如何旋轉UIImage 90度？我有一個UIImage那是UIImageOrientationUp(肖像)我想逆時針旋轉90度(對景觀)。我不想用CGAffineTransform..我要的像素UIImage移動位置。我使用的代碼塊(如下所示)最初是為了調整UIImage做這件事。我將目標大小設置為UIImage但我有個錯誤：(錯誤)：CGBitmapContextCreate：無效的數據字節/行：對于8個整數位/組件、3個組件、kCGImageAlphaPreMultiiedLast.應當至少為1708。(當我提供一個較小的大小作為目標大小BTW時，我不會收到錯誤)。如何旋轉我的UIImage90度CCW只使用核心圖形功能，同時保持當前大??？-(UIImage*)reverseImageByScalingToSize:(CGSize)targetSize:(UIImage*)anImage{
UIImage* sourceImage = anImage;
CGFloat targetWidth = targetSize.height;
CGFloat targetHeight = targetSize.width;
CGImageRef imageRef = [sourceImage CGImage];
CGBitmapInfo bitmapInfo = CGImageGetBitmapInfo(imageRef);
CGColorSpaceRef colorSpaceInfo = CGImageGetColorSpace(imageRef);
if (bitmapInfo == kCGImageAlphaNone) {
bitmapInfo = kCGImageAlphaNoneSkipLast;
}
CGContextRef bitmap;
if (sourceImage.imageOrientation == UIImageOrientationUp || sourceImage.imageOrientation == UIImageOrientationDown) {
bitmap = CGBitmapContextCreate(NULL, targetHeight, targetWidth, CGImageGetBitsPerComponent(imageRef),
CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
} else {
bitmap = CGBitmapContextCreate(NULL, targetWidth, targetHeight, CGImageGetBitsPerComponent(imageRef),
CGImageGetBytesPerRow(imageRef), colorSpaceInfo, bitmapInfo);
}
if (sourceImage.imageOrientation == UIImageOrientationRight) {
CGContextRotateCTM (bitmap, radians(90));
CGContextTranslateCTM (bitmap, 0, -targetHeight);
} else if (sourceImage.imageOrientation == UIImageOrientationLeft) {
CGContextRotateCTM (bitmap, radians(-90));
CGContextTranslateCTM (bitmap, -targetWidth, 0);
} else if (sourceImage.imageOrientation == UIImageOrientationDown) {
// NOTHING
} else if (sourceImage.imageOrientation == UIImageOrientationUp) {
CGContextRotateCTM (bitmap, radians(90));
CGContextTranslateCTM (bitmap, 0, -targetHeight);
}
}
3 回答
慕尼黑8549860
TA貢獻1818條經驗 獲得超11個贊
static inline double radians (double degrees) {return degrees * M_PI/180;}UIImage* rotate(UIImage* src, UIImageOrientation orientation){
UIGraphicsBeginImageContext(src.size);
CGContextRef context = UIGraphicsGetCurrentContext();
if (orientation == UIImageOrientationRight) {
CGContextRotateCTM (context, radians(90));
} else if (orientation == UIImageOrientationLeft) {
CGContextRotateCTM (context, radians(-90));
} else if (orientation == UIImageOrientationDown) {
// NOTHING
} else if (orientation == UIImageOrientationUp) {
CGContextRotateCTM (context, radians(90));
}
[src drawAtPoint:CGPointMake(0, 0)];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;}
忽然笑
TA貢獻1806條經驗 獲得超5個贊
//assume that the image is loaded in landscape mode from diskUIImage * landscapeImage = [UIImage imageNamed:imgname]; UIImage * portraitImage = [[UIImage alloc] initWithCGImage: landscapeImage.CGImage scale: 1.0 orientation: UIImageOrientationRight];
let portraitImage : UIImage = UIImage(CGImage: landscapeImage.CGImage , scale: 1.0 , orientation: UIImageOrientation.Right)
慕俠2389804
TA貢獻1719條經驗 獲得超6個贊
UIImage *rotatedImage = [originalImage imageRotatedByDegrees:90.0];
(UIImage*)ImageAtRect：(CGRect)RECT；
(UIImage*)imageByScalingProportionallyToMinimumSize：(CGSize)targetSize；)
(UIImage*)imageByScalingProportionallyToSize：(CGSize)targetSize；)
(UIImage*)ImageByScalingToSize：(CGSize)Target Size；
(UIImage*)ImageRotatedByRadians：(CGFloat)弧度；
(UIImage*)ImageRotatedByDegrees：(CGFloat)度；
//// UIImage-Extensions.h//// Created by Hardy Macia on 7/1/09.// Copyright 2009 Catamount Software. All rights reserved.
//#import <Foundation/Foundation.h>#import <UIKit/UIKit.h>@interface UIImage (CS_Extensions)- (UIImage *)imageAtRect:(CGRect)rect;
- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize;- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize;
- (UIImage *)imageByScalingToSize:(CGSize)targetSize;- (UIImage *)imageRotatedByRadians:(CGFloat)radians;- (UIImage *)imageRotatedByDegrees:
(CGFloat)degrees;@end;//// UIImage-Extensions.m//// Created by Hardy Macia on 7/1/09.
// Copyright 2009 Catamount Software. All rights reserved.//#import "UIImage-Extensions.h"CGFloat DegreesToRadians(CGFloat degrees)
{return degrees * M_PI / 180;};CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;};@implementation UIImage (CS_Extensions)
-(UIImage *)imageAtRect:(CGRect)rect{
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect);
UIImage* subImage = [UIImage imageWithCGImage: imageRef];
CGImageRelease(imageRef);
return subImage;}- (UIImage *)imageByScalingProportionallyToMinimumSize:(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;
else
scaleFactor = heightFactor;
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;
}
}
// this is actually the interesting part:
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;}- (UIImage *)imageByScalingProportionallyToSize:(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;
else
scaleFactor = heightFactor;
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;
}
}
// this is actually the interesting part:
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;}- (UIImage *)imageByScalingToSize:(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);
// this is actually the interesting part:
UIGraphicsBeginImageContext(targetSize);
CGRect thumbnailRect = CGRectZero;
thumbnailRect.origin = thumbnailPoint;
thumbnailRect.size.width = scaledWidth;
thumbnailRect.size.height = scaledHeight;
[sourceImage drawInRect:thumbnailRect];
newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
if(newImage == nil) NSLog(@"could not scale image");
return newImage ;}- (UIImage *)imageRotatedByRadians:(CGFloat)radians{
return [self imageRotatedByDegrees:RadiansToDegrees(radians)];}- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees
{
// calculate the size of the rotated view's containing box for our drawing space
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)];
CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees));
rotatedViewBox.transform = t;
CGSize rotatedSize = rotatedViewBox.frame.size;
[rotatedViewBox release];
// Create the bitmap context
UIGraphicsBeginImageContext(rotatedSize);
CGContextRef bitmap = UIGraphicsGetCurrentContext();
// Move the origin to the middle of the image so we will rotate and scale around the center.
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);
// // Rotate the image context
CGContextRotateCTM(bitmap, DegreesToRadians(degrees));
// Now, draw the rotated/scaled image into the context
CGContextScaleCTM(bitmap, 1.0, -1.0);
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]);
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;}@end;- 3 回答
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