# Create GUI Application with Python Qt6 

## Basic
- qt
	- `QApplication`
		- 维护了一个`event loop`
	- `QWidget`
		- 可以使用`layouts`任意组合形成复杂ui
	- `QMainWindow`
		- 预设的组件,提供了一些特性
			- toolbar, menu, status bar, dockable widget..
	- 练习1
	- signal/slots
		- 很多组件都有`public slots`, 可以直接和其他信号连接
			- 数据类型要对的上?
	- 组件
		- 对齐
			- `Qt.AlignmentFlag.Align*`
		- `QLabel`
			- 显式图片
				- `.setPixmap(QPixmap("xxx.jpg"))`
		- `QCheckBox`
			- 信号
				- `.stateChanged.connect(..)`
		- `QComboBox`
			- `.addItems([])`
			- 信号
				- `.currentIndexChanged.connect(..)
				- `.currentTextChanged.connect(..)`
		- `QListWidget`
			- `.addItems([])`
			- 信号
				- `.currentItemChanged.connect(..)`
					- `def item_changed(item)`
				- `.currentTextChanged.connect(..)`
					- `def text_changed(string)`
		- `QLineEdit`
			- `.setInputMask('000.0000.000.000;'`
	- 布局
		- `QHBoxLayout`
		- `QVBoxLayout`
		- `QGridLayout`
		- `QStackedLayout`
	- Actions/Toolbars/Menus
		- toolbar
			- 元素
				- 图标/文本/任意Qt widget






## 练习

### 1 概念熟悉

```python
import sys
from PySide6.QtCore import QSize, Qt
from PySide6.QtWidgets import QApplication, QMainWindow, QPushButton

class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        self.setWindowTitle("ex-1")
        btn = QPushButton("Press Me!")
        self.setCentralWidget(btn)
		self.setFixedSize(QSize(400, 400))

app = QApplication(sys.argv)
win = MainWindow()
win.show()
sys.exit(app.exec())
```

![[Pasted image 20220406013205.png]]
### 2. 布局/signal初试

```python
class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()
        self.setWindowTitle("ex-2")
        self.label = QLabel()
        self.input = QLineEdit()
        self.input.textChanged.connect(self.label.setText)
        vbox = QVBoxLayout()
        vbox.addWidget(self.input)
        vbox.addWidget(self.label)
        container = QWidget()
        container.setLayout(vbox)
        self.setCentralWidget(container)
```

![[Pasted image 20220406014236.png]]

### 3. 布局

```python
class MainWindow(QMainWindow):
    def __init__(self):
        super().__init__()

        # 纵向布局
        vl = QVBoxLayout()
        vl.addWidget(Color("red"))
        vl.addWidget(Color("green"))
        vl.addWidget(Color("blue"))

        # 横向布局
        hl = QHBoxLayout()
        hl.addWidget(Color("red"))
        hl.addWidget(Color("green"))
        hl.addWidget(Color("blue"))

        # 嵌套布局
        l1 = QHBoxLayout()
        l2 = QVBoxLayout()
        l3 = QVBoxLayout()

        l2.addWidget(Color("red"))
        l2.addWidget(Color("yellow"))
        l2.addWidget(Color("purple"))

        l1.addLayout(l2)
        l1.addWidget(Color("green"))

        l3.addWidget(Color("red"))
        l3.addWidget(Color("purple"))
        l1.addLayout(l3)

        l1.setContentsMargins(0,0,0,0)
        l1.setSpacing(20)

        # 表格布局
        gl = QGridLayout()
        gl.addWidget(Color("red"), 0, 0)
        gl.addWidget(Color("green"), 1, 0)
        gl.addWidget(Color("blue"), 1, 1)
        gl.addWidget(Color("purple"), 2, 1)

        # 堆栈布局
        sl = QStackedLayout()
        sl.addWidget(Color("red"))
        sl.addWidget(Color("green"))
        sl.addWidget(Color("blue"))
        sl.addWidget(Color("purple"))

        pl = QVBoxLayout()
        bl = QHBoxLayout()
        self.stack_layout = QStackedLayout()

        pl.addLayout(bl)
        pl.addLayout(self.stack_layout)

        btn = QPushButton("red")
        btn.pressed.connect(self.active_tab1)
        bl.addWidget(btn)
        self.stack_layout.addWidget(Color("red"))

        btn = QPushButton("green")
        btn.pressed.connect(self.active_tab2)
        bl.addWidget(btn)
        self.stack_layout.addWidget(Color("green"))

        btn = QPushButton("blue")
        btn.pressed.connect(self.active_tab3)
        bl.addWidget(btn)
        self.stack_layout.addWidget(Color("blue"))

        # tab布局
        tabs = QTabWidget()
        tabs.setTabPosition(QTabWidget.TabPosition.North)
        tabs.setMovable(True)

        for n, color in enumerate(["red", "green", "blue", "yellow"]):
            tabs.addTab(Color(color), color)

        w = QWidget()
        w.setLayout(pl)
        self.setCentralWidget(tabs)
    
    def active_tab1(self):
        self.stack_layout.setCurrentIndex(0)
    
    def active_tab2(self):
        self.stack_layout.setCurrentIndex(1)
    
    def active_tab3(self):
        self.stack_layout.setCurrentIndex(2)
```