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问题:

I'm trying to save all of the contents of a UIScrollView to a .pdf. I found some tutorials for saving the current view, and they all rely on creating a CGContextRef using UIGraphicsGetCurrentContext(). Right now, I capture my view with just

CGContextRef context = UIGraphicsGetCurrentContext();
[myView.layer renderInContext:context];

And that works fine for a plain UIView. However, when I try to pass a UIScrollView as myView, it passes the visible part of the UIScrollView fine, but anything offscreen is just white space. Is there a way I can expand context somehow to get all of the content in my UIScrollView, and not just what is currently visible? I suspect that I can't use UIGraphicsGetCurrentContext() for a UIScrollView, but I don't know what to use instead, and the Apple docs on this aren't really very helpful.

回答1:

If you have a subview taking the whole content size of the scrollView with the scrolling content you can do it like this:

CGContextRef context = UIGraphicsGetCurrentContext();
UIView *contentView = [scrollView subviews][0];
[contentView.layer renderInContext:context];

If there are multiple views in the scrollView you can do it like this:

UIView *contentView = [[UIView alloc] initWithFrame:CGRectMake(
                                                          scrollView.frame.origin.x,
                                                          scrollView.frame.origin.y, 
                                                          scrollView.contentSize.width, 
                                                          scrollView.contentSize.height)];
for(UIView *view in [scrollView subviews]){
 [contentView addSubview: view];
}

CGContextRef context = UIGraphicsGetCurrentContext();
[contentView.layer renderInContext:context];

Then you need to get the views back into the scrollView. Probably there is a way to copy them but I am not sure how. Anyhow here is what should work:

for(UIView *view in [contentView subviews]){
 [view removeFromSuperView];
 [scrollView addSubview:view];
}

回答2:

You can set frame of UIScrollView equal to content size of it and content offset to 0 before calling renderInContext. After that revert frame to original.

myView.frame = CGRectMake(myView.frame.origin.x,myView.frame.origin.y,myView.contentSize.with,myView.contentSize.height);

回答3:

This code i used to make pdf from uiscrollview and it does help but it will not be as good as if we draw on pdf -- please have look -- Pdf from UIScrollView

- (void) createPDF
{
    NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *directroyPath = nil;
    directroyPath = [documentsDirectory stringByAppendingPathComponent:@"temp"];
    NSString *filePath = [directroyPath stringByAppendingPathComponent:@"test.pdf"];
    // check for the "PDF" directory
    NSError *error;
    if ([[NSFileManager defaultManager] fileExistsAtPath:filePath]) {

    } else {
        [[NSFileManager defaultManager] createDirectoryAtPath:directroyPath
                                  withIntermediateDirectories:NO
                                                   attributes:nil
                                                        error:&error];
    }

    CGContextRef pdfContext = [self createPDFContext:_scrollView2.bounds path:(CFStringRef)filePath];
    NSLog(@"PDF Context created");

    /*
     Here limit of i is no of pages in your uiscrollview or
     you can use hit and trial here because there is a
     length of page is going to be equal to 
     the visible size of uiscrollView in your application 
   */

    for (int i = 0 ; i< 2 ; i++)
    {

        // page 1
        CGContextBeginPage (pdfContext,nil);

        //turn PDF upsidedown
        CGAffineTransform transform = CGAffineTransformIdentity;

       //here 365 is equal to the height of myScrollView.frame.size.height

        transform = CGAffineTransformMakeTranslation(0, (i+1) * 365);
        transform = CGAffineTransformScale(transform, 1.0, -1.0);
        CGContextConcatCTM(pdfContext, transform);

        //Draw view into PDF
        [_scrollView2.layer renderInContext:pdfContext];
        CGContextEndPage (pdfContext);
        [_scrollView2 setContentOffset:CGPointMake(0, (i+1) * 365) animated:NO];

    }
    CGContextRelease (pdfContext);
}

- (CGContextRef) createPDFContext:(CGRect)inMediaBox path:(CFStringRef) path
{
    CGContextRef myOutContext = NULL;
    CFURLRef url;
    url = CFURLCreateWithFileSystemPath (NULL, path,
                                         kCFURLPOSIXPathStyle,
                                         false);

    if (url != NULL) {
        myOutContext = CGPDFContextCreateWithURL (url,
                                                  &inMediaBox,
                                                  NULL);
        CFRelease(url);
    }
    return myOutContext;
}