擦除UIImageView [英] Erasing on UIImageView

问题描述

如何通过在手指上滑动来擦除前面UIImage上的内容并显示UIView背面的UIImage。

How can I erase content on front UIImage by swiping finger on it and display UIImage that is back side of UIView.

我在<$ c中使用了以下代码$ c> - （void）touchesMoved：（NSSet *）触及withEvent：（UIEvent *）事件删除正面图像：

-(void)eraseDrawingContents
{
    UIGraphicsBeginImageContext(frontImage.frame.size);
    [frontImage.image drawInRect:CGRectMake(0, 0, frontImage.frame.size.width, frontImage.frame.size.height)];

    CGContextSaveGState(UIGraphicsGetCurrentContext());
    CGContextSetShouldAntialias(UIGraphicsGetCurrentContext(), YES);
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 25.0);
    CGContextSetShadowWithColor(UIGraphicsGetCurrentContext(), CGSizeMake(0, 0), 50, [[UIColor whiteColor]CGColor]);

    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, nil, lastPoint.x, lastPoint.y);
    CGPathAddLineToPoint(path, nil, currentPoint.x, currentPoint.y);
    CGContextSetBlendMode(UIGraphicsGetCurrentContext(), kCGBlendModeClear);
    CGContextAddPath(UIGraphicsGetCurrentContext(), path);
    CGContextStrokePath(UIGraphicsGetCurrentContext());

    frontImage.image = UIGraphicsGetImageFromCurrentImageContext();
    CGContextRestoreGState(UIGraphicsGetCurrentContext());
    UIGraphicsEndImageContext();

    lastPoint = currentPoint;
}

我实现了以下输出。

但是我需要这样的输出。

But I need output like this.

我们如何实现这一功能？

How can we achieve this functionality?

请帮助我。

推荐答案

试试这个

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{


    UITouch *touch = [touches anyObject];
    CGPoint location = [touch locationInView:self.view];


   self.imgView.image = [self.imgView.image eraseImageAtPoint:location inImageView:self.imgView  fromEraser:eraserImg];



}



- (UIImage *)eraseImageAtPoint: (CGPoint)point inImageView: (UIImageView *)imgView fromEraser: (UIImage *)eraser
{
    UIGraphicsBeginImageContext(imgView.frame.size);

    [self drawInRect:CGRectMake(0, 0, imgView.frame.size.width, imgView.frame.size.height)];

    [eraser drawAtPoint:point blendMode:kCGBlendModeDestinationOut alpha:1.0];

    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;

}

并使用下图作为橡皮擦，这将完美适用于你。

And use the below image as eraser this will perfectly work for you.

此代码在我的工作结束时给出以下结果：

This code is working at my end give me the following result:

这篇关于擦除UIImageView的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！