12

如何通过在 UIImage 上滑动手指来擦除正面 UIImage 上的内容并显示 UIView 背面的 UIImage。

我使用以下代码- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event 擦除正面图像:

-(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。

在此处输入图像描述

但我需要这样的输出。

在此处输入图像描述

我们怎样才能实现这个功能?

请帮我。

4

3 回答 3

6

尝试这个

- (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,这将非常适合您。

橡皮擦图片

这段代码在我的最后工作给我以下结果:图片 1

图 2

图 3

图 4

于 2013-09-13T13:15:34.147 回答
2

检查此示例代码

它提供这样的功能

在此处输入图像描述

在此处输入图像描述

于 2013-09-13T11:37:37.717 回答
2

您可以通过混合两个图像来实现这一点

有很多方法,简单的方法如下,你也可以使用 GPUImage ..

只是您需要将两个图像与您想要的输出混合。

将两个图像相互融合..

混合更多你可以尝试

**kCGBlendModeOverlay,kCGBlendModeSoftLight,kCGBlendModeColorDodge,etc**

在下面函数的CGBlendMode参数中..仍然有很多选项可以超过两个图像并合并..(即使使用实时摄像头也可以这样做)

-(UIImage *)blenimagwithimage:(NSString *)imagename mode:(CGBlendMode)kmode with:(float)opeticy
    {
        processedimage=nil;
        UIImage *inputImage;
        inputImage = [UIImage imageNamed:imagename];
        UIGraphicsBeginImageContext(originalImage.size);
        [originalImage drawInRect:CGRectMake(0.0, 0.0, originalImage.size.width, originalImage.size.height)];
        [inputImage drawInRect:CGRectMake(0.0, 0.0, originalImage.size.width, originalImage.size.height) blendMode:kmode alpha:opeticy];
        UIImage *layeredImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        return layeredImage;
    }
于 2013-09-13T11:21:49.470 回答