vb.net – 圆角矩形不准确

发布时间：2020-12-17 00:05:33 所属栏目：大数据来源：网络整理

导读：我发现使用GDI绘制圆角矩形的每个示例代码都是这样的(从BobPowell.net解除并略微修改)： Private Sub Panel1_Paint(ByVal sender As Object,ByVal e As PaintEventArgs) Handles Panel1.Paint e.Graphics.Clear(SystemColors.Window) e.Graphics.SmoothingMo

我发现使用GDI绘制圆角矩形的每个示例代码都是这样的(从BobPowell.net解除并略微修改)：

Private Sub Panel1_Paint(ByVal sender As Object,ByVal e As PaintEventArgs) Handles Panel1.Paint
    e.Graphics.Clear(SystemColors.Window)
    e.Graphics.SmoothingMode = SmoothingMode.None

    Call DrawRoundRect(e.Graphics,Pens.Red,10,48,24,6)
  End Sub

  Public Sub DrawRoundRect(ByVal g As Graphics,ByVal p As Pen,ByVal x As Single,ByVal y As Single,ByVal width As Single,ByVal height As Single,ByVal radius As Single)
    Using gp As New GraphicsPath()
      gp.StartFigure()
      gp.AddArc(x + width - radius,y,radius * 2,270,90)
      gp.AddArc(x + width - radius,y + height - radius,90)
      gp.AddArc(x,90,180,90)
      gp.CloseFigure()
      g.DrawPath(p,gp)
    End Using
  End Sub

这会产生一个圆角矩形,其中只有左上角是准确的.

AntiAliasing必须关闭,因为它正在通过远程桌面连接,我不能依赖它可用.此外,我正在寻找一个清晰的圆角矩形.

我已经尝试调整其他角落的大小并更改笔对齐,但似乎没有任何东西可以产生简单,精确的圆角矩形.

有没有办法在旧的winforms中绘制比这更好的圆角矩形？

1)将源图像的大小调整为其原始大小的二进制倍数.通常,我将重新采样到比原始宽度和高度大4倍(或8或16)的宽度和高度.

2)执行我的所有GDI绘图操作(当然,考虑到我的坐标需要乘以4倍).没有必要使用任何花哨的抗锯齿.

3)将图像重新采样回原始尺寸.缩小图像会产生良好的平滑效果,并最大限度地减少线条,曲线等中的任何舍入误差.

private Bitmap GenerateButton(int overSampling) {

    int overSampling = 8;
    int width=(48 + 10 + 10 + 6) * overSampling;
    int height=(24 + 10 + 10 + 6) * overSampling;

    // Draw the button with the rounded corners,but do
    // so at 8 times the normal size.
    Bitmap bitmap=new Bitmap(width,height);
    using (Graphics g = Graphics.FromImage(bitmap)) {
        g.Clear(Color.White);
        g.SmoothingMode = SmoothingMode.None;
        DrawRoundRect(overSampling,g,new Pen(Color.Red,overSampling),6);
    }

    // Shrink the image down to its intended size
    Bitmap shrunkVersion=new Bitmap(bitmap.Width / overSampling,bitmap.Height / overSampling);
    using (Graphics g = Graphics.FromImage(shrunkVersion)) {
        // Use hi-quality resampling for a nice,smooth image.
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.DrawImage(bitmap,shrunkVersion.Width,shrunkVersion.Height);
    }

    return shrunkVersion;
}

private void DrawRoundRect(int overSampling,Graphics g,Pen p,float x,float y,float width,float height,float radius)
{
    using (GraphicsPath gp = new GraphicsPath())
    {
        gp.StartFigure();
        gp.AddArc((x + width - radius) * overSampling,y * overSampling,(radius * 2) * overSampling,90);
        gp.AddArc((x + width - radius) * overSampling,(y + height - radius) * overSampling,90);
        gp.AddArc(x * overSampling,radius * 2 * overSampling,90);
        gp.CloseFigure();
        g.DrawPath(p,gp);
    }
}

没有过采样：

进行8次过采样：

（编辑：李大同）

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