Question

UIView提供“方面适合”内容模式。但是，我是UIView的子类，并希望使用具有宽高比的drawInRect绘制UIImage。有没有办法让我在不使用UIImageView的情况下访问该功能？

Answer 1

这方面的数学有点毛茸茸，但幸运的是，这是我之前准备的解决方案：

- (UIImage *)imageScaledToSize:(CGSize)size
{
    //create drawing context
    UIGraphicsBeginImageContextWithOptions(size, NO, 0.0f);

    //draw
    [self drawInRect:CGRectMake(0.0f, 0.0f, size.width, size.height)];

    //capture resultant image
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return image;
}

- (UIImage *)imageScaledToFitSize:(CGSize)size
{
    //calculate rect
    CGFloat aspect = self.size.width / self.size.height;
    if (size.width / aspect <= size.height)
    {
        return [self imageScaledToSize:CGSizeMake(size.width, size.width / aspect)];
    }
    else
    {
        return [self imageScaledToSize:CGSizeMake(size.height * aspect, size.height)];
    }
}

第一个函数相当于“scale to fill”，第二个函数（调用第一个函数）相当于“纵横拟合”。这些方法是作为UIImage上的类别编写的，所以要在另一个类中使用它们，你需要通过将图像作为第二个参数传递来调整它们（或者像我一样在UIImage上创建一个类别）。

Answer 2

您必须在

提供的矩形中绘图

斯威夫特：

func AVMakeRect(aspectRatio: CGSize, insideRect boundingRect: CGRect) -> CGRect

<强>目标-C：

CGRect AVMakeRectWithAspectRatioInsideRect(CGSize aspectRatio, CGRect boundingRect);

请参阅doc

保留纵横比并使图形居中。

绝对适用于所有情况。

Answer 3

这是解决方案

CGSize imageSize = yourImage.size;
CGSize viewSize = CGSizeMake(450, 340); // size in which you want to draw

float hfactor = imageSize.width / viewSize.width;
float vfactor = imageSize.height / viewSize.height;

float factor = fmax(hfactor, vfactor);

// Divide the size by the greater of the vertical or horizontal shrinkage factor
float newWidth = imageSize.width / factor;
float newHeight = imageSize.height / factor;

CGRect newRect = CGRectMake(xOffset,yOffset, newWidth, newHeight);
[image drawInRect:newRect];

- 礼貌https://stackoverflow.com/a/1703210

方面适合的另一种选择

-(CGSize ) getImageSize :(CGSize )imgViewSize andActualImageSize:(CGSize )actualImageSize {

     // imgViewSize = size of view in which image is to be drawn
     // actualImageSize = size of image which is to be drawn

     CGSize drawImageSize;

     if (actualImageSize.height > actualImageSize.width) {

        drawImageSize.height = imgViewSize.height;
        drawImageSize.width = actualImageSize.width/actualImageSize.height * imgViewSize.height;

     }else {

        drawImageSize.width = imgViewSize.width;
        drawImageSize.height = imgViewSize.width * actualImageSize.height /  actualImageSize.width;
     }
     return drawImageSize;
}

swift 3.0代码：

func getAspectFitFrame(sizeImgView:CGSize, sizeImage:CGSize) -> CGRect{

    let imageSize:CGSize  = sizeImage
    let viewSize:CGSize = sizeImgView

    let hfactor : CGFloat = imageSize.width/viewSize.width
    let vfactor : CGFloat = imageSize.height/viewSize.height

    let factor : CGFloat = max(hfactor, vfactor)

    // Divide the size by the greater of the vertical or horizontal shrinkage factor
    let newWidth : CGFloat = imageSize.width / factor
    let newHeight : CGFloat = imageSize.height / factor

    var x:CGFloat = 0.0
    var y:CGFloat = 0.0
    if newWidth > newHeight{
        y = (sizeImgView.height - newHeight)/2
    }
    if newHeight > newWidth{
        x = (sizeImgView.width - newWidth)/2
    }
    let newRect:CGRect = CGRect(x: x, y: y, width: newWidth, height: newHeight)

    return newRect

}

Answer 4

这可能对你有所帮助，试一试

UIImage *logoImage = [UIImage imageNamed:@"logo.png"];

float newHeight = ((logoImage.size.height / logoImage.size.width) * 100.0);
CGRect newLogoImageRect = CGRectMake(0, 0, 80.0, newHeight);
[logoImage drawInRect:newLogoImageRect];

指定最大高度而不是100.0和最大宽度而不是80.0

Answer 5

这里有一个你可能会觉得有用的助手CGSize扩展：

extension CGSize
{
    func sizeThatFitsSize(_ aSize: CGSize) -> CGSize
    {
        let width = min(self.width * aSize.height / self.height, aSize.width)
        return CGSize(width: width, height: self.height * width / self.width)
    }
}

然后在-drawInRect:实施中，我们将执行以下操作：

let imageSizeThatFitsViewBounds = self.image.size.sizeThatFitsSize(self.bounds.size)
let imageRectX = (self.bounds.size.width - imageSizeThatFitsViewBounds.width) / 2
let imageRectY = (self.bounds.size.height - imageSizeThatFitsViewBounds.height) / 2
let imageRect = CGRect(origin: CGPoint(x: imageRectX, y: imageRectY), size: imageSizeThatFitsViewBounds)

Answer 6

以下内容可让您确定要绘制的大小。您可以指定宽高比和要适合的边界大小。

CGSizeAspectFit & CGSizeAspectFill

使用drawInRect时UIImage Aspect Fit？

6 个答案: