Merge pull request #11 from DocHoncho/issue-295-dev

Re-implement nearest-neighbor interpolation

src/raster/algorithm/resize_image.cpp

@@ -35,23 +35,22 @@ void resize_image(const Image* src, Image* dst, ResizeMethod method, const Palet
   switch (method) {
 
     // TODO optimize this
-    case RESIZE_METHOD_NEAREST_NEIGHBOR: {
+    case RESIZE_METHOD_NEAREST_NEIGHBOR: 
-      uint32_t color;
+    {
-      double u, v, du, dv;
+      int o_width = src->getWidth(), o_height = src->getHeight();
-      int x, y;
+      int n_width = dst->getWidth(), n_height = dst->getHeight();
+      double x_ratio = o_width / (double)n_width;
+      double y_ratio = o_height / (double)n_height;
+      double px, py;
+      int i;
 
-      u = v = 0.0;
+      for (int y = 0; y < n_height; y++) {
-      du = src->getWidth() * 1.0 / dst->getWidth();
+        for (int x = 0; x < n_width; x++) {
-      dv = src->getHeight() * 1.0 / dst->getHeight();
+          px = floor(x * x_ratio);
-      for (y=0; y<dst->getHeight(); ++y) {
+          py = floor(y * y_ratio);
-        for (x=0; x<dst->getWidth(); ++x) {
+          i = (int)(py * o_width + px);
-          color = src->getPixel(MID(0, u, src->getWidth()-1),
+          dst->putPixel(x, y, src->getPixel(i % o_width, i / o_width));
-                                MID(0, v, src->getHeight()-1));
-          dst->putPixel(x, y, color);
-          u += du;
         }
-        u = 0.0;
-        v += dv;
       }
       break;
     }

src/raster/resize_image_unittest.cpp

@@ -0,0 +1,111 @@
+// Aseprite Gfx Library
+// Copyright (C) 2001-2013 David Capello
+//
+// This source file is distributed under MIT license,
+// please read LICENSE.txt for more information.
+
+#ifdef HAVE_CONFIG_H
+#include "config.h"
+#endif
+
+#include <gtest/gtest.h>
+
+#include "raster/color.h"
+#include "raster/image.h"
+#include "raster/algorithm/resize_image.h"
+
+using namespace std;
+using namespace raster;
+
+/***************************
+ * Test dat
+ */
+
+// Base image
+color_t test_image_base_3x3[9] =
+{
+  0x000000, 0xffffff, 0x000000,
+  0xffffff, 0xffffff, 0xffffff,
+  0x000000, 0xffffff, 0x000000
+};
+
+// Base image scaled to 9x9 with nearest neighbor interpolation
+color_t test_image_scaled_9x9_nearest[81] =
+{
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000,
+  0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff,
+  0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff,
+  0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff,
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x000000, 0xffffff, 0xffffff, 0xffffff, 0x000000, 0x000000, 0x000000
+};
+
+// Base image scalled to 9x9 with bilinear interpolation
+color_t test_image_scaled_9x9_bilinear[81] =
+{
+  0x000000, 0x000000, 0x565656, 0xa9a9a9, 0xffffff, 0xa9a9a9, 0x565656, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x565656, 0xa9a9a9, 0xffffff, 0xa9a9a9, 0x565656, 0x000000, 0x000000,
+  0x565656, 0x565656, 0x8f8f8f, 0xc6c6c6, 0xffffff, 0xc6c6c6, 0x8f8f8f, 0x565656, 0x565656,
+  0xa9a9a9, 0xa9a9a9, 0xc6c6c6, 0xe2e2e2, 0xffffff, 0xe2e2e2, 0xc6c6c6, 0xa9a9a9, 0xa9a9a9,
+  0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff, 0xffffff,
+  0xa9a9a9, 0xa9a9a9, 0xc6c6c6, 0xe2e2e2, 0xffffff, 0xe2e2e2, 0xc6c6c6, 0xa9a9a9, 0xa9a9a9,
+  0x565656, 0x565656, 0x8f8f8f, 0xc6c6c6, 0xffffff, 0xc6c6c6, 0x8f8f8f, 0x565656, 0x565656,
+  0x000000, 0x000000, 0x565656, 0xa9a9a9, 0xffffff, 0xa9a9a9, 0x565656, 0x000000, 0x000000,
+  0x000000, 0x000000, 0x565656, 0xa9a9a9, 0xffffff, 0xa9a9a9, 0x565656, 0x000000, 0x000000
+};
+
+Image* create_image_from_data(PixelFormat format, color_t* data, int width, int height) 
+{
+  Image* new_image = Image::create(format, width, height);
+  for (int i = 0; i < width * height; i++) {
+    new_image->putPixel(i % width, i / width, data[i]);
+  }
+
+  return new_image;
+}
+
+// Simple pixel to pixel image comparison
+bool compare_images(Image* a, Image* b)
+{
+  for (int y = 0; y < a->getHeight(); y++) {
+    for (int x = 0; x < a->getWidth(); x++) {
+      if (!(a->getPixel(x, y) == b->getPixel(x, y)))
+        return false;
+    }
+  }
+  return true;
+}
+
+TEST(ResizeImage, NearestNeighborInterp)
+{
+  Image* src = create_image_from_data(IMAGE_RGB, test_image_base_3x3, 3, 3);
+  Image* dst = Image::create(IMAGE_RGB, 9, 9);
+
+  // Pre-rendered test image for comparison
+  Image* test_dst = create_image_from_data(IMAGE_RGB, test_image_scaled_9x9_nearest, 9, 9);
+
+  algorithm::resize_image(src, dst, algorithm::ResizeMethod::RESIZE_METHOD_NEAREST_NEIGHBOR, NULL, NULL);
+
+  ASSERT_TRUE(compare_images(dst, test_dst)) << "resize_image() result does not match test image!";
+}
+
+TEST(ResizeImage, BilinearInterpRGBType)
+{
+  Image* src = create_image_from_data(IMAGE_RGB, test_image_base_3x3, 3, 3);
+  Image* dst = Image::create(IMAGE_RGB, 9, 9);
+
+  // Pre-rendered test image for comparison
+  Image* test_dst = create_image_from_data(IMAGE_RGB, test_image_scaled_9x9_bilinear, 9, 9);
+
+  algorithm::resize_image(src, dst, algorithm::ResizeMethod::RESIZE_METHOD_BILINEAR, NULL, NULL);
+
+  ASSERT_TRUE(compare_images(dst, test_dst)) << "resize_image() result does not match test image!";
+}
+int main(int argc, char** argv)
+{
+  ::testing::InitGoogleTest(&argc, argv);
+  return RUN_ALL_TESTS();
+}