开发环境 Qt5.5.1、Qt Creator 3.5.1
Qt实现pdf阅读器和MFC实现pdf阅读器，其实原理都是差不多的。
需要用到Poppler开源库，下载地址如下 https://poppler.freedesktop.org/
如果只是要在window的gcc下运行的话，可以下载已经编译好的库 https://sourceforge.net/projects/poppler-win32/
注意：这个是MinGW版本的Qt，也就是运行在GCC环境下的库，里面只包含 *.dll 和 *.a 。如果是Vistual Studio版本的Qt ，那么很不幸里面没有 *.lib文件。
1、新建项目，在项目的根目录新建一个“poppler”文件夹，将poppler中qt5目录下的文件都丢进去（*.h头文件，另外再将编译好的2个*.a文件和2个*.dll丢进去，我这里多丢了实现的*.cc文件，因为*.cc已经被编译成动态库了，所以可以不用包含在代码中）
2、在项目的pro配置文件中添加以下内容，引用poppler的头文件和库文件（注意：我这里是win32，所以前面加了win32前缀）
|
1
2
3
|
INCLUDEPATH += $$PWD/popplerwin32: LIBS += -L$$PWD/poppler -llibpopplerwin32: LIBS += -L$$PWD/poppler -llibpoppler-qt5 |
3、创建pdf工具类（该类负责与poppler库做对接，主要负责获取pdf的总页数，和每页的图像）
（1）pdfutils.h
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
|
#ifndef PDFUTILS_H#define PDFUTILS_H#include <QObject>#include <QImage>#include <QSize>#include <QDebug>#include "poppler-qt5.h"class PdfUtils{public: explicit PdfUtils(QString filePath); ~PdfUtils(); //获取指定页pdf图像(页码从0开始) QImage getPdfImage(int pageNumber); //获取pdf总页码 int getNumPages(); //获取pdf页面大小 QSize getPageSize();private: QString filePath; int numPages; QSize pageSize; void getPdfInfo();};#endif // PDFUTILS_H |
（2）pdfutils.cpp
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
|
#include "pdfutils.h"PdfUtils::PdfUtils(QString filePath) { this->filePath = filePath; getPdfInfo();}PdfUtils::~PdfUtils() {}QImage PdfUtils::getPdfImage(int pageNumber) { QImage image; Poppler::Document* document = Poppler::Document::load(filePath); if (!document || document->isLocked()) { // ... error message .... delete document; return image; } // Document starts at page 0 Poppler::Page* pdfPage = document->page(pageNumber); if (pdfPage == 0) { // ... error message ... return image; } // Generate a QImage of the rendered page image = pdfPage->renderToImage(72, 72, -1, -1, -1, -1); if (image.isNull()) { // ... error message ... return image; } // after the usage, the page must be deleted delete pdfPage; delete document; return image;}int PdfUtils::getNumPages() { return numPages;}QSize PdfUtils::getPageSize() { return pageSize;}void PdfUtils::getPdfInfo() { numPages = 0; Poppler::Document* document = Poppler::Document::load(filePath); if (!document || document->isLocked()) { // ... error message .... delete document; return; } numPages = document->numPages(); Poppler::Page* pdfPage = document->page(0); pageSize = pdfPage->pageSize(); qDebug()<<pageSize; delete pdfPage; delete document;} |
4、pdf显示类（pdf的右侧显示滚动条，①拖动滚动条翻页 ②鼠标拖动pdf到最上或最底时翻页）
注意：本文省略了页面缓存，如果是真实的项目的话，本着严谨的态度，请务必缓存页面
（1）mypdfcanvas.h（继承父类的resizeEvent是为了 ①当pdf只有1页时不显示滚动条 ②当用户拖动缩放窗口时动态改变pdf显示尺寸）
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
|
#ifndef MYPDFCANVAS_H#define MYPDFCANVAS_H#include <QWidget>#include <QVector>#include <QMouseEvent>#include <QPaintEvent>#include <QPainter>#include <QPaintEvent>#include <QMap>#include <QPalette>#include <QResizeEvent>#include "pdfutils.h"class MyPdfCanvas : public QWidget{ Q_OBJECTpublic: explicit MyPdfCanvas(QWidget *parent = 0); ~MyPdfCanvas(); void resizeEvent(QResizeEvent* e); void paintEvent(QPaintEvent *e); void mousePressEvent(QMouseEvent *e); void mouseReleaseEvent(QMouseEvent *e); void mouseMoveEvent(QMouseEvent *e); void setMaxCachedNum(int maxCachedNum); //如果不能解析pdf返回false bool setPath(QString pdfPath); //页码从0开始 bool setPage(int pageNumber); //获取页数 int getNumPages(); float getScaledRatio(); //显示裁剪后的图片 bool showClipImage(int pageNumber, int x, int y, int w, int h); //取消显示裁剪图片,恢复正常显示 void cancelClip(); //实际获取的pdf宽高度 QSize pdfActualSize;signals: void pageChanged(int currentPage);private: PdfUtils* pdfUtils; QString pdfPath; //最大缓存图片数量 int maxCachedNum; //用来缓存pdf的每一个页面的图像(从0开始) QMap<int, QImage> cachedImageMap; //用来存储已缓存的pdf页面序号(从0开始)// QQueue<int> cachedPageQueue; //当前页码(从0开始) int currentPage; //总页码(从0开始) int numPages; bool isMouseDown; int lastMouseY; //当前pdf页面的图像 QImage image; int imageX; int imageY; int imageMinY; //是否是剪裁状态 bool isClip; //获取指定页的图片 bool getPdfImage(int pageNumber); void reachTop(); void reachBottom(); //判断是否需要发送重定位签名框的信号 void needLocateSignArea();};#endif // MYPDFCANVAS_H |
（2）pdfcanvas.cpp
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
|
#include "mypdfcanvas.h"MyPdfCanvas::MyPdfCanvas(QWidget *parent) : QWidget(parent) { pdfUtils = NULL; imageX = 0; imageY = 0; isClip = false; setAutoFillBackground(true);}MyPdfCanvas::~MyPdfCanvas() { if(pdfUtils != NULL) delete pdfUtils;}void MyPdfCanvas::resizeEvent(QResizeEvent *e) { image = this->cachedImageMap[currentPage]; if(!image.isNull()) { float radio = (float)e->size().width()/(float)e->oldSize().width(); int imageHeight = image.height()* e->size().width()/image.width(); image = image.scaled(e->size().width(), imageHeight); if(imageHeight < this->height()) { imageY = (this->height()-imageHeight)/2; //如果图片高度小于控件高度，则图片居中// imageMinY = imageY; imageMinY = 0; imageY = imageMinY; } else { if(radio>0) { imageY = (int)(imageY*radio); if(imageY > 0) { imageY = 0; } } else { imageY = 0; } } }}void MyPdfCanvas::paintEvent(QPaintEvent *e) { QPainter* painter = new QPainter(this); if(image.isNull()) { painter->fillRect(this->rect(), Qt::transparent); return; } painter->drawImage(0, imageY, image); delete painter;}void MyPdfCanvas::mousePressEvent(QMouseEvent *e) { isMouseDown = true; lastMouseY = e->y();}void MyPdfCanvas::mouseReleaseEvent(QMouseEvent *e){ isMouseDown = false;}void MyPdfCanvas::mouseMoveEvent(QMouseEvent *e){ if(!isMouseDown || image.isNull()) { return; } int distance = e->y() - lastMouseY; lastMouseY = e->y(); imageY += distance; if(imageY > 0) { imageY = 0; reachTop(); return; } else if(imageY < imageMinY) { imageY = imageMinY; reachBottom(); return; } update();}void MyPdfCanvas::setMaxCachedNum(int maxCachedNum) { this->maxCachedNum = maxCachedNum;}bool MyPdfCanvas::setPath(QString pdfPath) { this->pdfPath = pdfPath; if(pdfUtils != NULL) delete pdfUtils; pdfUtils = new PdfUtils(pdfPath); numPages = pdfUtils->getNumPages(); if(numPages > 0) { isClip = false; pdfActualSize = pdfUtils->getPageSize(); } cachedImageMap.clear(); currentPage = 0; imageY = 0; lastMouseY = 0; return numPages > 0;}bool MyPdfCanvas::setPage(int pageNumber) { if(!getPdfImage(pageNumber)) { return false; } isClip = false; isMouseDown = false; image = image.scaledToWidth(this->width()); imageMinY = this->height() - image.height(); if(image.height() < this->height()) { //如果图片高度小于控件高度，则图片居中// imageMinY /= 2; imageMinY = 0; imageY = imageMinY; } else { imageY = 0; } update(); return true;}int MyPdfCanvas::getNumPages() { return numPages;}float MyPdfCanvas::getScaledRatio() { int pdfWidth = pdfUtils->getPageSize().width(); return (float)this->width()/(float)pdfWidth;}bool MyPdfCanvas::showClipImage(int pageNumber, int x, int y, int w, int h) { if(!getPdfImage(pageNumber)) { return false; } isClip = true; imageY = 0; image = image.copy(x, y, w, h).scaled(this->size()); update();}void MyPdfCanvas::cancelClip() { isClip = false; setPage(currentPage);}bool MyPdfCanvas::getPdfImage(int pageNumber) { if(pageNumber<0 || pageNumber >= numPages) { return false; } if(cachedImageMap.contains(pageNumber)) { image = cachedImageMap.value(pageNumber); } else { image = pdfUtils->getPdfImage(pageNumber); if(!image.isNull()) { cachedImageMap[pageNumber] = image; pdfActualSize = image.size(); } } if(image.isNull()) { return false; } currentPage = pageNumber; return true;}void MyPdfCanvas::reachTop() { if(currentPage > 0) { emit pageChanged(currentPage-1); }}void MyPdfCanvas::reachBottom() { if(currentPage < numPages-1) { emit pageChanged(currentPage+1); }} |
5、pdf及右侧滑块的装载容器
（1）mainwindow.h
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
#ifndef MAINWINDOW_H#define MAINWINDOW_H#include <QMainWindow>#include <QScrollBar>#include "mypdfcanvas.h"#define SCROLLBAR_WIDTH 30class MainWindow : public QMainWindow{ Q_OBJECTpublic: explicit MainWindow(QWidget *parent = 0); ~MainWindow(); void resizeEvent(QResizeEvent* e); bool setPdfPath(QString path); //重新调整pdf界面大小 void resizeCanvas(); void setWidgetVisible(bool pdfCanvasVisible, bool scrollbarVisible);public slots: //当拖动pdf上滑到顶（或下滑到底）时触发该方法 onPageChange(int currentPage); //当滑动条的滑块被滑动时，会调用该方法 onScrollBarValueChange();private: MyPdfCanvas *pdfCanvas; QScrollBar *scrollbar;};#endif // MAINWINDOW_H |
（2）mainwindow.cpp
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
|
#include "mainwindow.h"MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent) { pdfCanvas = new MyPdfCanvas(this); scrollbar = new QScrollBar(Qt::Vertical, this); setWidgetVisible(false, false); connect(pdfCanvas, SIGNAL(pageChanged(int)), this, SLOT(onPageChange(int))); connect(scrollbar, SIGNAL(valueChanged(int)), this, SLOT(onScrollBarValueChange()));}MainWindow::~MainWindow() {}void MainWindow::resizeEvent(QResizeEvent *e) { resizeCanvas();}bool MainWindow::setPdfPath(QString path) { bool result = pdfCanvas->setPath(path); if(result) { int numPages = pdfCanvas->getNumPages(); if(numPages>1) { scrollbar->setMaximum(numPages-1); scrollbar->setValue(0); } pdfCanvas->setPage(0); } resizeCanvas(); return result;}void MainWindow::resizeCanvas() { qDebug()<<"resize "<<this->rect()<<", "<<pdfCanvas->rect(); int numPages = pdfCanvas->getNumPages(); if(numPages == 1) { pdfCanvas->setGeometry(this->rect()); setWidgetVisible(true, false); } else if(numPages > 1) { pdfCanvas->setGeometry(0, 0, this->width()-SCROLLBAR_WIDTH, this->height()); scrollbar->setGeometry(this->width()-SCROLLBAR_WIDTH, 0, this->width()-SCROLLBAR_WIDTH, this->height()); setWidgetVisible(true, true); } else { //numPages <= 0 setWidgetVisible(false, false); }}void MainWindow::setWidgetVisible(bool pdfCanvasVisible, bool scrollbarVisible) { pdfCanvas->setVisible(pdfCanvasVisible); scrollbar->setVisible(scrollbarVisible);}MainWindow::onPageChange(int currentPage) { pdfCanvas->setPage(currentPage);}MainWindow::onScrollBarValueChange() { pdfCanvas->setPage(scrollbar->value());} |
6、调用方式
（1）main.cpp
|
1
2
3
4
5
6
7
8
9
10
11
12
13
|
#include "mainwindow.h"#include <QApplication>int main(int argc, char *argv[]){ QApplication a(argc, argv); MainWindow w; w.resize(500, 500); w.show(); QString path = "D://test.pdf"; w.setPdfPath(path); w.setWindowTitle(path); return a.exec();} |
7、实际效果图
更新于2016-08-03
8、项目下载地址（使用当前最新的库poppler-0.45.0、poppler-0.39.0-win32）
http://download.csdn.net/detail/chy555chy/9593364
该项目在win7（Qt5.1）、win10（Qt5.7）下测试过了，均可正常运行。
下图为项目目录中的poppler文件夹（已经删去所有.cc文件），因为只用库和头文件，Qt便可隐式调用dll中的函数了。
更新于2016-08-22
你们评论中遇到的加载库的时候就奔溃现象我还真没遇到过。
下面是测试情况：
（1）当PDF文件未找到的情况，会输出错误日志，但是并不会崩溃。
（2）当路径中包含”中文“，且包含"空格"的情况，poppler是可以正常打开的。
以上这篇Qt 使用Poppler实现pdf阅读器的示例代码就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：http://blog.csdn.net/chy555chy/article/details/51613545
