I have a image in UIImageView. When user taps one particular area on image, that part of image should be highlighted by a square and the subpart of image in that square should be used for scaling.
How can I do it?
Well, it's actually going to involve:
user tap gesture handling
overlay a UIView for the square to highlight
crop and scale the certain area of the original image, you may need some helpers like: https://github.com/Nyx0uf/NYXImagesKit
Related
I have to make view where there will be multiple curved or irregular shaped imageview. Now when i will touch a UIImageview then it will import image from photo gallery.For example: Suppose
I have an UIView with background image.
On that view i have 3 irregular shaped UIImageview.every UIImageview is attached with each other.
Now suppose i have touch in the first UIImageview then it will take an image from photo gallery.
When i have imported the image then that image will be as the background image of the UIImageview.
I have to make sure that if my UIImageviewis smaller then its background image then i will able to move the image or rotate the image or scale or zoom the image to adjust the image according to the size of UIImageview.
How can i do that whole process??? any help by link,source code,tutorial or anything else will be cordially appreciable.
Basically my first priority is that how can i make those irregular shaped UIImageView pro-grammatically.
IF ANY FURTHER QUERY TO ASK THEN PLEASE DON'T HESITATE.
Thanks In Advance
The one way of doing this is as follows:
Subclass from UIImageView set touchesBegan methods for each UIImageView for import image, setting on background and whatever you want to do on touch.
What does 'attached' mean? If all of them should move together, then, again, you have to deal with it in touchesBegan methods, sending messages like 'Hey views, i've moved on this vector:[vector], please do it too'.
In pt. 3.2 i didn't get your point. :( You can set in UIImageView subclass self.contentMode = UIViewContentModeScaleAspectFit or UIViewContentModeScaleToFill, so its image will always fit the view.
About irregular shape, did you read links below? I suppose there's not an super easy way to do it :(
http://www.iphonedevsdk.com/forum/iphone-sdk-development/76923-hittest-collision-for-irregular-shaped-uiviews.html
Draggable UIImageView Partially Transparent & Irregular Shaped
Simple way of using irregular shaped buttons
I have an image which has a relatively large area of transparency, alpha space. So is there a way I can detect a tap on this UIImageView but not have any response if the user taps the alpha area?
This is theoretical and I don't have code to add, but you could create an identical button and add it for UIControlStateTouched so there's no change when the button/image is touched.
I have a UIViewController that implements a UIScrollView with the UIScrollViewDelegate. Attached to it is an UIImageView for which the user must crop the photo via zooming it and panning to fill the entire length of the screen. After the user has finished cropping and they hit done, the original UIImage gets sent to the next UIViewController.
I'm wondering, is there anyway, using the original image, to display it in a UIScrollView and allow the user to zoom and pan it so ONLY the cropped area gets shown? IE none of the image that was outside of the cropped area gets shown in zooming and panning? Is there a way to do this without explicitly cropping the image?
This might head you in the right direction: Displaying part of an image
Not to sure if this will work with the way you are displaying it. But if it does it could be a simple solution. You can also read through UIScrollviews and maybe use panGestureRecognizer and pinchGestureRecognizer to limit the area they can zoom and pan.
Set the content size of the UIScrollView to the rect of the cropped area.
I want to take an image from the UIImagePickerController and put it on a UIImageView that can move based on touch. I'm not sure how to get the picture onto the UIImageView. I thought the UIImageView automatically resizes the picture, so I couldn't grab just the top half of the picture and put that on the UIImageView. Is there an easy way to do this? thanks!
Use CGImageCreateWithImageInRect to crop (take a segment of?) a picture. Put a UIImageView inside a UIScrollView to let the user scroll through (move based on touch) a large image.
if you want to move and zoom your picture in a view, you need to use a UIScrollView. See Apple's ScrollViewSuite example. If you simply want to position the picture within a UIImageView, set the contentMode of the UIImageView to the setting you want e.g. scale, top, left, etc. See the UIImageView documentation for all options.
How can I get a non-rectangular shaped button?
For example I do have a PNG image with alpha transparency.
How can I set the shape of a button to this image without the transparent color.
Like the others say you should have a reasonable surface for registering touch events, but I'm sure you know that and have your reasons so I'll just tell you how I did it:
I needed to do this not so long ago and what I did is what Sixten Otto just suggested. There are some hints in my original question ("UPDATE" section) for getting the alpha value for your image at a certain point:
How to create a transparent window with non-rectangular buttons?
Edit: I suggest subclassing UIControl in the example below but if you don't need any special behavior on your button apart from the "non-rectangleness" of it then just subclassing a borderless UIButton set up with your PNG will do the job and require less work. You have more control on the control's behavior by subclassing UIControl and doing it the "hard way" though.
I would suggest that you subclass UIControl and override the touch event methods, then check for alpha under the tapped point and not handle the event if alpha == 0. For drawing you override drawRect: and use the NSImage's drawInRect:fromRec:operation:fraction: method in there to draw your image in the control's frame.
First you need to load the image and get a bitmap representation of it:
buttonImage = [NSImage imageNamed:#"myButtonImage"];
buttonImageRep = [[buttonImage representations] objectAtIndex:0];
Then you can draw it to the control's view: (where stateImage is a pointer to the image that must be drawn depending on if the button is pressed or not)
- (void)drawRect:(NSRect)aRect {
[stateImage drawInRect:[self bounds] fromRect:NSMakeRect(0.0,0.0,[buttonImage size].width,[buttonImage size].height)
operation:NSCompositeSourceOver fraction:1.0];
}
At this point you have drawn your button with your png image. You can override the touch event methods and handle the event if the alpha is not 0:
NSColor *colorUnderMouse = [buttonImageRep colorAtX:mouse.x y:mouse.y];
float alpha = [colorUnderMouse alphaComponent];
That's what I did and it works wonderfully. Hope this helps!
N.B: My example is for the Mac but it should also work on the iPhone, maybe with some slight modifications.
It sounds like you are looking to have the clickable area of the button exactly match the PNG you are using.
If that is what you are looking for, I would firstly say to not do that. The iPhone is pressed using a finger, which generally doesn't have the accuracy to distinguish such a small region.
However if you are stuck on the idea, then the solution is to not use buttons at all, instead handle the click in a parent frame and manually interpret the X/Y value of the click to determine if it is in some bounding region (In the case of a rounded edge button, would likely consist of oring the result of checking 4 circles and 2 rectangles)
Edit:
Realizing part of your original question, I noticed you mentioned you wanted to handle the function automatically based on the Alpha channel. While I would recommend my method of bounding regions, you could in theory accomplish this by sampling the PNG to test the Alpha channel at a value offset by the origin of the button. Potentially even doing this in a normal button's click event.
Rectangular buttons are a button type, you can use the custom button type and assign an image to get rid of the rectangular edges of the button...heres a reference to button types http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIButton_Class/UIButton/UIButton.html#//apple_ref/doc/c_ref/UIButtonType and to UIButton http://developer.apple.com/iphone/library/documentation/UIKit/Reference/UIButton_Class/UIButton/UIButton.html
As Guvante says, it's really not a good idea to rely on precision touches. Apple, for instance, recommends that controls be at least 44px across.
I'd recommend using a UIButton of type UIButtonTypeCustom, set the button's image to your PNG, and register for touch events (see here for more on event handling). Then, in your action method, you can get the coordinates of the touch out of the event, and test those coordinates against the alpha of your image to see whether you should treat it as a "real" touch or not.
Another option could be to split your button up into multiple, rectangular parts.
#Form right about using 'drawRect' to implement custom shape for button.
But better method to exam touch inside or not inside button is using of
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event;
You can create your button transparent for touches in some parts.
If you can't use custom image for button (for example if you draw text on the button) you can use new method to draw subviews hierarchy into a image:
- (BOOL)drawViewHierarchyInRect:(CGRect)rect afterScreenUpdates:(BOOL)afterUpdates;