1 files changed, 140 insertions, 0 deletions
diff --git a/test/geometry/dem_data.test.cpp b/test/geometry/dem_data.test.cpp
new file mode 100644
index 0000000000..30091973b2
--- /dev/null
+++ b/test/geometry/dem_data.test.cpp
@@ -0,0 +1,140 @@
+#include <mbgl/test/util.hpp>
+
+#include <mbgl/util/image.hpp>
+#include <mbgl/geometry/dem_data.hpp>
+
+using namespace mbgl;
+
+auto fakeImage = [](Size s) {
+    PremultipliedImage img = PremultipliedImage(s);
+
+    for (size_t i = 0; i < img.bytes(); i ++) {
+        img.data[i] = (i+1) % 4 == 0 ? 1 : std::rand() % 255;
+    }
+    return img;
+};
+
+TEST(DEMData, Constructor) {
+    PremultipliedImage image = fakeImage({16, 16});
+    DEMData pyramid(image);
+
+    EXPECT_EQ(pyramid.dim, 16);
+    EXPECT_EQ(pyramid.border, 8);
+    EXPECT_EQ(pyramid.stride, 32);
+    EXPECT_EQ(pyramid.getImage()->bytes(), size_t(32*32*4));
+    EXPECT_EQ(pyramid.dim, 16);
+    EXPECT_EQ(pyramid.border, 8);
+};
+
+TEST(DEMData, RoundTrip) {
+    PremultipliedImage image = fakeImage({16, 16});
+    DEMData pyramid(image);
+
+    pyramid.set(4, 6, 255);
+    EXPECT_EQ(pyramid.get(4, 6), 255);
+}
+
+TEST(DEMData, InitialBackfill) {
+
+    PremultipliedImage image1 = fakeImage({4, 4});
+    DEMData dem1(image1);
+
+    bool nonempty = true;
+    // checking that a 1 px border around the fake image has been populated
+    // with a non-empty pixel value
+    for (int x = -1; x < 5; x++){
+        for (int y = -1; y < 5; y ++) {
+            if (dem1.get(x, y) == -65536) {
+                nonempty = false;
+                break;
+            }
+        }
+    }
+    EXPECT_TRUE(nonempty);
+
+    bool verticalBorderMatch = true;
+    int vertx[] = {-1, 4};
+    for (int x : vertx) {
+        for (int y = 0; y < 4; y++) {
+            if (dem1.get(x, y) != dem1.get(x < 0 ? x + 1 : x - 1, y)) {
+                verticalBorderMatch = false;
+                break;
+            }
+        }
+    }
+    // vertical border of DEM data is initially equal to next column of data
+    EXPECT_TRUE(verticalBorderMatch);
+
+    // horizontal borders empty
+    bool horizontalBorderMatch = true;
+    int horiz[] = {-1, 4};
+    for (int y : horiz) {
+        for (int x = 0; x < 4; x++) {
+            if (dem1.get(x, y) != dem1.get(x, y < 0 ? y + 1 : y - 1)) {
+                horizontalBorderMatch = false;
+                break;
+            }
+        }
+    }
+    //horizontal border of DEM data is initially equal to next row of data
+
+    EXPECT_TRUE(horizontalBorderMatch);
+    // -1, 1 corner initially equal to closest corner data
+    EXPECT_TRUE(dem1.get(-1, 4) == dem1.get(0, 3));
+    // 1, 1 corner initially equal to closest corner data
+    EXPECT_TRUE(dem1.get(4, 4) == dem1.get(3, 3));
+    // -1, -1 corner initially equal to closest corner data
+    EXPECT_TRUE(dem1.get(-1, -1) == dem1.get(0, 0));
+    // -1, 1 corner initially equal to closest corner data
+    EXPECT_TRUE(dem1.get(4, -1) == dem1.get(3, 0));
+};
+
+TEST(DEMData, BackfillNeighbor) {
+    PremultipliedImage image1 = fakeImage({4, 4});
+    DEMData dem0(image1);
+
+    PremultipliedImage image2 = fakeImage({4, 4});
+    DEMData dem1(image2);
+
+    dem0.backfillBorder(dem1, -1, 0);
+    for (int y = 0; y < 4; y++) {
+        // dx = -1, dy = 0, so the left edge of dem1 should equal the right edge of dem0
+        // backfills Left neighbor
+        EXPECT_TRUE(dem0.get(-1, y) == dem1.get(3, y));
+
+    }
+
+    dem0.backfillBorder(dem1, 0, -1);
+    // backfills TopCenter neighbor
+    for (int x = 0; x < 4; x++) {
+        EXPECT_TRUE(dem0.get(x, -1) == dem1.get(x, 3));
+    }
+
+    dem0.backfillBorder(dem1, 1, 0);
+    // backfills Right neighbor
+    for (int y = 0; y < 4; y++) {
+        EXPECT_TRUE(dem0.get(4, y) == dem1.get(0, y));
+    }
+
+    dem0.backfillBorder(dem1, 0, 1);
+    // backfills BottomCenter neighbor
+    for (int x = 0; x < 4; x++) {
+        EXPECT_TRUE(dem0.get(x, 4) == dem1.get(x, 0));
+    }
+
+    dem0.backfillBorder(dem1, -1, 1);
+    // backfulls TopRight neighbor
+    EXPECT_TRUE(dem0.get(-1, 4) == dem1.get(3, 0));
+
+    dem0.backfillBorder(dem1, 1, 1);
+    // backfulls BottomRight neighbor
+    EXPECT_TRUE(dem0.get(4, 4) == dem1.get(0, 0));
+
+    dem0.backfillBorder(dem1, -1, -1);
+    // backfulls TopLeft neighbor
+    EXPECT_TRUE(dem0.get(-1, -1) == dem1.get(3, 3));
+
+    dem0.backfillBorder(dem1, 1, -1);
+    // backfulls BottomLeft neighbor
+    EXPECT_TRUE(dem0.get(4, -1) == dem1.get(0, 3));
+};