如何在 iPhone 中裁剪图像
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【中文标题】如何在 iPhone 中裁剪图像【英文标题】:How to crop the image in iPhone 【发布时间】:2011-12-18 12:57:55 【问题描述】:我想做与this 问题中提出的相同的事情。 在我的应用程序中,我想像在 Facebook 中进行图像裁剪一样裁剪图像,任何人都可以通过优秀教程的链接或任何示例代码来指导我。我提供的链接将完全描述我的要求。
【问题讨论】:
【参考方案1】:您可以创建具有任何属性的新图像。这是我的功能,女巫这样做。您只需要使用自己的新图像参数即可。在我的情况下,图像没有被裁剪,我只是做了一些效果,将像素从原始位置移动到另一个位置。但是如果你用另一个高度和宽度初始化新图像,你可以从你需要的旧图像的任何像素范围复制到新图像:
-(UIImage *)Color:(UIImage *)img
int R;
float m_width = img.size.width;
float m_height = img.size.height;
if (m_width>m_height) R = m_height*0.9;
else R = m_width*0.9;
int m_wint = (int)m_width; //later, we will need this parameters in float and int. you may just use "(int)" and "(float)" before variables later, and do not implement another ones
int m_hint = (int)m_height;
CGRect imageRect;
//cheking image orientation. we will work with image pixel-by-pixel, so we need to make top side at the top.
if(img.imageOrientation==UIImageOrientationUp
|| img.imageOrientation==UIImageOrientationDown)
imageRect = CGRectMake(0, 0, m_wint, m_hint);
else
imageRect = CGRectMake(0, 0, m_hint, m_wint);
uint32_t *rgbImage = (uint32_t *) malloc(m_wint * m_hint * sizeof(uint32_t));
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(rgbImage, m_wint, m_hint, 8, m_wint *sizeof(uint32_t), colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetShouldAntialias(context, NO);
CGContextTranslateCTM(context, 0, m_hint);
CGContextScaleCTM(context, 1.0, -1.0);
switch (img.imageOrientation)
case UIImageOrientationRight:
CGContextRotateCTM(context, M_PI / 2);
CGContextTranslateCTM(context, 0, -m_wint);
break;
case UIImageOrientationLeft:
CGContextRotateCTM(context, - M_PI / 2);
CGContextTranslateCTM(context, -m_hint, 0);
break;
case UIImageOrientationUp:
CGContextTranslateCTM(context, m_wint, m_hint);
CGContextRotateCTM(context, M_PI);
default:
break;
CGContextDrawImage(context, imageRect, img.CGImage);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
//here is new image. you can change m_wint and m_hint as you whant
uint8_t *result = (uint8_t *) calloc(m_wint * m_hint * sizeof(uint32_t), 1);
for(int y = 0; y < m_hint; y++) //new m_hint here
float fy=y;
double yy = (m_height*( asinf(m_height/(2*R))-asin(((m_height/2)-fy)/R) )) /
(2*asin(m_height/(2*R))); // (xx, yy) - coordinates of pixel of OLD image
for(int x = 0; x < m_wint; x++) //new m_wint here
float fx=x;
double xx = (m_width*( asin(m_width/(2*R))-asin(((m_width/2)-fx)/R) )) /
(2*asin(m_width/(2*R)));
uint32_t rgbPixel=rgbImage[(int)yy * m_wint + (int)xx];
int intRedSource = (rgbPixel>>24)&255;
int intGreenSource = (rgbPixel>>16)&255;
int intBlueSource = (rgbPixel>>8)&255;
result[(y * (int)m_wint + x) * 4] = 0;
result[(y * (int)m_wint + x) * 4 + 1] = intBlueSource;
result[(y * (int)m_wint + x) * 4 + 2] = intGreenSource;
result[(y * (int)m_wint + x) * 4 + 3] = intRedSource;
free(rgbImage);
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(result, m_wint, m_hint, 8, m_wint * sizeof(uint32_t), colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaNoneSkipLast ); //new m_wint and m_hint as well
CGImageRef image1 = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
UIImage *resultUIImage = [UIImage imageWithCGImage:image1];
CGImageRelease(image1);
@try
free(result);
@catch (NSException * e)
NSLog(@"proc. Exception: %@", e);
return resultUIImage;
【讨论】:
感谢 SentineL 的回复,但我想你没有收到我的问题,我想裁剪我正在使用这行代码CGRect cropRect = CGRectMake(100, 100, 200, 200); CGImageRef imageRef = CGImageCreateWithImageInRect(ImageREF.CGImage, cropRect);
做的图像,但这种裁剪是硬编码的,我想要用户调整此link中显示的图像链接的矩形@
所以...你只是想制作用户界面,选择矩形来裁剪图像?这很简单:只需实现触摸whatch 就可以了。 4 个 alpha 0.7 的空白条将静音区域将被裁剪。您可以处理 2 次触摸:根据那里的坐标,并且知道它们在 ractangle 对角线的不同侧,您将轻松计算 4 个暗条的大小。只是在每一步都改变它。或者,单点触控:您将需要 4 个空格(那个蓝色圆圈)。跟踪触摸并移动到移动 tham
感谢 SentineL 的回复以及您指导我的方式:)【参考方案2】:
CGRect rectImage = CGRectMake(p1.x,p1.y, p2.x - p1.x, p4.y - p1.y);
//Create bitmap image from original image data,
//using rectangle to specify desired crop area
CGImageRef imageRef = CGImageCreateWithImageInRect([imageForCropping CGImage], rectImage);
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
imageView1 = [[UIImageView alloc] initWithFrame:CGRectMake(p1.x, p1.y,p2.x-p1.x p4.y-p1.y)];
imageView1.image = croppedImage;
[self.view addSubview:imageView1];
CGImageRelease(imageRef);
【讨论】:
这里的 imageForcropping 是您要裁剪的图像..以及您要裁剪的部分的裁剪图像.. 知道如何在图像旋转时(即从 iPhone 相机拍摄时)进行这项工作吗?以上是关于如何在 iPhone 中裁剪图像的主要内容,如果未能解决你的问题,请参考以下文章