Improve C++ programming skills and realize the graphical display function of embedded systems

Improve C programming skills and realize the graphical display function of embedded systems

With the continuous advancement and development of science and technology, the application of embedded systems in daily life is becoming more and more important. coming more and more widely. The graphical display function of embedded systems is crucial to user experience, so it is very important to master C programming skills to implement the graphical display function. This article will introduce some techniques to improve C programming and implement the graphical display function of embedded systems through code examples.

1. Use object-oriented programming ideas
Object-oriented programming ideas make the code structure clearer, easier to maintain and expand. When implementing the graphics display function, an object-oriented approach can be used to manage and draw various graphics objects. Here is a simple example:

#include <iostream>
using namespace std;

class Shape {
public:
    virtual void draw() = 0;
};

class Circle : public Shape {
public:
    void draw() {
        cout << "Drawing a circle" << endl;
    }
};

class Rectangle : public Shape {
public:
    void draw() {
        cout << "Drawing a rectangle" << endl;
    }
};

int main() {
    Shape* shape1 = new Circle();
    Shape* shape2 = new Rectangle();

    shape1->draw();
    shape2->draw();

    delete shape1;
    delete shape2;

    return 0;
}

In the above example, Shape is an abstract class, and Circle and Rectangle are concrete subclasses. Through polymorphism, you can determine at runtime which subclass's draw() function is called to draw different graphics.

2. Use graphics libraries to implement drawing functions
In order to implement graphics display functions, we can use some open source graphics libraries, such as SDL, OpenGL, etc. These libraries provide a wealth of functions and interfaces that can help us draw various graphics conveniently. Here is an example using the SDL library:

#include <SDL.h>

int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_EVERYTHING);

    SDL_Window* window = SDL_CreateWindow("Hello SDL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
    
    SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);
    SDL_RenderClear(renderer);

    SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
    SDL_Rect rect = { 100, 100, 200, 200 };
    SDL_RenderFillRect(renderer, &rect);

    SDL_RenderPresent(renderer);

    SDL_Delay(3000);

    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);

    SDL_Quit();

    return 0;
}

In the above example, we used the SDL library to create a window and renderer, and set the draw color and size. By calling the SDL_RenderFillRect() function, we can draw a rectangle and display the drawing result on the window through the SDL_RenderPresent() function.

3. Optimize drawing efficiency
In embedded systems, resources are limited, so it is necessary to consider optimizing drawing efficiency. A common optimization method is to use double buffering technology, which uses a buffer to save the drawing results during the drawing process, and then displays the contents of the buffer on the screen after the drawing is completed. The following is an example of using double buffering technology:

#include <SDL.h>

int main(int argc, char* args[]) {
    SDL_Init(SDL_INIT_EVERYTHING);

    SDL_Window* window = SDL_CreateWindow("Hello SDL", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, 640, 480, SDL_WINDOW_SHOWN);
    SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC);
    
    SDL_Texture* buffer = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_ARGB8888, SDL_TEXTUREACCESS_STREAMING, 640, 480);
    Uint32* pixels = new Uint32[640 * 480];

    bool quit = false;
    while (!quit) {
        SDL_Event event;
        while (SDL_PollEvent(&event)) {
            if (event.type == SDL_QUIT) {
                quit = true;
            }
        }

        for (int i = 0; i < 640 * 480; i++) {
            pixels[i] = SDL_MapRGBA(SDL_AllocFormat(SDL_PIXELFORMAT_ARGB8888), 255, 255, 0, 255);
        }

        SDL_UpdateTexture(buffer, NULL, pixels, 640 * sizeof(Uint32));

        SDL_RenderCopy(renderer, buffer, NULL, NULL);
        SDL_RenderPresent(renderer);
    }

    delete[] pixels;

    SDL_DestroyTexture(buffer);
    SDL_DestroyRenderer(renderer);
    SDL_DestroyWindow(window);

    SDL_Quit();

    return 0;
}

In the above example, we first create a buffer (texture) with a size of 640x480, and write the drawing result through the SDL_UpdateTexture() function into the buffer. Then copy the contents of the buffer to the renderer through the SDL_RenderCopy() function, and then display the contents of the renderer on the window through the SDL_RenderPresent() function. In this way, you don't need to directly operate the window every time you draw, which can greatly improve the efficiency of drawing.

Summary:
By learning and mastering C programming skills, and combining the use of graphics libraries to implement the graphics display function of embedded systems, development efficiency and user experience can be improved. At the same time, it is also important to optimize drawing efficiency to make drawing more efficient in resource-limited embedded systems. I hope the content of this article can be helpful to readers in realizing the graphics display function of embedded systems.

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