画板例子实现

画板例子思路

步骤一：自定义一个画板视图
步骤二：监听手指触摸事件，当手指在视图滑动的时候，就画线.
2.1在手指开始触摸的时候，创建可变路径，并且设置路径起始点。
- (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. 当手指移动的时候，给路径添加目标点，并且重新绘制视图。
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [touches anyObject];
    CGPoint point = [touch locationInView:self];
    [_pathU addLineToPoint:point];
    // 重绘
    [self setNeedsDisplay];
}

2.3 当手指触摸结束，将路径保存起来，并释放当前路径
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
    [_pathM addObject:_pathU];
    CGPathRelease(_pathU.CGPath);
    NSLog(@"%s",__func__);
}
注意：

1. [self setNeedsDisplay];这段代码不能少，否则在画板画不出东西。

2.当画板与slider绑定时，要通过awakeFromNib设置线宽，不然线宽默认为0.

- (void)awakeFromNib
{
    _width = 2;
}
步骤三：实现绘制视图方法
3.1. 自定义路径类
+ (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.实现绘图方法
- (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];
        }
    }

步骤四、在storyboard中定义工具栏

4.1 清屏

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

直接把数组removeAllObjects

4.2 撤销

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

4.3 保存

- (IBAction)save:(id)sender
{
    // 截屏
    // 开启上下文
    UIGraphicsBeginImageContextWithOptions(_drawingView.bounds.size, NO, 0.0);
   
    // 获得当前上下文
    CGContextRef ctr = UIGraphicsGetCurrentContext();
    // 把画板上的内容渲染都上下文
    [_drawingView.layer renderInContext:ctr];
   
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
   
    // 关闭上下文
    UIGraphicsEndImageContext();
   
    // 保存到相册里面
    UIImageWriteToSavedPhotosAlbum(newImage, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
}

调用MBProgressHUD 第三方框架

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

4.4 照片

- (IBAction)selectedPicture:(id)sender
{
    // 去用户的操作
    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：去模拟器用户的相册要遵守UIImagePickerControllerDelegate协议，实现

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

以modal的形式

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

关闭当初Modal出来的控制器

[self dismissViewControllerAnimated:YES completion:nil];

步骤五、实现从相处里面选择一张图片能够用手势操作。

添加手势
- (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;
}

实现长按的操作
- (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);
                // 把图片传给控制器
                if ([self.delegate respondsToSelector:@selector(handleView:withImage:)]) {
                    [self.delegate handleView:self withImage:image];
                }
                // 从父控件中移除
                [self removeFromSuperview];
            }];
        }];
       
    }
}

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