Expose thumbnails of pages to iOS share extensions.

ios/chrome/browser/ui/ui_util.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef IOS_CHROME_BROWSER_UI_UI_UTIL_H_
 #define IOS_CHROME_BROWSER_UI_UI_UTIL_H_
 
 #include <CoreGraphics/CoreGraphics.h>
 
 // UI Util containing functions that do not require Objective-C.
@@ skipping 56 matching lines @@
 // integral values.
 //
 // The ProjectionMode describes in which way the stretching will apply.
 //
 enum class ProjectionMode {
   // Just stretches the source into the destination, not preserving aspect ratio
   // at all.
   // |projectTo| and |revisedTargetSize| will be set to |targetSize|
   kFill,
 
-  // Scale to the target, maintaining aspect ratio, clipping the excess. Large
-  // original sizes are shrunk until they fit on one side, small original sizes
-  // are expanded.
+  // Scale to the target, maintaining aspect ratio, clipping the excess, while
+  // keeping the image centered.
+  // Large original sizes are shrunk until they fit on one side, small original
+  // sizes are expanded.
   // |projectTo| will be a subset of |originalSize|
   // |revisedTargetSize| will be set to |targetSize|
   kAspectFill,
 
+  // Same as kAspectFill, except that the bottom part of the image will be
+  // clipped. The image will still be horizontally centered.
+  kAspectFillAlignTop,
+
   // Fit the image in the target so it fits completely inside, preserving aspect
   // ratio. This will leave bands with with no data in the target.
   // |projectTo| will be set to |originalSize|
   // |revisedTargetSize| will be a smaller in one direction from |targetSize|
   kAspectFit,
 
   // Scale to the target, maintaining aspect ratio and not clipping the excess.
   // |projectTo| will be set to |originalSize|
   // |revisedTargetSize| will be a larger in one direction from |targetSize|
   kAspectFillNoClipping,
 };
 void CalculateProjection(CGSize originalSize,
                          CGSize targetSize,
                          ProjectionMode projectionMode,
                          CGSize& revisedTargetSize,
                          CGRect& projectTo);
 
 #endif  // IOS_CHROME_BROWSER_UI_UI_UTIL_H_