第06章 - C语言API编程基础
第06章 - C语言API编程基础
6.1 API概述
6.1.1 头文件结构
LibreDWG提供两层API：
// 核心层 - 底层数据结构和函数
#include <dwg.h>
// API层 - 简化的高级接口
#include <dwg_api.h>
选择建议：
- 一般开发使用
dwg_api.h即可 - 需要底层控制时使用
dwg.h - 可以同时包含两者
6.1.2 编译和链接
基本编译命令：
# 使用gcc
gcc -o myapp myapp.c -lredwg
# 使用pkg-config
gcc -o myapp myapp.c $(pkg-config --cflags --libs libredwg)
Makefile示例：
CC = gcc
CFLAGS = $(shell pkg-config --cflags libredwg)
LDFLAGS = $(shell pkg-config --libs libredwg)
all: myapp
myapp: myapp.c
$(CC) $(CFLAGS) -o $@ $< $(LDFLAGS)
clean:
rm -f myapp
CMake配置：
cmake_minimum_required(VERSION 3.10)
project(MyDWGApp C)
find_package(PkgConfig REQUIRED)
pkg_check_modules(LIBREDWG REQUIRED libredwg)
add_executable(myapp myapp.c)
target_include_directories(myapp PRIVATE ${LIBREDWG_INCLUDE_DIRS})
target_link_libraries(myapp ${LIBREDWG_LIBRARIES})
6.2 基本读取操作
6.2.1 读取DWG文件
#include <stdio.h>
#include <string.h>
#include <dwg.h>
int main(int argc, char *argv[])
{
Dwg_Data dwg;
int error;
if (argc < 2) {
fprintf(stderr, "用法: %s <dwg文件>\n", argv[0]);
return 1;
}
// 初始化结构体（重要！）
memset(&dwg, 0, sizeof(Dwg_Data));
// 读取DWG文件
error = dwg_read_file(argv[1], &dwg);
if (error >= DWG_ERR_CRITICAL) {
fprintf(stderr, "读取文件失败，错误码: %d\n", error);
return 1;
}
// 打印基本信息
printf("DWG版本: %s\n", dwg.header.version);
printf("对象数量: %lu\n", (unsigned long)dwg.num_objects);
printf("类数量: %lu\n", (unsigned long)dwg.num_classes);
// 释放内存
dwg_free(&dwg);
return 0;
}
6.2.2 错误处理
#include <dwg.h>
int read_dwg_with_error_handling(const char *filename)
{
Dwg_Data dwg;
int error;
memset(&dwg, 0, sizeof(Dwg_Data));
error = dwg_read_file(filename, &dwg);
// 检查各种错误
if (error & DWG_ERR_IOERROR) {
fprintf(stderr, "IO错误：无法读取文件\n");
return -1;
}
if (error & DWG_ERR_INVALIDDWG) {
fprintf(stderr, "无效的DWG文件格式\n");
return -1;
}
if (error & DWG_ERR_OUTOFMEM) {
fprintf(stderr, "内存不足\n");
return -1;
}
// 非严重错误可以继续处理
if (error && error < DWG_ERR_CRITICAL) {
fprintf(stderr, "警告：存在非严重错误 (0x%x)\n", error);
}
if (error >= DWG_ERR_CRITICAL) {
fprintf(stderr, "严重错误，无法继续 (0x%x)\n", error);
dwg_free(&dwg);
return -1;
}
// 处理DWG数据...
dwg_free(&dwg);
return 0;
}
6.2.3 版本检测
#include <dwg.h>
void print_version_info(Dwg_Data *dwg)
{
printf("文件版本字符串: %s\n", dwg->header.version);
// 使用版本枚举
switch (dwg->header.version) {
case R_2018:
printf("版本: AutoCAD 2018 (R2018)\n");
break;
case R_2013:
printf("版本: AutoCAD 2013 (R2013)\n");
break;
case R_2010:
printf("版本: AutoCAD 2010 (R2010)\n");
break;
case R_2007:
printf("版本: AutoCAD 2007 (R2007)\n");
break;
case R_2004:
printf("版本: AutoCAD 2004 (R2004)\n");
break;
case R_2000:
printf("版本: AutoCAD 2000 (R2000)\n");
break;
case R_14:
printf("版本: AutoCAD R14\n");
break;
case R_13:
printf("版本: AutoCAD R13\n");
break;
default:
printf("版本: 其他 (%d)\n", dwg->header.version);
}
}
6.3 遍历对象
6.3.1 遍历所有对象
#include <dwg.h>
void iterate_all_objects(Dwg_Data *dwg)
{
BITCODE_BL i;
printf("对象列表（共 %lu 个）:\n", (unsigned long)dwg->num_objects);
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
printf("对象 %lu: 类型=%d (%s), 句柄=0x%lx\n",
(unsigned long)i,
obj->type,
obj->name ? obj->name : "unknown",
(unsigned long)obj->handle.value);
}
}
6.3.2 按类型遍历
#include <dwg.h>
// 统计各类型对象数量
void count_object_types(Dwg_Data *dwg)
{
BITCODE_BL i;
int line_count = 0;
int circle_count = 0;
int arc_count = 0;
int text_count = 0;
int mtext_count = 0;
int other_count = 0;
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
switch (obj->fixedtype) {
case DWG_TYPE_LINE:
line_count++;
break;
case DWG_TYPE_CIRCLE:
circle_count++;
break;
case DWG_TYPE_ARC:
arc_count++;
break;
case DWG_TYPE_TEXT:
text_count++;
break;
case DWG_TYPE_MTEXT:
mtext_count++;
break;
default:
other_count++;
break;
}
}
printf("类型统计:\n");
printf(" LINE: %d\n", line_count);
printf(" CIRCLE: %d\n", circle_count);
printf(" ARC: %d\n", arc_count);
printf(" TEXT: %d\n", text_count);
printf(" MTEXT: %d\n", mtext_count);
printf(" 其他: %d\n", other_count);
}
6.3.3 遍历模型空间实体
#include <dwg.h>
#include <dwg_api.h>
void iterate_model_space(Dwg_Data *dwg)
{
Dwg_Object_Ref *mspace_ref;
Dwg_Object *mspace_obj;
Dwg_Object_BLOCK_HEADER *mspace;
Dwg_Object *obj;
// 获取模型空间块记录
mspace_ref = dwg->header_vars.BLOCK_RECORD_MSPACE;
if (!mspace_ref || !mspace_ref->obj) {
fprintf(stderr, "无法获取模型空间\n");
return;
}
mspace_obj = mspace_ref->obj;
if (mspace_obj->fixedtype != DWG_TYPE_BLOCK_HEADER) {
fprintf(stderr, "模型空间类型错误\n");
return;
}
mspace = mspace_obj->tio.object->tio.BLOCK_HEADER;
printf("模型空间实体:\n");
// 从第一个实体开始遍历
if (mspace->first_entity && mspace->first_entity->obj) {
obj = mspace->first_entity->obj;
while (obj) {
if (obj->supertype == DWG_SUPERTYPE_ENTITY) {
printf(" 实体: %s (句柄: 0x%lx)\n",
obj->name ? obj->name : "unknown",
(unsigned long)obj->handle.value);
}
// 获取下一个实体
// 需要通过句柄链遍历
// 简化处理：检查owned entities
break; // 简化示例
}
}
}
6.4 访问实体属性
6.4.1 LINE实体
#include <dwg.h>
void process_line(Dwg_Object *obj)
{
Dwg_Entity_LINE *line;
if (obj->fixedtype != DWG_TYPE_LINE) {
return;
}
line = obj->tio.entity->tio.LINE;
printf("LINE:\n");
printf(" 起点: (%.6f, %.6f, %.6f)\n",
line->start.x, line->start.y, line->start.z);
printf(" 终点: (%.6f, %.6f, %.6f)\n",
line->end.x, line->end.y, line->end.z);
printf(" 厚度: %.6f\n", line->thickness);
printf(" 挤出: (%.6f, %.6f, %.6f)\n",
line->extrusion.x, line->extrusion.y, line->extrusion.z);
// 计算长度
double dx = line->end.x - line->start.x;
double dy = line->end.y - line->start.y;
double dz = line->end.z - line->start.z;
double length = sqrt(dx*dx + dy*dy + dz*dz);
printf(" 长度: %.6f\n", length);
}
6.4.2 CIRCLE实体
#include <dwg.h>
#include <math.h>
void process_circle(Dwg_Object *obj)
{
Dwg_Entity_CIRCLE *circle;
if (obj->fixedtype != DWG_TYPE_CIRCLE) {
return;
}
circle = obj->tio.entity->tio.CIRCLE;
printf("CIRCLE:\n");
printf(" 圆心: (%.6f, %.6f, %.6f)\n",
circle->center.x, circle->center.y, circle->center.z);
printf(" 半径: %.6f\n", circle->radius);
printf(" 厚度: %.6f\n", circle->thickness);
printf(" 挤出: (%.6f, %.6f, %.6f)\n",
circle->extrusion.x, circle->extrusion.y, circle->extrusion.z);
// 计算周长和面积
double circumference = 2 * M_PI * circle->radius;
double area = M_PI * circle->radius * circle->radius;
printf(" 周长: %.6f\n", circumference);
printf(" 面积: %.6f\n", area);
}
6.4.3 TEXT实体
#include <dwg.h>
void process_text(Dwg_Object *obj)
{
Dwg_Entity_TEXT *text;
if (obj->fixedtype != DWG_TYPE_TEXT) {
return;
}
text = obj->tio.entity->tio.TEXT;
printf("TEXT:\n");
printf(" 内容: %s\n", text->text_value ? text->text_value : "(空)");
printf(" 插入点: (%.6f, %.6f)\n",
text->ins_pt.x, text->ins_pt.y);
printf(" 高度: %.6f\n", text->height);
printf(" 旋转: %.6f 度\n", text->rotation * 180.0 / M_PI);
printf(" 宽度因子: %.6f\n", text->width_factor);
printf(" 水平对齐: %d\n", text->horiz_alignment);
printf(" 垂直对齐: %d\n", text->vert_alignment);
}
6.4.4 LWPOLYLINE实体
#include <dwg.h>
void process_lwpolyline(Dwg_Object *obj)
{
Dwg_Entity_LWPOLYLINE *lwpline;
BITCODE_BL i;
if (obj->fixedtype != DWG_TYPE_LWPOLYLINE) {
return;
}
lwpline = obj->tio.entity->tio.LWPOLYLINE;
printf("LWPOLYLINE:\n");
printf(" 点数: %lu\n", (unsigned long)lwpline->num_points);
printf(" 闭合: %s\n", (lwpline->flag & 1) ? "是" : "否");
printf(" 高程: %.6f\n", lwpline->elevation);
printf(" 厚度: %.6f\n", lwpline->thickness);
// 打印所有顶点
printf(" 顶点:\n");
for (i = 0; i < lwpline->num_points; i++) {
printf(" %lu: (%.6f, %.6f)",
(unsigned long)i,
lwpline->points[i].x,
lwpline->points[i].y);
// 打印凸度（如果有）
if (i < lwpline->num_bulges && lwpline->bulges) {
printf(", 凸度=%.6f", lwpline->bulges[i]);
}
// 打印宽度（如果有）
if (i < lwpline->num_widths && lwpline->widths) {
printf(", 宽度=(%.6f, %.6f)",
lwpline->widths[i].start,
lwpline->widths[i].end);
}
printf("\n");
}
}
6.5 访问图层和样式
6.5.1 遍历图层
#include <dwg.h>
void list_layers(Dwg_Data *dwg)
{
BITCODE_BL i;
printf("图层列表:\n");
printf("%-20s %-10s %-15s %s\n",
"名称", "颜色", "线型", "状态");
printf("----------------------------------------------------\n");
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->fixedtype == DWG_TYPE_LAYER) {
Dwg_Object_LAYER *layer = obj->tio.object->tio.LAYER;
const char *status = "";
if (layer->frozen) status = "冻结";
else if (!layer->on) status = "关闭";
else if (layer->locked) status = "锁定";
else status = "正常";
printf("%-20s %-10d %-15s %s\n",
layer->name ? layer->name : "(无名)",
layer->color.index,
layer->ltype && layer->ltype->obj ?
layer->ltype->obj->tio.object->tio.LTYPE->name : "Continuous",
status);
}
}
}
6.5.2 获取实体的图层信息
#include <dwg.h>
void get_entity_layer(Dwg_Data *dwg, Dwg_Object *obj)
{
Dwg_Object_Entity *ent;
Dwg_Object_LAYER *layer;
if (obj->supertype != DWG_SUPERTYPE_ENTITY) {
return;
}
ent = obj->tio.entity;
if (ent->layer && ent->layer->obj) {
if (ent->layer->obj->fixedtype == DWG_TYPE_LAYER) {
layer = ent->layer->obj->tio.object->tio.LAYER;
printf("实体所在图层: %s\n", layer->name);
}
} else {
printf("实体所在图层: 0 (默认)\n");
}
}
6.5.3 遍历文字样式
#include <dwg.h>
void list_styles(Dwg_Data *dwg)
{
BITCODE_BL i;
printf("文字样式列表:\n");
printf("%-15s %-15s %-10s %s\n",
"名称", "字体", "高度", "宽度因子");
printf("--------------------------------------------------\n");
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->fixedtype == DWG_TYPE_STYLE) {
Dwg_Object_STYLE *style = obj->tio.object->tio.STYLE;
printf("%-15s %-15s %-10.2f %.2f\n",
style->name ? style->name : "(无名)",
style->font_file ? style->font_file : "(默认)",
style->fixed_height,
style->width_factor);
}
}
}
6.6 使用dwg_api.h
6.6.1 简化的API函数
#include <dwg.h>
#include <dwg_api.h>
// 使用API获取实体属性
void demo_api_functions(Dwg_Data *dwg)
{
BITCODE_BL i;
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->fixedtype == DWG_TYPE_LINE) {
Dwg_Entity_LINE *line = obj->tio.entity->tio.LINE;
// 使用API宏/函数
dwg_point_3d start, end;
dwg_ent_line_get_start_point(line, &start, NULL);
dwg_ent_line_get_end_point(line, &end, NULL);
printf("LINE: (%.2f,%.2f,%.2f) -> (%.2f,%.2f,%.2f)\n",
start.x, start.y, start.z,
end.x, end.y, end.z);
}
if (obj->fixedtype == DWG_TYPE_CIRCLE) {
Dwg_Entity_CIRCLE *circle = obj->tio.entity->tio.CIRCLE;
dwg_point_3d center;
BITCODE_BD radius;
dwg_ent_circle_get_center(circle, ¢er, NULL);
dwg_ent_circle_get_radius(circle, &radius, NULL);
printf("CIRCLE: 圆心(%.2f,%.2f,%.2f), 半径%.2f\n",
center.x, center.y, center.z, radius);
}
}
}
6.6.2 API遍历宏
#include <dwg.h>
#include <dwg_api.h>
// 使用DWG_GETALL宏遍历特定类型
void demo_getall_macro(Dwg_Data *dwg)
{
BITCODE_BL error = 0;
Dwg_Entity_LINE *line;
Dwg_Entity_CIRCLE *circle;
// 遍历所有LINE
printf("所有LINE实体:\n");
line = dwg_getall_LINE(dwg);
while (line) {
printf(" LINE: (%.2f,%.2f) -> (%.2f,%.2f)\n",
line->start.x, line->start.y,
line->end.x, line->end.y);
line = (Dwg_Entity_LINE*)line->parent->parent->next_entity;
// 注意：实际遍历需要更复杂的逻辑
break;
}
}
6.7 通用实体处理
6.7.1 通用实体处理函数
#include <dwg.h>
#include <math.h>
// 通用实体处理器
void process_entity(Dwg_Object *obj)
{
if (obj->supertype != DWG_SUPERTYPE_ENTITY) {
return;
}
Dwg_Object_Entity *ent = obj->tio.entity;
// 打印通用信息
printf("实体: %s\n", obj->name);
printf(" 句柄: 0x%lx\n", (unsigned long)obj->handle.value);
printf(" 颜色索引: %d\n", ent->color.index);
printf(" 线型比例: %.2f\n", ent->ltype_scale);
printf(" 线宽: %d\n", ent->lineweight);
// 按类型处理
switch (obj->fixedtype) {
case DWG_TYPE_LINE:
process_line(obj);
break;
case DWG_TYPE_CIRCLE:
process_circle(obj);
break;
case DWG_TYPE_ARC:
process_arc(obj);
break;
case DWG_TYPE_TEXT:
process_text(obj);
break;
case DWG_TYPE_MTEXT:
process_mtext(obj);
break;
case DWG_TYPE_LWPOLYLINE:
process_lwpolyline(obj);
break;
// ... 其他类型
default:
printf(" (未实现的类型处理)\n");
break;
}
}
void process_arc(Dwg_Object *obj)
{
Dwg_Entity_ARC *arc = obj->tio.entity->tio.ARC;
printf(" 圆心: (%.6f, %.6f, %.6f)\n",
arc->center.x, arc->center.y, arc->center.z);
printf(" 半径: %.6f\n", arc->radius);
printf(" 起始角: %.2f 度\n", arc->start_angle * 180.0 / M_PI);
printf(" 终止角: %.2f 度\n", arc->end_angle * 180.0 / M_PI);
}
void process_mtext(Dwg_Object *obj)
{
Dwg_Entity_MTEXT *mtext = obj->tio.entity->tio.MTEXT;
printf(" 插入点: (%.6f, %.6f, %.6f)\n",
mtext->ins_pt.x, mtext->ins_pt.y, mtext->ins_pt.z);
printf(" 宽度: %.6f\n", mtext->rect_width);
printf(" 内容: %s\n", mtext->text ? mtext->text : "(空)");
}
6.7.2 计算范围（Extents）
#include <dwg.h>
#include <float.h>
#include <math.h>
typedef struct {
double min_x, min_y, min_z;
double max_x, max_y, max_z;
} Extents3D;
void init_extents(Extents3D *ext)
{
ext->min_x = ext->min_y = ext->min_z = DBL_MAX;
ext->max_x = ext->max_y = ext->max_z = -DBL_MAX;
}
void update_extents_point(Extents3D *ext, double x, double y, double z)
{
if (x < ext->min_x) ext->min_x = x;
if (y < ext->min_y) ext->min_y = y;
if (z < ext->min_z) ext->min_z = z;
if (x > ext->max_x) ext->max_x = x;
if (y > ext->max_y) ext->max_y = y;
if (z > ext->max_z) ext->max_z = z;
}
void calculate_extents(Dwg_Data *dwg, Extents3D *ext)
{
BITCODE_BL i;
init_extents(ext);
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->supertype != DWG_SUPERTYPE_ENTITY) {
continue;
}
switch (obj->fixedtype) {
case DWG_TYPE_LINE: {
Dwg_Entity_LINE *line = obj->tio.entity->tio.LINE;
update_extents_point(ext, line->start.x, line->start.y, line->start.z);
update_extents_point(ext, line->end.x, line->end.y, line->end.z);
break;
}
case DWG_TYPE_CIRCLE: {
Dwg_Entity_CIRCLE *circle = obj->tio.entity->tio.CIRCLE;
update_extents_point(ext,
circle->center.x - circle->radius,
circle->center.y - circle->radius,
circle->center.z);
update_extents_point(ext,
circle->center.x + circle->radius,
circle->center.y + circle->radius,
circle->center.z);
break;
}
case DWG_TYPE_POINT: {
Dwg_Entity_POINT *point = obj->tio.entity->tio.POINT;
update_extents_point(ext, point->x, point->y, point->z);
break;
}
// ... 其他类型
}
}
printf("图纸范围:\n");
printf(" 最小: (%.6f, %.6f, %.6f)\n", ext->min_x, ext->min_y, ext->min_z);
printf(" 最大: (%.6f, %.6f, %.6f)\n", ext->max_x, ext->max_y, ext->max_z);
}
6.8 完整示例程序
6.8.1 DWG信息查看器
/* dwg_info.c - DWG文件信息查看器 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <dwg.h>
// 版本名称映射
const char* get_version_name(Dwg_Version_Type version)
{
switch (version) {
case R_1_1: return "R1.1";
case R_1_2: return "R1.2";
case R_2_0: return "R2.0";
case R_9: return "R9";
case R_10: return "R10";
case R_11: return "R11/R12";
case R_13: return "R13";
case R_14: return "R14";
case R_2000: return "R2000";
case R_2004: return "R2004";
case R_2007: return "R2007";
case R_2010: return "R2010";
case R_2013: return "R2013";
case R_2018: return "R2018";
default: return "未知";
}
}
// 统计实体类型
void print_entity_stats(Dwg_Data *dwg)
{
int stats[100] = {0};
const char *type_names[100] = {0};
BITCODE_BL i;
int type_count = 0;
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->supertype == DWG_SUPERTYPE_ENTITY) {
int type = obj->fixedtype;
if (type < 100) {
if (stats[type] == 0 && obj->name) {
type_names[type] = obj->name;
}
stats[type]++;
}
}
}
printf("\n实体类型统计:\n");
printf("%-20s %s\n", "类型", "数量");
printf("--------------------------------\n");
for (i = 0; i < 100; i++) {
if (stats[i] > 0) {
printf("%-20s %d\n",
type_names[i] ? type_names[i] : "Unknown",
stats[i]);
}
}
}
// 打印图层信息
void print_layers(Dwg_Data *dwg)
{
BITCODE_BL i;
int layer_count = 0;
printf("\n图层列表:\n");
printf("%-25s %-10s %s\n", "名称", "颜色", "状态");
printf("------------------------------------------\n");
for (i = 0; i < dwg->num_objects; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->fixedtype == DWG_TYPE_LAYER) {
Dwg_Object_LAYER *layer = obj->tio.object->tio.LAYER;
const char *status = "正常";
if (layer->frozen) status = "冻结";
else if (!layer->on) status = "关闭";
else if (layer->locked) status = "锁定";
printf("%-25s %-10d %s\n",
layer->name ? layer->name : "(无名)",
layer->color.index,
status);
layer_count++;
}
}
printf("共 %d 个图层\n", layer_count);
}
// 打印文本内容
void print_texts(Dwg_Data *dwg, int max_count)
{
BITCODE_BL i;
int count = 0;
printf("\n文本内容（最多显示 %d 个）:\n", max_count);
printf("------------------------------------------\n");
for (i = 0; i < dwg->num_objects && count < max_count; i++) {
Dwg_Object *obj = &dwg->object[i];
if (obj->fixedtype == DWG_TYPE_TEXT) {
Dwg_Entity_TEXT *text = obj->tio.entity->tio.TEXT;
if (text->text_value && strlen(text->text_value) > 0) {
printf("[TEXT] %s\n", text->text_value);
count++;
}
}
else if (obj->fixedtype == DWG_TYPE_MTEXT) {
Dwg_Entity_MTEXT *mtext = obj->tio.entity->tio.MTEXT;
if (mtext->text && strlen(mtext->text) > 0) {
// 截取前50个字符
char buf[51];
strncpy(buf, mtext->text, 50);
buf[50] = '\0';
printf("[MTEXT] %s%s\n", buf,
strlen(mtext->text) > 50 ? "..." : "");
count++;
}
}
}
}
// 主函数
int main(int argc, char *argv[])
{
Dwg_Data dwg;
int error;
if (argc < 2) {
printf("用法: %s <dwg文件> [选项]\n", argv[0]);
printf("选项:\n");
printf(" -l 显示图层列表\n");
printf(" -t 显示文本内容\n");
printf(" -s 显示实体统计\n");
printf(" -a 显示所有信息\n");
return 1;
}
// 解析选项
int show_layers = 0, show_texts = 0, show_stats = 0;
for (int i = 2; i < argc; i++) {
if (strcmp(argv[i], "-l") == 0) show_layers = 1;
else if (strcmp(argv[i], "-t") == 0) show_texts = 1;
else if (strcmp(argv[i], "-s") == 0) show_stats = 1;
else if (strcmp(argv[i], "-a") == 0) {
show_layers = show_texts = show_stats = 1;
}
}
// 读取DWG
memset(&dwg, 0, sizeof(Dwg_Data));
error = dwg_read_file(argv[1], &dwg);
if (error >= DWG_ERR_CRITICAL) {
fprintf(stderr, "读取失败，错误码: 0x%x\n", error);
return 1;
}
// 基本信息
printf("==========================================\n");
printf("DWG文件信息: %s\n", argv[1]);
printf("==========================================\n");
printf("版本: %s (%s)\n",
dwg.header.version,
get_version_name(dwg.header.version));
printf("对象总数: %lu\n", (unsigned long)dwg.num_objects);
printf("类数量: %lu\n", (unsigned long)dwg.num_classes);
// 范围信息
printf("\n图纸范围:\n");
printf(" EXTMIN: (%.2f, %.2f, %.2f)\n",
dwg.header_vars.EXTMIN.x,
dwg.header_vars.EXTMIN.y,
dwg.header_vars.EXTMIN.z);
printf(" EXTMAX: (%.2f, %.2f, %.2f)\n",
dwg.header_vars.EXTMAX.x,
dwg.header_vars.EXTMAX.y,
dwg.header_vars.EXTMAX.z);
// 可选信息
if (show_stats) print_entity_stats(&dwg);
if (show_layers) print_layers(&dwg);
if (show_texts) print_texts(&dwg, 20);
dwg_free(&dwg);
return 0;
}
编译和使用：
# 编译
gcc -o dwg_info dwg_info.c -lredwg -lm
# 使用
./dwg_info drawing.dwg -a
6.9 本章小结
本章介绍了LibreDWG的C语言API编程基础：
- 头文件和编译：dwg.h和dwg_api.h的使用，编译链接方法
- 基本读取：dwg_read_file函数和错误处理
- 对象遍历：遍历所有对象和按类型遍历
- 实体访问：LINE、CIRCLE、TEXT等实体的属性访问
- 图层样式：遍历图层、获取实体图层信息
- API函数：dwg_api.h提供的简化接口
- 实用示例：完整的DWG信息查看器
下一章预告：第07章 - DWG文件读取与解析 - 深入学习DWG文件的读取和解析技术。
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