move drop image logic to FrameUtils, add unit test

src/js/service/FileDropperService.js

@@ -64,15 +64,17 @@
   };
 
   ns.FileDropperService.prototype.onImageLoaded_ = function () {
-    var droppedFrame = pskl.utils.FrameUtils.createFromImage(this.importedImage_);
     var currentFrame = this.piskelController.getCurrentFrame();
+    // Convert client coordinates to sprite coordinates
+    var spriteDropPosition = pskl.app.drawingController.getSpriteCoordinates(
+      this.dropPosition_.x,
+      this.dropPosition_.y
+    );
 
-    var origin = this.adjustDropPosition_(this.dropPosition_, droppedFrame);
-    droppedFrame.forEachPixel(function (color, x, y) {
-      if (color != pskl.utils.colorToInt(Constants.TRANSPARENT_COLOR)) {
-        currentFrame.setPixel(origin.x + x, origin.y + y, color);
-      }
-    });
+    var x = spriteDropPosition.x;
+    var y = spriteDropPosition.y;
+
+    pskl.utils.FrameUtils.addImageToFrame(currentFrame, this.importedImage_, x, y);
 
     $.publish(Events.PISKEL_RESET);
     $.publish(Events.PISKEL_SAVE_STATE, {
@@ -80,28 +82,4 @@
     });
   };
 
-  ns.FileDropperService.prototype.adjustDropPosition_ = function (position, droppedFrame) {
-    var framePosition = pskl.app.drawingController.getSpriteCoordinates(position.x, position.y);
-
-    var xCoord = framePosition.x - Math.floor(droppedFrame.width / 2);
-    var yCoord = framePosition.y - Math.floor(droppedFrame.height / 2);
-
-    xCoord = Math.max(0, xCoord);
-    yCoord = Math.max(0, yCoord);
-
-    var currentFrame = this.piskelController.getCurrentFrame();
-    if (droppedFrame.width <= currentFrame.width) {
-      xCoord = Math.min(xCoord, currentFrame.width - droppedFrame.width);
-    }
-
-    if (droppedFrame.height <= currentFrame.height) {
-      yCoord = Math.min(yCoord, currentFrame.height - droppedFrame.height);
-    }
-
-    return {
-      x : xCoord,
-      y : yCoord
-    };
-  };
-
 })();

src/js/utils/FrameUtils.js

@@ -123,6 +123,33 @@
       }
     },
 
+    /**
+     * Insert the provided image in the provided frame, at the x, y sprite coordinates.
+     * Coordinates will be adjusted so that the image fits in the frame, if possible.
+     */
+    addImageToFrame: function (frame, image, x, y) {
+      var imageFrame = pskl.utils.FrameUtils.createFromImage(image);
+      x = x - Math.floor(imageFrame.width / 2);
+      y = y - Math.floor(imageFrame.height / 2);
+
+      x = Math.max(0, x);
+      y = Math.max(0, y);
+
+      if (imageFrame.width <= frame.width) {
+        x = Math.min(x, frame.width - imageFrame.width);
+      }
+
+      if (imageFrame.height <= frame.height) {
+        y = Math.min(y, frame.height - imageFrame.height);
+      }
+
+      imageFrame.forEachPixel(function (color, frameX, frameY) {
+        if (color != pskl.utils.colorToInt(Constants.TRANSPARENT_COLOR)) {
+          frame.setPixel(x + frameX, y + frameY, color);
+        }
+      });
+    },
+
     resize : function (frame, targetWidth, targetHeight, smoothing) {
       var image = pskl.utils.FrameUtils.toImage(frame);
       var resizedImage = pskl.utils.ImageResizer.resize(image, targetWidth, targetHeight, smoothing);

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]
+    ]);
+  });
+});