更改列表框的颜色、突出显示、背景大小? [英] Changing color, highlight, background size of a ListBox?

问题描述

所以我四处搜索并设法突出显示我的 ListBox 中的值，但我正在尝试增加 ListBox 内文本的字体大小，但是它会生成以下图片:

这是我当前的代码:

Private Sub ListBox1_DrawItem(sender As System.Object, e As System.Windows.Forms.DrawItemEventArgs) 处理 ListBox1.DrawIteme.DrawBackground()如果 ListBox1.Items(e.Index).ToString().Contains("*") 那么e.Graphics.FillRectangle(Brushes.Red, e.Bounds)万一e.Graphics.DrawString(ListBox1.Items(e.Index), e.Font, Brushes.Black, New System.Drawing.PointF(e.Bounds.X, e.Bounds.Y))e.DrawFocusRectangle()

我尝试使用e.Bounds.X，e.Bounds.Y"来增加突出显示值的矩形/大小，但似乎没有任何效果.

如何让高亮矩形根据字体大小增加?

解决方案

当你设置

So I've searched around and managed to highlight the values in my ListBox, but I'm trying to increase the font size for the text inside the ListBox but it results in the following image as attached:

This is my current code:

Private Sub ListBox1_DrawItem(sender As System.Object, e As System.Windows.Forms.DrawItemEventArgs) Handles ListBox1.DrawItem

    e.DrawBackground()

    If ListBox1.Items(e.Index).ToString().Contains("*") Then
        e.Graphics.FillRectangle(Brushes.Red, e.Bounds)
    End If

    e.Graphics.DrawString(ListBox1.Items(e.Index), e.Font, Brushes.Black, New System.Drawing.PointF(e.Bounds.X, e.Bounds.Y))
    e.DrawFocusRectangle()

I've tried messing with the "e.Bounds.X, e.Bounds.Y" to increase the rectangle/size of the highlighted value but nothing seemed to work.

How does one allow the highlighted rectangle increase according to the font size?

解决方案

When you set the DrawMode of a ListBox control to OwnerDrawVariable or you change the Font size after the control handle has been created (i.e. after it has already processed the WM_MEASUREITEM message), you need to manually set the ItemHeigh property to the new Font height.

The ItemHeight property is set subscribing the ListBox MeasureItem event and setting the MeasureItemEventArgs e.ItemHeight property.

Also, if you change the Font size on the fly, you also need to force the WM_MEASUREITEM message to be re-sent to the ListBox control, otherwise the Items Bounds will not be updated.
In other words, when the DrawItem event is raised, the DrawItemEventArgs e.Bounds property will report wrong measures.

A way to force the ListBox control to re-measure its Items bounds, is to set ListBox.DrawMode = DrawMode.Normal and immediatly resetting it back to OwnerDrawVariable. This causes the WM_MEASUREITEM message to be processed again.

listBox1.DrawMode = DrawMode.Normal
listBox1.DrawMode = DrawMode.OwnerDrawVariable
listBox1.Update()

Here I'm using the Font.Height to measure the current ItemHeight in the MeasureItem event, because it rounds up the measure. You could use TextRenderer.MeasureText or Font.GetHeight(); you'll end up with the same measure, but rounded down.

Private Sub ListBox1_DrawItem(sender As Object, e As DrawItemEventArgs) Handles ListBox1.DrawItem

    Dim ItemForeColor As Color
    Dim ItemBackColor As Color

    e.Graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit

    If (e.State And DrawItemState.Selected) = DrawItemState.Selected Then
        ItemForeColor = Color.FromKnownColor(KnownColor.HighlightText)
        ItemBackColor = If(ListBox1.Items(e.Index).ToString().Contains("*"), Color.Red, Color.FromKnownColor(KnownColor.Highlight))
    Else
        ItemForeColor = ListBox1.ForeColor
        ItemBackColor = If(ListBox1.Items(e.Index).ToString().Contains("*"), Color.Red, ListBox1.BackColor)
    End If

    Using TextBrush As New SolidBrush(ItemForeColor)
        Using ItemBrush As New SolidBrush(ItemBackColor)
            e.Graphics.FillRectangle(ItemBrush, e.Bounds)
            e.Graphics.DrawString(ListBox1.Items(e.Index).ToString(), ListBox1.Font, TextBrush, e.Bounds, StringFormat.GenericTypographic)
        End Using
    End Using
    e.DrawFocusRectangle()
End Sub

Private Sub ListBox1_MeasureItem(sender As Object, e As MeasureItemEventArgs) Handles ListBox1.MeasureItem
    e.ItemHeight = ListBox1.Font.Height
End Sub

Test it resizing the Font:

ListBox1.Font = New Font(ListBox1.Font.FontFamily, ListBox1.Font.SizeInPoints + 2, ListBox1.Font.Style, GraphicsUnit.Point)
ListBox1.DrawMode = DrawMode.Normal
ListBox1.DrawMode = DrawMode.OwnerDrawVariable
ListBox1.Height = '[OriginalHeight]
ListBox1.Update()

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