I have a UIScrollView that I use to display PDF pages in.
I don't want to use paging (yet). I want to display content based on touchesmoved event (so after horizontal swipe).
This works (sort of), but instead of catching a single swipe and showing 1 page, the swipe seems to gets broken into 100s of pieces and 1 swipe acts as if you're moving a slider!
I have no clue what am I doing wrong.
Here's the experimental "display next page" code which works on single taps:
- (void)nacrtajNovuStranicu:(CGContextRef)myContext
{
CGContextTranslateCTM(myContext, 0.0, self.bounds.size.height);
CGContextScaleCTM(myContext, 1.0, -1.0);
CGContextSetRGBFillColor(myContext, 255, 255, 255, 1);
CGContextFillRect(myContext, CGRectMake(0, 0, 320, 412));
size_t brojStranica = CGPDFDocumentGetNumberOfPages(pdfFajl);
if(pageNumber < brojStranica){
pageNumber ++;
}
else{
// kraj PDF fajla, ne listaj dalje.
}
CGPDFPageRef page = CGPDFDocumentGetPage(pdfFajl, pageNumber);
CGContextSaveGState(myContext);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, self.bounds, 0, true);
CGContextConcatCTM(myContext, pdfTransform);
CGContextDrawPDFPage(myContext, page);
CGContextRestoreGState(myContext);
//osvjezi displej
[self setNeedsDisplay];
}
Here's the swiping code:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
UITouch *touch = [touches anyObject];
gestureStartPoint = [touch locationInView:self];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
CGPoint currentPosition = [touch locationInView:self];
CGFloat deltaX = fabsf(gestureStartPoint.x - currentPosition.x);
CGFloat deltaY = fabsf(gestureStartPoint.y - currentPosition.y);
if (deltaX >= kMinimumGestureLength && deltaY <= kMaximumVariance) {
[self nacrtajNovuStranicu:(CGContextRef)UIGraphicsGetCurrentContext()];
}
}
The code sits in UIView which displays the PDF content, perhaps I should place it into UIScrollView or is the "display next page" code wrong?
I think I figured it out.
I added:
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
[self nacrtajNovuStranicu:(CGContextRef)UIGraphicsGetCurrentContext()];
[self setNeedsDisplay];
}
and removed [self nacrtajNovuStranicu:(CGContextRef)UIGraphicsGetCurrentContext()]; from touchesmoved method.
Related
I wanna draw the transparent area with brush, but my code work not very well.I think someone can help me here. My code :
// Handles the start of a touch
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
CGRect bounds = [self bounds];
UITouch *touch = [[event touchesForView:self] anyObject];
if (![image isPointTransparent:[touch locationInView:self]]
|| ![image isPointTransparent:[touch previousLocationInView:self]])
{
return;
}
firstTouch = YES;
// Convert touch point from UIView referential to OpenGL one (upside-down flip)
location = [touch locationInView:self];
location.y = bounds.size.height - location.y;
}
// Handles the continuation of a touch.
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
CGRect bounds = [self bounds];
UITouch *touch = [[event touchesForView:self] anyObject];
if (![image isPointTransparent:[touch locationInView:self]]
|| ![image isPointTransparent:[touch previousLocationInView:self]])
{
return;
}
// Convert touch point from UIView referential to OpenGL one (upside-down flip)
if (firstTouch)
{
firstTouch = NO;
previousLocation = [touch previousLocationInView:self];
previousLocation.y = bounds.size.height - previousLocation.y;
}
else
{
location = [touch locationInView:self];
location.y = bounds.size.height - location.y;
previousLocation = [touch previousLocationInView:self];
previousLocation.y = bounds.size.height - previousLocation.y;
}
// Render the stroke
[self renderLineFromPoint:previousLocation toPoint:location];
}
// Handles the end of a touch event when the touch is a tap.
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
CGRect bounds = [self bounds];
UITouch *touch = [[event touchesForView:self] anyObject];
if (![image isPointTransparent:[touch locationInView:self]] || ![image isPointTransparent:[touch previousLocationInView:self]])
{
return;
}
if (firstTouch)
{
firstTouch = NO;
previousLocation = [touch previousLocationInView:self];
previousLocation.y = bounds.size.height - previousLocation.y;
[self renderLineFromPoint:previousLocation toPoint:location];
}
}
The important thing to know is that you should do your actual drawing in the drawRect: of your UIView. So the renderLineFromPoint:toPoint: method in your code should just be building up an array of lines and telling the view to redraw each time, something like this:
- (void)renderLineFromPoint:(CGPoint)from toPoint:(CGPoint)to
{
[lines addObject:[Line lineFrom:from to:to]];
[self setNeedsDisplay];
}
This assumes that you have a Line class which has 2 CGPoint properties. Your drawRect: may look something like this:
- (void)drawRect:(CGRect)rect
{
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetRGBStrokeColor(context, 0.0f, 0.0f, 0.0f, 1.0f);
for (Line *line in lines) {
CGContextMoveToPoint(context, line.from.x, line.from.y);
CGContextAddLineToPoint(context, line.to.x, line.to.y);
CGContextStrokePath(context);
}
}
If you do it like this (without OpenGL) there is no need to flip the y-axis.
The only thing left is to implement the isPointTransparent: method. It's difficult to know from your code how this should work.
This is a beginner's question I'm afraid:
I have an UIText which covers the entire screen. I have another transparent view on top of this UITextView so as to be able to recognise swiping gestures (horizontally and vertically), like so:
- (void)viewDidLoad
{
[super viewDidLoad];
// UITextView
CGRect aFrame = CGRectMake(0, 0, 320, 480);
aTextView = [[UITextView alloc] initWithFrame:aFrame];
aTextView.text = #"Some sample text.";
[self.view addSubview:aTextView];
// canTouchMe
CGRect canTouchMeFrame = CGRectMake(0, 0, 320, 480);
canTouchMe = [[UIView alloc] initWithFrame:canTouchMeFrame];
[self.view addSubview:canTouchMe];
}
Let's consider the user touches (not swipes) the canTouchMe View. In this case, I would like the canTouchMe view to disappear and pass on the touch to the UITextView hiding beneath so that it enters the editing mode and enable the 'natural' scrolling options an UITextView has (i.e. only horizontally).
My touches began method looks like this:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
UITouch *touch =[touches anyObject];
gestureStartPoint = [touch locationInView:self.view];
}
How do I tell this method that IF it recognises only ONE touch, that it should hide the canTouchMeFrame and PASS ON the touch to the UITextView?
Sorry if this is basic, but I have no idea how to implement this. Thanks for any suggestions.
EDIT:
I introduced a touchEnded method, but I still have no luck. The touch will not be forwarded to the UITextView. I need to tap twice in order to edit it:
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{
[super touchesMoved:touches withEvent:event];
UITouch *touch = [touches anyObject];
CGPoint currentPosition = [touch locationInView:self.view];
CGFloat deltaX = fabsf(gestureStartPoint.x - currentPosition.x); // will always be positive
CGFloat deltaY = fabsf(gestureStartPoint.y - currentPosition.y); // will always be positive
if (deltaY == 0 && deltaX == 0) {
label.text = #"Touch"; [self performSelector:#selector(eraseText) withObject:nil afterDelay:2];
[aTextView touchesBegan:touches withEvent:event];
[self.view bringSubviewToFront:aTextView];
[self.view bringSubviewToFront:doneEdit];
}
}
NSSet has a -count method. If touches only has one object, then you're responding to a single touch.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
[super touchesBegan:touches withEvent:event];
if ([touches count] == 1) {
[self hideMyRectangle];
[someOtherObject touchesBegan:touches withEvent:event];
//etc, etc.
return;
}
// if you get here, there's more than one touch.
UITouch *touch =[touches anyObject];
gestureStartPoint = [touch locationInView:self.view];
}
Is it possible to drag UIView around the iOS screen while it has both image and text? e.g. small cards. Could you point me to the similar (solved) topic? I haven't found any.
This is what a neat solution, based on pepouze's answer, would look like (tested, it works!)
- (void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *aTouch = [touches anyObject];
CGPoint location = [aTouch locationInView:self];
CGPoint previousLocation = [aTouch previousLocationInView:self];
self.frame = CGRectOffset(self.frame, (location.x - previousLocation.x), (location.y - previousLocation.y));
}
While UIView does not have a built-in support for moving itself along the user dragging, it should be not so difficult to implement it. It is even easier when you are only dealing with dragging on the view, and not other actions such as tapping, double tapping, multi-touches etc.
First thing to do is to make a custom view, say DraggableView, by subclassing UIView. Then override UIView's touchesMoved:withEvent: method, and you can get a current dragging location there, and move the DraggableView. Look at the following example.
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *aTouch = [touches anyObject];
CGPoint location = [aTouch locationInView:self.superview];
[UIView beginAnimations:#"Dragging A DraggableView" context:nil];
self.frame = CGRectMake(location.x, location.y,
self.frame.size.width, self.frame.size.height);
[UIView commitAnimations];
}
And because all subviews of the DraggableView object will be moved, too. So put all your images and texts as subviews of the DraggableView object.
What I implemented here is very simple. However, if you want more complex behaviors for the dragging, (for example, the user have to tap on the view for a few seconds to move the view), then you will have to override other event handling methods (touchesBegan:withEvent: and touchesEnd:withEvent) as well.
An addition to MHC's answer.
If you don't want the upper left corner of the view
to jump under your finger, you can also override touchesBegan
like this:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *aTouch = [touches anyObject];
offset = [aTouch locationInView: self];
}
and change MHC's touchesMoved to:
-(void) touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *aTouch = [touches anyObject];
CGPoint location = [aTouch locationInView:self.superview];
[UIView beginAnimations:#"Dragging A DraggableView" context:nil];
self.frame = CGRectMake(location.x-offset.x, location.y-offset.y,
self.frame.size.width, self.frame.size.height);
[UIView commitAnimations];
}
you should also define CGPoint offset in the interface:
#interface DraggableView : UIView
{
CGPoint offset;
}
EDIT:
Arie Litovsky provides more elegant solution that allows you to ditch the ivar: https://stackoverflow.com/a/10378382/653513
Even though rokjarc solution works, using
CGPoint previousLocation = [aTouch previousLocationInView:self.superview];
avoids the CGPoint offset creation and the call to touchesBegan:withEvent:
Here is a solution to drag a custom UIView (it can be scaled or rotated through its transform), which can hold images and/or text (just edit the Tile.xib as required):
- (void) touchesMoved:(NSSet*)touches withEvent:(UIEvent*)event
{
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self];
CGPoint previous = [touch previousLocationInView:self];
if (!CGAffineTransformIsIdentity(self.transform)) {
location = CGPointApplyAffineTransform(location, self.transform);
previous = CGPointApplyAffineTransform(previous, self.transform);
}
self.frame = CGRectOffset(self.frame,
(location.x - previous.x),
(location.y - previous.y));
}
This work for me. My UIView rotated and scaled
- (void) touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event{
UITouch *touch = [touches anyObject];
CGPoint location = [touch locationInView:self];
CGPoint previous = [touch previousLocationInView:self];
if (!CGAffineTransformIsIdentity(self.transform)) {
location = CGPointApplyAffineTransform(location, self.transform);
previous = CGPointApplyAffineTransform(previous, self.transform);
}
CGRect newFrame = CGRectOffset(self.frame,
(location.x - previous.x),
(location.y - previous.y));
float x = CGRectGetMidX(newFrame);
float y = CGRectGetMidY(newFrame);
self.center = CGPointMake(x, y);
}
In touchesBegan:
CGPoint touch_point = [[touches anyObject] locationInView:self.view];
There are tens of UIImageView around, stored in a NSMutableArray images. I'd like to know is there a built-in function to check if a CGPoint (touch_point) is inside one of the images, e.g.:
for (UIImageView *image in images) {
// how to test if touch_point is tapped on a image?
}
Thanks
Follow up:
For unknown reason, pointInside never returns true. Here is the full code.
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
touch_point = [touch locationInView:self.view];
for (UIImageView *image in piece_images) {
if ([image pointInside:touch_point withEvent:event]) {
image.hidden = YES;
} else {
image.hidden = NO;
}
NSLog(#"image %.0f %.0f touch %.0f %.0f", image.center.x, image.center.y, touch_point.x, touch_point.y);
}
}
although I can see the two points are sometimes identical in the NSLog output.
I also tried:
if ([image pointInside:touch_point withEvent:nil])
the result is the same. never returns a true.
To eliminate the chance of anything goes with with the images. I tried the following:
if (YES or [image pointInside:touch_point withEvent:event])
all images are hidden after the first click on screen.
EDIT 2:
Really weird. Even I hard coded this:
point.x = image.center.x;
point.y = image.center.y;
the code becomes:
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint point; // = [touch locationInView:self.view];
for (UIImageView *image in piece_images) {
point.x = image.center.x;
point.y = image.center.y;
if ([image pointInside:point withEvent:event]) {
image.hidden = YES;
NSLog(#"YES");
} else {
image.hidden = NO;
NSLog(#"NO");
}
NSLog(#"image %.0f %.0f touch %.0f %.0f", image.center.x, image.center.y, point.x, point.y);
}
}
pointInside always returns false ...
Sounds to me like the problem is you need to convert coordinates from your view's coordinates to the UIImageView's coordinates. You can use UIView's convertPoint method.
Try replacing
if ([image pointInside:touch_point withEvent:event]) {
with
if ([image pointInside: [self.view convertPoint:touch_point toView: image] withEvent:event]) {
(Note that you are allowed to pass nil instead of event.)
I guess this is a bit late for the questioner, but I hope it is of use to someone.
if ([image pointInside:touch_point withEvent:event]) {
// Point inside
}else {
// Point isn't inside
}
In this case event is taken from :
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
CGPoint point = [touch locationInView:self.view];
for (UIImageView *piece in piece_images) {
CGFloat x_min = piece.center.x - (piece.bounds.size.width / 2);
CGFloat x_max = x_min + piece.bounds.size.width;
CGFloat y_min = piece.center.y - (piece.bounds.size.height / 2);
CGFloat y_max = y_min + piece.bounds.size.height;
if (point.x > x_min && point.x < x_max && point.y > y_min && point.y < y_max ) {
piece.hidden = YES;
} else {
piece.hidden = NO;
}
}
}
too bad, I have do it myself...
it's OS 3.2, XCode 3.2.2, tried both on simulator and iPad
I have created a basic unlock slider like you use to unlock the iPhone.
In my touchesEnded function, I use an animation to move the slider back to home.
The first time the user moves the slider (and doesn't actually hit the end to unlock), the animation works fine and the slider moves back to home.
However, the next time the user tries to move the slider (and touchesMoved gets called), the slider gets pushed offscreen (to the left) by the amount they had slid the slider before.
So, what's happening?
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {
self.dragging = NO;
self.startX = 0;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:0.5];
self.unlock.frame = CGRectMake(0, 0, 75, 35);
[UIView commitAnimations];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if (!self.dragging ) { return; }
UITouch *touch = [[event allTouches] anyObject];
CGPoint point = [touch locationInView:self];
int offset = point.x - self.startX;
NSLog(#"%i", offset);
if (offset > (LENGTH-SIZE)) {
offset = (LENGTH-SIZE);
}
CGAffineTransform myTransform = CGAffineTransformMakeTranslation(offset, 0.0);
[self.unlock setTransform:myTransform];
if (point.x >= (LENGTH-(SIZE-self.startX))) {
NSLog(#"Slider reached end");
[self.sliderView removeFromSuperview];
}
}
EDIT
Here's the working function, cleaned up a bit, though it could be better (thanks to a couple answered questions on SO from one hacker). I'm going to blog the complete module since there doesn't seem to be a standard widget:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if (!self.dragging ) { return; }
UITouch *touch = [[event allTouches] anyObject];
CGPoint point = [touch locationInView:self];
if (point.x >= (LENGTH-(SIZE-self.startX))) {
NSLog(#"Slider reached end");
[self.sliderView removeFromSuperview];
}
// offset based on where the user clicked the slider
int offset = point.x - self.startX;
if (offset > (LENGTH-SIZE)) {
offset = (LENGTH-SIZE);
}
//move the slider
CGRect oldFrame = self.unlock.frame;
CGRect newFrame = CGRectMake(self.frame.origin.x+offset, self.frame.origin.y-5, oldFrame.size.width, oldFrame.size.height);
self.unlock.frame = newFrame;
}
IN your previous question I didn't realize you were moving the slider by changing its transform. Mixing up motion by changing its frame and transform is going to be moderately complicated.
Maybe you could try doing something more like this:
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
if (!self.dragging ) { return; }
UITouch *touch = [[event allTouches] anyObject];
CGPoint point = [touch locationInView:self];
int offset = point.x - self.startX;
NSLog(#"%i", offset);
if (offset > (LENGTH-SIZE)) {
offset = (LENGTH-SIZE);
}
CGRect oldFrame = self.frame;
CGRect newFrame = CGRectMake(oldFrame.origin.x+offset, oldFrame.origin.y, oldFrame.size.width, oldFrame.size.height);
self.frame = newFrame;
if (point.x >= (LENGTH-(SIZE-self.startX))) {
NSLog(#"Slider reached end");
[self.sliderView removeFromSuperview];
}
}
That moves the slider by modifying its frame, not its translation, which should cause it to interact better with the snap back animation. Alternatively, rather than resetting the frame in the implicit animator you could reset the translation there.
You need to reset the view transform in your touchesEnded handler:
[self.unlock setTransform:CGAffineTransformIdentity];
Try that instead of animating the frame property.