1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
|
#pragma once
#include "LayoutRenderObject.hpp"
namespace cru::ui::render {
// Measure Logic (v0.1):
// Cross axis measure logic is the same as stack layout.
//
// 1. Layout all children with unspecified(infinate) max main axis length.
//
// 2. Add up main axis length of children to get total main length.
//
// 2.1. If preferred main axis length of parent is specified, then compare
// total length with it. If bigger, shrink is performed. If smaller, expand is
// performed. And preferred main axis length is used as target length.
//
// 2.2. If preferred main axis length of parent is not specified.
//
// 2.2.1. If max main axis length is specified and total length is bigger
// than max main axis length, shrink is performed and max main axis length is
// used as target length.
//
// 2.2.2. Or if max main axis length is specified and total length is smaller
// than max main axis length and any child has a positive expand factor, then
// expand is performed and max main axis length is used as target length.
//
// 2.2.3. Or if min main axis length is specified and total length is smaller
// than min main axis length, expand is performed and min main axis length is
// used as target length.
//
// 3. If shrink or expand is needed, then
//
// 3.1. Shrink:
//
// 3.1.1. Find out all shrink_factor > 0 children to form a adjusting list.
//
// 3.1.2. Use total main length minus target length to get the total shrink
// length. Add up all shrink_factor in adjusting list to get total shrink
// factor.
//
// 3.1.3. Iterate all children in adjusting list:
//
// 3.1.3.1. Calculate its own shrink length as
// shrink_factor / total_shrink_factor * total_shrink_length .
// Use current main axis length of child minus shrink length to get new
// measure length.
//
// 3.1.3.2. If min main axis length of the child is specified and new
// measure length is less than it, then min main axis length is used as new
// measure length.
//
// 3.1.3.3. Or if new measure length is less than 0, then it is coerced to
// 0.
//
// 3.1.3.4. Call measure with max and preferred main axis length set to new
// measure length. Cross axis length requirement is the same as step 1.
//
// 3.1.3.5. After measure, if it has min main axis length specified and
// actual main axis length is equal to it or its actual main axis length is
// 0, then remove it from adjusting list.
//
// 3.1.4. Add up main axis length of children to update total main length. If
// total main length is less than or equal to target length, goto step 4.
//
// 3.1.4. If adjusting list is not empty, go to step 3.1.2.
//
// 3.2. Expand:
// The same as shrink after you exchange related things except some minor
// things like do not do special things on 0.
//
// 4. If final total main axis length exceeeds the max main axis length (if
// specified), then report an error. And result main axis length is the coerced
// length. If final total main axis length is smaller than min main axis length
// (if specified), then coerce the length to the min value but not report error
// and just fill the rest space with blank.
//
class FlexLayoutRenderObject : public LayoutRenderObject<FlexChildLayoutData> {
CRU_DEFINE_CLASS_LOG_TAG(u"cru::ui::render::FlexLayoutRenderObject")
public:
FlexLayoutRenderObject() = default;
FlexLayoutRenderObject(const FlexLayoutRenderObject& other) = delete;
FlexLayoutRenderObject& operator=(const FlexLayoutRenderObject& other) =
delete;
FlexLayoutRenderObject(FlexLayoutRenderObject&& other) = delete;
FlexLayoutRenderObject& operator=(FlexLayoutRenderObject&& other) = delete;
~FlexLayoutRenderObject() override = default;
FlexDirection GetFlexDirection() const { return direction_; }
void SetFlexDirection(FlexDirection direction) {
direction_ = direction;
InvalidateLayout();
}
FlexMainAlignment GetContentMainAlign() const { return content_main_align_; }
void SetContentMainAlign(FlexMainAlignment align) {
content_main_align_ = align;
InvalidateLayout();
}
FlexCrossAlignment GetItemCrossAlign() const { return item_cross_align_; }
void SetItemCrossAlign(FlexCrossAlignment align) {
item_cross_align_ = align;
InvalidateLayout();
}
protected:
Size OnMeasureContent(const MeasureRequirement& requirement,
const MeasureSize& preferred_size) override;
void OnLayoutContent(const Rect& content_rect) override;
private:
FlexDirection direction_ = FlexDirection::Horizontal;
FlexMainAlignment content_main_align_ = FlexMainAlignment::Start;
FlexCrossAlignment item_cross_align_ = FlexCrossAlignment::Center;
};
} // namespace cru::ui::render
|
