重要函數:
1.bool isNull(); //判斷圖片是否爲空白.
2.bool save(QString); //圖片保存到參數的路徑.
3.QPixmap grabWidget(WId,x=0,y=0,w=-1,h=-1); //截取圖片.
4.void scaled(QSize); //把圖片按比例縮放.
下面是一個簡單的截圖器的示例代碼:
首先從Qt設計師拖拽出如下界面，並且進行佈局.
以下是”c.cpp下的代碼:”
#include "c.h"c::c(QWidget *parent)
: QMainWindow(parent)
{
ui.setupUi(this); //設置按鈕的圖標.可不設置.只是爲了好看.
ui.grabScreenButton->setIcon(QIcon("Icons/cut.png"));
ui.saveButton->setIcon(QIcon("Icons/save.png")); //設置按鈕的快捷鍵.
ui.grabScreenButton->setShortcut(tr("Ctrl+G"));
ui.saveButton->setShortcut(tr("Ctrl+S"));
ui.cancelButton->setShortcut(tr("Ctrl+Q")); //連接信號與槽.
connect(ui.grabScreenButton, SIGNAL(clicked()), this, SLOT(cutScreenSlot()));
connect(ui.saveButton, SIGNAL(clicked()), this, SLOT(savePictureSlot()));
connect(ui.cancelButton, SIGNAL(clicked()), this, SLOT(closeSlot()));
}
c::~c()
{
}//保存圖片的槽.void c::savePictureSlot()
{ if (this->isSaved)
QMessageBox::information(this, "warning!", QString::fromLocal8Bit("沒有可以被保存的圖片!")); else
{ this->savePicture();
}
}void c::cutScreenSlot()
{ //先隱藏窗口.
this->hide(); //延遲3秒鐘.
Sleep(3000); //截取當前屏幕的圖片.
pixmap = QPixmap::grabWindow(QApplication::desktop()->winId()); //讓label框自動填滿內容.
ui.label->setScaledContents(true); //讓label框應用圖片，並且自動縮放像素.
ui.label->setPixmap(pixmap.scaled(ui.label->size())); this->isSaved = false; //顯示窗口.
this->show();
}void c::closeSlot()
{ if (this->isSaved)
{ this->close();
} else
{ //設置退出提示框.
QMessageBox temp(QMessageBox::NoIcon, QString::fromLocal8Bit("是否要退出"), QString::fromLocal8Bit("你的圖片尚未保存，是否要保存?"));
temp.setStandardButtons(QMessageBox::Yes | QMessageBox::No);
temp.setButtonText(QMessageBox::Yes, QString::fromLocal8Bit("保存"));
temp.setButtonText(QMessageBox::No, QString::fromLocal8Bit("退出")); int status = temp.exec(); if (status == QMessageBox::Yes)
{ this->savePicture();
} else if (status == QMessageBox::No)
{ this->close();
}
}
}void c::closeEvent(QCloseEvent*event)
{
closeSlot();
}void c::savePicture()
{ //調用文件的類.設置了標題和路徑.
QFileDialog temp(this, "Save Picture", "c:/users/administrator/desktop"); //修改模式爲保存模式.
temp.setAcceptMode(QFileDialog::AcceptSave); //自動添加後綴爲"jpg".
temp.setDefaultSuffix("jpg"); int status = temp.exec(); if (status == QDialog::Accepted)
{
QString path = temp.selectedFiles()[0]; //圖片保存到這個路徑裏去.
bool ok = pixmap.save(path); if (ok)
QMessageBox::information(this, QString::fromLocal8Bit("保存成功"), QString::fromLocal8Bit("圖片已成功保存!")); this->isSaved = true;
}
}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101以下是”c.h下的代碼:”
#ifndef C_H#define C_H#include <QtWidgets/QMainWindow>#include "ui_c.h"#include <QDesktopWidget>#include <QPixmap>#include <QLabel>#include <QPushButton>#include <QIcon>#include <windows.h>#include <QMessageBox>#include <QFileDialog>#include <QCloseEvent>class c : public QMainWindow{
Q_OBJECTpublic:
c(QWidget *parent = 0);
~c(); void savePicture();private slots: void cutScreenSlot(); void savePictureSlot(); void closeSlot();protected: void closeEvent(QCloseEvent*event);private:
Ui::cClass ui;
QPixmap pixmap; bool isSaved = true;
};#endif // C_H12345678910111213141516171819202122232425262728293031323334353637最後是”main.cpp下的代碼:”
#include "c.h"#include <QtWidgets/QApplication>int main(int argc, char *argv[])
{
QApplication a(argc, argv);
c w;
w.show(); return a.exec();
}1234567891011