C++ OSD水印叠加_rk1126 osd叠加

视频相关领域（监控、LED大屏）很多场合可能会涉及到在一幅画面上进行文字或时间的叠加，常规做法都是在后端实现，即先渲染图像，然后叠加OSD文字信息，这种方法简单且高效。但是有些场合必须要求在前端进行叠加，比如监控领域中视频名称信息、时间信息等这些都需要在前端图像编码的时候就已经叠加到图像上，以防止用户修改和验伪。如果你有这种想法，那么这篇文章就算是帮助到你了，算是抛砖引玉的作用吧。

示例中采用jpeg图像作为底图，所以需要借助libjpeg将图像解码还原RGB原始图像数据，叠加OSD文字信息需借助freetype生成点阵RGB图像数据，然后对2个图像进行像素合并或重写。

// JpegOSD.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。
//
 
#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <fstream>
#include <string>
#include <windows.h>
 
#include "./libjpeg-turbo-win/jpeglib.h"
#include "./libjpeg-turbo-win/jerror.h"
 
#ifdef _DEBUG
#pragma comment(lib, "./x64/debug/libjpeg-turbo-win.lib")
#else
#pragma comment(lib, "./x64/release/libjpeg-turbo-win.lib")
#endif // _DEBUG
 
#include "ft2build.h"
#include FT_FREETYPE_H
#pragma comment(lib, "./freetype/freetype.lib")
 
// 将图像数据编码为.jpeg图像文件
bool saveJPEG(const char* filename, const unsigned char* image, int width, int height, int channels, int quality) {
	struct jpeg_compress_struct cinfo;
	struct jpeg_error_mgr jerr;
 
	FILE* file = fopen(filename, "wb");
	if (!file) {
		std::cout << "无法创建文件：" << filename << std::endl;
		return false;
	}
 
	cinfo.err = jpeg_std_error(&jerr);
	jpeg_create_compress(&cinfo);
	jpeg_stdio_dest(&cinfo, file);
 
	cinfo.image_width = width;
	cinfo.image_height = height;
	cinfo.input_components = channels;
	cinfo.in_color_space = JCS_RGB;
 
	jpeg_set_defaults(&cinfo);
	jpeg_set_quality(&cinfo, quality, TRUE);
 
	jpeg_start_compress(&cinfo, TRUE);
 
	JSAMPROW row_pointer[1];
	while (cinfo.next_scanline < cinfo.image_height) {
		row_pointer[0] = const_cast<JSAMPROW>(&image[cinfo.next_scanline * width * channels]);
		jpeg_write_scanlines(&cinfo, row_pointer, 1);
	}
 
	jpeg_finish_compress(&cinfo);
	fclose(file);
	jpeg_destroy_compress(&cinfo);
 
	return true;
}
 
int main()
{
	const char* filename = "D:/1.jpg";
	FILE* file = fopen(filename, "rb");
	if (!file) {
		std::cout << "打开文件失败: " << filename << std::endl;
		return -1;
	}
 
	unsigned long long dw1 = GetTickCount64();
 
	jpeg_decompress_struct cinfo;
	jpeg_error_mgr jerr;
 
	cinfo.err = jpeg_std_error(&jerr);
	jpeg_create_decompress(&cinfo);
 
	// 加载图像文件
	jpeg_stdio_src(&cinfo, file);
 
	// 获取图像压缩信息
	jpeg_read_header(&cinfo, TRUE);
	jpeg_start_decompress(&cinfo);
 
	// 获取图像信息
	int width = cinfo.output_width;
	int height = cinfo.output_height;
	int channels = cinfo.output_components;
 
	// 申请图像数据内存
	unsigned char* image = new unsigned char[width * height * channels];
 
	while (cinfo.output_scanline < cinfo.output_height) {
		unsigned char* row = image + (cinfo.output_scanline * width * channels);
		jpeg_read_scanlines(&cinfo, &row, 1);
	}
 
	//加载FreeType字体库
	FT_Library ftLibrary;
	if (FT_Init_FreeType(&ftLibrary)) {
		std::cout << "Failed to initialize FreeType library" << std::endl;
		return -1;
	}
 
	FT_Face ftFace;
	if (FT_New_Face(ftLibrary, "font.ttf", 0, &ftFace)) {
		std::cout << "Failed to load font file" << std::endl;
		FT_Done_FreeType(ftLibrary);
		return -1;
	}
 
	// 设置字符大小
	int fontSize = 48; 
	FT_Set_Pixel_Sizes(ftFace, 0, fontSize);
 
	// 叠加OSD字符信息
	const char* osdString = "Hello World!";
 
	// OSD颜色
	unsigned char textColor[4] = { 255, 0, 0, 255 }; // 红色
 
	// OSD叠加位置
	int posX = 100;
	int posY = 200;
 
	// 水印叠加
	for (int i = 0; i < strlen(osdString); ++i) {
		if (FT_Load_Char(ftFace, osdString[i], FT_LOAD_RENDER))
			continue;
 
		FT_GlyphSlot ftGlyph = ftFace->glyph;
 
		int glyphWidth = ftGlyph->bitmap.width;
		int glyphHeight = ftGlyph->bitmap.rows;
		unsigned char* glyphBitmap = ftGlyph->bitmap.buffer;
 
		for (int y = 0; y < glyphHeight; ++y) {
			for (int x = 0; x < glyphWidth; ++x) {
				if (glyphBitmap[y * glyphWidth + x] != 0x00)//透明叠加 
				{
					int imgX = posX + ftGlyph->bitmap_left + x;
					int imgY = posY - ftGlyph->bitmap_top + y;
 
					if (imgX >= 0 && imgX < width && imgY >= 0 && imgY < height) {
						int pixelIndex = (imgY * width + imgX) * channels;
 
						for (int c = 0; c < channels; ++c) {
							image[pixelIndex + c] = textColor[c];
						}
					}
				}
			}			
		}
 
		posX += ftGlyph->advance.x >> 6; // 移动到下一个字符的位置
	}
 
	unsigned long long dw2 = GetTickCount64();
	std::cout << "水印叠加时间：" << (dw2 - dw1) << "ms" << std::endl;
 
	// 将修改后的图像数据编码为.jpeg图像文件
	const char* outputFilename = "D:/watermarked_image.jpg";
	int quality = 90;
	if (!saveJPEG(outputFilename, image, width, height, channels, quality)) {
		std::cout << "Failed to save JPEG file: " << outputFilename << std::endl;
	}
	else {
		unsigned long long dw3 = GetTickCount64();
		std::cout << "水印图像已保存至：" << outputFilename << "，保存时间：" << (dw3 - dw2) << "ms" << std::endl;
	}
 
	// 释放内存
	delete[] image;
	FT_Done_Face(ftFace);
	FT_Done_FreeType(ftLibrary);
	jpeg_finish_decompress(&cinfo);
	jpeg_destroy_decompress(&cinfo);
	fclose(file);
 
	return 0;
}