I'm reading pixels from an area of the main screen via NSOpenGLContext. Now I would like to draw a rect around that area to indicate where it actually is.
How would I do this?
My first thought was the "Cocoa way": create a transparent fullscreen NSWindow and a custom NSView to draw the rectangle path. But that feels a bit too complicated. Isn't it possible to draw directly on the NSOpenGLContext?
If you want to draw over elements not inside your application the floating window is the only correct way. There’s really no complication except mapping positions properly, which is easy to do with the coordinate-space conversions available on NSView and NSWindow.
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I'm building chat application for Mac OS, similar to iMessage. I wonder, how can I implement resizable text views in bubbles. I mean, when I resize chat window bubbles with text will resize to. Any ideas, links will be very useful. Thank you for help)
For text resizing, you use auto layout. If you have an NSScrollView containing MYBubbleViews containing NSTextViews, you can add NSLayoutConstraints using the leftAnchor and rightAnchor properties of the scroll view's content view and those of the bubble view, and add constraints between all edges of the text view and bubble view. Then pin the bubble views to the top/prev view.
Also make sure you set the NSTextView to wrap. The width of the intrinsic size of the text view will be set so that it fills the width and the intrinsic height will be set to fit the whole text.
I previously thought it was about drawing the bubbles, so I first gave this answer:
If you look at Messages.app, you'll see that they're not circular bubbles. They are basically composed of several shapes overlaid on each other. A rectangle with rounded corners, plus a bezier path of the tip.
So you should be able to take a NSTextView for the text, make it a subview of a custom view that draws a rounded rectangle and the tip in its drawRect method, and then use auto layout constraints to make your bubble view resize with the text view and the text view to the window width.
You could probably also have the bubble view host a CALayer with fill and rounded corners, plus one with an image for the tip (or aCAShapeLayer for the tip), but drawRect is the easier approach.
I am creating an app for practice that is a simple drawing app. The user drags his/her finger along the screen and it colors in a 100px x 100px square.
I currently achieve this by creating a new colored UIView where the user taps, and that is working. But, after a little time coloring in, there is substantial lag, which I believe is down to there being too many UIViews as a subview of the main view.
How can I, and others who similarly create UIViews on dragging a finger reduce the lag to none at all, no matter how many UIViews there are. I also think that perhaps this is an impossible task, so how else can someone like me color a cube of the size stated above in the main view on a finger dragged along the screen?
I know that this may seem like a specific question, but I believe that it could help others understand how to reduce lag if there are a very large amount of UIViews where a less performance reducing option is available.
One approach is to draw each square into an image and display that image, rather than keeping around an UIView for each square.
If your drawing is simple enough, though, you can use OpenGL to do this, which is much faster. You should look at Apple's GL Paint Sample Code which shows how to do this in OpenGL.
If your drawing is too complex for OpenGL, you could create, for example, a CGBitmapContext, and draw each square into that context when the user drags their finger. Whenever you draw a new square into that bitmap, you can turn the bitmap into an image (via CGBitmapConxtextCreateImage) and display that image an a UIImageView.
There are two things that come to my mind:
1- Use Instruments tool to check if you are leaking any memory
2- If you are just coloring the views than instead of creating images for each of them, either set the background color property of UIView or override the drawRect method to do custom drawing
I think what you are looking for is the drawRect: method of UIView. You could create your custom UIView (you propably have that already) and override the drawRect method and do your drawing there! You will have to save your drawings in an array or another container and call the setNeedsDisplay method whenever the array content is changed.
I have two different UIImageViews. I'd like to make the top UIImageView blend in using the Screen blend mode with the bottom UIImageView.
I know of the property of CALayer: compositingFilter and I know that it doesn't work in iOS. I've searched a lot for solutions, and I've found how one should subclass UIView and override drawRect.
I've tried to set the context in drawRect to the screen blend mode, although it still draws every one of the images normally. Perhaps I am doing something wrong, or the approach should be different. Maybe I need OpenGL or CALayer to achieve this. Could someone assist?
Unfortunately there is no way to do a non-composite blend between UIViews on iOS. UIKit doesn't provide the functionality, and you've already noted, CALayer can't do it either.
In general, implementing -drawRect in a UIView won't help you. You're drawing into an empty bitmap -- it doesn't contain the bits of the views behind it, since those might change at any time (any view or layer might be animated). CA fundamentally assumes that layers' contents should be independent of each other.
You could try, in your -drawRect:
create an image context
capture the views under your view using -[CALayer renderInContext:] for each
create an image from the image context
draw that image into your view
set the blend mode and draw on top of that
But that will be slow and fragile, and won't work if you animate any of the views. I wouldn't recommend it.
If you really need to do this, you're going to have to switch your whole scene to render with OpenGL, where you've got more freedom.
I am creating a custom NSWindow with no title bar and am using NSBorderlessWindowMask to make it completely borderless. The problem I have with this however is that the window has sharp edges. As well as this there is no resize control.
How would I give a borderless window rounded corners?
This is not a duplicate of this
question as that question was more
about removing the title bar and it
currently holds no answers.
You can make the window totally transparent and handle drawing everything yourself. The sample I have is for an OpenGL view, but it should work for a Quartz view or Cocoa view as well.
Add the following to the initializer of your NSWindow subclass where you create the new window using the NSBorderlessWindowMask constant.
[self setOpaque:NO];
[self setBackgroundColor:[NSColor clearColor]];
You will probably have to draw the resize control yourself. The sample I took this from is a full screen window so resizing isn't necessary.
Good Luck.
The easiest way to get a window with rounded corners is to place a NSBox into the window as these boxes have customizable rounded corners and customizable borders. If you then set the window to non-opaque and the background color to transparent ("clear color"), you have a NSWindow with rounded corners that draws a normal window shadow (even on older systems where such a window would otherwise not have a shadow). Most of it can be done in Interface Builder. See here for details.
Only titled windows get the rounded corners. So the only thing you have to do is this:
window.styleMask = [.titled]
window.titleVisibility = .hidden
window.titlebarAppearsTransparent = true
This should be the minimal configuration for a rounded window without a title bar.
I have a custom view subclass similar to NSBox that draws a rounded box background. The problem is that if I place a view like an NSTableView in the box view, it does not clip to the rounded corners. Is there any way to round the corners of NSTableView and its parent scroll view?
I haven't tried this with a table view but have with other controls.
In a subclass of NSTableView (or whatever view/control you want to clip)
Override drawRect:
Create an NSBezierPath with the shape you want (probably appendBezierPathWithRoundedRect:xRadius:yRadius: just remember to use the view's bounds as the size)
Send the path the addClip message to add that shape to the view's clipping path
Call super's drawRect:
If the table view has a header you may need to clip the top corners by subclassing NSTableHeaderView. And if you have scrollbars you may have to do the same thing to them except only clip certain corners. Hopefully you don't have scrollbars because I doubt that would look right. Basically you want to clip the view/control that draws that part, clipping the parent will not cause subviews to be clipped.
If you look at Apple's Welcome to Xcode window they get away with it by drawing a custom header at the top and a text block at the bottom so they don't have to round the table view itself. If you can do something like that I would.