I have a UIView. I am drawing a line inside the UIView programmativally. But when the line goes outside the UIView, the part of the line which goes out, is invisible. How can I resize the UIView so that whatever I draw inside the drawRect method is visible?
you can change the frame of view. If your line is horizontal then give width to view else increase height of view.
view.frame = CGRectMake(view.frame.origine.x, view.frame.origine.y,view.frame.size.width,lengthOfLine );
If the curve you are drawing is a subview, then you can make use of sizeToFit method. This will make the view's frame enclose the curve(and all subviews, for that matter). Then you can reposition and scale the view's frame to make it fit in the window.
You have mentioned in a comment that you are actually drawing a curve. From what I can tell, you will need to calculate the curve's bounding box yourself.
Based on the bounding box, update the UIView's bounds property (as Durgaprasad suggested). This also resizes the underlying CALayer, which also gives its underlying Core Graphics rendering context a larger bitmap.
Without knowing more about your curve, it's hard to help, apart from linking to some very generic discussion on quadratic Beziers.
You may want to update your question with a minimal implementation of -drawRect: that will allow someone to reproduce your issue.
Related
I'm trying to draw a complex border around a UIView in it's drawRect method using core graphics. The border is being clipped because it's outside of the view's bounds. Is there any way to prevent this clipping? Setting clipsToBounds to NO doesn't work.
drawRect: gives you a CGRect. This defines the area in which you can draw. As it stands, you cannot draw outside this area.
You'd have to look into a different solution to your problem. I'd suggest CALayers, or a subview/superview hierarchy, perhaps a border view and a content view. But don't try doing that in drawRect:, unless you can get the desired results while keeping within the area specified by drawRect:.
I have two UIViews. My aim is to draw the smallest rectangle which contains both these UIViews. I thought to draw a rectangle using the frame which I'll get out of
CGRectUnion(view1.frame, view2.frame);
But when I move any of the two UIViews, I need to update the frame of the outlining rectangle.
I thought I could do this by :
1) Resizing the previously drawn rectangle.
(or)
2) Deleting the previously drawn rectangle and drawing a new one.
The problem is that, I don't know how to get the instance of the previously drawn rectangle. So, I don't know how to update or delete it..
Can any of you guys help?
Is there any other solution to this problem?
Perhaps you can declare the following in your .h file:
CGRect *transformingRect;
Doing so should retain the rectangle and its properties so long as whatever view controller this is in is visible and loaded. This way you can have a method that resizes the same drawn rect. You would simply call this whenever you need to resize it.
-(void)resizeRect {
transformingRect = CGRectUnion(view1.frame, view2.frame);
}
In CALayer's API, 'position' is used for setting the position of the layer.
By my own testing, setting bounds.origin does not do anything. Am I missing something?
The bounds.origin controls where the origin of the layer's coordinate system is, relative to the layer's frame in its superlayer. Changing it has two visible effects:
The position of sublayers of the layer. For example, when you scroll a UIScrollView, the scroll view doesn't change its subview's frames. It simply changes its bounds.origin. I suggest setting up a toy app with a scroll view and doing NSLog("scroll view bounds = %#", NSStringFromCGRect(scrollView.bounds)); from a timer or some other trigger to get a sense of what's happening.
The origin of the graphics context coordinate system in drawInContext:. Mostly commonly you would see this effect in a view's drawRect: method. Your CGContext inside drawRect: will have been translated by the self.bounds.origin.
You may find it helpful to read about “View Geometry and Coordinate Systems” in the View Programming Guide for iOS and “Layer Objects Define Their Own Geometry” in the Core Animation Programming Guide, although really neither of them have a good discussion of the bounds origin.
Changing the bounds rectangle changes the position and size of the content in the coordinate system of the layer itself. Changing the frame (or position) changes the position of the layer in the coordinate system of its super layer. Usually you only want to change the frame, not the bounds.
I have multiple views with many UILabels on the views. (all constructed in Interface Builder).
I am then trying to create a "smaller" replica of my view when you pinch the screen.
To do this I apply:
view.transform = CGAffineTransformMakeScale(.5, .5);
and then I also adjust the frame of view.
The problem is that after the transformation, the text in all of my UILabels becomes "blurry". It doesn't stay pixel perfect as it is in full-scale view.
Is there a way to increase the pixelation of the labels after the transformation?
Applying a transform to a UIView or CALayer merely scales the rasterized bitmap of that layer or view. This can lead to blurriness of the resulting UI element, because they aren't re-rendered at that new scale.
If you really want your text or images to be crisp at the new scale factor, you're going to need to manually resize them and cause them to redraw instead of applying a transform. I described one way that I did this with a UIView hosted in a UIScrollView in this answer.
You might be able to create a single method that traverses your view hierarchy for your one main view, recursively reads each subview's frame, scales that down, and then forces a redraw of its contents. Transforms are still great to use for interactive manipulation or animation, but you can then trigger a full manual scaling and redraw at the end of the manipulation or animation.
Well although it's late in the dark night, I don't get it why there are two different rectangles: frame and bounds.
Like I understand it, one single rectangle would have been just enough to do everything. Positioning the View itself relative to another coordinate system, and then clipping it's content to a specified size. What else would you do with two rectangles? And how do they interact with each other?
Does anyone have a good explanation? The one from the Apple docs with the kid holding the fruit is not very good for understanding.
Here's the cheatsheet:
frame is where the view is (with respect to the superview)
bounds is where the view is allowed to draw (with respect to itself)
Some more clarification:
If you are positioning the view in its superview, you almost always change the frame origin.
If you are clipping where the UIView is drawing, you almost always modify its bounds.
Note that you are allowed to have bounds that is bigger than the frame. That is, you can draw "outside the lines" of where you are.
Frame is in the superview's coordinate system, bounds is in the view's coordinate system. From my perspective, it is a convenience to have both. Frame seems to be the more useful of the two, unless there is some case I am unaware of where a subview can have a completely different coordinate system (e.g. pixels scaled differently) than the superview.
I've been having troubles with bounds lately and have done some experimentation. The bounds property does limit where a UIView can draw, but does not limit its subviews. The other thing bounds controls is touch event dispatching. A view will not, as far a I can tell, receive touch events that are outside its bounds. Furthermore, any subview that outside of the parent view's bounds will also not receive touch events. In these situations, you have to pretty meticulously update the bounds of the container view as the size and position of its subviews change. Everything will always draw fine (because subviews aren't clipped by the bounds of their parent) but touches won't be received.
(This really should be a reply to an earlier post, but since I can't reply yet, it's stuck here...)