bananarchy/src/dwm-plugins/media_utils.h

#ifndef DWM_PLUGINS_MEDIA_UTILS_H
#define DWM_PLUGINS_MEDIA_UTILS_H

#include <algorithm>
#include <cctype>
#include <csetjmp>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <string>
#include <vector>

#include <jpeglib.h>
#include <png.h>

namespace bananarchy {

struct JpegErrMgr {
  struct jpeg_error_mgr pub;
  jmp_buf setjmpBuf;
};

inline void jpegErrorExit(j_common_ptr cinfo) {
  JpegErrMgr* myerr = reinterpret_cast<JpegErrMgr*>(cinfo->err);
  longjmp(myerr->setjmpBuf, 1);
}

inline bool saveRgb24AsJpeg(const std::string& path,
                            const uint8_t* rgb,
                            int width,
                            int height,
                            int quality = 92) {
  if (!rgb || width <= 0 || height <= 0) {
    return false;
  }
  FILE* fp = std::fopen(path.c_str(), "wb");
  if (!fp) {
    return false;
  }

  struct jpeg_compress_struct cinfo {};
  JpegErrMgr jerr {};
  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = jpegErrorExit;
  if (setjmp(jerr.setjmpBuf)) {
    jpeg_destroy_compress(&cinfo);
    std::fclose(fp);
    return false;
  }

  jpeg_create_compress(&cinfo);
  jpeg_stdio_dest(&cinfo, fp);
  cinfo.image_width = static_cast<JDIMENSION>(width);
  cinfo.image_height = static_cast<JDIMENSION>(height);
  cinfo.input_components = 3;
  cinfo.in_color_space = JCS_RGB;

  jpeg_set_defaults(&cinfo);
  jpeg_set_quality(&cinfo, quality, TRUE);
  jpeg_start_compress(&cinfo, TRUE);

  int rowStride = width * 3;
  while (cinfo.next_scanline < cinfo.image_height) {
    JSAMPROW rowPtr =
        const_cast<JSAMPROW>(rgb + cinfo.next_scanline * rowStride);
    jpeg_write_scanlines(&cinfo, &rowPtr, 1);
  }

  jpeg_finish_compress(&cinfo);
  jpeg_destroy_compress(&cinfo);
  std::fclose(fp);
  return true;
}

inline bool loadJpegRgb24(const std::string& path,
                          std::vector<uint8_t>* outRgb,
                          int* outW,
                          int* outH) {
  FILE* fp = std::fopen(path.c_str(), "rb");
  if (!fp) {
    return false;
  }

  struct jpeg_decompress_struct cinfo {};
  JpegErrMgr jerr {};
  cinfo.err = jpeg_std_error(&jerr.pub);
  jerr.pub.error_exit = jpegErrorExit;
  if (setjmp(jerr.setjmpBuf)) {
    jpeg_destroy_decompress(&cinfo);
    std::fclose(fp);
    return false;
  }

  jpeg_create_decompress(&cinfo);
  jpeg_stdio_src(&cinfo, fp);
  if (jpeg_read_header(&cinfo, TRUE) != JPEG_HEADER_OK) {
    jpeg_destroy_decompress(&cinfo);
    std::fclose(fp);
    return false;
  }

  // Use libjpeg fast DCT downscaling for large images so decoding is instant
  if (cinfo.image_width > 960 || cinfo.image_height > 960) {
    cinfo.scale_num = 1;
    cinfo.scale_denom = 2;
  }
  cinfo.out_color_space = JCS_RGB;
  jpeg_start_decompress(&cinfo);

  int w = static_cast<int>(cinfo.output_width);
  int h = static_cast<int>(cinfo.output_height);
  if (w <= 0 || h <= 0 || w > 8192 || h > 8192) {
    jpeg_destroy_decompress(&cinfo);
    std::fclose(fp);
    return false;
  }

  outRgb->resize(static_cast<size_t>(w) * h * 3);
  int rowStride = w * 3;
  while (cinfo.output_scanline < cinfo.output_height) {
    JSAMPROW rowPtr = outRgb->data() + cinfo.output_scanline * rowStride;
    jpeg_read_scanlines(&cinfo, &rowPtr, 1);
  }

  jpeg_finish_decompress(&cinfo);
  jpeg_destroy_decompress(&cinfo);
  std::fclose(fp);
  *outW = w;
  *outH = h;
  return true;
}

inline bool loadPngRgb24(const std::string& path,
                         std::vector<uint8_t>* outRgb,
                         int* outW,
                         int* outH) {
  png_image image {};
  image.version = PNG_IMAGE_VERSION;
  if (!png_image_begin_read_from_file(&image, path.c_str())) {
    return false;
  }
  image.format = PNG_FORMAT_RGB;
  int w = static_cast<int>(image.width);
  int h = static_cast<int>(image.height);
  if (w <= 0 || h <= 0 || w > 8192 || h > 8192) {
    png_image_free(&image);
    return false;
  }
  outRgb->resize(PNG_IMAGE_SIZE(image));
  if (!png_image_finish_read(&image, nullptr, outRgb->data(), 0, nullptr)) {
    png_image_free(&image);
    return false;
  }
  png_image_free(&image);
  *outW = w;
  *outH = h;
  return true;
}

inline bool loadImageRgb24(const std::string& path,
                           std::vector<uint8_t>* outRgb,
                           int* outW,
                           int* outH) {
  std::string low = path;
  for (char& c : low) {
    c = static_cast<char>(std::tolower(static_cast<unsigned char>(c)));
  }
  if (low.size() >= 4 && low.substr(low.size() - 4) == ".png") {
    if (loadPngRgb24(path, outRgb, outW, outH)) {
      return true;
    }
  }
  if (loadJpegRgb24(path, outRgb, outW, outH)) {
    return true;
  }
  if (loadPngRgb24(path, outRgb, outW, outH)) {
    return true;
  }
  return false;
}

inline void scaleRgb24ToBgrxCanvas(const uint8_t* srcRgb,
                                   int srcW,
                                   int srcH,
                                   uint32_t* dstBgrx,
                                   int canvasW,
                                   int canvasH,
                                   uint32_t bgPixel = 0x111111) {
  for (int i = 0; i < canvasW * canvasH; ++i) {
    dstBgrx[i] = bgPixel;
  }
  if (!srcRgb || srcW <= 0 || srcH <= 0 || canvasW <= 0 || canvasH <= 0) {
    return;
  }

  int drawW = canvasW;
  int drawH = (srcH * canvasW) / srcW;
  if (drawH > canvasH) {
    drawH = canvasH;
    drawW = (srcW * canvasH) / srcH;
  }
  drawW = std::max(1, drawW);
  drawH = std::max(1, drawH);

  int offX = (canvasW - drawW) / 2;
  int offY = (canvasH - drawH) / 2;

  for (int dy = 0; dy < drawH; ++dy) {
    int sy = std::min(srcH - 1, (dy * srcH) / drawH);
    const uint8_t* srow = srcRgb + static_cast<size_t>(sy) * srcW * 3;
    uint32_t* drow = dstBgrx + static_cast<size_t>(offY + dy) * canvasW + offX;
    for (int dx = 0; dx < drawW; ++dx) {
      int sx = std::min(srcW - 1, (dx * srcW) / drawW);
      const uint8_t* px = srow + sx * 3;
      drow[dx] = (static_cast<uint32_t>(px[0]) << 16) |
                 (static_cast<uint32_t>(px[1]) << 8) |
                 static_cast<uint32_t>(px[2]);
    }
  }
}

inline void downscaleViewfinder800x600To240x180(const uint8_t* srcRgb,
                                                uint32_t* dstBgrx,
                                                int zoomFactor = 1) {
  if (!srcRgb || !dstBgrx) {
    return;
  }
  zoomFactor = std::clamp(zoomFactor, 1, 4);
  int cropW = 800 / zoomFactor;
  int cropH = 600 / zoomFactor;
  int startX = (800 - cropW) / 2;
  int startY = (600 - cropH) / 2;

  for (int dy = 0; dy < 180; ++dy) {
    int sy = startY + (dy * cropH) / 180;
    const uint8_t* srow = srcRgb + static_cast<size_t>(sy) * 800 * 3;
    uint32_t* drow = dstBgrx + static_cast<size_t>(dy) * 240;
    for (int dx = 0; dx < 240; ++dx) {
      int sx = startX + (dx * cropW) / 240;
      const uint8_t* px = srow + sx * 3;
      drow[dx] = (static_cast<uint32_t>(px[0]) << 16) |
                 (static_cast<uint32_t>(px[1]) << 8) |
                 static_cast<uint32_t>(px[2]);
    }
  }
}

inline std::string formatFileSize(off_t bytes) {
  char buf[32];
  if (bytes >= 1024LL * 1024LL * 1024LL) {
    std::snprintf(buf, sizeof(buf), "%.1fG",
                  static_cast<double>(bytes) / (1024.0 * 1024.0 * 1024.0));
  } else if (bytes >= 1024LL * 1024LL) {
    std::snprintf(buf, sizeof(buf), "%.1fM",
                  static_cast<double>(bytes) / (1024.0 * 1024.0));
  } else if (bytes >= 1024LL) {
    std::snprintf(buf, sizeof(buf), "%.1fK",
                  static_cast<double>(bytes) / 1024.0);
  } else {
    std::snprintf(buf, sizeof(buf), "%lldB", static_cast<long long>(bytes));
  }
  return buf;
}

}  // namespace bananarchy

#endif  // DWM_PLUGINS_MEDIA_UTILS_H