FromArgb和FromScRgb [英] FromArgb vs FromScRgb

问题描述

这两个表达式的颜色是否应该大致相同?

Should these two expressions result in colors which are roughly the same?

Color.FromArgb(255, 255, 255, (byte)0.25 * 255))

Color.FromScRgb(1.0f, 1.0f, 1.0f, 0.25f))

此测试程序演示了它们显示的看似不同的alpha值:

This test program demonstrates that they show up with seemingly different alpha values:

using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Shapes;

namespace Test_FromArgb_FromScRbg
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            var panel = new StackPanel();

            Content = panel;

            panel.Children.Add(
                new Rectangle()
                {
                    Width = 100,
                    Height = 100,
                    Fill = new SolidColorBrush(
                        Color.FromArgb(
                            255, 
                            255, 
                            255, 
                            (byte)0.25 * 255))
                });

            panel.Children.Add(
                new Rectangle()
                {
                    Width = 100,
                    Height = 100,
                    Fill = new SolidColorBrush(
                        Color.FromScRgb(
                            1.0f,
                            1.0f,
                            1.0f,
                            0.25f))
                });
        }
    }
}

这是演示程序在我的系统上的样子:

Here's what the demo program looks like on my system:

推荐答案

上面的mzzzzb提到了其背后的基本原因:

The basic reason behind this is mentioned by mzzzzb above:

比例尺0.0-1.0不会线性映射到0-255

the scale 0.0 - 1.0 does not map linearly to 0 - 255

即ScRgb成分与Argb成分不是线性映射.

I.e. the ScRgb components do not map linearly to the Argb components.

这篇关于FromArgb和FromScRgb的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！