Question

我正在使用这个 raywenderlich教程来绘制Image。该教程在背景中没有图像，但在这里我想从图库中绘制图像。

所以基本上有两个UIImageView一个是mainImage和tempDrawImage。我正在做self.mainImage.image = randomImageFromGallery作为我想要绘制的背景图像现在它出现了很好的n绘图也发生但问题是图像在每个触摸端都得到了比例。

为什么图像继续缩放我的代码是否错误tempDrawImage所有绘图都发生了什么？

- (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，你就有了一张照片，而你想要绘制这张照片......

我建议：

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

Answer 2

检查您正在使用的所有视图的帧大小。某处存在不匹配，因此您正在显示的某个图像将被缩放以供显示。无论是绘制图像的大小还是需要更改其显示的大小。

在绘制之后，图像在每个触摸端都会得到比例 - iOS

2 个答案: