1 #ifndef DALI_TOOLKIT_LAYOUTING_MEASURE_SPEC_H
2 #define DALI_TOOLKIT_LAYOUTING_MEASURE_SPEC_H
5 * Copyright (c) 2018 Samsung Electronics Co., Ltd.
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
20 #include <dali/public-api/common/dali-common.h>
21 #include <dali-toolkit/devel-api/layouting/layout-length.h>
22 #include <dali-toolkit/public-api/dali-toolkit-common.h>
32 * A MeasureSpec is used during the Measure pass by a LayoutGroup to inform it's children
33 * how to be measured. For instance, it may measure a child with an exact width and an unspecified
34 * height in order to determine height for width.
36 class DALI_TOOLKIT_API MeasureSpec
39 using IntType = LayoutLength::IntType;
43 UNSPECIFIED, ///< This is used by a parent to determine the desired dimension of a child layout.
44 EXACTLY, /** This is used by a parent to impose an exact size on the child. The child must use
45 this size, and guarantee that all of its descendants will fit within this size */
46 AT_MOST /** This is used by the parent to impose a maximum size on the child. The child must guarantee
47 * that it and all of it's descendants will fit within this size. */
50 MeasureSpec( LayoutLength measureSpec, MeasureSpec::Mode mode )
51 : mSize( measureSpec.mValue ),
56 MeasureSpec( IntType measureSpec )
57 : mSize( measureSpec ),
58 mMode( Mode::UNSPECIFIED )
62 ~MeasureSpec() = default;
64 MeasureSpec& operator=( const MeasureSpec& rhs )
68 this->mSize = rhs.mSize;
69 this->mMode = rhs.mMode;
74 bool operator==( MeasureSpec value )
76 return mSize == value.mSize;
79 bool operator!=( MeasureSpec value )
81 return mSize != value.mSize;
85 * @brief Get the mode of the measure spec.
87 * @return The mode of the measure spec
89 MeasureSpec::Mode GetMode() const
95 * @brief Get the size of the measure spec
97 * @return the size of the measure spec
99 IntType GetSize() const
105 * @brief Adjust the measure size by the given delta.
107 * Used only for EXACT and AT_MOST modes.
108 * @param[in] measureSpec the measure spec to adjust
109 * @param[in] delta A positive or negative value to adjust the measure spec by.
111 * @note if the adjusted size is negative, it is zeroed.
112 * @return A new measure spec with the adjusted values.
114 static MeasureSpec Adjust( MeasureSpec measureSpec, int delta )
116 auto mode = measureSpec.GetMode();
117 auto size = measureSpec.GetSize();
119 if( mode == MeasureSpec::Mode::UNSPECIFIED )
121 return MeasureSpec( size, MeasureSpec::Mode::UNSPECIFIED );
124 if( delta < 0 && measureSpec.mSize < static_cast<IntType>(abs(delta)) )
132 return MeasureSpec( size, mode );
136 IntType mSize; ///< The specified size
137 Mode mMode; ///< The measure mode
140 inline std::ostream& operator<< (std::ostream& o, const MeasureSpec& measureSpec )
142 return o << ( (measureSpec.GetMode() == MeasureSpec::Mode::UNSPECIFIED ? "Unspecified"
143 : (measureSpec.GetMode() == MeasureSpec::Mode::EXACTLY ? "Exactly":"At most" ) ) )
144 << " " << measureSpec.GetSize();
147 } //namespace Toolkit
151 #endif // DALI_TOOLKIT_LAYOUTING_MEASURE_SPEC_H