一、简介

利用背景图片设计出QLineEdit新的样式，起到美化界面的效果，并增加自动补全历史记录的功能，就可以作为一个完整的库。

二、详解

1、知识点

（1）切换QLineEdit的背景

void InnerLineEdit::setNormal(){    setText("");    setTextMargins(-5,0,this->height(),0);    //solve the cursor problem    setStyleSheet("background-image:url(:/searchInput.png);border:1px solid #536874;");}void InnerLineEdit::setSearching(){    setTextMargins(0,0,this->height(),0);    setStyleSheet("background-image:url(:/searchInput_click.png);border:1px solid #536874;");}

（2）QLineEdit模糊匹配

QCompleter *completer = new QCompleter(this);    listModel = new QStringListModel(valueList, this);    completer->setCaseSensitivity(Qt::CaseInsensitive);    completer->setModel(listModel);    this->setCompleter(completer);

（3）记录历史输入

connect(this, SIGNAL(editingFinished()), this, SLOT(editComplete()));

void InnerLineEdit::editComplete(){    QString text = this->text();    if(QString::compare(text, QString("")) != 0) {        bool flag = valueList.contains(text, Qt::CaseInsensitive);        if(!flag) {            addValue(text);        }    }}

2、完整代码

（1）searchlineedit.h

#ifndef SEARCHLINEEDIT_H#define SEARCHLINEEDIT_H#include 
   
    class InnerLineEdit;class SearchLineEdit : public QWidget{    Q_OBJECTpublic:    SearchLineEdit(QWidget *parent = 0);    ~SearchLineEdit();protected:    void resizeEvent(QResizeEvent *event);signals:    void searchTextChanged(QString);private slots:    void textChange(QString text);    void editClicked();    void btnClicked();private:    InnerLineEdit *lineEdit;    QPushButton *btn;};class InnerLineEdit : public QLineEdit{    Q_OBJECT public:    explicit InnerLineEdit(QWidget *parent = 0);    void setNormal();    void setSearching();    void addValue(const QString &value);protected:   void focusInEvent(QFocusEvent *event);   void focusOutEvent(QFocusEvent *event); signals:    void pressed();private slots:    void editComplete();private:    QStringList valueList;    QStringListModel *listModel;};#endif // SEARCHLINEEDIT_H

（2）searchlineedit.cpp

#include "searchlineedit.h"SearchLineEdit::SearchLineEdit(QWidget *parent)    : QWidget(parent){    lineEdit = new InnerLineEdit(this);    lineEdit->move(8,38);    lineEdit->resize(168,23);    connect(lineEdit,SIGNAL(textChanged(QString)),this,SLOT(textChange(QString)));    connect(lineEdit,SIGNAL(pressed()),this,SLOT(editClicked()));    btn = new QPushButton(this);    btn->setFocusPolicy(Qt::NoFocus);    btn->setCursor(Qt::PointingHandCursor);    btn->resize(14,14);    btn->move(157,42);    btn->setStyleSheet("QPushButton{background-color:transparent;border:0px;}");    btn->setFocusPolicy(Qt::NoFocus);    btn->setVisible(false);    connect(btn,SIGNAL(clicked()),this,SLOT(btnClicked()));    this->setFocus();    lineEdit->addValue("C");    lineEdit->addValue("C++");    lineEdit->addValue("Python");    lineEdit->addValue("Php");    lineEdit->addValue("Perl");    lineEdit->addValue("Qt");}SearchLineEdit::~SearchLineEdit(){}void SearchLineEdit::resizeEvent(QResizeEvent *event){    move((QApplication::desktop()->width() - width())/2,  (QApplication::desktop()->height() - height())/2);    QWidget::resizeEvent(event);}void SearchLineEdit::textChange(QString text){    emit searchTextChanged(text);}void SearchLineEdit::editClicked(){    lineEdit->setSearching();    btn->setVisible(true);}void SearchLineEdit::btnClicked(){    lineEdit->setNormal();    btn->setVisible(false);    this->setFocus();}/*******************************/InnerLineEdit::InnerLineEdit(QWidget *parent)   : QLineEdit(parent){    setTextMargins(0,0,this->height(),0);    setStyleSheet("background-image:url(:/searchInput.png);border:1px solid #536874;");    QCompleter *completer = new QCompleter(this);    listModel = new QStringListModel(valueList, this);    completer->setCaseSensitivity(Qt::CaseInsensitive);    completer->setModel(listModel);    this->setCompleter(completer);    connect(this, SIGNAL(editingFinished()), this, SLOT(editComplete()));}void InnerLineEdit::setNormal(){    setText("");    setTextMargins(-5,0,this->height(),0);    //solve the cursor problem    setStyleSheet("background-image:url(:/searchInput.png);border:1px solid #536874;");}void InnerLineEdit::setSearching(){    setTextMargins(0,0,this->height(),0);    setStyleSheet("background-image:url(:/searchInput_click.png);border:1px solid #536874;");}void InnerLineEdit::addValue(const QString &value){    valueList.append(value);    listModel->setStringList(valueList);}void InnerLineEdit::focusInEvent(QFocusEvent *event){    emit pressed();    QLineEdit::focusInEvent(event);}void InnerLineEdit::focusOutEvent(QFocusEvent *event){    QLineEdit::focusInEvent(event);}void InnerLineEdit::editComplete(){    QString text = this->text();    if(QString::compare(text, QString("")) != 0) {        bool flag = valueList.contains(text, Qt::CaseInsensitive);        if(!flag) {            addValue(text);        }    }}

（3）main.cpp

#include "searchlineedit.h"#include 
   
    int main(int argc, char *argv[]){    QApplication a(argc, argv);    SearchLineEdit w;    w.show();    return a.exec();}

（4）编译运行

其中的默认值有C、C++、Python、Php、Perl、Qt，输入第一个字符会自动不区分大小写的匹配判断，并显示在下拉列表中。若输入一个不存在的字符串，按回车后会保存下来，下次便会提示该字符串。

三、总结

（1）上述代码已上传到CSDN：。

（2）若有问题或建议，请留言，在此感谢！

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