滚动时面板背景不刷新 (C#/VB.net) [英] Panel Background not refreshing during scrolling (C#/VB.net)

问题描述

我在 C# 和 VB.net 中有这个奇怪的滚动/背景错误.当我创建一个面板并使用 Autoscroll 时，滚动过程中背景不会更新.最后看起来真的很奇怪(视频:

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VB.NET

公共类 PanelEx继承面板公共子新建()双缓冲 = 真结束子Protected Overrides Sub OnPaintBackground(e As PaintEventArgs)如果不是 BackgroundImage 什么都不是如果 BackgroundImageLayout = ImageLayout.Tile 那么将 x 调暗为整数，将 y 调为整数而 x <= DisplayRectangle.Widthy = 0当 y <= DisplayRectangle.Heighte.Graphics.DrawImage(背景图片，新点(x - Horizo​​ntalScroll.Value，y - VerticalScroll.Value))y += 背景图像.高度结束时间x += BackgroundImage.Width结束时间别的e.Graphics.DrawImage(BackgroundImage,新点(-Horizo​​ntalScroll.Value，-VerticalScroll.Value))万一别的MyBase.OnPaintBackground(e)万一结束子结束类

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如何使用

1. 右键单击您的项目，然后在菜单中选择Add，然后选择Class.将类命名为 PanelEx.vb
2. 将上面的代码复制并粘贴到该类文件中.
3. 在包含您要修改的面板的表单中，进入设计器文件(请看下图)
4. 将 Panel 的所有实例更改为 PanelEx
5. 保存，重新构建并运行.

I have this weird scrolling/background bug in C# and VB.net. When I create a panel and I use Autoscroll the background isnt updating during scrolling. In the end it looks really weird (video: https://youtu.be/0vaO-zmWFmk) I tried the same with a TabControl and the background scrolled like it should. I tried external scrollbars and the same happened. And I tried VB.net too. I think this is a bug from Visual Studios and I would appreciate if someone could help me Thanks, LG!

解决方案

If you want the image to scroll with the scrollbar, you can do this easily by simply extending the Panel and overriding OnPaintBackground.

Keep in mind, if you do this, you must make the control DoubleBuffered (this is done for you in the code below).

In this example, I added in a "Tiled" option. So you could use one big image, or use a seamless tile and tile it (set via BackgroundImageLayout property. All other options will paint the same).

C#

using System.Drawing;
using System.Windows.Forms;

public class PanelEx : Panel
{
    public PanelEx()
    {
        DoubleBuffered = true;
    }

    protected override void OnPaintBackground(PaintEventArgs e)
    {
        if (BackgroundImage != null)
        {
            if (ImageLayout.Tile == BackgroundImageLayout)
            {
                for (int x = 0; x <= DisplayRectangle.Width;
                    x += BackgroundImage.Width)
                {
                    for (int y = 0; y <= DisplayRectangle.Height;
                        y += BackgroundImage.Height)
                    {
                        e.Graphics.DrawImage(BackgroundImage,
                            new Point(x - HorizontalScroll.Value,
                                y - VerticalScroll.Value));
                    }
                }
            }
            else
            {
                e.Graphics.DrawImage(BackgroundImage,
                    new Point(-HorizontalScroll.Value, -VerticalScroll.Value));
            }
        }
        else
        {
            base.OnPaintBackground(e);
        }
    }
}

How to use this

1. Right-click on your project and in the menu select Add then Class. Name the class PanelEx.cs
2. Copy and paste the code above in to that class file.
3. In the form that has the panel you want to modify, go in to the designer file (Look at image below)
4. Change all instances of System.Windows.Forms.Panel(); to PanelEx();
5. Save, do a full rebuild and run.

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VB.NET

Public Class PanelEx
    Inherits Panel

    Public Sub New()
        DoubleBuffered = True
    End Sub

    Protected Overrides Sub OnPaintBackground(e As PaintEventArgs)
        If Not BackgroundImage Is Nothing Then
            If BackgroundImageLayout = ImageLayout.Tile Then

                Dim x As Integer, y As Integer
                While x <= DisplayRectangle.Width
                    y = 0
                    While y <= DisplayRectangle.Height
                        e.Graphics.DrawImage(
                            BackgroundImage,
                            New Point(x - HorizontalScroll.Value,
                                      y - VerticalScroll.Value))
                        y += BackgroundImage.Height
                    End While
                    x += BackgroundImage.Width
                End While
            Else
                e.Graphics.DrawImage(BackgroundImage,
                                     New Point(-HorizontalScroll.Value,
                                               -VerticalScroll.Value))
            End If
        Else
            MyBase.OnPaintBackground(e)
        End If
    End Sub
End Class

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How to use this

1. Right-click on your project and in the menu select Add then Class. Name the class PanelEx.vb
2. Copy and paste the code above in to that class file.
3. In the form that has the panel you want to modify, go in to the designer file (Look at image below)
4. Change all instances of Panel to PanelEx
5. Save, do a full rebuild and run.

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