Question

这是我的代码

Public Class Form1

Public MyFormObject As Graphics = Me.CreateGraphics
Public objFont = New System.Drawing.Font("arial", 20)
Public a, b As Integer
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
    Randomize()
    For i = 1 To 10
        a = CInt(Int(Rnd() * Me.Width))
        b = CInt(Int(Rnd() * Me.Height))
        MyFormObject.DrawString("text", objFont, System.Drawing.Brushes.Black, a, b)
    Next
End Sub
End Class

正如您所看到的，我有一个按钮，在表单中随机抽取字符串“text”10次。我的问题是它只会在表单的左上角绘制字符串，从0,0开始大约260x260。如果它超越，它实际上会切断文本。为什么是这样？它不应该适用于整个表格吗？

Answer 1

您需要在子内移动CreateGraphics。来自Microsoft's documentation：

通过CreateGraphics检索的Graphics对象在当前Windows之后通常不应保留方法消息已被处理，因为任何用该对象绘制的内容将使用下一个WM_PAINT消息擦除。 因此你不能缓存Graphics对象以便重用。

Public Class Form1

    Public objFont = New System.Drawing.Font("arial", 20)
    Public a, b As Integer

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click

        Dim MyFormObject As Graphics = Me.CreateGraphics

        Randomize()
        For i = 1 To 10
            a = CInt(Int(Rnd() * Me.Width))
            b = CInt(Int(Rnd() * Me.Height))
            MyFormObject.DrawString("text", objFont, System.Drawing.Brushes.Black, a, b)
        Next

        MyFormObject.Dispose

    End Sub

End Class

DrawString仅适用于vb.net形式的左上角

1 个答案: