scrollview的无缝循环滚动
1.循环滚动
若本次滚动是向后一页滚动，则把三页都向前放置，第一页放到末尾
初始化UISCrollView
float x,y,width,height;
x = WIDTH_OFF_SET;
y = HEIGHT_OFF_SET;
width = WIDTH_OFF_SET;
height = SCROLLVIEW_HEIGHT;
for (int j=0; j<3; j++) {
UIView *view = [[UIView alloc] initWithFrame:CGRectMake(x*(j), y, width, height)];
[view setTag:10+j];//view的tag为10，11，12
[view setBackgroundColor:[UIColor yellowColor]];
for (int i=0; i<count; i++) {
UIButton*pointNButton = [UIButton buttonWithType:UIButtonTypeCustom];
[pointNButton setTitle:[NSString stringWithFormat:@"%d",100+i] forState:UIControlStateNormal];
[pointNButton setBackgroundColor:[UIColor blueColor]];
[pointNButton setTag:100+i];
[pointNButton setFrame:CGRectMake(6.5+(13+65)*i, 8, 65, 65)];
[pointNButton addTarget:self action:@selector(pointBtnClicked:) forControlEvents:UIControlEventTouchUpInside];
[view addSubview:pointNButton];
}
[scrollView addSubview:view];
[view release];
}
[scrollView setDelegate:self];
[scrollView setPagingEnabled:NO];
[scrollView setContentSize:CGSizeMake(WIDTH_OFF_SET*3, 80.0)];
[scrollView setShowsHorizontalScrollIndicator:NO];
#define WIDTH_OFF_SET630.0
#define HEIGHT_OFF_SET0
#define SCROLLVIEW_WIDTH390.0
#define SCROLLVIEW_HEIGHT80.0
#define SET_FRAME(ARTICLEX) x = ARTICLEX.frame.origin.x + increase;\
if(x < 0) x = pageWidth * 2;\
if(x > pageWidth * 2) x = 0.0f;\
[ARTICLEX setFrame:CGRectMake(x, \
ARTICLEX.frame.origin.y,\
ARTICLEX.frame.size.width,\
ARTICLEX.frame.size.height)]
#pragma mark -
#pragma mark UIScrollViewDelegate
//将三个view都向右移动，并更新三个指针的指向，article1永远指向当前显示的view，article0是左边的，article2是右边的
- (void)allArticlesMoveRight:(CGFloat)pageWidth {
UIView *view0 = [scrollView viewWithTag:10];
UIView *view1 = [scrollView viewWithTag:11];
UIView *view2 = [scrollView viewWithTag:12];
UIView *tmpView = view2;
view2 = view1;
view1 = view0;
view0 = tmpView;
float increase = pageWidth;
CGFloat x = 0.0f;
SET_FRAME(view2);
SET_FRAME(view0);
SET_FRAME(view1);
}
- (void)allArticlesMoveLeft:(CGFloat)pageWidth {
UIView *view0 = [scrollView viewWithTag:10];
UIView *view1 = [scrollView viewWithTag:11];
UIView *view2 = [scrollView viewWithTag:12];
UIView *tmpView = view0;
view0 = view1;
view1 = view2;
view2 = tmpView;
float increase = -pageWidth;
CGFloat x = 0.0f;
SET_FRAME(view1);
SET_FRAME(view2);
SET_FRAME(view0);
}
- (void)scrollViewDidScroll:(UIScrollView *)theScrollView
{
CGFloat pageWidth = WIDTH_OFF_SET;
// 0 1 2
int page = floor((theScrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
if(page == 1) {
//用户拖动了，但是滚动事件没有生效
return;
} else if (page == 0) {
[self allArticlesMoveRight:pageWidth];
} else {
[self allArticlesMoveLeft:pageWidth];
}
CGPoint p = CGPointZero;
p.x = pageWidth;
[theScrollView setContentOffset:p animated:NO];
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)theScrollView
{
CGFloat pageWidth = WIDTH_OFF_SET;
// 0 1 2
int page = floor((theScrollView.contentOffset.x - pageWidth / 2) / pageWidth) + 1;
if(page == 1) {
//用户拖动了，但是滚动事件没有生效
return;
} else if (page == 0) {
[self allArticlesMoveRight:pageWidth];
} else {
[self allArticlesMoveLeft:pageWidth];
}
CGPoint p = CGPointZero;
p.x = pageWidth;
[theScrollView setContentOffset:p animated:NO];
}
2.种方法思想是一样的，运用scrollRectToVisible
- (void)scrollViewDidEndDecelerating:(UIScrollView *)_scrollView
{
float currentPage =scrollView.contentOffset.x;
NSLog(@"=======bao===scrollViewDidEndDragging==currentPage=%d",currentPage);
if (currentPage >WIDTH_OFF_SET&¤tPage<WIDTH_OFF_SET*2) {
[scrollView scrollRectToVisible:CGRectMake(0,0,SCROLLVIEW_WIDTH,SCROLLVIEW_HEIGHT) animated:NO];
} else if (currentPage<0) {
[scrollView scrollRectToVisible:CGRectMake(WIDTH_OFF_SET,0,SCROLLVIEW_WIDTH,SCROLLVIEW_HEIGHT) animated:NO];
}
}
3。改变conentOffset
#pragma mark UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)_scrollView
{
int currentPage =(int)scrollView.contentOffset.x;
if (currentPage >WIDTH_OFF_SET) {
scrollView.contentOffset = CGPointMake(abs(currentPage-WIDTH_OFF_SET), HEIGHT_OFF_SET);
} else if (currentPage<0) {
scrollView.contentOffset = CGPointMake(currentPage+WIDTH_OFF_SET,HEIGHT_OFF_SET);
}
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)_scrollView
{
int x= (int)scrollView.contentOffset.x/BUTTON_OFFSET*BUTTON_OFFSET;
[scrollView setContentOffset:CGPointMake(x, HEIGHT_OFF_SET) animated:YES];
}
- (void)scrollViewDidEndDragging:(UIScrollView *)_scrollView willDecelerate:(BOOL)decelerate {
if (!decelerate) {
int x = (int)scrollView.contentOffset.y/BUTTON_OFFSET*BUTTON_OFFSET;
[scrollView setContentOffset:CGPointMake(x, HEIGHT_OFF_SET) animated:YES];
}
}
总之要想实现无缝链接就必须准备三屏你的数据，通过改变offset或是view的frame的的横纵坐标进而实现循环滚动