位图上的着色不准确(我已经看过:如何在C#.NET中更改图像的像素颜色) [英] Coloring on bitmap not accurate (i already looked at: How to Change Pixel Color of an Image in C#.NET)

问题描述

我想做的是在事件发生后，我将所有箭头图片设置为紫色.

What I am trying to do is after a event happens i set all my arrow pictures to purple.

这是我的箭头图片在绘制之前的样子:

Here is what my arrow picture looks like before drawing:

这是绘制后的样子:

Here is what it looks like after drawing:

首先，我用箭头列出所有图片框:

First I make a list of all the pictureboxes with the arrow:

 List<PictureBox> arrows = new List<PictureBox>();
 foreach (var item in Controls.OfType<PictureBox>())
        {
            if (item.Name.StartsWith("arrow"))
            {
                arrows.Add(item);
            }    
        }

这是我用来给图片着色的代码:

And this is the code I use to color the pictures:

System.Drawing.Color purple = System.Drawing.Color.Purple;

        foreach (var item in arrows)
        {
            Bitmap bmp = new Bitmap(item.Image, item.Height, item.Width);
            for (int i = 0; i < item.Height; i++)
            {
                for (int j = 0; j < item.Width; j++)
                {
                    var actualColor = bmp.GetPixel(i, j).ToArgb();
                    var purpleA = bmp.GetPixel(i, j).A;
                    if (actualColor != System.Drawing.Color.White.ToArgb())
                    {
                        bmp.SetPixel(i, j, System.Drawing.Color.FromArgb(purpleA, purple));
                    } else
                    {
                        bmp.SetPixel(i, j, System.Drawing.Color.FromArgb(actualColor));
                    }
                }
            }
            item.Image = bmp;
        }

如何准确为图像着色?此刻紫色的确很烂.我需要它与黑色箭头完全相同，但不是黑色，我需要紫色.

How can I color the image accurately? At the moment the purple is really badly drawn. I need it to be the exact same as the black arrow but instead of black I need it to be purple.

注意:将黑色箭头图像放在图片框中时，我会调整其大小，因此在形式上，黑色箭头和紫色箭头的大小相同.我上传了带有屏幕截图的紫色箭头，而黑色箭头来自我的计算机.这就是为什么它们的大小不一样.

Note: I resize the black arrow image when I put it in the picturebox, so on the form the black and the purple arrow are the same size. I uploaded the purple arrow with a screenshot and the black arrow was from my computer. That's why they are not the same size.

推荐答案

您可以使用颜色映射表将颜色替换为另一种颜色.它比循环每个像素快得多.

You could use the color map to replace a color by another one. it's much faster than looping for each pixels.

    Graphics g = pictureBox.GetGraphics; // get the picture box graphics (i doubt this line compile but you get the idea of the object you need)    
    using (Bitmap bmp = new Bitmap("img.bmp")) // or the image currently in the picture box
    {        
        // create the color map
        var colorMap = new ColorMap[1];
        colorMap[0] = new ColorMap();

        // old color
        colorMap[0].OldColor = Color.Black;

        // replaced by this color
        colorMap[0].NewColor = Color.Purple;

        // attribute to remap the table of colors
        var att = new ImageAttributes();
        att.SetRemapTable(colorMap);

        // draw result
        Rectangle rect = new Rectangle(0, 0, bmp.Width, bmp.Height);
        g.DrawImage(bmp, rect, 0, 0, rect.Width, rect.Height, GraphicsUnit.Pixel, att);
    }

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