move drop image logic to FrameUtils, add unit test

test/js/utils/FrameUtilsTest_add_image.js

@@ -0,0 +1,144 @@
+describe("FrameUtils addImageToFrame tests", function() {
+  var black = '#000000';
+  var red = '#ff0000';
+  var transparent = Constants.TRANSPARENT_COLOR;
+  var B = black, R = red, T = transparent;
+
+  // shortcuts
+  var toFrameGrid = test.testutils.toFrameGrid;
+
+  /**
+   * The three helpers below enable using only "visual" grids, while
+   * most frame helpers use rotated grids.
+   */
+  var frameEqualsGrid = function (frame, grid) {
+    test.testutils.frameEqualsGrid(frame, grid);
+  };
+
+  var createFrameFromGrid = function (grid) {
+    return pskl.model.Frame.fromPixelGrid(toFrameGrid(grid));
+  };
+
+  var createImageFromGrid = function (grid) {
+    return pskl.utils.FrameUtils.toImage(createFrameFromGrid(grid));
+  };
+
+  it("adds smaller image at drop position", function () {
+    // Transparent frame 2x2
+    var frame = createFrameFromGrid([
+      [T, T],
+      [T, T]
+    ]);
+
+    // Single red pixel image
+    var image = createImageFromGrid([[R]]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 0, 0);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [R, T],
+      [T, T]
+    ]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 1, 1);
+    // Verify
+    frameEqualsGrid(frame, [
+      [R, T],
+      [T, R]
+    ]);
+  });
+
+  it("adds line image at drop position", function () {
+    // Transparent frame 2x2
+    var frame = createFrameFromGrid([
+      [T, T],
+      [T, T]
+    ]);
+
+    // Line of 2 red pixels
+    var image = createImageFromGrid([[R, R]]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 0, 0);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [R, R],
+      [T, T]
+    ]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 0, 1);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [R, R],
+      [R, R]
+    ]);
+  });
+
+  it("does not erase under transparent areas", function () {
+    // Black frame 2x2
+    var frame = createFrameFromGrid([
+      [B, B],
+      [B, B]
+    ]);
+
+    // 2x2 image with 3 transparent pixels and a red pixel
+    var image = createImageFromGrid([
+      [T, T],
+      [T, R]
+    ]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 0, 0);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [B, B],
+      [B, R]
+    ]);
+  });
+
+  it("offsets drop position", function () {
+    // Transparent frame 2x2
+    var frame = createFrameFromGrid([
+      [T, T],
+      [T, T]
+    ]);
+
+    // Line of 2 red pixels
+    var image = createImageFromGrid([
+      [R, R]
+    ]);
+
+    // Drop it on the right side, should be moved back to te left
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 1, 0);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [R, R],
+      [T, T]
+    ]);
+  });
+
+  it("offsets drop position take 2", function () {
+    // Transparent frame 2x2
+    var frame = createFrameFromGrid([
+      [T, T],
+      [T, T]
+    ]);
+
+    // 2x2 image
+    var image = createImageFromGrid([
+      [B, R],
+      [R, B]
+    ]);
+
+    pskl.utils.FrameUtils.addImageToFrame(frame, image, 1, 1);
+
+    // Verify
+    frameEqualsGrid(frame, [
+      [B, R],
+      [R, B]
+    ]);
+  });
+});