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OpenGL笔记之事件驱动设计将相机控制类和应用程序类分离

—— 2024-10-02 下午

bilibili赵新政老师的教程看后笔记

code review!

1.代码图片

运行

Mouse button 1 pressed at (100, 200)
Mouse dragged by (50, 50)
Key pressed: 65
Updating camera control

2.分析

类图:

上面的类图展示了代码中主要类的结构和关系:

• Application 类包含一个 CameraControl 指针和事件回调函数指针,通过 setMouseCallback 和 setKeyCallback 设置事件回调。
• CameraControl 是一个抽象基类,定义了处理鼠标事件、键盘事件和更新的接口。
• SimpleCameraControl 继承自 CameraControl,实现了具体的事件处理逻辑。
• MouseEvent 和 KeyEvent 分别表示鼠标事件和键盘事件的数据结构。

事件处理流程图:

事件处理流程如下:

1. 应用程序触发鼠标或键盘事件
2. 事件通过 Application::triggerMouseEvent 或 Application::triggerKeyEvent 分发到对应的全局回调函数
3. 回调函数 onMouseEvent 或 onKeyEvent 调用 SimpleCameraControl 的对应事件处理函数
4. SimpleCameraControl 的事件处理函数根据事件数据进行相应的处理

主程序流程图:

主程序的流程如下:

1. 创建 Application 对象
2. 设置鼠标回调函数为 onMouseEvent
3. 设置键盘回调函数为 onKeyEvent
4. 调用 Application::run
   • 模拟触发鼠标事件
   • 模拟触发键盘事件
   • 调用 CameraControl::update 更新相机状态

3.UML

+------------------+
|  CameraControl   |  <<abstract>>
+------------------+
| +handleMouseEvent(MouseEvent) : void |
| +handleKeyEvent(KeyEvent) : void     |
| +update() : void                     |
+------------------+^||
+----------------------+
| SimpleCameraControl  |
+----------------------+
| -mousePressed : bool |
| -lastX : double      |
| -lastY : double      |
| -keys : map<int, bool> |
+----------------------+
| +handleMouseEvent(MouseEvent) : void |
| +handleKeyEvent(KeyEvent) : void     |
| +update() : void                     |
+----------------------++-------------------+
|    Application    |
+-------------------+
| -cameraControl : SimpleCameraControl*
| -mouseCallback : MouseCallback       |
| -keyCallback : KeyCallback           |
+-------------------+
| +setMouseCallback(MouseCallback) : void |
| +setKeyCallback(KeyCallback) : void     |
| +triggerMouseEvent(MouseEvent) : void   |
| +triggerKeyEvent(KeyEvent) : void       |
| +run() : void                           |
+-------------------++-------------------+
|    MouseEvent     |
+-------------------+
| +x : int          |
| +y : int          |
| +button : int     |
| +pressed : bool   |
+-------------------++-----------------+
|    KeyEvent     |
+-----------------+
| +key : int      |
+-----------------++--------------------+
|   Global Functions |
+--------------------+
| +onMouseEvent(MouseEvent) : void |
| +onKeyEvent(KeyEvent) : void     |
+--------------------+

4.代码

#include <iostream>
#include <map>// 定义事件类型
enum class EventType {MouseClick,KeyPress
};// 定义鼠标事件信息
struct MouseEvent {int x, y;int button;bool pressed;
};// 定义键盘事件信息
struct KeyEvent {int key;
};// 事件回调函数指针类型
using MouseCallback = void (*)(const MouseEvent&);
using KeyCallback = void (*)(const KeyEvent&);// 抽象相机控制器基类
class CameraControl {
public:virtual void handleMouseEvent(const MouseEvent& event) = 0;virtual void handleKeyEvent(const KeyEvent& event) = 0;virtual void update() = 0;
};// 一个简单的相机控制器实现
class SimpleCameraControl : public CameraControl {
public:void handleMouseEvent(const MouseEvent& event) override {if (event.pressed) {mousePressed = true;lastX = event.x;lastY = event.y;std::cout << "Mouse button " << event.button << " pressed at ("<< event.x << ", " << event.y << ")\n";} else {mousePressed = false;double deltaX = event.x - lastX;double deltaY = event.y - lastY;std::cout << "Mouse dragged by (" << deltaX << ", " << deltaY << ")\n";lastX = event.x;lastY = event.y;}}void handleKeyEvent(const KeyEvent& event) override {keys[event.key] = true;std::cout << "Key pressed: " << event.key << "\n";}void update() override {std::cout << "Updating camera control\n";}private:bool mousePressed = false;double lastX = 0.0, lastY = 0.0;std::map<int, bool> keys;
};// 应用程序类
class Application {
public:Application(): cameraControl(new SimpleCameraControl()) {}void setMouseCallback(MouseCallback callback) {mouseCallback = callback;}void setKeyCallback(KeyCallback callback) {keyCallback = callback;}void triggerMouseEvent(const MouseEvent& event) {if (mouseCallback) {mouseCallback(event);}}void triggerKeyEvent(const KeyEvent& event) {if (keyCallback) {keyCallback(event);}}void run() {// 模拟事件触发triggerMouseEvent(MouseEvent{100, 200, 1, true});triggerMouseEvent(MouseEvent{150, 250, 1, false});triggerKeyEvent(KeyEvent{65});// 更新相机控制cameraControl->update();}private:SimpleCameraControl* cameraControl;MouseCallback mouseCallback = nullptr;KeyCallback keyCallback = nullptr;
};// 全局函数
void onMouseEvent(const MouseEvent& event) {static SimpleCameraControl control;control.handleMouseEvent(event);
}void onKeyEvent(const KeyEvent& event) {static SimpleCameraControl control;control.handleKeyEvent(event);
}int main() {Application app;app.setMouseCallback(onMouseEvent);app.setKeyCallback(onKeyEvent);app.run();return 0;
}