Rotate an image bitmap in ImageLoader extension when loading detached.

ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js

Index: ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js
diff --git a/ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js b/ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js
index cc3508a1d597f327c8fa78d6370b5de46671de7e..bab051877dab2d525df93f5befbf0a5a2f811715 100644
--- a/ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js
+++ b/ui/file_manager/file_manager/foreground/js/metadata/image_orientation.js
@@ -73,14 +73,25 @@ ImageOrientation.fromExifOrientation = function(orientation) {
  * @return {!ImageOrientation}
  */
 ImageOrientation.fromDriveOrientation = function(rotation90) {
+  return ImageOrientation.fromClockwiseRotation(rotation90);
+};
+
+/**
+ * @param {number} rotation90 Clockwise degrees / 90.
+ * @return {!ImageOrientation}
+ */
+ImageOrientation.fromClockwiseRotation = function(rotation90) {
   switch (~~(rotation90 % 4)) {
     case 0:
       return new ImageOrientation(1, 0, 0, 1);
     case 1:
+    case -3:
       return new ImageOrientation(0, -1, 1, 0);
     case 2:
+    case -2:
       return new ImageOrientation(-1, 0, 0, -1);
     case 3:
+    case -1:
       return new ImageOrientation(0, 1, -1, 0);
     default:
       console.error('Invalid orientation number.');
@@ -89,6 +100,27 @@ ImageOrientation.fromDriveOrientation = function(rotation90) {
 };
 
 /**
+ * Builds a transformation matrix from the image transform parameters.
+ * @param {{scaleX: number, scaleY: number, rotate90: number}} transform
+ *     rotate90: counterclockwise degrees / 90.

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

rotate() in CSS transform property is clockwise.
https://drafts.csswg.org/css-transforms/#two-d-transform-functions

(We are making this parameter compatible to the one used here.
https://cs.chromium.org/chromium/src/ui/file_manager/file_manager/common/js/u...
)

+ * @return {!ImageOrientation}
+ */
+ImageOrientation.fromRotationAndScale = function(transform) {
+  var scaleX = transform.scaleX;
+  var scaleY = transform.scaleY;
+  var rotate90 = transform.rotate90;
+
+  var orientation = ImageOrientation.fromClockwiseRotation(-rotate90);
+
+  // Flip X and Y.
+  return new ImageOrientation(
+    orientation.a * scaleX,
+    orientation.b * scaleY,

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

This was wrong.
https://www.w3.org/TR/2dcontext/#transformations
see the comment in the latest revision.

[yamaguchi, 2017/02/16 14:03:21]

See my source code comment in the latest Patchset.

+    orientation.c * scaleX,
+    orientation.d * scaleY);
+}
+
+/**
  * Obtains the image size after cancelling its orientation.
  * @param {number} imageWidth
  * @param {number} imageHeight