trackBar 亮度控制不会滚动从黑色到白色的整个颜色范围

Question

我有一个用于调整表单背景颜色亮度的轨迹栏控件。最后，我将对其进行修改以调整图像的亮度。如果您查看 Microsoft colorDialog 控件中的亮度滑块是如何工作的，当您上下移动时，值会从白色变为黑色，但在中间，原始颜色的色调永远不会丢失。最初，我失去了色调，只是进行了灰度调整，但我终于找到了解决方法。

我目前的问题是我无法调整整个颜色范围。 For example, when selecting the color R 192, G 128, B 255, I can scroll all the way down to black, and all the way back up to my original color, but I can't scroll up to white.我已经每天处理这个代码几个小时了 10 天了，要么从黑色变为白色并失去色调（已解决），要么得到当前的问题：我可以从 lavendar 滚动到黑色再到 lavendar ，但不能向上滚动到白色。我非常感谢一些帮助。谢谢你。

public partial class Form1 : Form
{

   double xRed, xGreen, xBlue, xColor; 
   bool count = true;

    private void Form1_BackColorChanged(object sender, EventArgs e)
    {
        //Do this once, when user sets a new BG color 
        if (count == true)
        {                     
            //Get a % of the color value instead of the absolute value,  when using absolute value, if it goes down near 0, or up near 255, hue is lost.  
            xRed = (double) this.BackColor.R / 255; 
            xGreen = (double) this.BackColor.G / 255; 
            xBlue = (double) this.BackColor.B / 255;

            xColor = (((xRed + xGreen + xBlue) * 255 ) / 3); 
            xColor = Math.Round(xColor, 0);

            //Label is just so I can see RGB and trackBar values 
            lblBGColor.Enabled = true; 
            trackBar1.Enabled = true; 
            trackBar1.Value = (int)xColor; 
            label1.Text = Convert.ToString(trackBar1.Value);
            count = false; 
        }      
    }

    private void trackBar1_Scroll(object sender, EventArgs e)
    {
        double bgRed = 0, bgGreen = 0, bgBlue = 0;
        //Once it goes down to black or up to white, restore the hue value as a percent. Percent of R (value / 255), Percent of G (value / 255), Percent of B (value / 255). SO if red is 196 and 196 is 80% of 255, red is 80% of trackbar value, if green is 128 and 128 is 50% of 255, green is 50% of trackbar value, etc... 

        //I suspect the problem is here, with trackBar1.Value.  I also tried adding the trackBar1.Value change since last scroll, but that didn't help.  Also tried setting trackBar1.Value to 128, but no help.  
        bgRed = xRed * trackBar1.Value;
        bgGreen = xGreen * trackBar1.Value; 
        bgBlue = xBlue * trackBar1.Value; 

        bgRed = Math.Round(bgRed, 0);
        bgGreen = Math.Round(bgGreen, 0);
        bgBlue = Math.Round(bgBlue, 0); 

        if (bgRed > 255)
            bgRed = 255;
        if (bgGreen > 255)
            bgGreen = 255;
        if (bgBlue > 255)
            bgBlue = 255;

        //Avoid unneeded looping through BackColorChanged event   
        count = false;  
        //Set form and label values 
        this.BackColor = Color.FromArgb(255, (int)bgRed, (int)bgGreen, (int)bgBlue); 
        label1.Text = Convert.ToString((int)bgRed + " " + (int)bgGreen + " " + (int)bgBlue + " trackBar: " + trackBar1.Value); 
}

这是我的第一篇文章，我阅读了关于不问重复问题的新帐户声明。我对此进行了研究，并且在这里之前没有看到过这个问题。谢谢你。

Answer 1

在您的代码中，变量xRed, xGreen and xBlue 将根据表单背景颜色的rgb 值分配一个值。例如，如果表单的背景颜色的 RGB 值为（150、170 和 180），则 xRed 将为 0.588，G 为 0.667，B 为 0.705

当您将轨迹栏移动到最大值（例如 255）时，表单的背景颜色将为 bgRed = xRed * trackBar1.value (150)，bgGreen 将为 170，bgBlue 将为 180，这是表单的原始背景颜色。

在我看来，以 100% 亮度显示原始颜色是正确的行为。如果您想以 100% 显示白色作为背景色，您应该将代码更改为如下所示

private void trackBar1_Scroll(object sender, EventArgs e)
    {
        double bgRed = 0, bgGreen = 0, bgBlue = 0;
        if(this.trackBar1.value==this.trackBar1.Maximum)
        {
            bgRed=255;
            bgGreen=255;
            bgBlue=255;
        }

       else{
            //Once it goes down to black or up to white, restore the hue value as a percent. Percent of R (value / 255), Percent of G (value / 255), Percent of B (value / 255). SO if red is 196 and 196 is 80% of 255, red is 80% of trackbar value, if green is 128 and 128 is 50% of 255, green is 50% of trackbar value, etc... 
        //I suspect the problem is here, with trackBar1.Value.  I also tried adding the trackBar1.Value change since last scroll, but that didn't help.  Also tried setting trackBar1.Value to 128, but no help.  
        bgRed = xRed * trackBar1.Value;
        bgGreen = xGreen * trackBar1.Value; 
        bgBlue = xBlue * trackBar1.Value; 

        bgRed = Math.Round(bgRed, 0);
        bgGreen = Math.Round(bgGreen, 0);
        bgBlue = Math.Round(bgBlue, 0); 

        if (bgRed > 255)
            bgRed = 255;
        if (bgGreen > 255)
            bgGreen = 255;
        if (bgBlue > 255)
            bgBlue = 255;
    }
    //Avoid unneeded looping through BackColorChanged event   
    count = false;  
    //Set form and label values 
    this.BackColor = Color.FromArgb(255, (int)bgRed, (int)bgGreen, (int)bgBlue); 
    label1.Text = Convert.ToString((int)bgRed + " " + (int)bgGreen + " " + (int)bgBlue + " trackBar: " + trackBar1.Value); 
}