screenshotLabel = new QLabel;
screenshotLabel->setSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding);//使用QSizePolicy::Expanding QLabel就会随着窗体的变化而变化
screenshotLabel->setAlignment(Qt::AlignCenter); // 对齐
screenshotLabel->setMinimumSize(240, 160); // 最小
让qtextedit 不能输入,只读
m_Logw=newQTextEdit();
m_Logw->setReadOnly(true);
让qlinetext 按enter键 就能执行,触发returnPressed() 信号
connect(m_InputArea,SIGNAL(returnPressed()),
this,SLOT(execute()));