iOS簡單畫板開發(fā)案例分享

更新時間：2016年04月08日 09:57:32 作者：神戶牛肉

這篇文章主要為大家分享了iOS實現(xiàn)簡單畫板開發(fā)案例，具有一定的參考價值，感興趣的小伙伴們可以參考一下

最近在學習Quartz2D，學習了一個簡單畫板的實現(xiàn)，現(xiàn)在把實現(xiàn)過程記錄一下。

主要用到的點就是畫線，截屏，繪制圖片，選擇圖片，以及保存所有繪制的線。

首先在storyboard上布局好控件，設置約束等等，最后的效果是這樣：

自定義畫板DrawView，使用時可能是從xib中加載，也可能是手動創(chuàng)建，所以創(chuàng)建對象的方法需要實現(xiàn)兩個：

#import <UIKit/UIKit.h>
 
@interface DrawView : UIView
/** 線寬 */
@property (nonatomic, assign) NSInteger lineWidth;
 
/** 顏色 */
@property(nonatomic, strong) UIColor *pathColor;
 
/** 圖片 */
@property(nonatomic, strong) UIImage *image;
 
- (void)clear;
 
- (void)undo;

- (void)awakeFromNib {
   
  [self setUp];
   
}
 
- (instancetype)initWithFrame:(CGRect)frame {
   
  if (self == [super initWithFrame:frame]) {
    [self setUp];
  }
  return self;
}

setUp初始化方法，初始化時要做的事情就是給畫板添加拖動手勢，也可以將畫筆路徑的線寬在這里設置

//自定義初始化方法
- (void)setUp {
   
  //添加手勢
  UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
  [self addGestureRecognizer:pan];
   
  //初始化時設置路徑線寬
  _lineWidth = 2;
   
}

手指在畫板上移動時開始繪制線條，這里因為原生的UIBezierPath類沒有辦法設置路徑顏色，所以這里只能自定義Path類了

#import <UIKit/UIKit.h>
 
@interface DrawPath : UIBezierPath
 
@property (nonatomic, strong) UIColor *pathColor;
 
@end

手指移動時，繪制線條，路徑是自定義的Path類

@interface DrawView ()
 
@property(nonatomic, strong)DrawPath *path;
/** 保存所有路徑的數(shù)組 */
@property(nonatomic, strong) NSMutableArray *pathArr;
 
@end
 
//懶加載
- (NSMutableArray *)pathArr {
  if (_pathArr == nil) {
     
    _pathArr = [NSMutableArray array];
     
  }
  return _pathArr;
}

- (void)pan:(UIPanGestureRecognizer *)pan {
   
  //獲取開始的觸摸點
  CGPoint startP = [pan locationInView:self];
   
  if (pan.state == UIGestureRecognizerStateBegan) {
     
    //創(chuàng)建貝塞爾路徑
    _path = [[DrawPath alloc]init];
    _path.lineWidth = _lineWidth;
    _path.pathColor = _pathColor;
     
    //不能在手指抬起時將路徑添加到數(shù)組，因為在遍歷數(shù)組畫線時路徑還沒有被添加到數(shù)組里面
    [_pathArr addObject:_path];
     
    //設置起點
    [_path moveToPoint:startP];
     
  }
   
  //連線
  [_path addLineToPoint:startP];
   
  //重繪，調(diào)用drawRect方法
  [self setNeedsDisplay];
   
}

畫線實現(xiàn)drawRect方法，繪制線條或者圖片時，是把數(shù)組中的路徑全部畫出來

- (void)drawRect:(CGRect)rect {
   
  //把所有路徑畫出來
  for (DrawPath *path in self.pathArr) {
     
    if ([path isKindOfClass:[UIImage class]]) {
      //畫圖
      UIImage *image = (UIImage *)path;
      [image drawInRect:rect];
    }else {
      //畫線
      [path.pathColor set];
      [path stroke];
    }
  }
   
}

當把圖片添加到畫板時

- (void)setImage:(UIImage *)image {
   
  _image = image;
   
  [self.pathArr addObject:image];
   
  //重繪調(diào)用drawRect才能在畫板上顯示圖片
  [self setNeedsDisplay];
}

還可以把直接更新路徑數(shù)組的操作封裝在畫板中

- (void)clear {
  //清除
  [self.pathArr removeAllObjects];
   
  [self setNeedsDisplay];
   
}
 
- (void)undo {
  //撤銷
  [self.pathArr removeLastObject];
   
  [self setNeedsDisplay];
}

控制器中：

@interface ViewController () <UIImagePickerControllerDelegate, UINavigationControllerDelegate>
@property (weak, nonatomic) IBOutlet DrawView *drawView;
@end

實現(xiàn)幾個按鈕對畫板的操作：

- (IBAction)clear:(id)sender {
   
  //清屏
  [_drawView clear];
   
}
 
- (IBAction)undo:(id)sender {
   
  //撤銷
  [_drawView undo];
   
}
 
- (IBAction)eraser:(id)sender {
   
  //擦除 就是把路徑的顏色設置為畫板的背景色，假象
  _drawView.pathColor = _drawView.backgroundColor;
  _drawView.lineWidth = 20;
   
}
 
- (IBAction)changeLineWidth:(UISlider *)sender {
   
  //改變路徑線寬
  _drawView.lineWidth = sender.value;
   
}
 
- (IBAction)changeColor:(UIButton *)sender {
   
   
  //改變路徑顏色
  _drawView.pathColor = sender.backgroundColor;
   
}
 
- (IBAction)pickPhoto:(id)sender {
   
  //選擇照片
  //彈出系統(tǒng)相冊
  UIImagePickerController *picker = [[UIImagePickerController alloc]init];
   
  //設置選擇控制器的來源 UIImagePickerControllerSourceTypeSavedPhotosAlbum:照片庫
  picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
   
  //設置代理
  picker.delegate = self;
   
  //modal出控制器
  [self presentViewController:picker animated:YES completion:nil];
   
}
 
- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary<NSString *,id> *)info {
   
  //獲取選擇的圖片
  UIImage *image = info[UIImagePickerControllerOriginalImage];
   
  //創(chuàng)建一個處理圖片的view
  ImageHandleView *handleView = [[ImageHandleView alloc]initWithFrame:self.drawView.bounds];
   
  handleView.handleCompletionBlock = ^(UIImage *image){
     
    _drawView.image = image;
  };
   
  [self.drawView addSubview:handleView];
   
  //將圖片畫在畫板上
  handleView.image = image;
   
  //_drawView.image = image;
   
  //dismiss
  [self dismissViewControllerAnimated:YES completion:nil];
  //NSLog(@"%@", info);
   
}
 
- (IBAction)save:(id)sender {
   
  [UIView animateWithDuration:0.15 animations:^{
    //保存當前畫板上的內(nèi)容
     
    //開啟上下文
    UIGraphicsBeginImageContextWithOptions(_drawView.bounds.size, NO, 0);
     
    //獲取位圖上下文
    CGContextRef ctx = UIGraphicsGetCurrentContext();
     
    //把控件上的圖層渲染到上下文
    [_drawView.layer renderInContext:ctx];
     
    //獲取上下文中的圖片
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
     
    //關(guān)閉上下文
    UIGraphicsEndImageContext();
     
    //保存圖片到相冊
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
     
    self.drawView.alpha = 0;
  } completion:^(BOOL finished) {
    [UIView animateWithDuration:0.15 animations:^{
      self.drawView.alpha = 1;
    }];
  }];
   
}
 
//保存成功后的方法必須是這個，不能隨便寫
- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
   
  NSLog(@"保存成功");
   
}

從相冊選擇完圖片后把圖片顯示在畫板上了但是還沒有渲染到layer，這時候需要對圖片進行移動縮放旋轉(zhuǎn)這些操作的話，但是UIImage是不能拉伸旋轉(zhuǎn)這些操作的，UIImageView才可以，所以解決思路就是自定義一個view來專門處理對圖片的操作，在自定義view上放一個UIImageView，從相冊選擇圖片后獲取的image設置給UIImageView，這樣的自定義view上操作UIIamgeView。

#import <UIKit/UIKit.h>
 
@interface ImageHandleView : UIView
/** 圖片 */
@property(nonatomic, strong) UIImage *image;
 
/** block */
@property(nonatomic, strong) void(^handleCompletionBlock)(UIImage *image);
@end

#import "ImageHandleView.h"
 
@interface ImageHandleView () <UIGestureRecognizerDelegate>
 
/** image */
@property(nonatomic, weak) UIImageView *imageView;
 
@end
 
@implementation ImageHandleView
 
//防止圖片上的觸摸事件傳遞到畫板
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
   
  return _imageView;
}
 
- (UIImageView *)imageView {
   
  if (_imageView == nil) {
    UIImageView *imageV = [[UIImageView alloc]initWithFrame:self.bounds];
     
    _imageView = imageV;
     
    //設置imgaeview允許與用戶交互
    _imageView.userInteractionEnabled = YES;
     
    //添加手勢
    [self setUpGestureRecognizer];
     
    //把這個imageview添加到圖片處理的view上
    [self addSubview:imageV];
     
  }
  return _imageView;
}
 
#pragma mark - 添加手勢
- (void)setUpGestureRecognizer {
   
  //平移手勢
  UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(pan:)];
  [_imageView addGestureRecognizer:pan];
   
  //旋轉(zhuǎn)手勢
  UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc]initWithTarget:self action:@selector(rotation:)];
  rotation.delegate = self;
  [_imageView addGestureRecognizer:rotation];
   
  //縮放手勢
  UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc]initWithTarget:self action:@selector(pinch:)];
  pinch.delegate = self;
  [_imageView addGestureRecognizer:pinch];
   
  //長按手勢
  UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc]initWithTarget:self action:@selector(longPress:)];
  [_imageView addGestureRecognizer:longPress];
   
}
 
#pragma mark - 處理平移手勢
- (void)pan:(UIPanGestureRecognizer *)pan {
   
  //獲取手指的偏移量
  CGPoint tranp = [pan translationInView:self.imageView];
   
  //設置imageview的形變
  self.imageView.transform = CGAffineTransformTranslate(self.imageView.transform, tranp.x, tranp.y);
   
  //復位
  [pan setTranslation:CGPointZero inView:self.imageView];
   
}
 
#pragma mark - 處理旋轉(zhuǎn)手勢
- (void)rotation:(UIRotationGestureRecognizer *)rotation {
   
  //設置imageview的形變
  self.imageView.transform = CGAffineTransformRotate(self.imageView.transform, rotation.rotation);
   
  //復位
  rotation.rotation = 0;
   
}
 
#pragma mark - 處理縮放手勢
- (void)pinch:(UIPinchGestureRecognizer *)pinch {
   
  //設置imageview的形變
  self.imageView.transform = CGAffineTransformScale(self.imageView.transform, pinch.scale, pinch.scale);
   
  //復位
  pinch.scale = 1;
   
}
 
#pragma mark - 處理長按手勢
- (void)longPress:(UILongPressGestureRecognizer *)longPress {
   
  //圖片處理完成
  if (longPress.state == UIGestureRecognizerStateBegan) {
     
    //高亮效果
    [UIView animateWithDuration:0.25 animations:^{
      self.imageView.alpha = 0;
    } completion:^(BOOL finished) {
      
      [UIView animateWithDuration:0.25 animations:^{
        self.imageView.alpha = 1;
      } completion:^(BOOL finished) {
         
        //高亮時生成一張新的圖片
        //開啟位圖上下文
        UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0);
         
        //獲取位圖上下文
        CGContextRef ctx = UIGraphicsGetCurrentContext();
         
        //把控件的圖層渲染到上下文
        [self.layer renderInContext:ctx];
         
        //從上下文中獲取新的圖片
        UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
         
        //關(guān)閉上下文
        UIGraphicsEndImageContext();
         
        //調(diào)用block
        if(_handleCompletionBlock) {
          _handleCompletionBlock(image);
        }
         
        //移除父控件
        [self removeFromSuperview];
         
      }];
       
    }];
     
     
  }
   
}
 
#pragma mark - 手勢代理方法 <UIGestureRecognizerDelegate>
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {
   
  //yes表示同時支持多個手勢
  return YES;
   
}
 
- (void)setImage:(UIImage *)image {
   
  _image = image;
   
  //把圖片展示到UIImageView上
  self.imageView.image = image;
 
}
 
@end

需要注意的是，當長按將操作過的圖片繪制都畫板上生成一張新的圖片后，這時候需要把這個image設置給畫板drawView，但是這時候就必須要在專門處理圖片的view中去import畫板view，這樣耦合性太強。所以為了解耦，可以使用代理或者Block。我用了Block將剛剛生成的image先保存起來，在控制器中初始化imageHandleView之后再賦值給drawView。

最后保存畫板上的內(nèi)容就是將畫板上的內(nèi)容生成圖片保存到相冊即可。注意，保存完之后執(zhí)行的方法必須是這個：

復制代碼代碼如下:

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo;

最后效果圖是這樣的:

以上就是本文的全部內(nèi)容，希望對大家學習iOS程序設計有所幫助。

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