具有透明背景的图片框答案

【问题标题】：Pictureboxes with transparent background具有透明背景的图片框
【发布时间】：2014-08-07 04:58:21
【问题描述】：

我有两个图片框：一个在背景中，里面有一个图像（picturebox1），另一个（pic1）我想画一些东西（这个背景应该是透明的。--> pic1.BackColor = Color.Transparent ;)

看起来像这样：

除了字体，一切都很好。为什么它有黑色边框？

我的代码是这样的：

private void InBitmapZeichnen()
{
    Graphics g1 = Graphics.FromImage(bmp12);
    g1.PageUnit = GraphicsUnit.Pixel;
    //g1.InterpolationMode = InterpolationMode.HighQualityBilinear;

    Font f = new Font("Verdana", 8f);
    Font f1 = new Font("Verdana", 8f);
    Font f2 = new Font("Verdana", 10, System.Drawing.FontStyle.Bold);
    Brush b = new SolidBrush(Color.YellowGreen);
    Brush b1 = new SolidBrush(Color.YellowGreen);
    Pen PenRaster = new Pen(Color.Black, 0.1f);

    if (mnuRaster.Checked == true)
    {
        float j = Rohrdurchmesser / (float)(trk.Value + 2);
        //g1.SmoothingMode = SmoothingMode.HighSpeed;
        for (int i = pic1.Width / (trk.Value + 2); i <= pic1.Width - pic1.Width / (trk.Value + 2); i += pic1.Width / (trk.Value + 2))
        {
            PointF PRaster1 = new PointF(i, 0);
            PointF PRaster2 = new PointF(i, pic1.Bottom);
            PointF PRaster3 = new PointF(0, i+4);
            PointF PRaster4 = new PointF(pic1.Right, i+4);
            g1.DrawString((j).ToString("0") + " mm", f, b, new PointF(i + 5, 5));
            g1.DrawString((j).ToString("0") + " mm", f, b, new PointF(5, i + 5));
            g1.DrawLine(PenRaster, PRaster1, PRaster2);
            g1.DrawLine(PenRaster, PRaster3, PRaster4);
            j += Rohrdurchmesser / (float)(trk.Value + 2);
        }                   
    }
}

当我为背景色选择一种颜色时，它可以正常工作：

【问题讨论】：

我已经编辑了你的标题。请不要包含有关问题标题中使用的语言的信息，除非没有它就没有意义。标签用于此目的。另请参阅"Should questions include “tags” in their titles?"，其中的共识是“不，他们不应该

标签： c# image transparency picturebox

【解决方案1】：

如果您想在透明背景上绘制文本，请尝试使用GraphicsPath：

private void InBitmapZeichnen()
{
    Graphics g1 = Graphics.FromImage(bmp12);
    g1.PageUnit = GraphicsUnit.Pixel;
    g1.SmoothingMode = SmoothingMode.AntiAlias;
    //g1.InterpolationMode = InterpolationMode.HighQualityBilinear;

    Font f = new Font("Verdana", 8f);
    Font f1 = new Font("Verdana", 8f);
    Font f2 = new Font("Verdana", 10, System.Drawing.FontStyle.Bold);
    Brush b = new SolidBrush(Color.YellowGreen);
    Brush b1 = new SolidBrush(Color.YellowGreen);
    Pen PenRaster = new Pen(Color.Black, 0.1f);

    if (mnuRaster.Checked == true)
    {
        float j = Rohrdurchmesser / (float)(trk.Value + 2);
        //g1.SmoothingMode = SmoothingMode.HighSpeed;
        for (int i = pic1.Width / (trk.Value + 2); i <= pic1.Width - pic1.Width / (trk.Value + 2); i += pic1.Width / (trk.Value + 2))
        {
            PointF PRaster1 = new PointF(i, 0);
            PointF PRaster2 = new PointF(i, pic1.Bottom);
            PointF PRaster3 = new PointF(0, i + 4);
            PointF PRaster4 = new PointF(pic1.Right, i + 4);

            using (var path = new GraphicsPath())
            {
                path.AddString((j).ToString("0") + " mm", f.FontFamily, (int)f.Style, f.Size, new Point(i + 5, 5), null);
                path.AddString((j).ToString("0") + " mm", f.FontFamily, (int)f.Style, f.Size, new Point(5, i + 5), null);
                g1.FillPath(b, path);
            }

            //g1.DrawString((j).ToString("0") + " mm", f, b, new PointF(i + 5, 5));
            //g1.DrawString((j).ToString("0") + " mm", f, b, new PointF(5, i + 5));
            g1.DrawLine(PenRaster, PRaster1, PRaster2);
            g1.DrawLine(PenRaster, PRaster3, PRaster4);
            j += Rohrdurchmesser / (float)(trk.Value + 2);
        }
    }
}

如您所见，我使用的是FillPath，而不是DrawString。

【讨论】：

【解决方案2】：

我认为在开始在图片框上绘图之前需要清除背景颜色。

          Graphics g1 = Graphics.FromImage(bmp12);
          // add clear
          g1.Clear(BackColor);

所以在你的代码中试试这个语句...！！！

【讨论】：