Function bm_ScaleBitmapToBitmap

bitmap/bitmain.cpp:1289–1345

Given two bitmaps, scales the data from src to the size of dest Not a particularly fast implementation

// Given two bitmaps, scales the data from src to the size of dest
// Not a particularly fast implementation
void bm_ScaleBitmapToBitmap(int dest, int src) {
  uint16_t *dp = bm_data(dest, 0);
  uint16_t *sp = bm_data(src, 0);
  ASSERT(GameBitmaps[dest].used && dp);
  ASSERT(GameBitmaps[src].used && sp);
  int smipped = bm_mipped(src);
  int dmipped = bm_mipped(dest);
  int limit;
  ASSERT(smipped == dmipped);
  ASSERT(GameBitmaps[dest].format == GameBitmaps[src].format);

  int sw = bm_w(src, 0);
  int sh = bm_h(src, 0);
  int dw = bm_w(dest, 0);
  int dh = bm_h(dest, 0);
  int i, t;
  uint16_t *sdata;
  uint16_t *ddata;
  if (sw == dw && sh == dh) {
    if (smipped)
      limit = bm_miplevels(src);
    else
      limit = 1;
    for (i = 0; i < limit; i++) {
      sdata = (uint16_t *)bm_data(src, i);
      ddata = (uint16_t *)bm_data(dest, i);
      dw = bm_w(dest, i);
      dh = bm_h(dest, i);
      memcpy(ddata, sdata, dw * dh * sizeof(uint16_t));
    }
    return;
  }
  if (smipped)
    limit = bm_miplevels(src);
  else
    limit = 1;
  for (int m = 0; m < limit; m++) {
    sw = bm_w(src, m);
    sh = bm_h(src, m);
    dw = bm_w(dest, m);
    dh = bm_h(dest, m);

    sdata = (uint16_t *)bm_data(src, m);
    ddata = (uint16_t *)bm_data(dest, m);
    // These are our interpolant variables
    float xstep = (float)sw / (float)dw;
    float ystep = (float)sh / (float)dh;
    float xoff = 0;
    float yoff = 0;
    for (i = 0; i < dh; i++, yoff += ystep) {
      for (xoff = 0, t = 0; t < dw; t++, xoff += xstep) {
        ddata[i * dw + t] = sdata[(int)yoff * sw + (int)xoff];
      }
    }
  }
  GameBitmaps[dest].flags |= BF_CHANGED;
}
// given a handle and a miplevel, returns the bytes per bitmap row