image/lib/src/draw/draw_image.dart

import '../image.dart';
import 'draw_pixel.dart';

/**
 * Draw the image [src] onto the image [dst].
 *
 * In other words, copyInto will take an rectangular area from src of
 * width [src_w] and height [src_h] at position ([src_x],[src_y]) and place it
 * in a rectangular area of [dst] of width [dst_w] and height [dst_h] at
 * position ([dst_x],[dst_y]).
 *
 * If the source and destination coordinates and width and heights differ,
 * appropriate stretching or shrinking of the image fragment will be performed.
 * The coordinates refer to the upper left corner. This function can be used to
 * copy regions within the same image (if [dst] is the same as [src])
 * but if the regions overlap the results will be unpredictable.
 */
Image drawImage(Image dst, Image src,
                {int dstX, int dstY, int srcX, int srcY,
                 int srcW, int srcH, bool blend: true}) {
  if (dstX == null) {
    dstX = 0;
  }
  if (dstY == null) {
    dstY = 0;
  }
  if (srcX == null) {
    srcX = 0;
  }
  if (srcY == null) {
    srcY = 0;
  }
  if (srcW == null) {
    srcW = src.width;
  }
  if (srcH == null) {
    srcH = src.height;
  }

  for (int y = 0; y < srcH; ++y) {
    for (int x = 0; x < srcW; ++x) {
      if (blend) {
        drawPixel(dst, dstX + x, dstY + y, src.getPixel(srcX + x, srcY + y));
      } else {
        dst.setPixel(dstX + x, dstY + y, src.getPixel(srcX + x, srcY + y));
      }
    }
  }

  return dst;
}