WINFORM FORM/CONTROL不规则形状

主要思路是通过图片获取目标形状GraphicsPath，并赋值给Form或Control的Region属性。

1. 通过SetStyle设置支持透明背景

SetStyle(ControlStyles.SupportsTransparentBackColor, true);

UpdateStyles();

内部链接

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2. 设置Size

control.Width = bitmap.Width;

control.Height = bitmap.Height;

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3. FormBorderStyle.None(限Form)

form.FormBorderStyle = FormBorderStyle.None;

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4. 获取图形路径

private static GraphicsPath CalculateControlGraphicsPath(Bitmap bitmap)

{

    // Create GraphicsPath for our bitmap calculation

    //创建 GraphicsPath

    GraphicsPath graphicsPath = new GraphicsPath();

    // Use the top left pixel as our transparent color

    //使用左上角的一点的颜色作为我们透明色

    Color colorTransparent = bitmap.GetPixel(0, 0);

    // This is to store the column value where an opaque pixel is first found.

    // This value will determine where we start scanning for trailing opaque pixels.

    //第一个找到点的X

    int colOpaquePixel = 0;

    // Go through all rows (Y axis)

    // 偏历所有行（Y方向）

    for (int row = 0; row < bitmap.Height; row++)

    {

        // Reset value

        //重设

        colOpaquePixel = 0;

        // Go through all columns (X axis)

        //偏历所有列（X方向）

        for (int col = 0; col < bitmap.Width; col++)

        {

            // If this is an opaque pixel, mark it and search for anymore trailing behind

            //如果是不需要透明处理的点则标记，然后继续偏历

            if (bitmap.GetPixel(col, row) != colorTransparent)

            {

                // Opaque pixel found, mark current position

                //记录当前

                colOpaquePixel = col;

                // Create another variable to set the current pixel position

                //建立新变量来记录当前点

                int colNext = col;

                // Starting from current found opaque pixel, search for anymore opaque pixels

                // trailing behind, until a transparent   pixel is found or minimum width is reached

                ///从找到的不透明点开始，继续寻找不透明点,一直到找到或则达到图片宽度

                for (colNext = colOpaquePixel; colNext < bitmap.Width; colNext++)

                    if (bitmap.GetPixel(colNext, row) == colorTransparent)

                        break;

                // Form a rectangle for line of opaque   pixels found and add it to our graphics path

                //将不透明点加到graphics path

                graphicsPath.AddRectangle(new Rectangle(colOpaquePixel, row, colNext - colOpaquePixel, 1));

                // No need to scan the line of opaque pixels just found

                col = colNext;

            }

        }

    }

    // Return calculated graphics path

    return graphicsPath;

}

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5. Control.Region

control.Region = new Region(graphicsPath);

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6. 设置图片(图片可后续更换)

form.BackgroundImage = bitmap;

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