dragged it into the contentView yourself inside IB. Only it will draw the darn thing in the correct Z position.
You loose IB's constraints this way and have to it manually
One could also just subclass and CAOpenGLLayer and use that as a backing layer inside of a regular NSView. There too it is drawn correctly...
Here is Apple's way of wanting to do that. CALayers are a Godsend ;)
Enter following String ** NSOpenGLLayer** in search and hit enter to get to where it is...
NSOpenGLLayer
Hope this helps....