What is SDL?
SDL is actually a function library convenient for game development. SDL provides several functions to control image, sound, output and input, so that developers can develop application software across multiple platforms (Linux, Windows, Mac OS X, etc.) with the same or similar code.
What's the use of learning SDL?
At present, SDL is mostly used to develop multimedia applications such as games, simulators and media players.
What are the difficulties of SDL learning?
Using vs Software, we need to introduce SDL library functions. SDL is used as a writing tool. Our purpose is to flexibly master the use methods of SDL functions, including: the type, number and meaning of passed parameters; Function return value type and its meaning; How to debug if there are errors in the use of functions; Individual functions must have corresponding function aftertreatment after use (functions that open up memory, release memory in order after use, so as to facilitate the recycling of memory)..., we will learn according to this mode.
Configuration of 0/0 SDl project
1. Create a project in vs and create a new main function.
2. Add the SDL header file include to the attachment of the property page.
3. Add SDL static library file to vs project.
1 / 0 display window with SDL
#include "SDL.h"
#include <stdio.h>
#include <Windows.h>
int main(void)
{
SDL_Window * pWindow = NULL;
// 1 initialize SDL Library
if(SDL_Init(SDL_INIT_EVERYTHING) != 0)
{
printf("SDL initialization failed!%s\n", SDL_GetError());
return -1;
}
printf("SDL Initialization succeeded!\n");
// 2 create window
pWindow = SDL_CreateWindow("Lesson01",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, //In the middle of the display
400, 400,//400px length and width
SDL_WINDOW_SHOWN);
if(pWindow == NULL)
{
printf("SDL Window creation failed!\n");
}
else
{
printf("SDL Window created successfully!\n");
}
// Delay 2000 ms for easy observation
SDL_Delay(2000);
// 3 destroy window
SDL_DestroyWindow(pWindow);
// 4 exit SDL Library
SDL_Quit();
return 0;
Two common SDL functions used above:
1. int SDL_Init(Uint32 flags)
Function: initialize the subsystem of SDL library
Parameter: Flag subsystem identifier
SDL_INIT_TIMER Timer subsystem
SDL_INIT_AUDIO Audio subsystem
SDL_INIT_VIDEO Video subsystem
SDL_INIT_JOYSTICK Lever subsystem
SDL_INIT_HAPTIC Touch screen feedback subsystem
SDL_INIT_GAMECONTROLLER Controller subsystem
SDL_INIT_EVENTS Event subsystem
SDL_INIT_EVERYTHING All subsystems
SDL_INIT_NOPARACHUTE Non capture lethal signal subsystem
Return value: 0 when successful
- 1 on failure
2. SDL_Window SDL_CreateWindow(const char title,
int x,
int y,
int w,
int h,
Uint32 flags)
Function: create window
Parameters:
title The title of the window, UTF-8 code.(Chinese is not supported)
x, y The position of the screen where the window is located, X Coordinates, Y coordinate
SDL_WINDOWPOS_CENTERED Center
w, h The width and height of the window
flags Type identifier of the window when it was created
SDL_WINDOW_FULLSCREEN Window full screen
SDL_WINDOW_FULLSCREEN_DESKTOP Window full screen at current desktop resolution
SDL_WINDOW_OPENGL OpenGL Available windows under
SDL_WINDOW_SHOWN The window is visible and the window is displayed
SDL_WINDOW_HIDDEN The window is invisible and hidden
SDL_WINDOW_BORDERLESS Windows have no borders
SDL_WINDOW_RESIZABLE The window can be resized
SDL_WINDOW_MINIMIZED window minimizing
SDL_WINDOW_MAXIMIZED window maximizing
SDL_WINDOW_INPUT_GRABBED The window has input focus
SDL_WINDOW_INPUT_FOCUS The window has input focus
SDL_WINDOW_MOUSE_FOCUS The window can get the mouse focus
SDL_WINDOW_FOREIGN Window is not SDL Created
SDL_WINDOW_ALLOW_HIGHDPI Windows should be created in high-DPI Mode(>= SDL 2.0.1)
SDL_WINDOW_MOUSE_CAPTURE The window can capture the mouse focus(>= SDL 2.0.4)
(And SDL_WINDOW_INPUT_GRABBED irrelevant)
Return value: SDL is returned after the creation is successful_ Window * window pointer
Creation failed, NULL returned
1. Pay attention to the way of debug ging in the code.
Use the return value of the function to judge whether the function successfully completes the task. Use SDL at the same time_ Geterror() function to determine the bug type—— Because the compiler will not tell the SDL function to use the error. This is a different place to study.
2. Functions in pairs (free memory)
Initialize SDL library and exit SDL Library:
SDL_Window* SDL_CreateWindow()
SDL_Destroywindow()
Create and destroy windows:
SDL_CreatWindow()
SDL_DestroyeWindow()
2 / 0 color fill the window
Note: the fill color actually changes the relevant code information stored in the Surface layer of Window.
SDL_Surface * pSurface = NULL;
// Get the Surface of the window
pSurface = SDL_GetWindowSurface(pWindow);
// Fill the Surface with red
SDL_FillRect(pSurface, NULL, SDL_MapRGB(pSurface->format,152, 29, 29));
Here, you may think that the color filling is completed, but the window is displayed immediately when it is created successfully. When the color filling code is executed, the window will not be updated automatically. Therefore, we need to add a WindowSurface update function.
// Update window Surface
SDL_UpdateWindowSurface(pWindow);
At this time, the goal is completed!
3/0 SDL loads and displays a picture
#include <stdio.h>
#include "SDL.h"
int main(void)
{
SDL_Window * pWindow = NULL; // window
SDL_Renderer * pRenderer = NULL; // Renderer
SDL_Surface * pSurface = NULL; // layer
SDL_Texture * pTexture = NULL; // texture
// Initialize SDL Library
if(SDL_Init(SDL_INIT_EVERYTHING) != 0)
{
printf("%s\n", SDL_GetError());
return -1;
}
// create a window
pWindow = SDL_CreateWindow("lesson02",
SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
1000, 600, SDL_WINDOW_SHOWN);
if(NULL == pWindow)
{
printf("%s\n", SDL_GetError());
return -1;
}
// Create renderer
pRenderer = SDL_CreateRenderer(pWindow, -1,
SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC);
if(NULL == pRenderer)
{
printf("%s\n", SDL_GetError());
return -1;
}
// Load picture generation layer according to picture path
pSurface = SDL_LoadBMP("../image/HelloWorld.bmp");
if(NULL == pSurface)
{
printf("%s\n", SDL_GetError());
return -1;
}
// Generate textures from layers based on a renderer
pTexture = SDL_CreateTextureFromSurface(pRenderer, pSurface);
if(NULL == pTexture)
{
printf("%s\n", SDL_GetError());
return -1;
}
// Release layer
SDL_FreeSurface(pSurface);
// Copy image to renderer
SDL_RenderCopy(pRenderer, pTexture, NULL, NULL);
// Change line renderer
SDL_RenderPresent(pRenderer);
// delayed
SDL_Delay(3000);
// Destroy renderer
SDL_DestroyRenderer(pRenderer);
// Destroy Window
// SDL_DestroyWindow(pWindow);
// Exit SDL Library
SDL_Quit();
return 0;
}
SDL_Renderer SDL_CreateRenderer(SDL_Window window,**
int index,
Uint32 flags)
Parameters: target window of the window renderer
index The index value of the device to be initialized,-1 Indicates that the default rendering device is initialized
flags Render mode identifier
SDL_RENDERER_SOFTWARE Using software rendering
SDL_RENDERER_ACCELERATED Hardware accelerated rendering
SDL_RENDERER_PRESENTVSYNC Synchronize with the refresh rate of the display
SDL_RENDERER_TARGETTEXTURE The renderer supports rendering textures
**Return value: * * if the creation is successful, the created renderer will be returned
Creation failed, NULL returned
technological process:
Initialize SDL Library - > create Window - > createrenderer - > loadmp (generate layer from Image) - > createtexturefromsurface (assign texture generated by layer) to renderer - > freesurface (free space occupied by layer) - > renderercopy (copy Image by renderer) - > rendererpresent (update renderer) - > destroyrenderer - > d Estroywindow - > quit