用iText7设置高亮注释上的外观流
用iText7设置高亮注释上的外观流
提问于 2018-12-07 14:00:27
我有一个PDF查看器，如果它们没有外观流，就不会显示高光。我正在java中试用iText 7内核，尝试在PDF中添加高亮注释，但是这些注释没有外观流，因此我希望在将注释写入PDF文件时自己尝试添加它们。
我遇到了this的旧答案，但这是针对C#和iText 5的，我似乎不知道如何在iText 7中复制它，并取得成功的结果。
因此，我的问题是:如何在正在工作的iText 7核心中的突出显示注释上设置外观流？
我从代码中得到的最远的信息如下所示。我使用RegexBasedLocationExtrationStrategy类来查找pdf中所有搜索单词的位置。
RegexBasedLocationExtractionStrategy evntlstnr = new RegexBasedLocationExtractionStrategy(pattern);
for (int pIdx = 0; pIdx < pdfDoc.getNumberOfPages(); ++pIdx) {
final PdfPage page = pdfDoc.getPage(pIdx + 1);
new PdfCanvasProcessor(evntlstnr).processPageContent(page);
Collection<IPdfTextLocation> locations = evntlstnr.getResultantLocations();
for (IPdfTextLocation location : locations) {
Rectangle rect = location.getRectangle();
// Specify quad points in Z-like order
// [0,1] x1,y1 [2,3] x2,y2
// [4,5] x3,y3 [6,7] x4,y4
float[] quads = new float[8];
quads[0] = rect.getX();
quads[1] = rect.getY() + rect.getHeight();
quads[2] = rect.getX() + rect.getWidth();
quads[3] = quads[1];
quads[4] = quads[0];
quads[5] = rect.getY();
quads[6] = quads[2];
quads[7] = quads[5];
Color highlightColor = new DeviceRgb(0f, 0f, 1f);
PdfTextMarkupAnnotation highlight = PdfTextMarkupAnnotation.createHighLight(rect, quads);
highlight.setColor(highlightColor);
Rectangle appearRect = new Rectangle(0f, 0f, rect.getWidth(), rect.getHeight());
PdfFormXObject appearObj = new PdfFormXObject(appearRect);
final PdfResources appearRes = appearObj.getResources();
PdfExtGState extGState = new PdfExtGState();
extGState.setBlendMode(PdfExtGState.BM_MULTIPLY);
appearRes.addExtGState(extGState);
appearObj.setBBox(new PdfArray(new float[] {0f, 0f, rect.getWidth(), rect.getHeight()}));
PdfShading appearShading = new PdfShading.Axial(highlightColor.getColorSpace(), 0f, 0f, highlightColor.getColorValue(), 1f, 1f, highlightColor.getColorValue());
appearRes.addShading(appearShading);
appearRes.addColorSpace(highlightColor.getColorSpace());
PdfAnnotationAppearance appearance = new PdfAnnotationAppearance(appearObj.getPdfObject());
highlight.setNormalAppearance(appearance);
highlight.setFlag(PdfAnnotation.PRINT);
page.addAnnotation(highlight);
}
}回答 1
Stack Overflow用户
回答已采纳
发布于 2018-12-10 12:04:13
利用塞缪尔的回答，我无意中找到了一个可行的答案。
我并不期望在PDF标准和这个框架(iText)中，但基于下面的工作示例，我的假设是，当查看器无法呈现注释(因为它们没有外观流)时，我试图为高亮显示编写的矩形是一个粗略的回退方法，用于“伪造”突出显示矩形。意识到这两个操作没有链接，我来看下面的工作示例。希望这对未来的其他人有所帮助。
RegexBasedLocationExtractionStrategy evntlstnr = new RegexBasedLocationExtractionStrategy(pattern);
for (int pIdx = 0; pIdx < pdfDoc.getNumberOfPages(); ++pIdx) {
final PdfPage page = pdfDoc.getPage(pIdx + 1);
new PdfCanvasProcessor(evntlstnr).processPageContent(page);
Collection<IPdfTextLocation> locations = evntlstnr.getResultantLocations();
for (IPdfTextLocation location : locations) {
Rectangle rect = location.getRectangle();
// Specify quad points in Z-like order
// [0,1] x1,y1 [2,3] x2,y2
// [4,5] x3,y3 [6,7] x4,y4
float[] quads = new float[8];
quads[0] = rect.getX();
quads[1] = rect.getY() + rect.getHeight();
quads[2] = rect.getX() + rect.getWidth();
quads[3] = quads[1];
quads[4] = quads[0];
quads[5] = rect.getY();
quads[6] = quads[2];
quads[7] = quads[5];
Color highlightColor = new DeviceRgb(1f, 1f, 0f);
PdfTextMarkupAnnotation highlight = PdfTextMarkupAnnotation.createHighLight(rect, quads);
highlight.setColor(highlightColor);
highlight.setFlag(PdfAnnotation.PRINT);
page.addAnnotation(highlight);
PdfCanvas canvas = new PdfCanvas(page);
PdfExtGState extGState = new PdfExtGState();
extGState.setBlendMode(PdfExtGState.BM_MULTIPLY);
canvas.setExtGState(extGState);
canvas.rectangle(rect.getX(), rect.getY(), rect.getWidth(), rect.getHeight());
canvas.setFillColor(highlightColor);
canvas.fill();
canvas.release();
}
}页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/53671074
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