Add a couple UIKit util functions in src/ui/ios/

BUG=None

Review URL: https://codereview.chromium.org/539253002

Cr-Commit-Position: refs/heads/master@{#293933}

ui/ios/NSString+CrStringDrawing.mm

@@ -5,25 +5,14 @@
 #import "ui/ios/NSString+CrStringDrawing.h"
 
 #include "base/logging.h"
-
-namespace {
-// Returns the closest pixel-aligned value higher than |value|, taking the scale
-// factor into account. At a scale of 1, equivalent to ceil().
-// TODO(lliabraa): Move this method to a common util file (crbug.com/409823).
-CGFloat alignValueToUpperPixel(CGFloat value) {
-  CGFloat scale = [[UIScreen mainScreen] scale];
-  return ceil(value * scale) / scale;
-}
-}  // namespace
+#include "ui/ios/uikit_util.h"
 
 @implementation NSString (CrStringDrawing)
 
 - (CGSize)cr_pixelAlignedSizeWithFont:(UIFont*)font {
   DCHECK(font) << "|font| can not be nil; it is used as a NSDictionary value";
   NSDictionary* attributes = @{ NSFontAttributeName : font };
-  CGSize size = [self sizeWithAttributes:attributes];
-  return CGSizeMake(alignValueToUpperPixel(size.width),
-                    alignValueToUpperPixel(size.height));
+  return ui::AlignSizeToUpperPixel([self sizeWithAttributes:attributes]);
 }
 
 - (CGSize)cr_sizeWithFont:(UIFont*)font {

ui/ios/ui_ios.gyp

@@ -21,6 +21,8 @@
       'sources': [
         'NSString+CrStringDrawing.h',
         'NSString+CrStringDrawing.mm',
+        'uikit_util.h',
+        'uikit_util.mm',
       ],
     },
   ],

ui/ios/ui_ios_tests.gyp

@@ -19,6 +19,7 @@
       ],
       'sources' : [
         'NSString+CrStringDrawing_unittest.mm',
+        'uikit_util_unittest.mm',
       ],
     },
   ],

ui/ios/uikit_util.h

+// Copyright 2014 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 UI_IOS_UIKIT_UTIL_H_
+#define UI_IOS_UIKIT_UTIL_H_
+
+#import <UIKit/UIKit.h>
+
+#include "base/compiler_specific.h"
+
+// UI Util containing functions that require UIKit.
+
+namespace ui {
+
+// Returns the closest pixel-aligned value higher than |value|, taking the scale
+// factor into account. At a scale of 1, equivalent to ceil().
+CGFloat AlignValueToUpperPixel(CGFloat value) WARN_UNUSED_RESULT;
+
+// Returns the size resulting from applying AlignToUpperPixel to both
+// components.
+CGSize AlignSizeToUpperPixel(CGSize size) WARN_UNUSED_RESULT;
+
+} // namespace ui
+
+#endif  // UI_IOS_UIKIT_UTIL_H_

ui/ios/uikit_util.mm

+// Copyright 2014 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.
+
+#include "ui/ios/uikit_util.h"
+
+#import <UIKit/UIKit.h>
+
+#include <cmath>
+
+namespace ui {
+
+CGFloat AlignValueToUpperPixel(CGFloat value) {
+  CGFloat scale = [[UIScreen mainScreen] scale];
+  return std::ceil(value * scale) / scale;
+}
+
+CGSize AlignSizeToUpperPixel(CGSize size) {
+  return CGSizeMake(AlignValueToUpperPixel(size.width),
+                    AlignValueToUpperPixel(size.height));
+}
+
+} // namespace ui

ui/ios/uikit_util_unittest.mm

+// Copyright 2014 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.
+
+#import <Foundation/Foundation.h>
+
+#include "base/basictypes.h"
+#include "testing/platform_test.h"
+#import "ui/ios/uikit_util.h"
+
+namespace {
+
+typedef PlatformTest UIKitUtilTest;
+
+TEST_F(UIKitUtilTest, AlignValueToUpperPixel) {
+   CGFloat scale = [[UIScreen mainScreen] scale];
+   // Pick a few interesting values: already aligned, aligned on retina, and
+   // some unaligned values that would round differently. Ensure that all are
+   // "integer" values within <1 of the original value in the scaled space.
+   CGFloat test_values[] = { 10.0, 55.5, 3.1, 2.9 };
+   const CGFloat kMaxAlignDelta = 0.9999;
+   size_t value_count = arraysize(test_values);
+   for (unsigned int i = 0; i < value_count; ++i) {
+     CGFloat aligned = ui::AlignValueToUpperPixel(test_values[i]);
+     EXPECT_FLOAT_EQ(aligned * scale, floor(aligned * scale));
+     EXPECT_NEAR(aligned * scale, test_values[i] * scale, kMaxAlignDelta);
+   }
+}
+
+TEST_F(UIKitUtilTest, AlignSizeToUpperPixel) {
+  CGFloat scale = [[UIScreen mainScreen] scale];
+  // Pick a few interesting values: already aligned, aligned on retina, and
+  // some unaligned values that would round differently. Ensure that all are
+  // "integer" values within <1 of the original value in the scaled space.
+  CGFloat test_values[] = { 10.0, 55.5, 3.1, 2.9 };
+  const CGFloat kMaxAlignDelta = 0.9999;
+  size_t value_count = arraysize(test_values);
+  for (unsigned int i = 0; i < value_count; ++i) {
+    CGFloat width = test_values[i];
+    CGFloat height = test_values[(i + 1) % value_count];
+    CGSize alignedSize = ui::AlignSizeToUpperPixel(CGSizeMake(width, height));
+    EXPECT_FLOAT_EQ(floor(alignedSize.width * scale),
+                    alignedSize.width * scale);
+    EXPECT_FLOAT_EQ(floor(alignedSize.height * scale),
+                    alignedSize.height * scale);
+    EXPECT_NEAR(width * scale, alignedSize.width * scale, kMaxAlignDelta);
+    EXPECT_NEAR(height * scale, alignedSize.height * scale, kMaxAlignDelta);
+  }
+}
+
+}  // namespace