使用 CGPDF 在 PDF 中查找超链接答案

【问题标题】：Finding hyperlinks in PDF with CGPDF使用 CGPDF 在 PDF 中查找超链接
【发布时间】：2011-10-12 21:32:19
【问题描述】：

我正在尝试查找 PDF 文档页面上的所有超链接，并在它们上方放置一个 UIButton。

我已经找到并使用了下面应该能够做到的脚本。它找到超链接并将 UIButtons 放置在它们不在链接顶部的位置。谁能告诉我为什么会这样？

我附上了一张图片来显示按钮是如何关闭的。最上方的按钮应位于蓝色“METROPOLITAN”文字的上方，最下方的按钮应位于“SÆSONEN 2008-2009”文字的上方。

这是我用来查找链接和放置按钮的代码。

    NSMutableArray *rectArrays;
    NSMutableArray *storeURLs;

    CGPDFPageRef pdfPage = CGPDFDocumentGetPage(_pdf, pageNumber);
    CGPDFDictionaryRef pageDictionary = CGPDFPageGetDictionary(pdfPage);

    CGPDFArrayRef outputArray;
    if(!CGPDFDictionaryGetArray(pageDictionary, "Annots", &outputArray)) {
        //break;
    }

    int arrayCount = 0;
    arrayCount = CGPDFArrayGetCount(outputArray);
    if(arrayCount > 0) {
        for(int j = 0; j < arrayCount; ++j) {
            CGPDFObjectRef aDictObj;
            if(!CGPDFArrayGetObject(outputArray, j, &aDictObj)) {
                return;
            }

            CGPDFDictionaryRef annotDict;
            if(!CGPDFObjectGetValue(aDictObj, kCGPDFObjectTypeDictionary, &annotDict)) {
                return;
            }

            CGPDFDictionaryRef aDict;
            if(!CGPDFDictionaryGetDictionary(annotDict, "A", &aDict)) {
                return;
            }

            CGPDFStringRef uriStringRef;
            if(!CGPDFDictionaryGetString(aDict, "URI", &uriStringRef)) {
                return;
            }

            CGPDFArrayRef rectArray;
            if(!CGPDFDictionaryGetArray(annotDict, "Rect", &rectArray)) {
                return;
            }

            int arrayCount = CGPDFArrayGetCount( rectArray );
            CGPDFReal coords[4];
            for(int k = 0; k < arrayCount; ++k) {
                CGPDFObjectRef rectObj;
                if(!CGPDFArrayGetObject(rectArray, k, &rectObj)) {
                    return;
                }

                CGPDFReal coord;
                if(!CGPDFObjectGetValue(rectObj, kCGPDFObjectTypeReal, &coord)) {
                    return;
                }

                coords[k] = coord;
            }

            char *uriString = (char *)CGPDFStringGetBytePtr(uriStringRef);

            NSString *uri = [NSString stringWithCString:uriString encoding:NSUTF8StringEncoding];

            CGRect rect = CGRectMake(coords[0], coords[1], coords[2], coords[3]);

            NSLog(@"Found: %f ; %f => %f x %f", coords[0], coords[1], coords[2], coords[3]);

            CGPDFInteger pageRotate = 0;
            CGPDFDictionaryGetInteger(pageDictionary, "Rotate", &pageRotate); 
            CGRect pageRect = CGRectIntegral( CGPDFPageGetBoxRect(pdfPage, kCGPDFMediaBox));
            if(pageRotate == 90 || pageRotate == 270) {
                CGFloat temp = pageRect.size.width;
                pageRect.size.width = pageRect.size.height;
                pageRect.size.height = temp;
            }

            rect.size.width = rect.size.width - rect.origin.x;
            rect.size.height = rect.size.height - rect.origin.y;

            CGAffineTransform trans = CGAffineTransformIdentity;
            trans = CGAffineTransformTranslate(trans, 0, pageRect.size.height);
            trans = CGAffineTransformScale(trans, 1.0, -1.0);

            rect = CGRectApplyAffineTransform(rect, trans);

            NSURL *url = [NSURL URLWithString:uri];
            [rectArrays addObject:[NSValue valueWithCGRect:rect]];
            [storeURLs addObject:url];

            for(int i = 0; i <= [rectArrays count]; i++) {
                UIButton *button = [UIButton buttonWithType:UIButtonTypeRoundedRect];
                [button setFrame:rect];
                [button setTitle:@"Link" forState:UIControlStateNormal];
                [[self view] addSubview:button];

                NSLog(@"Added: %f ; %f => %f x %f", button.frame.origin.x, button.frame.origin.y, button.frame.size.width, button.frame.size.height);
            }
        }
    }

编辑：尝试调整比例因子，但不起作用。 UIButtons 仍然放置错误。

CGAffineTransform trans = CGAffineTransformIdentity;
trans = CGAffineTransformTranslate(trans, 0, pageRect.size.height * 1.5);
trans = CGAffineTransformScale(trans, 1.5, -1.5);

编辑我查看了 iPDFDev 链接的源代码，似乎我现在已经定位工作了。我的按钮现在太长了。有谁知道为什么会这样？如果我从viewRect.size.width 中减去viewRext.origin.x，则按钮太短了。

这是我现在的代码。

    CGPDFPageRef pdfPage = CGPDFDocumentGetPage(_pdf, pageNumber);
    CGPDFDictionaryRef pageDictionary = CGPDFPageGetDictionary(pdfPage);

    CGPDFArrayRef outputArray;
    if(!CGPDFDictionaryGetArray(pageDictionary, "Annots", &outputArray)) {
        //break;
    }

    int arrayCount = 0;
    arrayCount = CGPDFArrayGetCount(outputArray);
    if(arrayCount > 0) {
        for(int j = 0; j < arrayCount; ++j) {
            CGPDFObjectRef aDictObj;
            if(!CGPDFArrayGetObject(outputArray, j, &aDictObj)) {
                return;
            }

            CGPDFDictionaryRef annotDict;
            if(!CGPDFObjectGetValue(aDictObj, kCGPDFObjectTypeDictionary, &annotDict)) {
                return;
            }

            CGPDFDictionaryRef aDict;
            if(!CGPDFDictionaryGetDictionary(annotDict, "A", &aDict)) {
                return;
            }

            CGPDFStringRef uriStringRef;
            if(!CGPDFDictionaryGetString(aDict, "URI", &uriStringRef)) {
                return;
            }

            CGPDFArrayRef rectArray;
            if(!CGPDFDictionaryGetArray(annotDict, "Rect", &rectArray)) {
                return;
            }

            int arrayCount = CGPDFArrayGetCount( rectArray );
            CGPDFReal coords[4];
            for(int k = 0; k < arrayCount; ++k) {
                CGPDFObjectRef rectObj;
                if(!CGPDFArrayGetObject(rectArray, k, &rectObj)) {
                    return;
                }

                CGPDFReal coord;
                if(!CGPDFObjectGetValue(rectObj, kCGPDFObjectTypeReal, &coord)) {
                    return;
                }

                coords[k] = coord;
            }

            char *uriString = (char *)CGPDFStringGetBytePtr(uriStringRef);

            NSString *uri = [NSString stringWithCString:uriString encoding:NSUTF8StringEncoding];

            CGRect rect = CGRectMake(coords[0], coords[1], coords[2], coords[3]);

            CGPoint pdfPoint = CGPointMake(rect.origin.x, rect.origin.y);
            CGPoint viewPoint = CGPointMake(0, 0);

            CGRect cropBox = CGPDFPageGetBoxRect(pdfPage, kCGPDFCropBox);

            int rotation = CGPDFPageGetRotationAngle(pdfPage);

            CGRect pageRenderRect;
            switch (rotation) {
                case 90:
                case -270:
                    pageRenderRect = CGRectMake(0, 0, 1024, 768);

                    viewPoint.x = pageRenderRect.size.width * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
                    viewPoint.y = pageRenderRect.size.height * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
                    break;
                case 180:
                case -180:
                    pageRenderRect = CGRectMake(0, 0, 768, 1024);

                    viewPoint.x = pageRenderRect.size.width * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
                    viewPoint.y = pageRenderRect.size.height * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
                    break;
                case -90:
                case 270:
                    pageRenderRect = CGRectMake(0, 0, 1024, 768);

                    viewPoint.x = pageRenderRect.size.width * (cropBox.size.height - (pdfPoint.y - cropBox.origin.y)) / cropBox.size.height;
                    viewPoint.y = pageRenderRect.size.height * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
                    break;
                case 0:
                default:
                    pageRenderRect = CGRectMake(0, 0, 768, 1024);

                    viewPoint.x = pageRenderRect.size.width * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
                    viewPoint.y = pageRenderRect.size.height * (cropBox.size.height - pdfPoint.y) / cropBox.size.height;
                    break;
            }

            viewPoint.x = viewPoint.x + pageRenderRect.origin.x;
            viewPoint.y = viewPoint.y + pageRenderRect.origin.y;

            CGRect viewRect = CGRectMake(viewPoint.x, viewPoint.y, rect.size.width, rect.size.height - rect.origin.y);
            viewRect = CGRectMake(viewRect.origin.x, viewRect.origin.y - viewRect.size.height, viewRect.size.width, viewRect.size.height);

            UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
            [button setFrame:viewRect];
            [button setBackgroundColor:[UIColor greenColor]];
            [button setAlpha:0.65];
            [button setTag:kPDFLinkButton];
            [[self view] addSubview:button];
        }
    }

编辑：这是我的最终代码。有关更多信息，请参阅 iPDFDev 的答案。

- (void)getLinksFromPDF:(CGPDFDocumentRef)_pdf withPageNumber:(NSUInteger)pageNumber
{
    CGPDFPageRef pdfPage = CGPDFDocumentGetPage(_pdf, pageNumber);
    CGPDFDictionaryRef pageDictionary = CGPDFPageGetDictionary(pdfPage);

    CGPDFArrayRef outputArray;
    if(!CGPDFDictionaryGetArray(pageDictionary, "Annots", &outputArray)) {
        //break;
    }

    int arrayCount = 0;
    arrayCount = CGPDFArrayGetCount(outputArray);
    if(arrayCount > 0) {
        for(int j = 0; j < arrayCount; ++j) {
            CGPDFObjectRef aDictObj;
            if(!CGPDFArrayGetObject(outputArray, j, &aDictObj)) {
                return;
            }

            CGPDFDictionaryRef annotDict;
            if(!CGPDFObjectGetValue(aDictObj, kCGPDFObjectTypeDictionary, &annotDict)) {
                return;
            }

            CGPDFDictionaryRef aDict;
            if(!CGPDFDictionaryGetDictionary(annotDict, "A", &aDict)) {
                return;
            }

            CGPDFStringRef uriStringRef;
            if(!CGPDFDictionaryGetString(aDict, "URI", &uriStringRef)) {
                return;
            }

            CGPDFArrayRef rectArray;
            if(!CGPDFDictionaryGetArray(annotDict, "Rect", &rectArray)) {
                return;
            }

            int arrayCount = CGPDFArrayGetCount( rectArray );
            CGPDFReal coords[4];
            for(int k = 0; k < arrayCount; ++k) {
                CGPDFObjectRef rectObj;
                if(!CGPDFArrayGetObject(rectArray, k, &rectObj)) {
                    return;
                }

                CGPDFReal coord;
                if(!CGPDFObjectGetValue(rectObj, kCGPDFObjectTypeReal, &coord)) {
                    return;
                }

                coords[k] = coord;
            }

            char *uriString = (char *)CGPDFStringGetBytePtr(uriStringRef);

            NSString *uri = [NSString stringWithCString:uriString encoding:NSUTF8StringEncoding];

            CGPoint lowerLeft = [self convertPDFPointToViewPoint:CGPointMake(coords[0], coords[1])];
            CGPoint upperRight = [self convertPDFPointToViewPoint:CGPointMake(coords[2], coords[3])];

            // This is the rectangle positioned under the link
            CGRect viewRect = CGRectMake(lowerLeft.x, lowerLeft.y, upperRight.x - lowerLeft.x, lowerLeft.y - upperRight.y);

            // Now adjusting the rectangle to be on top of the link
            viewRect = CGRectMake(viewRect.origin.x, viewRect.origin.y - viewRect.size.height, viewRect.size.width, viewRect.size.height);

            NSLog(@"%@", uri);

            UIButton *button = [UIButton buttonWithType:UIButtonTypeCustom];
            [button setFrame:viewRect];
            [button setBackgroundColor:[UIColor greenColor]];
            [button setAlpha:0.65];
            [button setTag:kPDFLinkButton];
            [[self view] addSubview:button];
        }
    }   
}

- (CGPoint)convertPDFPointToViewPoint:(CGPoint)pdfPoint
{
    CGPoint viewPoint = CGPointMake(0, 0);

    CGPDFPageRef pdfPage = CGPDFDocumentGetPage(pdf, currentPage);

    CGRect cropBox = CGPDFPageGetBoxRect(pdfPage, kCGPDFCropBox);

    int rotation = CGPDFPageGetRotationAngle(pdfPage);

    CGRect pageRenderRect;
    switch (rotation) {
        case 90:
        case -270:
            pageRenderRect = CGRectMake(0, 0, 1024, 768);

            viewPoint.x = pageRenderRect.size.width * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
            viewPoint.y = pageRenderRect.size.height * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
            break;
        case 180:
        case -180:
            pageRenderRect = CGRectMake(0, 0, 768, 1024);

            viewPoint.x = pageRenderRect.size.width * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
            viewPoint.y = pageRenderRect.size.height * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
            break;
        case -90:
        case 270:
            pageRenderRect = CGRectMake(0, 0, 1024, 768);

            viewPoint.x = pageRenderRect.size.width * (cropBox.size.height - (pdfPoint.y - cropBox.origin.y)) / cropBox.size.height;
            viewPoint.y = pageRenderRect.size.height * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
            break;
        case 0:
        default:
            pageRenderRect = CGRectMake(0, 0, 768, 1024);

            viewPoint.x = pageRenderRect.size.width * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
            viewPoint.y = pageRenderRect.size.height * (cropBox.size.height - pdfPoint.y) / cropBox.size.height;
            break;
    }

    viewPoint.x = viewPoint.x + pageRenderRect.origin.x;
    viewPoint.y = viewPoint.y + pageRenderRect.origin.y;

    return viewPoint;
}

【问题讨论】：

标签： iphone objective-c ipad pdf hyperlink

【解决方案1】：

链接存储在页面字典的 Annots 数组中。当您遍历 Annots 数组时，您通过验证注解字典中的 Subtype 键来定位链接注解，它必须是“Link”（名称对象）。如果您有链接注释，则验证它是否有存储在 A 条目中的操作。如果它有一个动作，则验证它是否是一个网络链接，动作字典中的 S 条目必须具有值“URI”（名称对象）。如果您有一个 URI 操作，那么您可以从操作字典中的 URI 条目中检索链接。

PDF 页面上的注释位置存储在 Rect 数组中。这些是 2 个对角的 4 个值，通常是左下 x、左下 y、右上角 x、右上 y。这些值相对于页面媒体框的左下角。这些值必须根据这些变量在视图坐标中进行转换： 1. 显示页面的视图中的位置； 2. 显示页面视图中的大小（当前缩放系数*PDF页面大小）； 3.页面裁剪框； 4. 页面旋转。

转换方法如下：

- (CGPoint)convertPDFPointToViewPoint:(CGPoint)pdfPoint {
    CGPoint viewPoint = CGPointMake(0, 0);

    CGRect cropBox = CGPDFPageGetBoxRect(pdfPage, kCGPDFCropBox);

    int rotation = CGPDFPageGetRotationAngle(pdfPage);

    switch (rotation) {
        case 90:
        case -270:
            viewPoint.x = pageRenderRect.size.width * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
            viewPoint.y = pageRenderRect.size.height * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
            break;
        case 180:
        case -180:
            viewPoint.x = pageRenderRect.size.width * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
            viewPoint.y = pageRenderRect.size.height * (pdfPoint.y - cropBox.origin.y) / cropBox.size.height;
            break;
        case -90:
        case 270:
            viewPoint.x = pageRenderRect.size.width * (cropBox.size.height - (pdfPoint.y - cropBox.origin.y)) / cropBox.size.height;
            viewPoint.y = pageRenderRect.size.height * (cropBox.size.width - (pdfPoint.x - cropBox.origin.x)) / cropBox.size.width;
            break;
        case 0:
        default:
            viewPoint.x = pageRenderRect.size.width * (pdfPoint.x - cropBox.origin.x) / cropBox.size.width;
            viewPoint.y = pageRenderRect.size.height * (cropBox.size.height - pdfPoint.y) / cropBox.size.height;
            break;
    }

    viewPoint.x = viewPoint.x + pageRenderRect.origin.x;
    viewPoint.y = viewPoint.y + pageRenderRect.origin.y;

    return viewPoint;
}

其中 pageRenderRect 是视图中显示页面的矩形。您可以在此处找到其他参考源代码：http://ipdfdev.com/2011/06/21/links-navigation-in-a-pdf-document-on-iphone-and-ipad/

【讨论】：

我刚刚查看了您链接的源代码，现在我的定位似乎有效。非常感谢你。你知道为什么我的按钮太长了吗？我已经更新了我的原始帖子以播下代码。
您的 rect.size 仍在 PDF 坐标中。您需要将注释矩形的左下角（coords[0]，coords[1]）和右上角（coords[2]，coords[3]）转换为视点，并从这两个视点构建一个矩形。这两个视点之间的差异将是按钮的宽度和高度。
啊，是的！我知道了。非常感谢。我真的很感谢你的帮助。它现在运行良好。我已经更新了我的原始帖子以显示我的最终代码。

【解决方案2】：

猜测一下，您是否可能应用了一些计算转换来将 PDF 内容缩放到您拥有的任何框架，但未能将其应用到按钮框架？您似乎已将转换硬编码到显示的代码中，假设 PDF 将以一个源点等于一个目标点呈现，如果您要缩放 PDF，那么显然情况并非如此。

该诊断可以解释为什么这些按钮看起来像是要覆盖“Metropolitan”和“Saesonen 2008-2009”，但它们的坐标系已向左上角缩小。

【讨论】：

你说得对，我完全忘记了比例因子。我将 PDF 缩放 1.5。转换代码是我在论坛上找到的。我已经尝试阅读 CGAffineTransformTranslate 和 CGAffineTransformScale 的文档，但我没有让它正常工作。 UIButtons 在我调整属性时四处移动，但我无法将它们置于正确的位置。您知道应该如何设置这些值吗？我已经更新了我原来的帖子，以展示我认为它们应该是怎样的。
@simonbs 这是一篇不错的博客文章，解释了 CGAffineTransform iphonedevelopment.blogspot.com/2008/10/…