[英]When using avfoundation - crop visible portion of captured image represented in display layer
[英]AVFoundation crop captured still image according to the preview aspect ratio
我的問題與這個問題大體相似:
我有一個使用 AVFoundation 來捕獲靜止圖像的應用程序。 我的 AVCaptureVideoPreviewLayer 具有 AVLayerVideoGravityResizeAspectFill 視頻重力,因此可以從頂部和底部裁剪向用戶顯示的預覽圖片。
當用戶按下“捕獲”按鈕時,實際捕獲的圖像與顯示給用戶的預覽圖片不同。 我的問題是如何相應地裁剪捕獲的圖像?
提前致謝。
我使用了此處提供的UIImage+Resize
類別和我編寫的一些新方法來完成這項工作。 我重新格式化了一些代碼以使其看起來更好並且未經測試,但它應該可以工作。 :))
- (UIImage*)cropAndResizeAspectFillWithSize:(CGSize)targetSize
interpolationQuality:(CGInterpolationQuality)quality {
UIImage *outputImage = nil;
UIImage *imageForProcessing = self;
// crop center square (AspectFill)
if (self.size.width != self.size.height) {
CGFloat shorterLength = 0;
CGPoint origin = CGPointZero;
if (self.size.width > self.size.height) {
origin.x = (self.size.width - self.size.height)/2;
shorterLength = self.size.height;
}
else {
origin.y = (self.size.height - self.size.width)/2;
shorterLength = self.size.width;
}
imageForProcessing = [imageForProcessing normalizedImage];
imageForProcessing = [imageForProcessing croppedImage:CGRectMake(origin.x, origin.y, shorterLength, shorterLength)];
}
outputImage = [imageForProcessing resizedImage:targetSize interpolationQuality:quality];
return outputImage;
}
// fix image orientation, which may wrongly rotate the output.
- (UIImage *)normalizedImage {
if (self.imageOrientation == UIImageOrientationUp) return self;
UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
[self drawInRect:(CGRect){0, 0, self.size}];
UIImage *normalizedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return normalizedImage;
}
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