比如黑色的50%透明，就设置#80000000
100% --- FF
99% --- FC
98% --- FA
97% --- F7
96% --- F5
95% --- F2
94% --- F0
93% --- ED
92% --- EB
91% --- E8
90% --- E6
89% --- E3
88% --- E0
87% --- DE
86% --- DB
85% --- D9
84% --- D6
83% --- D4
82% --- D1
81% --- CF
80% --- CC
79% --- C9
78% --- C7
77% --- C4
76% --- C2
75% --- BF
74% --- BD
73% --- BA
72% --- B8
71% --- B5
70% --- B3
69% --- B0
68% --- AD
67% --- AB
66% --- A8
65% --- A6
64% --- A3
63% --- A1
62% --- 9E
61% --- 9C
60% --- 99
59% --- 96
58% --- 94
57% --- 91
56% --- 8F
55% --- 8C
54% --- 8A
53% --- 87
52% --- 85
51% --- 82
50% --- 80
49% --- 7D
48% --- 7A
47% --- 78
46% --- 75
45% --- 73
44% --- 70
43% --- 6E
42% --- 6B
41% --- 69
40% --- 66
39% --- 63
38% --- 61
37% --- 5E
36% --- 5C
35% --- 59
34% --- 57
33% --- 54
32% --- 52
31% --- 4F
30% --- 4D
29% --- 4A
28% --- 47
27% --- 45
26% --- 42
25% --- 40
24% --- 3D
23% --- 3B
22% --- 38
21% --- 36
20% --- 33
19% --- 30
18% --- 2E
17% --- 2B
16% --- 29
15% --- 26
14% --- 24
13% --- 21
12% --- 1F
11% --- 1C
10% --- 1A
9% --- 17
8% --- 14
7% --- 12
6% --- 0F
5% --- 0D
4% --- 0A
3% --- 08
2% --- 05
1% --- 03
0% --- 00