ios 使用drawInRect时UIImage Aspect Fit？
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UIImage Aspect Fit when using drawInRect?
提问by Ana
UIView provides for the "aspect fit" content mode. However, I've subclasses UIView and would like to draw a UIImage using drawInRect with an aspect fit. Is there any way for me to access that functionality without using a UIImageView?
UIView 提供了“方面适合”的内容模式。但是，我已经对 UIView 进行了子类化，并且想使用带有方面适合的 drawInRect 来绘制 UIImage 。有什么方法可以让我在不使用 UIImageView 的情况下访问该功能？
回答by Nick Lockwood
The math for that is a little bit hairy, but fortunately, here's a solution I prepared earlier:
数学有点麻烦，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)];
}
}
The first function is equivalent to "scale to fill", the second (which calls the first) is equivalent to "aspect fit". These methods were written as a category on UIImage so to use them from within another class you'll need to tweak them by passing the image in as a second parameter (or just make a category on UIImage like I did).
第一个函数相当于“缩放填充”，第二个（调用第一个）相当于“方面适合”。这些方法是作为 UIImage 上的一个类别编写的，因此要在另一个类中使用它们，您需要通过将图像作为第二个参数传入来调整它们（或者像我一样在 UIImage 上创建一个类别）。
回答by Antzi
You have to draw in the rect provided by
您必须绘制由提供的矩形
Swift:
迅速：
func AVMakeRect(aspectRatio: CGSize, insideRect boundingRect: CGRect) -> CGRect
func AVMakeRect(aspectRatio: CGSize, insideRect boundingRect: CGRect) -> CGRect
Objective-C:
目标-C：
CGRect AVMakeRectWithAspectRatioInsideRect(CGSize aspectRatio, CGRect boundingRect);
See doc
见文档
The aspect ratio is preserved and the drawing centred.
纵横比被保留并且绘图居中。
It works in absolutely all cases.
它绝对适用于所有情况。
回答by Haider
here's the solution
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];
-- courtesy https://stackoverflow.com/a/1703210
- 礼貌https://stackoverflow.com/a/1703210
another alternative for aspect fit
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;
}
Code for swift 3.0:
swift 3.0 的代码：
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
}
回答by Nathan
this might help you, give it a try
这可能对你有帮助，试试看
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];
specify your maximum height instead of 100.0 and maximum width instead of 80.0
指定最大高度而不是 100.0 和最大宽度而不是 80.0
回答by Russian
Here's a helper CGSize extension that you might find useful:
这是您可能会发现有用的辅助 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)
}
}
Then in -drawInRect:implementation one would do the following:
然后在-drawInRect:实现中，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)
回答by Timo
The following will let you determine the size to draw in. You specify the aspect ratio and the bounding size to fit into.
下面将让您确定要绘制的大小。您指定要适应的纵横比和边界大小。
