修复使用枚举来组织事件处理的代码

Question

当我运行以下代码时，我预计按下三个按钮中的一个按钮将分别触发一个匹配状态，该状态将呈现与这些按钮相邻的匹配图像，允许我在每次连续按下按钮时随意旋转新图像。

与这种愉快的场景不同，任何最初按下的按钮都会跳到最后一张图片。。。或者什么都不做。。。或者渲染一个空白的白色屏幕，这取决于我如何处理初始状态声明的位置，以及我是将状态开关放置在事件处理开关内还是不放置。整个系统崩溃了，完全停在了轨道上。发生了什么事，我该如何解决？

#include <string>
#include <SDL/SDL.h>
#include <SDL/SDL_image.h>
#include "cleanup.h"
SDL_Window* window = NULL;
SDL_Renderer* renderer = NULL;
SDL_Rect* clip = NULL;
const int LONGBUTTON_HEIGHT = 128;
const int LONGBUTTON_WIDTH = 256;
int Screen_Width  = 640;
int Screen_Height = 480;
int mouse_x;
int mouse_y;
int alphabutton_x = 0;
int alphabutton_y = 5;
int alphabutton_h = Screen_Width / 10;
int alphabutton_w = Screen_Width / 5;
int betabutton_x = 0;
int betabutton_y = 0.5 * (Screen_Width / 5) + 5;
int betabutton_h = Screen_Width / 10;
int betabutton_w = Screen_Width / 5;
int gammabutton_x = 0;
int gammabutton_y = 1 * (Screen_Width / 5) + 5;
int gammabutton_h = Screen_Width / 10;
int gammabutton_w = Screen_Width / 5;
int alpha_x = Screen_Width / 5;
int alpha_y = 0;
int alpha_h = Screen_Height;
int alpha_w = (4* Screen_Width)/5;
int beta_x = Screen_Width / 5;
int beta_y = 0;
int beta_h = Screen_Height;
int beta_w = (4* Screen_Width)/5;
int gamma_x = Screen_Width / 5;
int gamma_y = 0;
int gamma_h = Screen_Height;
int gamma_w = (4* Screen_Width)/5;
enum alphaButtonSprite {ALPHA_DEFAULT, ALPHA_HOVER, ALPHA_INACTIVE, ALPHA_PRESSED, ALPHA_TOTAL};
enum betaButtonSprite {BETA_DEFAULT, BETA_HOVER, BETA_INACTIVE, BETA_PRESSED, BETA_TOTAL};
enum gammaButtonSprite {GAMMA_DEFAULT, GAMMA_HOVER, GAMMA_INACTIVE, GAMMA_PRESSED, GAMMA_TOTAL};
enum State {ALPHA_STATE, BETA_STATE, GAMMA_STATE};
State state;
SDL_Texture* loadTexture(const std::string& file, SDL_Renderer* renderer)
{
SDL_Texture* texture = IMG_LoadTexture(renderer, file.c_str());
return texture;
}
void renderTexture(SDL_Texture* texture, SDL_Renderer* renderer, SDL_Rect dest,
SDL_Rect* clip = nullptr)
{
SDL_RenderCopy(renderer, texture, clip, &dest);
}
void renderTexture(SDL_Texture* texture, SDL_Renderer* renderer, int x, int y, int h, int w,
SDL_Rect* clip = nullptr)
{
SDL_Rect dest;
dest.x = x;
dest.y = y;
dest.h = h;
dest.w = w;
renderTexture(texture, renderer, dest, clip);
}
// Main Function
int main(int, char**) 
{
SDL_Init(SDL_INIT_VIDEO);
SDL_Window* window = SDL_CreateWindow("New Window", SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED, Screen_Width, Screen_Height, SDL_WINDOW_RESIZABLE);
SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
SDL_Texture* longbutton_image = loadTexture("longbuttonSpriteSheet.png", renderer);
SDL_Texture* alpha_image = loadTexture("alphaImage.png", renderer);
SDL_Texture* beta_image = loadTexture("betaImage.png", renderer);
SDL_Texture* gamma_image = loadTexture("gammaImage.png", renderer);
state = BETA_STATE;
SDL_Rect alpha_clips[alphaButtonSprite::ALPHA_TOTAL];
for (int i = 0; i < alphaButtonSprite::ALPHA_TOTAL; i++)
{
alpha_clips[i].x = i * LONGBUTTON_WIDTH;
alpha_clips[i].y = 0;
alpha_clips[i].w = LONGBUTTON_WIDTH;
alpha_clips[i].h = LONGBUTTON_HEIGHT;
}
int usealpha_Clip = ALPHA_DEFAULT;
SDL_Rect beta_clips[betaButtonSprite::BETA_TOTAL];
for (int i = 0; i < betaButtonSprite::BETA_TOTAL; i++)
{
beta_clips[i].x = i * LONGBUTTON_WIDTH;
beta_clips[i].y = 4 * LONGBUTTON_HEIGHT;
beta_clips[i].w = LONGBUTTON_WIDTH;
beta_clips[i].h = LONGBUTTON_HEIGHT;
}
int usebeta_Clip = BETA_DEFAULT;
SDL_Rect gamma_clips[gammaButtonSprite::GAMMA_TOTAL];
for (int i = 0; i < gammaButtonSprite::GAMMA_TOTAL; i++)
{
gamma_clips[i].x = i * LONGBUTTON_WIDTH;
gamma_clips[i].y = 5 * LONGBUTTON_HEIGHT;
gamma_clips[i].w = LONGBUTTON_WIDTH;
gamma_clips[i].h = LONGBUTTON_HEIGHT;
}
int usegamma_Clip = GAMMA_DEFAULT;
SDL_Event e;
bool quit = false;
while (!quit)
{
while (SDL_PollEvent(&e))
{
switch (e.type)
{
case SDL_MOUSEBUTTONDOWN:
mouse_x = e.button.x;
mouse_y = e.button.y;
if ((mouse_x <= (alphabutton_x + alphabutton_w)) && (mouse_x > alphabutton_x) &&
(mouse_y <= (alphabutton_y + alphabutton_h)) && (mouse_y > alphabutton_y))
usealpha_Clip = ALPHA_PRESSED;
state = ALPHA_STATE;
if ((mouse_x <= (betabutton_x + betabutton_w)) && (mouse_x > betabutton_x) &&
(mouse_y <= (betabutton_y + betabutton_h)) && (mouse_y > betabutton_y))
usebeta_Clip = BETA_PRESSED;
state = BETA_STATE;
if ((mouse_x <= (gammabutton_x + gammabutton_w)) && (mouse_x > gammabutton_x) &&
(mouse_y <= (gammabutton_y + gammabutton_h)) && (mouse_y > gammabutton_y))
usegamma_Clip = GAMMA_PRESSED;
state = GAMMA_STATE;
break;
}
}
switch (state)
{
case ALPHA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(alpha_image, renderer, alpha_x, alpha_y, alpha_h, alpha_w, nullptr);
SDL_RenderPresent(renderer);
break;
case BETA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(beta_image, renderer, beta_x, beta_y, beta_h, beta_w, nullptr);
SDL_RenderPresent(renderer);
break;
case GAMMA_STATE:
SDL_RenderClear(renderer);
renderTexture(longbutton_image, renderer, alphabutton_x, alphabutton_y, alphabutton_h, alphabutton_w, &alpha_clips[usealpha_Clip]);
renderTexture(longbutton_image, renderer, betabutton_x, betabutton_y, betabutton_h, betabutton_w, &beta_clips[usebeta_Clip]);
renderTexture(longbutton_image, renderer, gammabutton_x, gammabutton_y, gammabutton_h, gammabutton_w, &gamma_clips[usegamma_Clip]);
renderTexture(gamma_image, renderer, gamma_x, gamma_y, gamma_h, gamma_w, nullptr);
SDL_RenderPresent(renderer);
break;
}

}
//Destroy the various items
cleanup(longbutton_image, alpha_image, beta_image, gamma_image, renderer, window);
IMG_Quit();
SDL_Quit();
return 0;
}

Answer 1

找到了这个问题的答案。在mousebuttondown事件开关的情况下，只需将状态代码放在useclip代码之前。为什么它会有不同，我不知道，但它有效。咳嗽此外，在mousebuttonup开关盒中而不是在mouseuttondown中进行操作效果更好。