将PDF转换为一页PDF，这是因为PDF页的页面高度不同 [英] Convert a PDF to one page PDF reason for this is PDF pages doesnot have same page height

问题描述

我有一个PDF，我希望将其缩小到一页.

I have a PDF and I want to shrink it down to one page.

这不起作用:

//pages
size_t pages = CGPDFDocumentGetNumberOfPages(document);
pageRect.size.height = pageRect.size.height*pages;
CGDataConsumerRef dataConsumer = CGDataConsumerCreateWithCFData(mutableData);
CGContextRef pdfContext = CGPDFContextCreate(dataConsumer, &pageRect, NULL);

CGPDFContextBeginPage(pdfContext, NULL);
for (int i =1; i<=pages; i++)
{
   CGPDFPageRef pageRef = CGPDFDocumentGetPage(document, i);
   CGContextDrawPDFPage(pdfContext, pageRef);
}
CGPDFContextEndPage(pdfContext);

推荐答案

您的代码将所有页面打印在同一位置，一个页面位于另一个页面上.如果页面有明显的白色背景，那么您只会看到最后一页.
解决方案是在绘制页面后以已绘制页面的高度平移坐标系.
更新:这是完整的代码.假定源文件中的所有页面具有相同的大小和旋转度:

Your code prints all the pages at the same location, one on top of another. If by any chance the pages have an explicit white background then you will see only the last page.
The solution is to translate the coordinate system after the page is drawn with the height of the page that has been drawn.
UPDATE: This is the complete code. It assumes that all pages in the source file have the same size and rotation:

NSURL *pdfURL = [[NSBundle mainBundle] URLForResource:@"source.pdf" withExtension:nil];
pdf = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL);

int pageCount = CGPDFDocumentGetNumberOfPages(pdf);
CGPDFPageRef pageRef = CGPDFDocumentGetPage(pdf, 1);
CGRect pageRect = CGPDFPageGetBoxRect(pageRef, kCGPDFMediaBox);
float pageHeight = pageRect.size.height;
pageRect.size.height = pageRect.size.height * pageCount;

NSMutableData* pdfData = [[NSMutableData alloc] init];
CGDataConsumerRef pdfConsumer = CGDataConsumerCreateWithCFData((CFMutableDataRef)pdfData);
CGContextRef pdfContext = CGPDFContextCreate(pdfConsumer, &pageRect, NULL);

CGPDFContextBeginPage(pdfContext, NULL);
CGContextTranslateCTM(pdfContext, 0, pageRect.size.height);
for (int i = 1; i <= pageCount; i++) {
    pageRef = CGPDFDocumentGetPage(pdf, i);
    CGContextTranslateCTM(pdfContext, 0, -pageHeight);
    CGContextDrawPDFPage(pdfContext, pageRef);
}
CGPDFContextEndPage(pdfContext);
CGPDFContextClose(pdfContext);

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
NSString *documentsDirectory = [paths objectAtIndex:0];
NSString *pdfFile = [documentsDirectory stringByAppendingPathComponent:@"destination.pdf"];

[pdfData writeToFile: pdfFile atomically: NO];
[pdfData release];

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