Question

从API调用我的项目时出现了这个异常。

当我们更改某个值时从事件调用throw消息的方法，它将重新绘制背景并重绘字符串。当正常使用应用程序时，这种情况永远不会发生，但是当我从API更改了值时，有时会抛出它。

System.Runtime.InteropServices.ExternalException: A generic error occurred in GDI+.
   at System.Drawing.Graphics.Clear(Color color) at MyCompany.Project.GUI.Drawable.DrawLabel() in D:\Source\MyCompany\Project\GUI\Drawable.cs:line 191
   at MyCompany.Project.GUI.Drawable.OnPaint(PaintEventArgs e) in D:\Source\MyCompany\Project\GUI\Drawable.cs:line 26
   at System.Windows.Forms.Control.PaintWithErrorHandling(PaintEventArgs e, Int16 layer, Boolean disposeEventArgs)
   at System.Windows.Forms.Control.WmPaint(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.ContainerControl.WndProc(Message& m)
   at System.Windows.Forms.UserControl.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

以下是我的代码的样子

public class Drawable : UserControl
{
    private Graphics g;
    public void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);
        DrawLabel();
    }
    private void DrawLabel()
    {
        if ((TopLabels != null) || (LeftLabels != null))
        {    
            g.Clear( BackColor ); //tje error is in here.
            g = CreateGraphics();
            /* another things to do*/
        }
    }
}

Answer 1

您需要将图形从OnPaint（）传递给DrawLabel（）方法。

变化：

DrawLabel();

要：

DrawLabel(e.Graphics);

并改变：

private void DrawLabel()

要：

private void DrawLabel(Graphics g)

...并摆脱CreateGraphics（）调用。

清除时GDI +中的一般错误

1 个答案: