如何在运行时从文本生成图像

Question

任何人都可以指导如何从输入文本生成图像.图像可能有任何扩展无关紧要.

Answer 1

好吧,假设你想在C#中的图像上绘制一个字符串,你需要在这里使用System.Drawing命名空间:

private Image DrawText(String text, Font font, Color textColor, Color backColor)
{
    //first, create a dummy bitmap just to get a graphics object
    Image img = new Bitmap(1, 1);
    Graphics drawing = Graphics.FromImage(img);

    //measure the string to see how big the image needs to be
    SizeF textSize = drawing.MeasureString(text, font);

    //free up the dummy image and old graphics object
    img.Dispose();
    drawing.Dispose();

    //create a new image of the right size
    img = new Bitmap((int) textSize.Width, (int)textSize.Height);

    drawing = Graphics.FromImage(img);

    //paint the background
    drawing.Clear(backColor);

    //create a brush for the text
    Brush textBrush = new SolidBrush(textColor);

    drawing.DrawString(text, font, textBrush, 0, 0);

    drawing.Save();

    textBrush.Dispose();
    drawing.Dispose();

    return img;

}

此代码将首先测量字符串,然后创建正确大小的图像.

如果要保存此函数的返回,只需调用返回图像的Save方法即可.

Answer 2

谢谢Kazar.使用USING处理图像/图形对象以及引入最小尺寸参数之前的答案略有改进

    private Image DrawTextImage(String currencyCode, Font font, Color textColor, Color backColor) {
        return DrawTextImage(currencyCode, font, textColor, backColor, Size.Empty);
    }
    private Image DrawTextImage(String currencyCode, Font font, Color textColor, Color backColor, Size minSize) {
        //first, create a dummy bitmap just to get a graphics object
        SizeF textSize;
        using (Image img = new Bitmap(1, 1)) {
            using (Graphics drawing = Graphics.FromImage(img)) {
                //measure the string to see how big the image needs to be
                textSize = drawing.MeasureString(currencyCode, font);
                if (!minSize.IsEmpty) {
                    textSize.Width = textSize.Width > minSize.Width ? textSize.Width : minSize.Width;
                    textSize.Height = textSize.Height > minSize.Height ? textSize.Height : minSize.Height;
                }
            }
        }

        //create a new image of the right size
        Image retImg = new Bitmap((int)textSize.Width, (int)textSize.Height);
        using (var drawing = Graphics.FromImage(retImg)) {
            //paint the background
            drawing.Clear(backColor);

            //create a brush for the text
            using (Brush textBrush = new SolidBrush(textColor)) {
                drawing.DrawString(currencyCode, font, textBrush, 0, 0);
                drawing.Save();
            }
        }
        return retImg;
    }

Answer 3

这是 Kazar 答案的 Panayiotis 版本，带有可选参数和文档，适合添加到库类中。

/// <summary>
/// Creates an image containing the given text.
/// NOTE: the image should be disposed after use.
/// </summary>
/// <param name="text">Text to draw</param>
/// <param name="fontOptional">Font to use, defaults to Control.DefaultFont</param>
/// <param name="textColorOptional">Text color, defaults to Black</param>
/// <param name="backColorOptional">Background color, defaults to white</param>
/// <param name="minSizeOptional">Minimum image size, defaults the size required to display the text</param>
/// <returns>The image containing the text, which should be disposed after use</returns>
public static Image DrawText(string text, Font fontOptional=null, Color? textColorOptional=null, Color? backColorOptional=null, Size? minSizeOptional=null)
{
    Font font = Control.DefaultFont;
    if (fontOptional != null)
        font = fontOptional;

    Color textColor = Color.Black;
    if (textColorOptional != null)
        textColor = (Color)textColorOptional;

    Color backColor = Color.White;
    if (backColorOptional != null)
        backColor = (Color)backColorOptional;

    Size minSize = Size.Empty;
    if (minSizeOptional != null)
        minSize = (Size)minSizeOptional;

    //first, create a dummy bitmap just to get a graphics object
    SizeF textSize;
    using (Image img = new Bitmap(1, 1))
    {
        using (Graphics drawing = Graphics.FromImage(img))
        {
            //measure the string to see how big the image needs to be
            textSize = drawing.MeasureString(text, font);
            if (!minSize.IsEmpty)
            {
                textSize.Width = textSize.Width > minSize.Width ? textSize.Width : minSize.Width;
                textSize.Height = textSize.Height > minSize.Height ? textSize.Height : minSize.Height;
            }
        }
    }

    //create a new image of the right size
    Image retImg = new Bitmap((int)textSize.Width, (int)textSize.Height);
    using (var drawing = Graphics.FromImage(retImg))
    {
        //paint the background
        drawing.Clear(backColor);

        //create a brush for the text
        using (Brush textBrush = new SolidBrush(textColor))
        {
            drawing.DrawString(text, font, textBrush, 0, 0);
            drawing.Save();
        }
    }
    return retImg;
}