图像在绘制后在每个触摸端上都会缩放-iOS

Question

我正在使用此raywenderlich教程来绘制Image。 该教程在背景中没有图像，但是在这里我想从画廊中提取图像。

因此，基本上有两个UIImageView之一是mainImage和tempDrawImage 。 我正在将self.mainImage.image = randomImageFromGallery做为我要在其上绘制的背景图像现在它很好地显示了n绘制也发生了，但是问题是图像在每个触摸端都得到缩放。

为什么图像会继续缩放，而代码却出了什么问题我在所有绘制发生的tempDrawImage上没有做任何事情？

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

    mouseSwiped = NO;
    UITouch *touch = [touches anyObject];
    lastPoint = [touch locationInView:self.view];

    UIGraphicsBeginImageContext(self.view.frame.size);
}

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

    mouseSwiped = YES;
    UITouch *touch = [touches anyObject];
    CGPoint currentPoint = [touch locationInView:self.view];

    CGContextRef ctxt = UIGraphicsGetCurrentContext();
    CGContextMoveToPoint(ctxt, lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(ctxt, currentPoint.x, currentPoint.y);
    CGContextSetLineCap(ctxt, kCGLineCapRound);
    CGContextSetLineWidth(ctxt, brush );
    CGContextSetRGBStrokeColor(ctxt, red, green, blue, 1.0);
    CGContextSetBlendMode(ctxt,kCGBlendModeNormal);

    CGContextStrokePath(ctxt);
    self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    [self.tempDrawImage setAlpha:opacity];

    lastPoint = currentPoint;
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    [super touchesCancelled:touches withEvent:event];

    UIGraphicsEndImageContext();

    if(!mouseSwiped)
    {
        self.tempDrawImage.image = nil;
    }
}

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

    if(!mouseSwiped) {
        UIGraphicsEndImageContext();

        UIGraphicsBeginImageContext(self.view.frame.size);
        [self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
        CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
        CGContextSetLineWidth(UIGraphicsGetCurrentContext(), brush);
        CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), red, green, blue, opacity);
        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextStrokePath(UIGraphicsGetCurrentContext());
        CGContextFlush(UIGraphicsGetCurrentContext());
        self.tempDrawImage.image = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
    }

    UIGraphicsBeginImageContext(self.mainImage.frame.size);
    [self.mainImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
    [self.tempDrawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height) blendMode:kCGBlendModeNormal alpha:opacity];
    self.mainImage.image = UIGraphicsGetImageFromCurrentImageContext();
    self.tempDrawImage.image = nil;
    UIGraphicsEndImageContext();
}

Answer 1

如果我理解得很好，您有一张照片，并且想要绘制这张照片...

我提议 ：

1. 将您的tempDrawImage设置为继承自UIView而不是UIImageView。
2. 在触摸动作时将点存储在数组中（touchesBegan，touchesMoved等）
3. 绘制过程（void）drawRect：（CGRect）rect

Answer 2

检查您正在使用的所有视图的框架大小。 在某处存在不匹配，因此正在缩放显示的图像之一以进行显示。 绘制图像的尺寸或显示图像的尺寸都需要更改。