I have a UIImage which is inside a UIScrollView so I can zoom-in and zoom-out, crop, move around, etc.
How do I get the coordinates of the visible part of the UIImage inside the UIScrollView.
I want to crop the image in it's native resolution (using GPUIImage) but I need to x, y, width and height for the rectangle.
I use a scrollview to enable zoom of a UIImage. A cropping button presents an overlaid resizable cropping view. The following is the code I use to ensure the user defined crop box in the UIScrollView gets added with the correct coordinates to the UIImageView (can then use to crop image).
To find the x and y coordinates use the scrollview contentOffset multiplied by inverse of zoomscale:
float origX = 0;
float origY = 0;
float widthCropper = 0;
float heightCropper = 0;
if (_scrollView.contentOffset.x > 0){
origX = (_scrollView.contentOffset.x) * (1/_scrollView.zoomScale);
}
if (_scrollView.contentOffset.y > 0){
origY = (_scrollView.contentOffset.y) * (1/_scrollView.zoomScale);
}
If you need to create a properly sized cropping box for what is displayed in the scrollview you will need to adjust the width and the height for any zoom factor:
widthCropper = (_scrollView.frame.size.width * (1/_scrollView.zoomScale));
heightCropper = (_scrollView.frame.size.height * (1/_scrollView.zoomScale));
and to add this properly sized rectangle as a cropping view to the UIImageView:
CGRect cropRect = CGRectMake((origX + (SIDE_MARGIN/2)), (origY + (SIDE_MARGIN / 2)), (widthCropper - SIDE_MARGIN), (heightCropper - SIDE_MARGIN));
_cropView = [[UIView alloc]initWithFrame:cropRect];
[_cropView setBackgroundColor:[UIColor grayColor]];
[_cropView setAlpha:0.7];
[_imageView addSubview:_cropView];
[_imageView setCropView:_cropView];
I'm adding buttons to my scrollview via code but when I run the app, I see all the buttons and they exceed the scrollview boundries instead of only some.
In the attached screenshot, you can see that the scrollbar is inside the boundries of the scrollview, only the buttons exceed.
why do I need self.recentFriendsScrollView.delegate = self;??
Here is my code:
//recentOpponents is an array
NSInteger xOffset = 0;
CGFloat size = 38;
CGFloat padding = 5;
self.recentFriendsScrollView.delegate = self;
for (User *user in recentOpponents) {
UIButton *tagButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
tagButton.backgroundColor = [UIColor lightGrayColor];
tagButton.frame = CGRectMake(xOffset, 8, size, size);
[self.recentFriendsScrollView addSubview:tagButton];
xOffset += size;
xOffset += padding;
}
[self.recentFriendsScrollView setContentSize:CGSizeMake(xOffset, 50.0f)];
image
Thanks
D
Your scrollview frame is not proper.
If you have set it programmatically, show the rect of frame. If it is set via sib, check your resizing flags again.
I am trying to implement an NSTextView which resizes to fit its content. I am trying to make it so it has a maximum amount of lines. Meaning, that when this limit is reached, it will not grow any further and the user will be able to scroll it.
There seem to be a lot of people wanting this but I have not found a complete implementation of this.
The idea is to take the content size of the NSTextView and resize it so that it matches. I just can't figure out how to set the layout size of the NSTextView. It does not seem to be it's frame which needs to be set and which one might expect.
Can anyone please tell me how to set the frame of the NSTextView?
It turns out that it's the height of the scroll view which should be changed. Changing the height of an NSTextView can be done by overwriting the -didChangeText method like below.
- (void)didChangeText
{
NSScrollView *scrollView = (NSScrollView *) self.superview.superview;
NSRect frame = scrollView.frame;
// Calculate height
NSUInteger numberOfLines = [self numberOfLines];
NSUInteger height = frame.size.height;
if (numberOfLines <= 13)
{
height = 22 + (numberOfLines - 1) * 14;
if (height < 22)
height = 22;
}
// Update height
frame.size.height = height;
self.superview.superview.frame = frame;
}
Play around with the constants to get the result you wish for.
1.Create a cocoa application (not document-based)
2.Create a new class "StretchView"(subclass NSView)
3.Open the Interface builder and drag a "Scroll view" to the main window
4.Choose the "Scroll view" and set the class "StretchView" (in class identity window)
The size of the contentview is 500*500 and the size of the strechview is also 500*500
(horizontal Scroll is enabled).
Then I start to draw some numbers(1,2,3,4......) horizontally one after the other.
When the number is out of ranger(the x pos is larger than 500) I increase the width
of the StretchView. (Everything works fine up till this point)
Then I tried to make the horizontal scroller to automatically scroll to the end so
that everytime I increase the width of the StretchView the last number coulde be
seen.
Here's the code:
//The timer is called every sec
-(void)myTimerAction:(NSTimer *) timer
{
NSLog(#"myTimerAction");
//......
int i = _myArray.count;
NSRect rect = [self frame];
int width = rect.size.width;
//The width between two number is 10
//When the x pos of current num is bigger then the scroll's width
if((i * 10) > width) {
//reset the width
width = i * 10;
[self setFrameSize:CGSizeMake(width, rect.size.height)];
//How to make it autoscroll???
//...............................
}
//......
[self setNeedsDisplay:YES];
}
Try this:
NSView *contentView = [[self enclosingScrollView] contentView];
CGFloat newXPosition = width - NSWidth([contentView bounds]);
if (newXPosition > 0.0) [self scrollPoint:NSMakePoint(newXPosition, 0.0)];
contentView is the clipping view in the enclosing scroll view. You want to scroll your current view to the x point in your view such that this x point + the clipping view width give the last clipping view width points of your view.
I've got an NSView (myView) wrapped in an NSScrollView (myScrollView). Using zoom-in/out buttons, the user can alter the scale of myView. If the user is currently scrolled to a particular spot in myView, I'd like to keep that part of the view on-screen after the zooming has taken place.
I've got code that looks like this:
// preserve current position in scrollview
NSRect oldVisibleRect = [[myScrollView contentView] documentVisibleRect];
NSPoint oldCenter = NSPointFromCGPoint(CGPointMake(oldVisibleRect.origin.x + (oldVisibleRect.size.width / 2.0),
oldVisibleRect.origin.y + (oldVisibleRect.size.height / 2.0)));
// adjust my zoom
++displayZoom;
[self scaleUnitSquareToSize:NSSizeFromCGSize(CGSizeMake(0.5, 0.5))];
[self calculateBounds]; // make sure my frame & bounds are at least as big as the visible content view
[self display];
// Adjust scroll view to keep the same position.
NSRect newVisibleRect = [[myScrollView contentView] documentVisibleRect];
NSPoint newOffset = NSPointFromCGPoint(CGPointMake((oldCenter.x * 0.5) - (newVisibleRect.size.width / 2.0),
(oldCenter.y * 0.5) - (newVisibleRect.size.height / 2.0)));
if (newOffset.x < 0)
newOffset.x = 0;
if (newOffset.y < 0)
newOffset.y = 0;
[[myScrollView contentView] scrollToPoint: newOffset];
[myScrollView reflectScrolledClipView: [myScrollView contentView]];
And it seems sort of close, but it's not quite right and I can't figure out what I'm doing wrong. My two questions are:
1) Is there not a built-in something along the lines of:
[myView adjustScaleBy: 0.5 whilePreservingLocationInScrollview:myScrollView];
2) If not, can anyone see what I'm doing wrong in my "long way around" approach, above?
Thanks!
Keeping the same scroll position after scaling isn't easy. One thing you need to decide is what you mean by "the same" - do you want the top, middle, or bottom of the visible area before scaling to stay in place after scaling?
Or, more intuitively, do you want the position that stays in place a percentage down the visible rect equal to the percentage that you are scrolled down the document when you start (eg, so the center of the scroller's thumb doesn't move up or down during a scale, the thumb just grows or shrinks).
If you want the latter effect, one way to do it is get the NSScrollView's verticalScroller and horizontalScroller, and then read their 'floatValue's. These are normalized from 0 to 1, where '0' means you're at the top of the document and 1 means you're at the end. The nice thing about asking the scroller for this is that if the document is shorter than the NSScrollView, the scroller still returns a sane answer in all cases for 'floatValue,' so you don't have to special-case this.
After you resize, set the NSScrollView's scroll position to be the same percentage it was before the scale - but, sadly, here's where I wave my hands a little bit. I haven't done this in a while in my code, but as I recall you can't just set the NSScrollers' 'floatValue's directly - they'll LOOK scrolled, but they won't actually affect the NSScrollView.
So, you'll have to write some math to calculate the new top-left point in your document based on the percentage you want to be through it - on the y axis, for instance, it'll look like, "If the document is now shorter than the scrollView's contentView, scroll to point 0, otherwise scroll to a point that's ((height of contentView - height of documentView) * oldVerticalPercentage) down the document." X axis is of course similar.
Also, I'm almost positive you don't need a call to -display here, and in general shouldn't ever call it, ever. (-setNeedsDisplay: at most.)
-Wil
Me thinks you like to type too much… ;-)
// instead of this:
NSPoint oldCenter = NSPointFromCGPoint(CGPointMake(oldVisibleRect.origin.x +
(oldVisibleRect.size.width / 2.0),
// use this:
NSPoint oldCenter = NSMakePoint(NSMidX(oldVisibleRect), NSMaxY(oldVisibleRect));
// likewise instead of this:
[self scaleUnitSquareToSize:NSSizeFromCGSize(CGSizeMake(0.5, 0.5))];
// use this:
[self scaleUnitSquareToSize:NSMakeSize(0.5, 0.5)];
// and instead of this
NSPoint newOffset = NSPointFromCGPoint(CGPointMake(
(oldCenter.x * 0.5) - (newVisibleRect.size.width / 2.0),
(oldCenter.y * 0.5) - (newVisibleRect.size.height / 2.0)));
// use this:
NSPoint newOffset NSMakePoint(
(oldCenter.x - NSWidth(newVisibleRect)) / 2.f,
(oldCenter.y - NSHeight(newVisibleRect)) / 2.f);
This is an old question, but I hope someone looking for this finds my answer useful...
float zoomFactor = 1.3;
-(void)zoomIn
{
NSRect visible = [scrollView documentVisibleRect];
NSRect newrect = NSInsetRect(visible, NSWidth(visible)*(1 - 1/zoomFactor)/2.0, NSHeight(visible)*(1 - 1/zoomFactor)/2.0);
NSRect frame = [scrollView.documentView frame];
[scrollView.documentView scaleUnitSquareToSize:NSMakeSize(zoomFactor, zoomFactor)];
[scrollView.documentView setFrame:NSMakeRect(0, 0, frame.size.width * zoomFactor, frame.size.height * zoomFactor)];
[[scrollView documentView] scrollPoint:newrect.origin];
}
-(void)zoomOut
{
NSRect visible = [scrollView documentVisibleRect];
NSRect newrect = NSOffsetRect(visible, -NSWidth(visible)*(zoomFactor - 1)/2.0, -NSHeight(visible)*(zoomFactor - 1)/2.0);
NSRect frame = [scrollView.documentView frame];
[scrollView.documentView scaleUnitSquareToSize:NSMakeSize(1/zoomFactor, 1/zoomFactor)];
[scrollView.documentView setFrame:NSMakeRect(0, 0, frame.size.width / zoomFactor, frame.size.height / zoomFactor)];
[[scrollView documentView] scrollPoint:newrect.origin];
}