我需要在大型PDF文件中嵌入缩略图,我使用UIGraphicsBeginPDFContextToFile和UIGraphicsBeginPDFPage创建,并在其上绘制文本和图像。
有谁知道,如何嵌入页面拇指?
Ciao,Arno
答案 0 :(得分:0)
如果要从PDF创建缩略图,则可以使用以下代码。此代码将其写入磁盘。它很容易改变,以便该方法返回图像。
- (void)createPDFThumbnailForFile:(NSString *)theFilename {
if (!theFilename) {return;}
@try {
NSString *path = [FileInfo fullPathForFile:theFilename];
NSURL *pdfFileUrl = [NSURL fileURLWithPath:path];
CFURLRef pdfFileRef = (__bridge CFURLRef) pdfFileUrl;
CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL(pdfFileRef);
CGPDFPageRef page;
CGRect aRect = CGRectMake(0, 0, 70, 100); // thumbnail size
UIGraphicsBeginImageContext(aRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
UIImage *thumbnailImage;
// NSUInteger totalNum = CGPDFDocumentGetNumberOfPages(pdf);
//we only want the first page
for (int i = 0; i < 1; i++) {
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, aRect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextSetGrayFillColor(context, 1.0, 1.0);
CGContextFillRect(context, aRect);
// Grab the first PDF page
page = CGPDFDocumentGetPage(pdf, 1);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFMediaBox, aRect, 0, true);
// And apply the transform.
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, page);
// Create the new UIImage from the context
thumbnailImage = UIGraphicsGetImageFromCurrentImageContext();
CGContextRestoreGState(context);
}
CGPDFDocumentRelease(pdf);
NSString *pngPath = [path stringByReplacingOccurrencesOfString:@".pdf" withString:@".png"];
// [@"test" writeToFile:pngPath atomically:YES encoding:NSUTF8StringEncoding error:nil];
[UIImagePNGRepresentation(thumbnailImage) writeToFile:pngPath atomically:YES];
}
@catch (NSException *exception) {
DebugLog(@"Could not write thumbnail to : %@ /n --> %@", theFileToSave, exception.description);
}
}