如何使用标准C进行对htm文件中图片的读取与绘图

标准C语言本身并不提供直接读取和绘制HTML文件中图片的功能，但可以通过使用第三方库实现。

对于读取HTML文件中的图片，可以使用第三方库libxml2或者libcurl来解析HTML文件并提取其中的图片信息。

对于绘制图片，可以使用图形库，例如SDL或者OpenGL来实现。

以下是一个使用SDL库读取HTML文件中的图片并显示的示例代码：

#include <stdio.h>
#include <stdlib.h>
#include <SDL2/SDL.h>
#include <SDL2/SDL_image.h>
#include <libxml/parser.h>
#include <libxml/xpath.h>

int main(int argc, char *argv[])
{
    xmlDocPtr doc;
    xmlXPathContextPtr xpath_ctx;
    xmlXPathObjectPtr xpath_obj;
    xmlNodeSetPtr nodeset;
    xmlChar *xpath_expr = (xmlChar*) "//img/@src";
    int i;
    SDL_Window *win;
    SDL_Renderer *ren;
    SDL_Texture *tex;
    SDL_Surface *bmp;
    SDL_Rect rect;

    // Initialize SDL
    SDL_Init(SDL_INIT_VIDEO);

    // Create window and renderer
    win = SDL_CreateWindow("Image Viewer",
                           SDL_WINDOWPOS_UNDEFINED,
                           SDL_WINDOWPOS_UNDEFINED,
                           640, 480,
                           SDL_WINDOW_SHOWN);
    ren = SDL_CreateRenderer(win, -1, SDL_RENDERER_ACCELERATED);

    // Initialize libxml2
    xmlInitParser();

    // Parse HTML file
    doc = xmlReadFile(argv[1], NULL, 0);
    if (doc == NULL) {
        printf("Failed to parse document\n");
        return 1;
    }

    // Create XPath context
    xpath_ctx = xmlXPathNewContext(doc);
    if (xpath_ctx == NULL) {
        printf("Failed to create XPath context\n");
        return 1;
    }

    // Evaluate XPath expression
    xpath_obj = xmlXPathEvalExpression(xpath_expr, xpath_ctx);
    if (xpath_obj == NULL) {
        printf("Failed to evaluate XPath expression\n");
        return 1;
    }

    // Get nodeset from XPath object
    nodeset = xpath_obj->nodesetval;

    // Loop through nodeset and display images
    for (i = 0; i < nodeset->nodeNr; i++) {
        xmlChar *src = xmlNodeListGetString(doc, nodeset->nodeTab[i]->xmlChildrenNode, 1);
        bmp = IMG_Load((char*)src);
        if (bmp == NULL) {
            printf("Failed to load image %s\n", src);
            continue;
        }
        tex = SDL_CreateTextureFromSurface(ren, bmp);
        SDL_FreeSurface(bmp);
        xmlFree(src);
        if (tex == NULL) {
            printf("Failed to create texture\n");
            continue;
        }
        SDL_QueryTexture(tex, NULL, NULL, &rect.w, &rect.h);
        rect.x = i * rect.w;
        rect.y = 0;
        SDL_RenderCopy(ren, tex, NULL, &rect);
        SDL_DestroyTexture(tex);
    }

    // Free XPath object and context
    xmlXPathFreeObject(xpath_obj);
    xmlXPathFreeContext(xpath_ctx);

    // Free document
    xmlFreeDoc(doc);

    // Cleanup libxml2
    xmlCleanupParser();

    // Render and wait for user to close window
    SDL_RenderPresent(ren);
    SDL_Delay(3000);

    // Cleanup SDL
    SDL_DestroyRenderer(ren);
    SDL_DestroyWindow(win);
    SDL_Quit();

    return 0;
}

这段代码使用libxml2库解析HTML文件，提取其中的图片信息，并使用SDL库显示图片。你可以根据自己的需要修改代码，例如将图片保存到文件中，或者使用其他图形库进行绘制。