C# 使用SDL2进行视频播放窗口截图和字幕添加
使用SDL2进行视频播放窗口截图和字幕添加
SDL API查看：https://wiki.libsdl.org/APIByCategory
视频截图
///
/// SDL2截图操作类
///
public unsafe class SDLScreenshot
{
IntPtr window;// 窗口对象
IntPtr renderer;// 播放窗口的渲染器（来自于已初始化的播放窗口渲染器）
public SDLScreenshot(IntPtr window, IntPtr renderer)
{
this.window = window;
this.renderer = renderer;
}
///
/// 保存截图
///
///
///
///
public void SaveBMP(int width, int height,string path)
{
// 判断渲染器是否初始化
if (renderer == IntPtr.Zero)
{
Console.WriteLine("renderer is null ,please call Init() method.");
return;
}
uint Rmask=0x00FF0000, Gmask = 0x0000FF00, Bmask = 0x000000FF, Amask = 0x00000000;
// 获取图像数据
SDL.SDL_Surface* surface= (SDL.SDL_Surface*)SDL.SDL_CreateRGBSurface(0, width, height, 32, Rmask, Gmask, Bmask, Amask);
//设置纹理的数据
SDL.SDL_Rect destrect;
destrect.x = 0;
destrect.y = 0;
destrect.w = width;
destrect.h = height;
// 读取并渲染图像数据
SDL.SDL_RenderReadPixels(renderer, ref destrect, SDL.SDL_PIXELFORMAT_ARGB8888, surface->pixels, surface->pitch);
//保存图片
int i = SDL.SDL_SaveBMP((IntPtr)surface, path);
if (i != 0)
{
Console.WriteLine("screenshot failed." + SDL.SDL_GetError());
}
SDL.SDL_FreeSurface((IntPtr)surface);
//SDL.SDL_RenderClear(renderer);
//SDL.SDL_DestroyRenderer(renderer);
}
///
/// 加载截图
///
///
///
///
public void LoadBMP(int width, int height, string path)
{
// 判断渲染器是否初始化
if (renderer == IntPtr.Zero)
{
Console.WriteLine("renderer is null ,please call Init() method.");
return;
}
// 加载图片
IntPtr surface = SDL.SDL_LoadBMP(path);
if (surface == IntPtr.Zero)
{
Console.WriteLine("load bmp failed." + SDL.SDL_GetError());
return;
}
IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
if (texture == IntPtr.Zero)
{
Console.WriteLine("create texture failed." + SDL.SDL_GetError());
return;
}
SDL.SDL_FreeSurface(surface);
//设置纹理的数据
SDL.SDL_Rect destrect;
destrect.x = 0;
destrect.y = 0;
destrect.w = width;
destrect.h = height;
SDL.SDL_Rect srcrect = destrect;
//SDL.SDL_RenderClear(renderer);
SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
SDL.SDL_RenderPresent(renderer);
//SDL.SDL_Delay(20);
SDL.SDL_DestroyTexture(texture);
//SDL.SDL_DestroyRenderer(renderer);
//SDL.SDL_DestroyWindow(screen);
//Quit SDL
//SDL.SDL_Quit();
}
}播放测试代码：
if (isSaveScreenshot)
{
SDLScreenshot screenshot = new SDLScreenshot(sdlVideo.window, sdlVideo.sdlrenderer);
screenshot.SaveBMP(nvVideoframe.VideoFrame->width, nvVideoframe.VideoFrame->height, "screenshot.bmp");
isSaveScreenshot = false;
}测试效果图：
注：此处截图是直接获取的播放窗口的图像像素来实现的。
视频字幕
///
/// SDL2字幕显示类
///
public unsafe class SDLTTF
{
IntPtr renderer;// 播放窗口的渲染器（来自于已初始化的播放窗口渲染器）
public SDLTTF(IntPtr renderer)
{
this.renderer = renderer;
}
///
/// 展示字幕文字
///
///
public void ShowText(string ttfPath, int fontSize,string text)
{
// 初始化 ttf
if (SDL_ttf.TTF_Init() < 0)
{
Console.WriteLine("SDL_ttf.TTF_Init() failed.");
return;
}
// 是否初始化完成
int was_init = SDL_ttf.TTF_WasInit();
if (was_init == 1)
// SDL_ttf was already initialized
Console.WriteLine("SDL_ttf was already initialized");
else if (was_init == 0)
// SDL_ttf was not already initialized
Console.WriteLine("SDL_ttf was not already initialized");
// 判断是否初始化
if (renderer == IntPtr.Zero)
{
Console.WriteLine("Not initialized by SDL_ttf.TTF_Init() ,please call Init() method.");
return;
}
//如：打开ttfPath=simfang.ttf 字库，设字体为fontSize=20号
IntPtr font = SDL_ttf.TTF_OpenFont(ttfPath, fontSize);
if (font == IntPtr.Zero)
{
Console.WriteLine("open font failed." + SDL.SDL_GetError());
return;
}
// 设置文字颜色
SDL.SDL_Color color;
color.a = 255;
color.r = 255;
color.g = 255;
color.b = 255;
// 渲染文字效果
//IntPtr surface = SDL_ttf.TTF_RenderUTF8_Blended(font, text, color);
IntPtr surface = SDL_ttf.TTF_RenderUNICODE_Blended(font, text, color);
if (surface == IntPtr.Zero)
{
Console.WriteLine("show surface failed." + SDL.SDL_GetError());
}
IntPtr texture = SDL.SDL_CreateTextureFromSurface(renderer, surface);
if (texture == IntPtr.Zero)
{
Console.WriteLine("create texture failed." + SDL.SDL_GetError());
}
SDL.SDL_FreeSurface(surface);
// 关闭字体
SDL_ttf.TTF_CloseFont(font);
// 停止显示
SDL_ttf.TTF_Quit();
//设置纹理的数据
SDL.SDL_Rect destrect;
destrect.x = 0;
destrect.y = 0;
destrect.w = text.Length * 20;
destrect.h = 20;
SDL.SDL_Rect srcrect = destrect;
SDL.SDL_RenderClear(renderer);
SDL.SDL_RenderCopy(renderer, texture, ref srcrect, ref destrect);
SDL.SDL_RenderPresent(renderer);
SDL.SDL_DestroyTexture(texture);
SDL.SDL_DestroyRenderer(renderer);
}
}事件测试字幕添加：
需要的引用库下载：https://www.libsdl.org/projects/SDL_ttf/
///
/// 字幕叠加****需要添加三个dll库：SDL2_ttf.dll 、libfreetype-6.dll 、zlib1.dll
///
///
///
private void mbtnAddFontText_Click(object sender, EventArgs e)
{
Console.WriteLine("叠加字幕...............");
sdlTTF = new SDLTTF(sdlVideo.sdlrenderer);
// 中英文都需要兼容
string text = "Hello 世界!";
// 设置一个字体库并设置字体大小和显示文字内容
sdlTTF.ShowText("simkai.ttf",12, text);
}测试效果图：
如果是播放过程中显示字幕一定要在视频渲染完成后渲染字幕，如下面工具类的方法：
///
/// 播放视频
///
///
///
///
///
///
///
/// 设置字幕显示内容
///
///
///
public void SDL_TTF_TEXT(string ttfPath, string text, int fontSize)
{
this.ttfPath = ttfPath;
this.ttfText = text;
this.ttfFontSize = fontSize;
}
///
/// 渲染字幕
///
///
private void RenderToShowTTF(string text)
{
// 初始化 ttf
if (SDL_ttf.TTF_Init() < 0)
{
Console.WriteLine("SDL_ttf.TTF_Init() failed.");
return;
}
// 是否初始化完成
int was_init = SDL_ttf.TTF_WasInit();
if (was_init == 1)
// SDL_ttf was already initialized
Console.WriteLine("SDL_ttf was already initialized");
else if (was_init == 0)
// SDL_ttf was not already initialized
Console.WriteLine("SDL_ttf was not already initialized");
//如：打开ttfPath=simfang.ttf 字库，设字体为fontSize=20号
IntPtr font = SDL_ttf.TTF_OpenFont(ttfPath, ttfFontSize);
if (font == IntPtr.Zero)
{
Console.WriteLine("open font failed." + SDL.SDL_GetError());
return;
}
// 设置文字字体
SDL_ttf.TTF_SetFontStyle(font, SDL_ttf.TTF_STYLE_BOLD);
// 设置文字颜色
SDL.SDL_Color color;
color.a = 255;
color.r = 255;
color.g = 255;
color.b = 255;
// 渲染文字效果
//IntPtr surface = SDL_ttf.TTF_RenderText_Blended(font, text, color);
IntPtr surface = SDL_ttf.TTF_RenderUTF8_Blended(font, text, color);
//IntPtr surface = SDL_ttf.TTF_RenderUNICODE_Blended(font, text, color);
if (surface == IntPtr.Zero)
{
Console.WriteLine("show surface failed." + SDL.SDL_GetError());
}
IntPtr texture = SDL.SDL_CreateTextureFromSurface(sdlrenderer, surface);
if (texture == IntPtr.Zero)
{
Console.WriteLine("create texture failed." + SDL.SDL_GetError());
}
SDL.SDL_FreeSurface(surface);
// 关闭字体
SDL_ttf.TTF_CloseFont(font);
// 停止显示
SDL_ttf.TTF_Quit();
// 计算合适的宽度和高度
int texWidth = 0;
int texHeight = 0;
uint format = 0;
int access = 0;
// 下面这行代码解决字体虚浮不清问题
SDL.SDL_QueryTexture(texture, out format, out access, out texWidth, out texHeight);
//设置纹理的数据
SDL.SDL_Rect destrect;
destrect.x = 0;
destrect.y = 0;
destrect.w = texWidth;
destrect.h = texHeight;
SDL.SDL_Rect srcrect = destrect;
SDL.SDL_RenderCopy(sdlrenderer, texture, ref srcrect, ref destrect);
}效果就会好很多：
，请看这里的“中华人民共和国”
注意：常用中英文ttf字体包中包含了：times new roman，中山行书百年纪念版，calibri，Christopherhand，DejaVuSansMono，方正兰亭黑，James Fajardo，Monaco，微软雅黑，仿宋，黑体，楷体，宋体，yahei_mono，仿宋_GB2312，楷体_GB2312，迷你简行楷碑等。本文使用的是simkai.ttf。下面是部分字体文件名：
bb1550.ttf
calibri.ttf
calibrib.ttf
calibrii.ttf
calibriz.ttf
comesinhandy.ttf
DejaVuSansMono-Bold.ttf
DejaVuSansMono-BoldOblique.ttf
DejaVuSansMono-Oblique.ttf
DejaVuSansMono.ttf
DroidSansFallback.ttf
James_Fajardo.ttf
Monaco.ttf
msyh.ttf
msyhbd.ttf
simfang.ttf
simhei.ttf
simkai.ttf
simsun.ttc
times.ttf
timesbd.ttf
timesbi.ttf
timesi.ttf
yahei_mono.ttf
如果懒得下载，Windows里面有字体，在C:\Windows\Fonts目录下。
参考资料
sdl2.0 如何才能实现截图功能：http://tieba.baidu.com/p/5214857530
True type fonts with SDL_ttf : http://www.willusher.io/sdl2%20tutorials/2013/12/18/lesson-6-true-type-fonts-with-sdl_ttf
SDL TTF: http://www.sdltutorials.com/sdl-ttf
SDL 使用SDL_ttf显示文字: http://blog.csdn.net/rankun1/article/details/51393732