[英]iphone - how to scroll uiscrollview from event touched by uibutton in scrollview
structure UIViewController - UIScrollview - UIButton 结构 UIViewController-UIScrollview-UIButton
I'm going to make scrollview can receive button event. 我将使scrollview可以接收按钮事件。 So whenever user do scrolling(dragging) on the button, the scrollview react as scrolling itself.
因此,每当用户在按钮上进行滚动(拖动)时,scrollview都会自动滚动。
I made button down and moved handler with event forwarding like below 我按下按钮并通过事件转发移动了处理程序,如下所示
- (IBAction)buttonTouchedMove:(id)sender withEvent:(UIEvent *)event {
[[sender nextResponder] touchesMoved:[event allTouches] withEvent:event];
}
- (IBAction)buttonTouchedDown:(id)sender withEvent:(UIEvent *)event {
[[sender nextResponder] touchesBegan:[event allTouches] withEvent:event];
}
and to move scrollview as touches change, I made below codes 并随着滚动变化移动滚动视图,我做了以下代码
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
UITouch *touch = [touches anyObject];
self.oldPoint = [touch locationInView:self.view];
}
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
CGPoint offset = self.scrollView1.contentOffset;
UITouch *touch = [touches anyObject];
self.newPoint = [touch locationInView:self.view];
int diffX = newPoint.x - oldPoint.x;
offset.x = offset.x - diffX;
[scrollView1 setContentOffset:offset animated:YES];
self.oldPoint = self.newPoint;
}
but, scrollview react strange.. not move enough as I touch moved. 但是,scrollview的反应很奇怪。
// get the button width
CGFloat buttonWidth = self.theButton.frame.size.width;
// replace your button name here
// now get the view width
CGFloat viewWidth = self.view.frame.size.width;
// replace your view name here
// now get the multiplier which i said u as 10
CGFloat mult = viewWidth / buttonWidth;
// and now use it in your code
.
.
.
diffX = mult*(newPoint.x - oldPoint.x);
.
.
.
Final answer, Using UIView animation, I got what i want. 最终答案,使用UIView动画,我得到了想要的东西。
- (IBAction)buttonTouchedDown:(id)sender withEvent:(UIEvent *)event {
UITouch *touch = [[event allTouches] anyObject];
self.oldPoint = [touch locationInView:self.view];
self.velocity = 0;
isButtonTouchedDown = YES;
}
- (IBAction)buttonTouchedMove:(id)sender withEvent:(UIEvent *)event {
CGPoint offset = self.scrollView1.contentOffset;
UITouch *touch = [[event allTouches] anyObject];
self.newPoint = [touch locationInView:self.view];
int diffX = self.newPoint.x - self.oldPoint.x;
velocity = diffX;
offset.x = offset.x - diffX;
[self.scrollView1 setContentOffset:offset animated:NO];
self.oldPoint = self.newPoint;
}
There is a trick..I calculated velocity by differentiating moved distance in TouchedMove function. 有一个窍门。我通过在TouchedMove函数中区分移动距离来计算速度。 In Button TouchUp event handler, I controlled Scrollview with velocity value and CurveEaseout animation to scroll more.
在Button TouchUp事件处理程序中,我使用速度值和CurveEaseout动画控制Scrollview来滚动更多内容。 By offering very short duration of animation and repeating it if there is no event(button touched down).
通过提供非常短的动画持续时间,如果没有事件(按下按钮),则重复动画。 It becomes very similar with scrollview's animation.
它与scrollview的动画非常相似。
- (IBAction)buttonTouchedUp:(id)sender withEvent:(UIEvent *)event {
CGPoint offset = self.scrollView1.contentOffset;
amountX = (self.velocity)*(abs(self.velocity));
dX = amountX;
isButtonTouchedDown = NO;
if (offset.x - amountX < 0) {
offset.x = 0;
[scrollView1 setContentOffset:offset animated:YES];
}
else if (abs(dX) < 70) { // 70: content item size
offset.x = roundf(offset.x/70)*70;
[scrollView1 setContentOffset:offset animated:YES];
}
else {
[self endScrollAnimation];
}
- (void)startAnimation:(float)x moveAmount:(float)moveAmount
{
CGPoint offset = self.scrollView1.contentOffset;
[UIView beginAnimations:nil context:nil];
[UIView setAnimationDuration:duration];
offset.x = x < 0 ? offset.x + moveAmount : offset.x -moveAmount;
[UIView setAnimationCurve:UIViewAnimationCurveLinear];
[UIView setAnimationDelegate:self];
[UIView setAnimationDidStopSelector:@selector(endScrollAnimation)];
[scrollView1 setContentOffset:offset animated:NO];
[UIView commitAnimations];
}
- (void)endScrollAnimation
{
CGPoint offset = self.scrollView1.contentOffset;
float slowMoveAmount = abs(amountX) * 0.05;
float fastMoveAmount = abs(amountX) * 0.1;
if (isButtonTouchedDown) {
return;
}
else if (abs(dX) > abs(amountX)*0.35 && offset.x > 0) {
[self startAnimation:dX moveAmount:fastMoveAmount];
dX = dX < 0 ? dX + fastMoveAmount : dX -fastMoveAmount;
}
else if (abs(dX) > slowMoveAmount && offset.x > 0) {
[self startAnimation:dX moveAmount:slowMoveAmount];
dX = dX < 0 ? dX + slowMoveAmount : dX - slowMoveAmount;
}
else {
offset.x = roundf(offset.x/70)*70;
[scrollView1 setContentOffset:offset animated:YES];
}
}
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