标签UserPaint绘制的文本不适合

问题描述

我有一个自定义的Label类，绘制的文本不适合.我在这里做什么错了?

I have a custom Label class, drawn text doesn't fits. What am I doing wrong here?

class MyLabel: Label
{
    public MyLabel()
    {
        SetStyle(ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        using (LinearGradientBrush brush = new LinearGradientBrush(ClientRectangle, Color.Black, Color.LightGray, LinearGradientMode.ForwardDiagonal))
            e.Graphics.DrawString(Text, Font, brush, ClientRectangle);
    }
}

如果我将MyLabel的文本设置为"123456790 123456790"( AutoSize = true )，那么我会在Designer中(或在运行时)看到"1234567890 123456789"(没有最后一个零，但是一些空间).如果我尝试使用"1234567890 1234567890 1234567890 1234567890"，则将出现"1234567890 1234567890 1234567890 12345678"(不包含"90"，但还会有一些空格).

If I set text of MyLabel to be "123456790 123456790" (AutoSize = true), then I see in Designer (or at run-time) "1234567890 123456789 " (no last zero, but some space). If I try "1234567890 1234567890 1234567890 1234567890", then there will be "1234567890 1234567890 1234567890 12345678 " (no "90", but again some space).

推荐答案

此处介绍了上述问题的一种解决方案(可能不是最好的解决方案)，可以将其重新表述为带有渐变文本颜色的自动调整大小的标签".

Here goes a solution (possible not the best one) to the described problem which can be rephrased as "Autosized Label with Graditent text color".

class MyLabel: Label
{
    private bool _autoSize = true;
    /// <summary>
    /// Get or set auto size
    /// </summary>
    public new bool AutoSize
    {
        get { return _autoSize; }
        set
        {
            _autoSize = value;
            Invalidate();
        }
    }

    public MyLabel()
    {
        SetStyle(ControlStyles.SupportsTransparentBackColor | ControlStyles.UserPaint, true);
        base.AutoSize = false;
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        // auto size
        if (_autoSize)
        {
            SizeF size = e.Graphics.MeasureString(Text, Font);
            if (ClientSize.Width < (int)size.Width + 1 || ClientSize.Width > (int)size.Width + 1 ||
            ClientSize.Height < (int)size.Height + 1 || ClientSize.Height > (int)size.Height + 1)
            {
                // need resizing
                ClientSize = new Size((int)size.Width + 1, (int)size.Height + 1);
                return;
            }
        }
        using (LinearGradientBrush brush = new LinearGradientBrush(ClientRectangle, Color.Black, Color.LightGray, LinearGradientMode.ForwardDiagonal))
        e.Graphics.DrawString(Text, Font, brush, ClientRectangle);
    }
}

后面的想法非常简单:如果所需的文本大小与ClientSize不同，请重写AutoSize并在Paint事件(所有内容都放在一个地方)中对其进行处理-调整大小控件(这将导致重新绘制).一件事是您必须在宽度和高度上加上+1，因为SizeF带有小数，最好是+1像素多于松散的1像素，并且文本不适合.

Idea behind is very simple: override AutoSize and process it within Paint event (everything in one place), if required size of text is different from ClientSize - resize control (which will cause redraw). One thing is what you have to add +1 to the width and height because SizeF have fractions and it's better to have +1 pixel more than loose 1 pixel sometimes and have your text not fitting.

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