chore: 添加 bmp_to_framebuffer
This commit is contained in:
288
C++/bmp_to_framebuffer.cpp
Normal file
288
C++/bmp_to_framebuffer.cpp
Normal file
@@ -0,0 +1,288 @@
|
||||
// 将 BMP 图片写入到 FrameBuffer
|
||||
// 示例：sudo bmp_to_framebuffer ./image.bmp /dev/fb0
|
||||
|
||||
#include <iostream>
|
||||
#include <fstream>
|
||||
#include <vector>
|
||||
#include <cstdint>
|
||||
#include <fcntl.h>
|
||||
#include <sys/mman.h>
|
||||
#include <sys/ioctl.h>
|
||||
#include <linux/fb.h>
|
||||
#include <unistd.h>
|
||||
#include <cstring>
|
||||
|
||||
#pragma pack(push, 1)
|
||||
struct BMPFileHeader {
|
||||
uint16_t type; // 文件类型 "BM" (0x4D42)
|
||||
uint32_t size; // 文件大小
|
||||
uint16_t reserved1; // 保留
|
||||
uint16_t reserved2; // 保留
|
||||
uint32_t offset; // 像素数据偏移量
|
||||
};
|
||||
|
||||
struct BMPInfoHeader {
|
||||
uint32_t size; // 信息头大小
|
||||
int32_t width; // 宽度
|
||||
int32_t height; // 高度 (正数表示倒序，负数表示正序)
|
||||
uint16_t planes; // 色彩平面数
|
||||
uint16_t bitCount; // 位深度 (1, 4, 8, 16, 24, 32)
|
||||
uint32_t compression; // 压缩类型 (0:BI_RGB, 1:BI_RLE8, 2:BI_RLE4, 3:BI_BITFIELDS)
|
||||
uint32_t sizeImage; // 像素数据大小
|
||||
int32_t xPelsPerMeter; // 水平分辨率
|
||||
int32_t yPelsPerMeter; // 垂直分辨率
|
||||
uint32_t clrUsed; // 使用的颜色数
|
||||
uint32_t clrImportant; // 重要颜色数
|
||||
};
|
||||
#pragma pack(pop)
|
||||
|
||||
// 辅助结构：用于解析 BI_BITFIELDS 掩码
|
||||
struct BitFieldInfo {
|
||||
uint32_t mask;
|
||||
int shift;
|
||||
int width;
|
||||
};
|
||||
|
||||
// 计算掩码的移位和宽度
|
||||
BitFieldInfo getBitFieldInfo(uint32_t mask) {
|
||||
BitFieldInfo info{};
|
||||
info.mask = mask;
|
||||
if (mask == 0) return info;
|
||||
|
||||
// 计算右移位数
|
||||
info.shift = 0;
|
||||
uint32_t temp = mask;
|
||||
while ((temp & 1) == 0) {
|
||||
temp >>= 1;
|
||||
info.shift++;
|
||||
}
|
||||
|
||||
// 计算位宽
|
||||
info.width = 0;
|
||||
while ((temp & 1) == 1) {
|
||||
temp >>= 1;
|
||||
info.width++;
|
||||
}
|
||||
return info;
|
||||
}
|
||||
|
||||
// RLE8 解压函数
|
||||
std::vector<uint8_t> decodeRLE8(const uint8_t* data, size_t dataSize, int width, int height) {
|
||||
std::vector<uint8_t> output(width * height, 0);
|
||||
int x = 0, y = 0;
|
||||
size_t pos = 0;
|
||||
|
||||
while (pos < dataSize) {
|
||||
uint8_t count = data[pos++];
|
||||
if (count == 0) {
|
||||
uint8_t escape = data[pos++];
|
||||
if (escape == 0) { // 行结束
|
||||
x = 0;
|
||||
y++;
|
||||
} else if (escape == 1) { // 图像结束
|
||||
break;
|
||||
} else if (escape == 2) { // Delta 偏移
|
||||
x += data[pos++];
|
||||
y += data[pos++];
|
||||
} else { // 绝对模式
|
||||
for (int i = 0; i < escape; i++) {
|
||||
if (x < width && y < height) {
|
||||
output[y * width + x] = data[pos];
|
||||
x++;
|
||||
}
|
||||
pos++;
|
||||
}
|
||||
if (escape % 2 != 0) pos++; // 2字节对齐
|
||||
}
|
||||
} else { // 编码模式
|
||||
uint8_t color = data[pos++];
|
||||
for (int i = 0; i < count; i++) {
|
||||
if (x < width && y < height) {
|
||||
output[y * width + x] = color;
|
||||
x++;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
return output;
|
||||
}
|
||||
|
||||
// RLE4 解压函数
|
||||
std::vector<uint8_t> decodeRLE4(const uint8_t* data, size_t dataSize, int width, int height) {
|
||||
std::vector<uint8_t> output(width * height, 0);
|
||||
int x = 0, y = 0;
|
||||
size_t pos = 0;
|
||||
|
||||
while (pos < dataSize) {
|
||||
uint8_t count = data[pos++];
|
||||
if (count == 0) {
|
||||
uint8_t escape = data[pos++];
|
||||
if (escape == 0) { // 行结束
|
||||
x = 0;
|
||||
y++;
|
||||
} else if (escape == 1) { // 图像结束
|
||||
break;
|
||||
} else if (escape == 2) { // Delta 偏移
|
||||
x += data[pos++];
|
||||
y += data[pos++];
|
||||
} else { // 绝对模式
|
||||
bool highNibble = true;
|
||||
uint8_t byte = 0;
|
||||
for (int i = 0; i < escape; i++) {
|
||||
if (highNibble) byte = data[pos++];
|
||||
uint8_t idx = highNibble ? (byte >> 4) : (byte & 0x0F);
|
||||
if (x < width && y < height) {
|
||||
output[y * width + x] = idx;
|
||||
x++;
|
||||
}
|
||||
highNibble = !highNibble;
|
||||
}
|
||||
// 对齐检查：如果读取的字节数是奇数，跳过填充
|
||||
if (((escape + 1) / 2) % 2 != 0) pos++;
|
||||
}
|
||||
} else { // 编码模式
|
||||
uint8_t byte = data[pos++];
|
||||
bool highNibble = true;
|
||||
for (int i = 0; i < count; i++) {
|
||||
uint8_t idx = highNibble ? (byte >> 4) : (byte & 0x0F);
|
||||
if (x < width && y < height) {
|
||||
output[y * width + x] = idx;
|
||||
x++;
|
||||
}
|
||||
highNibble = !highNibble;
|
||||
}
|
||||
}
|
||||
}
|
||||
return output;
|
||||
}
|
||||
|
||||
int main(int argc, char* argv[]) {
|
||||
const char* filename = "image.bmp";
|
||||
const char* fbname = "/dev/fb0";
|
||||
if (argc > 1) filename = argv[1];
|
||||
if (argc > 2) fbname = argv[2];
|
||||
|
||||
// 1. 打开 Framebuffer
|
||||
int fbfd = open(fbname, O_RDWR);
|
||||
if (fbfd == -1) { perror("打开 fb 失败"); return 1; }
|
||||
|
||||
// 2. 获取屏幕信息
|
||||
struct fb_var_screeninfo vinfo;
|
||||
struct fb_fix_screeninfo finfo;
|
||||
ioctl(fbfd, FBIOGET_VSCREENINFO, &vinfo);
|
||||
ioctl(fbfd, FBIOGET_FSCREENINFO, &finfo);
|
||||
|
||||
uint8_t* fbp = (uint8_t*)mmap(nullptr, finfo.smem_len, PROT_READ | PROT_WRITE, MAP_SHARED, fbfd, 0);
|
||||
if (fbp == MAP_FAILED) { perror("内存映射失败"); close(fbfd); return 1; }
|
||||
|
||||
// 3. 读取 BMP 文件
|
||||
std::ifstream file(filename, std::ios::binary);
|
||||
if (!file) { std::cerr << "无法打开文件" << std::endl; munmap(fbp, finfo.smem_len); close(fbfd); return 1; }
|
||||
|
||||
BMPFileHeader fileHeader;
|
||||
BMPInfoHeader infoHeader;
|
||||
file.read(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));
|
||||
file.read(reinterpret_cast<char*>(&infoHeader), sizeof(infoHeader));
|
||||
|
||||
if (fileHeader.type != 0x4D42) { std::cerr << "非 BMP 文件" << std::endl; return 1; }
|
||||
|
||||
int imgWidth = infoHeader.width;
|
||||
int imgHeight = abs(infoHeader.height);
|
||||
bool isTopDown = (infoHeader.height < 0);
|
||||
|
||||
// 4. 读取颜色表 (如果是索引色)
|
||||
std::vector<uint32_t> colorTable;
|
||||
if (infoHeader.bitCount <= 8) {
|
||||
int colorCount = infoHeader.clrUsed == 0 ? (1 << infoHeader.bitCount) : infoHeader.clrUsed;
|
||||
colorTable.resize(colorCount);
|
||||
file.read(reinterpret_cast<char*>(colorTable.data()), colorCount * 4);
|
||||
}
|
||||
|
||||
// 5. 读取并解压像素数据
|
||||
std::vector<uint8_t> pixelData; // 存储解压后的索引或原始数据
|
||||
bool isIndexed = (infoHeader.bitCount <= 8);
|
||||
|
||||
file.seekg(fileHeader.offset, std::ios::beg);
|
||||
std::vector<uint8_t> rawData(infoHeader.sizeImage);
|
||||
file.read(reinterpret_cast<char*>(rawData.data()), rawData.size());
|
||||
|
||||
if (infoHeader.compression == 0) { // BI_RGB (无压缩)
|
||||
int rowSize = ((imgWidth * infoHeader.bitCount + 31) / 32) * 4;
|
||||
pixelData.resize(rowSize * imgHeight);
|
||||
file.seekg(fileHeader.offset, std::ios::beg);
|
||||
file.read(reinterpret_cast<char*>(pixelData.data()), pixelData.size());
|
||||
}
|
||||
else if (infoHeader.compression == 1) { // BI_RLE8
|
||||
pixelData = decodeRLE8(rawData.data(), rawData.size(), imgWidth, imgHeight);
|
||||
}
|
||||
else if (infoHeader.compression == 2) { // BI_RLE4
|
||||
pixelData = decodeRLE4(rawData.data(), rawData.size(), imgWidth, imgHeight);
|
||||
}
|
||||
else {
|
||||
std::cerr << "不支持的压缩格式: " << infoHeader.compression << std::endl;
|
||||
return 1;
|
||||
}
|
||||
|
||||
// 6. 绘制到 Framebuffer
|
||||
int drawW = std::min(imgWidth, (int)vinfo.xres);
|
||||
int drawH = std::min(imgHeight, (int)vinfo.yres);
|
||||
|
||||
for (int y = 0; y < drawH; ++y) {
|
||||
// 处理 BMP 上下翻转
|
||||
int srcY = isTopDown ? y : (imgHeight - 1 - y);
|
||||
|
||||
for (int x = 0; x < drawW; ++x) {
|
||||
uint8_t r, g, b, a = 255;
|
||||
|
||||
if (isIndexed) {
|
||||
uint8_t idx = 0;
|
||||
// 从解压数据或无压缩数据中获取索引
|
||||
if (infoHeader.compression == 1 || infoHeader.compression == 2) {
|
||||
idx = pixelData[srcY * imgWidth + x];
|
||||
} else {
|
||||
int rowSize = ((imgWidth * infoHeader.bitCount + 31) / 32) * 4;
|
||||
uint8_t* srcRow = pixelData.data() + srcY * rowSize;
|
||||
if (infoHeader.bitCount == 8) {
|
||||
idx = srcRow[x];
|
||||
} else if (infoHeader.bitCount == 4) {
|
||||
idx = (x % 2 == 0) ? (srcRow[x/2] >> 4) : (srcRow[x/2] & 0x0F);
|
||||
}
|
||||
}
|
||||
// 从颜色表获取 RGB (BMP 颜色表格式为 BGRX)
|
||||
uint32_t color = colorTable[idx];
|
||||
b = color & 0xFF;
|
||||
g = (color >> 8) & 0xFF;
|
||||
r = (color >> 16) & 0xFF;
|
||||
} else {
|
||||
// 直接读取 RGB (24/32位)
|
||||
int rowSize = ((imgWidth * infoHeader.bitCount + 31) / 32) * 4;
|
||||
uint8_t* srcRow = pixelData.data() + srcY * rowSize;
|
||||
if (infoHeader.bitCount == 24) {
|
||||
b = srcRow[x*3+0]; g = srcRow[x*3+1]; r = srcRow[x*3+2];
|
||||
} else if (infoHeader.bitCount == 32) {
|
||||
b = srcRow[x*4+0]; g = srcRow[x*4+1]; r = srcRow[x*4+2]; a = srcRow[x*4+3];
|
||||
}
|
||||
}
|
||||
|
||||
// 写入 Framebuffer (假设是 32位 BGRA 模式，这是最常见的)
|
||||
long fbIdx = (x + vinfo.xoffset) * (vinfo.bits_per_pixel/8) +
|
||||
(y + vinfo.yoffset) * finfo.line_length;
|
||||
|
||||
if (vinfo.bits_per_pixel == 32) {
|
||||
fbp[fbIdx+0] = b;
|
||||
fbp[fbIdx+1] = g;
|
||||
fbp[fbIdx+2] = r;
|
||||
fbp[fbIdx+3] = a;
|
||||
} else if (vinfo.bits_per_pixel == 16) { // RGB565
|
||||
uint16_t c = ((r>>3)<<11) | ((g>>2)<<5) | (b>>3);
|
||||
*(uint16_t*)(&fbp[fbIdx]) = c;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
// 清理
|
||||
munmap(fbp, finfo.smem_len);
|
||||
close(fbfd);
|
||||
std::cout << "显示完成" << std::endl;
|
||||
return 0;
|
||||
}
|
||||
Reference in New Issue
Block a user