每日分享 - 图像压缩成指定大小(高度/宽度)
复制代码
#import <Foundation/Foundation.h>
@interface UIImage (UIImageExt)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize;
@end
复制代码
#import "UIImageExt.h"
@implementation UIImage (UIImageExt)
- (UIImage*)imageByScalingAndCroppingForSize:(CGSize)targetSize
{
UIImage *sourceImage = self;
UIImage *newImage = nil;
CGSize imageSize = sourceImage.size;
CGFloat width = imageSize.width;
CGFloat height = imageSize.height;
CGFloat targetWidth = targetSize.width;
CGFloat targetHeight = targetSize.height;
CGFloat scaleFactor = 0.0;
CGFloat scaledWidth = targetWidth;
CGFloat scaledHeight = targetHeight;
CGPoint thumbnailPoint = CGPointMake(0.0,0.0);
if (CGSizeEqualToSize(imageSize, targetSize) == NO)
{
CGFloat widthFactor = targetWidth / width;
CGFloat heightFactor = targetHeight / height;
if (widthFactor > heightFactor)
scaleFactor = widthFactor; // scale to fit height
else
scaleFactor = heightFactor; // scale to fit width
scaledWidth = width * scaleFactor;
scaledHeight = height * scaleFactor;
// center the image
if (widthFactor > heightFactor)
{
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5;
}
else
if (widthFactor < heightFactor)
{
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5;
}
}
UIGraphicsBeginImageContext(targetSize); // this will crop
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
if(newImage == nil)
NSLog(@"could not scale image");
//pop the context to get back to the default
UIGraphicsEndImageContext();
return newImage;
}
@end
裁剪图片和等比列缩放图片
@interface UIImage(UIImageScale) -(UIImage*)getSubImage:(CGRect)rect; -(UIImage*)scaleToSize:(CGSize)size; @end @implementation UIImage(UIImageScale) //截取部分图像 -(UIImage*)getSubImage:(CGRect)rect { CGImageRef subImageRef = CGImageCreateWithImageInRect(self.CGImage, rect); CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(subImageRef), CGImageGetHeight(subImageRef)); UIGraphicsBeginImageContext(smallBounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextDrawImage(context, smallBounds, subImageRef); UIImage* smallImage = [UIImage imageWithCGImage:subImageRef]; UIGraphicsEndImageContext(); return smallImage; } //等比例缩放 -(UIImage*)scaleToSize:(CGSize)size { CGFloat width = CGImageGetWidth(self.CGImage); CGFloat height = CGImageGetHeight(self.CGImage); float verticalRadio = size.height*1.0/height; float horizontalRadio = size.width*1.0/width; float radio = 1; if(verticalRadio>1 && horizontalRadio>1) { radio = verticalRadio > horizontalRadio ? horizontalRadio : verticalRadio; } else { radio = verticalRadio < horizontalRadio ? verticalRadio : horizontalRadio; } width = width*radio; height = height*radio; int xPos = (size.width - width)/2; int yPos = (size.height-height)/2; // 创建一个bitmap的context // 并把它设置成为当前正在使用的context UIGraphicsBeginImageContext(size); // 绘制改变大小的图片 [self drawInRect:CGRectMake(xPos, yPos, width, height)]; // 从当前context中创建一个改变大小后的图片 UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext(); // 使当前的context出堆栈 UIGraphicsEndImageContext(); // 返回新的改变大小后的图片 return scaledImage; } @end 然后在下面方法里面调用就可以了! - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { // Override point for customization after application launch. UIImage *image = [[UIImage alloc] initWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:@"http://img21.mtime.cn/mg/2011/09/24/112524.53149978.jpg"]] ]; // 裁剪图片 //image = [image getSubImage:CGRectMake(10, 10, 70, 80)]; //等比列缩放 image = [image scaleToSize:CGSizeMake(200, 300)]; UIImageView *imageView = [[UIImageView alloc] initWithImage:image]; [self.window addSubview:imageView]; NSLog(@"image.size:%@",NSStringFromCGSize(CGSizeMake(imageView.image.size.width, imageView.image.size.height))); //打印获取的网络图片的宽度和高度 [self.window makeKeyAndVisible]; return YES; } //--------------截取部分图片到指定位置------------------------- 图片(UIImage*) img 要截取的起始坐标sx:(int) sx1 sy:(int)sy1 要截取的长度和宽度sw:(int) sw1 sh:(int) sh1 最终要显示的坐标desx:(int) desx1 desy:(int)desy1 -(UIImage*)objectiveDrawRegion:(UIImage*) img sx:(int) sx1 sy:(int)sy1 sw:(int) sw1 sh:(int) sh1 desx:(int) desx1 desy:(int)desy1{ [self saveImage:img name:@"objectiveDrawRegion1.png"]; //创建图片缓冲 void *imageDataRegion=malloc(screenWidth*screenHeight*32); CGColorSpaceRef iColorSpaceRegion=CGColorSpaceCreateDeviceRGB(); CGContextRefiDeviceRegion=CGBitmapContextCreate(imageDataRegion,screenWidth,screenHeight,8,4*screenWidth,iColorSpaceRegion,kCGImageAlphaPremultipliedLast); //剪切区域 CGRect clipRegion=CGRectMake(sx1,sy1,sw1,sh1); CGContextClipToRect(iDeviceRegion, clipRegion); CGFloat widthf=img.size.width; CGFloat heightf=img.size.height; CGRect cg=CGRectMake(0.0, 0.0, widthf, heightf); //画底图 CGContextDrawImage(iDeviceRegion,cg, img.CGImage); //将缓冲形成图片 CGImageRef ioffRegion=CGBitmapContextCreateImage(iDeviceRegion); CGRect cg1=CGRectMake(desx1, desy1, sw1, sh1); UIImage *ui=[UIImage imageWithCGImage:ioffRegion]; CGContextDrawImage(当前context,cg1, ui.CGImage); //清除缓冲 CGColorSpaceRelease(iColorSpaceRegion); CGContextRelease(iDeviceRegion); CGImageRelease(ioffRegion); free(imageDataRegion); // iDeviceRegion=NULL; // imageDataRegion=0; return ui; }