I want to know if it's possible to use gradient colors in the launchscreen.storyboards if so where can I edit it. I'm not looking to add images because it can make the app to heavy but maybe a transition to change the gradient from a-colors to b-colors.
thanks in advance.
If you want to render gradients programmatically in a storyboard, you can generally define a UIView subclass to do that, but you cannot use custom classes in the launch screen. You’ll have to use an image.
If your gradient is a simple vertical or horizontal gradient, and you’re really concerned about asset size, you can define a very narrow image and then add an image view with “scale to fill” content mode.
But these images are so small anyway, the amount of space saved will be negligible, so I’m not sure it’s worth worrying about.
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I have a large image background with several areas or objects in the images which can be clicked and an event is triggered. The method I'm currently using to accomplish this is by slicing the images of objects and area and positioning them over the background image and assigning a click handler to them.
This works for the moment but I feel that there should be a better way of doing this. One way I thought and tried is to fill the sliced images with black or white, position them over the background image, make their opacity 0, make them hit testable and assign a click handler.
Does this method have advantage over the previous one? Does making an image object transparent use less texture memory or is it the same?
And are there other better ways to do so? My main objective is about making the game use less texture memory and cutting the overall project file size by using less of those sliced images.
Use display.newRect/newCircle to mark down area, make them transparent and hit testable.
This should be more efficient than using images.
I am creating a simple photo filter app for OS X and I am displaying a photo on an NSImageView (actually two photos on top of each other with two NSImageViews, but the question still applies for a single view too). Everything works super, but when I try to resize the window that contains the NSImageViews, the window (which also resizes the NSImageViews) resizes very slowly, at about less than 1fps, creating a negative impact on the user experience. I want resizing windows to be as smooth as possible. When I disable resizing the image views, the window resizes smoothly, so the cause of the slowdown is those NSImageViews.
I'm loading 20-megapixel images from my DSLR. When I scale them down to a reasonable size for screen (e.g. 1024x768), they scale smoothly, so the problem is the way NSImageView renders the images. It (I assume as the result of this behavior) tries to re-render 20MP image every time it needs to redraw it into whatever the target frame of the view is.
How can I make NSImageView rescale more smoothly? Should I feed it with a scaled-down version of my images? I don't want to do that as it's a photo editing app that also targets retina display screens and the viewport would actually be quite large. I can do it, but it's my final option. Other than scaling down, how can I make NSImageView resize faster?
I believe part of the solution your are looking for is in NSImage's representations. You can add many representations to an image with addRepresentation: I believe there is some intelligent selection done when drawing. In your case, I think you would need to add both representations (the scaled-down and the full resolution bitmap) to NSImage. I strongly suspect drawRect: should pick the low resolution version. I would make sure "scale up or down" is selected in NSImageView, because the default is scale down only, which may force your full resolution image to be used most of the time. There are some discussion in Apple's documentation regarding "matching" under "Setting the Image Representation Selection Criteria" in NSImage, although at first sight this may not be sufficient.
Then, whenever you need to do something with the full image, you would request the full resolution image by going through the representations ([NSImage representations] returns an array of NSImageRep).
I have been looking for the solution on the web for a long time. Most tutorials are fairly simple about adding shadow to a UIView. I also noticed that if we add a shadow to an UIImageView. The shadow shape could perfectly fit the shape of the content image if the image itself has alpha channel in it. Say for example, if the image is an animal with transparent background, the shadow shape is also the same as that animal (not a rectangle shadow as same as UIImageView frame).
But these are not enough. What I need to do is to add some changes to the shadow so it may have some rotation angle and compressed (squeezed or shift) effect so that looks like the sunlight comes from a certain spot.
To demonstrate what I need, I upload 2 images below, which I captured from the Google Map App created by Apple. You can imagine the Annotation Pin is an image which has the Pin shape, so the shadow is also "pin shaped", but it is not simply "offset" with a CGSize, you can see the top of the shadow is shifted right about 35 degrees and slightly squeezed the height.
When we tap and hold and pin, the shadow is also animated away from the pin, so I believe that such shadow can be made programmably.
The best shadow tutorial I can found so far is http://nachbaur.com/blog/fun-shadow-effects-using-custom-calayer-shadowpaths But unfortunately, that cannot make this effect.
If anyone know the answer or know any better words to search for, please let me know. Thank you.
(Please note that the shape of the image is dynamic in the App, so using any tool like Photoshop to pre-render the shadow is not an option.)
In order to create dynamic effects like this, you have to use Core Graphics. It's incredibly powerful once you know how to use it. Basically you need to set a skew transform on the context, set up a shadow and draw the image. You will probably have to use transparency layers as well.
It doesn't sound like you can use CALayer shadows, since that is meant to solve a specific use-case. The approach Apple takes with the pin marks on the map is to have two separate images that are created ahead of time (e.g. in Photoshop) and they position them within the map relative to a reference point.
If you really do need to do this at run-time, it should still be possible by using either Core Graphics or ImageKit. To get a blurred shadow appearance, you can use the kCICategoryBlur CIFilter. You can then convert the image to grayscale. And to get that compressed look you just need to resize and skew the image.
Once you have two separate images, you can either take the CGImageRef for the shadow image and can set that as the content of another sublayer, or you can add it as a separate view.
If you know what all the shapes are, you could just render a shadow image in Photoshop or something.
I have several UIButtons on a UIScrollView. I want the buttons to have rounded corners, so I call maskToBounds: on each of them. When I do this and run on the device, the scrolling framerate is pretty bad (it works fine on the simulator). Any ideas on a workaround for this problem?
You're causing the view to be composited offscreen with that call to masksToBounds:, which slows things down quite a bit. Are you rendering custom button images? If so use UIImage -stretchableImageWithLeftCapWidth:topCapHeight: with an image which is the minimum width to encompass it's rounded edges. This allows the GPU to handle stretching the image in the most efficient way possible, while still giving you a button made out of an image. There is a session in the WWDC 2011 videos on Drawing in UIKit - watch that, as it addresses exactly this problem, and a few others you're likely to have.
A few alternative methods:
Tweeties implementation of fast scrolling, by drawing everything manually
Matt Gallaghers implementation of custom drawing. This is the method I use, as it's easy to maintain
Im not sure how else I should approach it, but if I was to (in my mac application) have a grid of NSViews, which the user can change the colour of each, is it possible to then translate this, so now I have been given a colour for each pixel by the user, make this into an exportable image?
I honestly can't think of how else to do this. I don't want to go ahead an realise I have taken a rather foolish path.
The idea is I will have a grid of squares which the user can paint, a colour in each square, a square representing a pixel in the final image. So they paint with like a paint bucket filling each one, then export it into an actual image file.
Any help much appreciated, thanks.
A grid of NSViews sounds really heavy for what you're doing. Why not write one single custom view that checks the mouse position and modifies the data appropriately? Then you'd write a custom drawing method to fill the custom view, and you could use the same exact draw method to write to an NSImage which you could export.
You'll need to do a bit o' math. For each "pixel", call -set on the appropriate NSColor, then use NSBezierPath's -fillRect method. It may help you to get out a pencil & paper to figure out the math for the rect origins & sizes.
Check http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CocoaDrawingGuide/Introduction/Introduction.html for help if you've never done custom drawing before. It's really not that bad, just takes a little reading. :)