iosquartz2d-04-picture Trim and save to album

Achieve results

• Operation Steps
  
  • Draws a rectangle, pops up a alertview, prompts whether to save the picture
  • Click "Yes" to save the picture to the album
  • View a saved picture in an album

Implementation ideas

• Add a ImageView to the view on the controller, set the picture
• Add a pan gesture to the view on the controller
• Track pan gestures, draw a rectangular box ( 图片的剪切区域 )
• At the end of the pan gesture, Alertview prompts "Do you want to save the picture to the album?" ”
  
  • Click "Yes" to save the image
  • Click "No" to temporarily do nothing

Implementation steps

• Add a ImageView () to the controller's view via storyboard 设置图片 and have the attribute in the controller's. m file

  @property (weaknonatomicIBOutletUIImageView *imageView;

• Set the clipping area of a picture drawn by gesture

  • ClipView the clipping area of a picture as a member property

  @property (nonatomicweakUIView *clipView;

  • Create a ClipView by lazy loading, and initialize

  -(uiview  *) clipView{    //if ClipView is created, create a  if     (_clipview = = nil )        {uiview  *view = [[uiview  alloc] init];        _clipview = view; //set ClipView background color and transparency  view.backgroundcolor  =        [uicolor  Blackcolor];        View.alpha  = 0.5 ;        //adds ClipView to the controller's view, at which point the ClipView is not displayed (no frame is set)     [self  .view  Addsubview:_clipview]; } return  _clipview;}  

• Add pan gestures to the view of the controller, track pan gestures, draw a picture clipping area

  • Create and add gestures

  /**创建手势**/UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];    /**    *每当pan手势的位置发生变化，就会调用pan:方法，并将手势作为参数传递    *//**添加手势**/[self.view addGestureRecognizer:pan];

  • Add member properties to record the point at which the pan gesture started

  @property (nonatomicassignCGPoint startPoint;

  • The movement of the listening gesture

  - (void) Pan: (Uipangesturerecognizer *) pan{cgpoint endPoint = Cgpointzero;if(pan.state = = Uigesturerecognizerstatebegan) {/** start Clicking, record the starting point of the gesture **/Self.startpoint = [Pan LocationInView:self.view]; }Else if(pan.state = = uigesturerecognizerstatechanged) {/** dynamically changes the value of the end point when the gesture moves, and calculates the rectangular area between the start and end points **/EndPoint = [Pan LocationInView:self.view];//Calculate width and height of rectangular areaCGFloat w = endpoint.x-self.startpoint.x; CGFloat h = endpoint.y-self.startpoint.y;//Calculate frame for rectangular areaCGRect clipRect = CGRectMake (Self.startpoint.x, Self.startpoint.y, W, h);//Set frame for clipping areaSelf.clipView.frame = ClipRect; }Else if(pan.state = = uigesturerecognizerstateended) {/** If the gesture stops, the picture contents of the clipping area are drawn into the graphical context **/        //Open Bitmap contextUigraphicsbeginimagecontextwithoptions (Self.imageView.bounds.size, NO,0);//Create a closed path with size equal to the size of the clipping areaUibezierpath *path = [Uibezierpath bezierPathWithRect:self.clipView.frame];//settings out of the content is not displayed,[Path Addclip];//Get drawing contextCgcontextref context = Uigraphicsgetcurrentcontext ();//The context in which the picture is rendered[Self.imageView.layer Renderincontext:context];//Get pictures in contextUIImage *image = Uigraphicsgetimagefromcurrentimagecontext ();//Close bitmap contextUigraphicsendimagecontext ();//Remove the Cut Area view control and clear[Self.clipview Removefromsuperview]; Self.clipview = nil;//Display the picture on the ImageViewSelf.imageView.image = image;//Prompts the user via Alertview, whether to save the picture to the albumUialertview *alertview = [[Uialertview alloc] initwithtitle:@"Save Picture"message:@"Do you want to save the picture to an album?" "Delegate:self cancelbuttontitle:@"No"otherbuttontitles:@"Yes", nil]; [Alertview show];}}

• Set the proxy method for Alertview to determine whether to save the picture

  - (void)alertView:(nonnull UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex{    //若点击了“是”，则保存图片    if1)    {        UIImageWriteToSavedPhotosAlbum(self.imageView.image, nil, nil, nil);        /**        * 该方法可以设置保存完毕调用的方法，此处未进行设置        */    }}

The latest status of this blog will be synced to Sina Weibo account: secular island

Copyright NOTICE: This article for Bo Master original article, without Bo Master permission not reproduced.

iosquartz2d-04-picture Trim and save to album