我知道这是相当古老的,作者可能不再在意,但我已经搜索了网络上的这个问题的答案,我找不到任何。
评论bobpowell.net/pgb.htm中的KeithS链接对我来说不起作用,因为我无法找到一种方法来获取用于绘制曲线的实际点数。 (请参阅段落“让他们包围”)
尝试模拟色轮我因此编写了此代码: (我不是专业人士,任何提高代码的建议都非常受欢迎 - 特别是我的边缘是有点模糊)
这个想法是为了产生一个看起来像甜甜圈的多边形,为从彩色贴图插入的每个“顶点”和置于“虚拟”甜甜圈中心的白色中心颜色应用颜色。 (我使用doublebuffering,以避免闪烁)
List<PointF> drawDonut(float angleA, float angleB, float width, int controlPointCount, float scaling, float centerX, float centerY)
{
List<PointF> points = new List<PointF>();
if (controlPointCount < 2)
{
throw (new ArgumentOutOfRangeException("controlPointCount", "controlPointCount must be >1"));
}
if (width <= 0 || width > 100)
{
throw (new ArgumentOutOfRangeException("width", "width must be comprised between ]0:100]"));
}
List<float> angles = new List<float>();
for (int i = 0; i < controlPointCount; i++)
{
angles.Add(angleA + (angleB - angleA) * (float)i/((float)controlPointCount - 1.0f));
}
for (int i = 0; i < angles.Count; i++)
{
points.Add(new PointF((float)Math.Cos(angles[i]) * scaling + centerX, (float)Math.Sin(angles[i]) * scaling + centerY));
}
for (int i = 0; i < angles.Count; i++)
{
points.Add(new PointF(((100.0f - width)/100.0f * (float)Math.Cos(angles[angles.Count - 1 - i])) * scaling + centerX, ((100.0f - width)/100.0f * (float)Math.Sin(angles[angles.Count - 1 - i])) * scaling + centerY));
}
return points;
}
private List<Color> pieColor(Color[] MainColors, float[] mainStops, float[] stops)
{
List<Color> resultColors = new List<Color>();
int index = 0;
float percent;
if (MainColors.Length != mainStops.Length)
{
throw new Exception("number of MainColors and mainStops must be the same");
}
if (MainColors.Length < 2)
{
for (int i = 0; i < stops.Length; i++)
{
resultColors.Add((MainColors.Length == 1) ? MainColors[0] : Color.White);
}
}
else
{
for (int i = 0; i < stops.Length; i++)
{
index = Array.FindIndex(mainStops, x => x > stops[i]);
if (index == 0)
{
resultColors.Add(MainColors[0]);
}
else
{
if (index == -1)
{
resultColors.Add(MainColors.Last());
}
else
{
percent = (stops[i] - mainStops[index - 1])/(mainStops[index] - mainStops[index - 1]) * 100f;
resultColors.Add(alphaBlend(MainColors[index - 1], MainColors[index], percent));
}
}
}
}
return resultColors;
}
private Color alphaBlend(Color color1, Color color2, float percent)
{
byte R = (byte)(((float)color1.R * (100f - percent)/100f) + ((float)color2.R * (percent)/100f));
byte G = (byte)(((float)color1.G * (100f - percent)/100f) + ((float)color2.G * (percent)/100f));
byte B = (byte)(((float)color1.B * (100f - percent)/100f) + ((float)color2.B * (percent)/100f));
return Color.FromArgb(R, G, B);
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
RectangleF rec = e.ClipRectangle;
float midx = rec.Width/2;
float midy = rec.Height/2;
float pieSize = (float)Math.Min(midx, midy) * 0.9f;
float pieWidth = 5f;
float angleA = -225;
float angleB = 45;
int nstops = (int)(Math.Abs(angleA - angleB)/5 + 1);
float[] stops;
stops = new float[nstops];
for (int i = 0; i < stops.Length; i++)
{
stops[i] = i * 100f/(stops.Length - 1);
}
List<PointF> myDonut = drawDonut(angleA * (float)Math.PI/180f, angleB * (float)Math.PI/180f, pieWidth, nstops, pieSize, midx, midy);
List<Color> myColors = pieColor(new Color[] { Color.Red, Color.Yellow, Color.Green, Color.Cyan, Color.Blue, Color.Magenta, Color.Red },
new float[] { 0.0f, 100f/6f, 200f/6f, 300f/6f, 400f/6f, 500f/6f, 600f/6f },
stops);
Color[] myPieColor = new Color[myDonut.Count];
for (int i = 0; i < (myPieColor.Length/2); i++)
{
myPieColor[i] = myColors[i];
myPieColor[myPieColor.Length - i - 1] = myColors[i];
}
GraphicsPath gp = new GraphicsPath();
gp.AddLines(myDonut.ToArray());
e.Graphics.SmoothingMode = SmoothingMode.HighQuality;
using (PathGradientBrush b = new PathGradientBrush(gp))
{
b.CenterPoint = new PointF(midx, midy);
b.CenterColor = Color.White;
b.SurroundColors = myPieColor;
e.Graphics.FillPath(b, gp);
}
}
}
我想我可以,但如何绘制一个完整的圆形帮助?即时通讯试图让梯度沿着它的边缘,而不是从内部到外部? – Aviel 2011-02-15 16:26:09