有没有办法以编程方式在osx上截图(低质量)?
我开发了如下功能:
CGImageRef resizeImage(CGImageRef imageRef) {
CGRect thumRect;
CGPoint point;
point.x = 0;
point.y = 0;
thumRect.origin = point;
thumRect.size.height = 225;
thumRect.size.width = 360;
CGImageAlphaInfo alphaInfo = CGImageGetAlphaInfo(imageRef);
if (aplhaInfo == kCGImageAlphaNone)
alphaInfo = kCGImageAlphaNoneSkipLast;
CGContextRef bitmap = CGBitmapContextCreate(NULL, thumRect.size.width, thumRect.size.height, CGImageGetBitsPerComponent(imageRef), 4 * thumRect.size.width, CGImageGetColorSpace(imageRef), alphaInfo);
CGContextDrawImage(bitmap, thumRect, imageRef);
imageRef = CGBitmapContextCreateImage(bitmap);
CGContextRelease(bitmap);
return imageRef;
}
运行此功能时,我拍摄了150KB至600KB的图像。如果减小thumRect大小,则无法读取图像中的任何字符。但是,我想将这些图像尽可能降低。有什么建议或其他可能的解决方案吗?
谢谢。
我找到了以下解决方案:首先,用我的问题中的代码调整图像的大小。
然后压缩它:)
//imageRef is CGImageRef
NSImage * image = [[NSImage alloc] initWithCGImage:imageRef size:NSZeroSize];
NSBitmapImageRep *bmpImageRep = [NSBitmapImageRep imageRepWithData [image TIFFRepresentation]];
CGFloat compressionFactor = 1.0 //Read it : (1)
NSDictionary *jpgProperties = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithDouble:compressionFactor], NSImageCompressionFactor, [NSNumber numberWithBool:NO], NSImageProgressive, nil];
NSData *jpgData = [bmpImageRep representationUsingType:NSJPEGFileType properties:jpgProperties];
(1):https : //developer.apple.com/library/mac/documentation/Cocoa/Reference/ApplicationKit/Classes/NSBitmapImageRep_Class/index.html#//apple_ref/doc/constant_group/Bitmap_image_properties
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我来说两句