Rotate an image bitmap in ImageLoader extension when loading detached.

ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js

Index: ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js
diff --git a/ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js b/ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js
index a3d94969af51bd4ecc5cc24161e1a13f7ef2ce98..da7bf85a08ec479ef866024652c47cc9e1d3c12b 100644
--- a/ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js
+++ b/ui/file_manager/file_manager/foreground/js/metadata/image_orientation_unittest.js
@@ -41,3 +41,46 @@ function testCancelImageOrientation() {
   var destinationImageData = destinationContext.getImageData(0, 0, 1, 2);
   assertArrayEquals([255, 0, 0, 100, 0, 0, 0, 100], destinationImageData.data);
 }
+
+function assertImageOrientationEquals(expected, actual) {
+  assertEquals(expected.a, actual.a);
+  assertEquals(expected.b, actual.b);
+  assertEquals(expected.c, actual.c);
+  assertEquals(expected.d, actual.d);
+}
+
+function testFromRotationAndScale() {
+  var rotate90 = {scaleX: 1, scaleY: 1, rotate90: 1};
+  var flipX = {scaleX: -1, scaleY: 1, rotate90: 0 };
+  var flipY = {scaleX: 1, scaleY: -1, rotate90: 0 };
+  var flipBoth = {scaleX: -1, scaleY: -1, rotate90: 0};
+  var rotate180 = {scaleX: 1, scaleY: 1, rotate90: 2};
+  var rotateAndFlipX = {scaleX: -1, scaleY: 1, rotate90: 1};

[yamaguchi, 2017/02/16 14:01:18]

In CSS transformations, this means
"rotate 90[deg] CW and then scale along the X axis (which is made vertical now)
by -1". However, I think it's simpler to say "flip X and then rotate it 90[deg]
CW".

+  var rotateAndFlipY = {scaleX: 1, scaleY: -1, rotate90: 1};
+  var rotate1080 = {scaleX: 1, scaleY: 1, rotate90: 12};
+  var flipBothAndRotate180 = {scaleX: -1, scaleY: -1, rotate90: 2};
+  /*
+   The image coordinate system is aligned to the screen. (Y+ pointing down)
+   O----> e_x                 ^
+   |           rotate 90 CCW  | e'_x = (0, -1) = (a, c)
+   |             =====>       |
+   V e_y                      O----> e'_y = (1, 0) = (b, d)
+  */
+  assertImageOrientationEquals(new ImageOrientation(0, 1, -1, 0),
+      ImageOrientation.fromRotationAndScale(rotate90));
+  assertImageOrientationEquals(new ImageOrientation(-1, 0, 0, 1),
+      ImageOrientation.fromRotationAndScale(flipX));
+  assertImageOrientationEquals(new ImageOrientation(1, 0, 0, -1),
+      ImageOrientation.fromRotationAndScale(flipY));
+  assertImageOrientationEquals(new ImageOrientation(-1, 0, 0, -1),
+      ImageOrientation.fromRotationAndScale(flipBoth));
+  assertImageOrientationEquals(new ImageOrientation(-1, 0, 0, -1),
+      ImageOrientation.fromRotationAndScale(rotate180));
+  assertImageOrientationEquals(new ImageOrientation(0, 1, 1, 0),
+      ImageOrientation.fromRotationAndScale(rotateAndFlipX));
+  assertImageOrientationEquals(new ImageOrientation(0, -1, -1, 0),
+      ImageOrientation.fromRotationAndScale(rotateAndFlipY));
+  assertTrue(ImageOrientation.fromRotationAndScale(flipBothAndRotate180)
+      .isIdentity());
+  assertTrue(ImageOrientation.fromRotationAndScale(rotate1080).isIdentity());
+}