畫板例子實現

畫板例子思路

步驟一：自定義一個畫板視圖
步驟二：監聽手指觸摸事件，當手指在視圖滑動的時候，就畫線.
2.1在手指開始觸摸的時候，創建可變路徑，並且設置路徑起始點。
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self];
    SUNBezierPath *path = [SUNBezierPath bezierPathWithWidth:_width andWithColor:_color andWithPoint:point];
    _pathU = path;
    [self.arrayM addObject:path];
   
}

2.2. 當手指移動的時候，給路徑添加目標點，並且重新繪製視圖。
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self];
    [_pathU addLineToPoint:point];
    // 重繪
    [self setNeedsDisplay];
}

2.3 當手指觸摸結束，將路徑保存起來，並釋放當前路徑
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [_pathM addObject:_pathU];
    CGPathRelease(_pathU.CGPath);
    NSLog(@"%s",__func__);
}
注意：

1. [self setNeedsDisplay];這段代碼不能少，否則在畫板畫不出東西。

2.當畫板與slider綁定時，要通過awakeFromNib設置線寬，不然線寬默認爲0.

- (void)awakeFromNib
{
    _width = 2;
}
步驟三：實現繪製視圖方法
3.1. 自定義路徑類
+ (instancetype)bezierPathWithWidth:(CGFloat)width andWithColor:(UIColor *)color andWithPoint:(CGPoint)point
{
    SUNBezierPath *path = [[SUNBezierPath alloc] init];
    path.lineWidth = width;
    path.color = color;
    [path moveToPoint:point];
    return path;
}

3.2.實現繪圖方法
- (void)drawRect:(CGRect)rect
{
    for (SUNBezierPath *path in self.arrayM) {
        if ([path isKindOfClass:[UIImage class]])  {
            UIImage *image = (UIImage *)path;
            [image drawAtPoint:CGPointZero];
        }else{
            [path.color set];
            [path stroke];
        }
    }

步驟四、在storyboard中定義工具欄

4.1 清屏

- (void)clearScreen
{
    [self.arrayM removeAllObjects];
    [self setNeedsDisplay];
}

直接把數組removeAllObjects

4.2 撤銷

- (void)undo
{
    [self.arrayM removeLastObject];
    [self setNeedsDisplay];
}

4.3 保存

- (IBAction)save:(id)sender
{
    // 截屏
    // 開啓上下文
    UIGraphicsBeginImageContextWithOptions(_drawingView.bounds.size, NO, 0.0);
   
    // 獲得當前上下文
    CGContextRef ctr = UIGraphicsGetCurrentContext();
    // 把畫板上的內容渲染都上下文
    [_drawingView.layer renderInContext:ctr];
   
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
   
    // 關閉上下文
    UIGraphicsEndImageContext();
   
    // 保存到相冊裏面
    UIImageWriteToSavedPhotosAlbum(newImage, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

調用MBProgressHUD 第三方框架

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {// 保存失敗
        [MBProgressHUD showError:@"保存失敗"];
    }else{// 保存成功
        [MBProgressHUD showSuccess:@"保存成功"];
    }
}

4.4 照片

- (IBAction)selectedPicture:(id)sender
{
    // 去用戶的操作
    UIImagePickerController *picker = [[UIImagePickerController alloc] init];
   
    picker.sourceType = UIImagePickerControllerSourceTypeSavedPhotosAlbum;
    [self presentViewController:picker animated:YES completion:nil];
    picker.delegate = self;

}

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    NSLog(@"%@",info);
    UIImage *newImage = info[UIImagePickerControllerOriginalImage];
    SUNHandleView *handleV = [[SUNHandleView alloc] initWithFrame:self.drawingView.frame];
    handleV.delegate = self;
    handleV.image = newImage;
    [self.view addSubview:handleV];
    [self dismissViewControllerAnimated:YES completion:nil];

}

注意：去模擬器用戶的相冊要遵守UIImagePickerControllerDelegate協議，實現

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info

以modal的形式

[self presentViewController:picker animated:YES completion:nil];

關閉當初Modal出來的控制器

[self dismissViewControllerAnimated:YES completion:nil];

步驟五、實現從相處裏面選擇一張圖片能夠用手勢操作。

添加手勢
- (void)addGestureRecognizer
{
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];
    pan.delegate = self;
    [_imageView addGestureRecognizer:pan];
   
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];
    rotation.delegate = self;
    [_imageView addGestureRecognizer:rotation];
   
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    pinch.delegate = self;
    [_imageView addGestureRecognizer:pinch];
   
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
    longPress.delegate = self;
    [_imageView addGestureRecognizer:longPress];
}

- (void)pan:(UIPanGestureRecognizer *)pan
{
    CGPoint point = [pan translationInView:self];
    _imageView.transform = CGAffineTransformTranslate(_imageView.transform, point.x, point.y);
    [pan setTranslation:CGPointZero inView:_imageView];
}

- (void)rotation:(UIRotationGestureRecognizer *)rotation
{
    _imageView.transform = CGAffineTransformRotate(_imageView.transform, rotation.rotation);
    rotation.rotation = 0;
}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
    _imageView.transform = CGAffineTransformScale(_imageView.transform, pinch.scale, pinch.scale);
    pinch.scale = 1;
}

實現長按的操作
- (void)longPress:(UILongPressGestureRecognizer *)longPress
{
    if (longPress.state == UIGestureRecognizerStateEnded) {
        [UIView animateWithDuration:0.5 animations:^{
            _imageView.alpha = 0.3;
        } completion:^(BOOL finished) {
            [UIView animateWithDuration:0.5 animations:^{
                _imageView.alpha = 1;
            } completion:^(BOOL finished) {
                // 截屏
                UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0.0);
                CGContextRef ctr = UIGraphicsGetCurrentContext();
                [self.layer renderInContext:ctr];
                UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
                NSData *data = UIImagePNGRepresentation(image);
                [data writeToFile:@"/Users/sunjinshuai/Desktop/image.png" atomically:YES];
                UIGraphicsEndImageContext();
                UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
                // 把圖片傳給控制器
                if ([self.delegate respondsToSelector:@selector(handleView:withImage:)]) {
                    [self.delegate handleView:self withImage:image];
                }
                // 從父控件中移除
                [self removeFromSuperview];
            }];
        }];
       
    }
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    if (error) {
        [MBProgressHUD showError:@"保存失敗"];
    }else{
        [MBProgressHUD showSuccess:@"保存成功"];
    }
}

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

- (void)setImage:(UIImage *)image
{
    _image = image;
    _imageView.image = image;
}

- (void)addImageView
{
    UIImageView *imageV = [[UIImageView alloc] initWithFrame:self.bounds];
    imageV.userInteractionEnabled = YES;
    _imageView = imageV;
    [self addSubview:imageV];
}