C#中重写OnPaint方法的PictureBox

问题描述

我想在PictureBox(连续4 x 32px图像)中绘制一些小图片，所以我应该重写OnPaint方法还是需要创建扩展PictureBox的新组件？ 我试过这个，它在Java中起作用，但在这里不行：

        this.pictureBox1 = new System.Windows.Forms.PictureBox()
        {
            protected override void OnPaint(PaintEventArgs e)
            {
               // If there is an image and it has a location, 
               // paint it when the Form is repainted.
                Graphics g = e.Graphics;

                // Draw a string on the PictureBox.
                g.DrawString("Test, is that working?",
                new Font("Arial", 10), System.Drawing.Brushes.Blue, new Point(30, 30));
             }
        }

InitializeComponent方法完整代码：

   private void InitializeComponent()
    {
        System.ComponentModel.ComponentResourceManager resources = new System.ComponentModel.ComponentResourceManager(typeof(Tools));
        this.pictureBox1 = new System.Windows.Forms.PictureBox()
        {
            protected override void OnPaint(PaintEventArgs e)
            {
               // If there is an image and it has a location, 
               // paint it when the Form is repainted.
                Graphics g = e.Graphics;

                // Draw a string on the PictureBox.
                g.DrawString("Test, is that working?",
                new Font("Arial", 10), System.Drawing.Brushes.Blue, new Point(30, 30));
             }
        }
        this.vscrollb = new System.Windows.Forms.VScrollBar();
        this.vScrollBar1 = new System.Windows.Forms.VScrollBar();
        ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).BeginInit();
        this.SuspendLayout();
        // 
        // pictureBox1
        // 
        this.pictureBox1.Dock = System.Windows.Forms.DockStyle.Left;
        this.pictureBox1.Image = ((System.Drawing.Image)(resources.GetObject("pictureBox1.Image")));
        this.pictureBox1.InitialImage = null;
        this.pictureBox1.Location = new System.Drawing.Point(0, 0);
        this.pictureBox1.Name = "pictureBox1";
        this.pictureBox1.Size = new System.Drawing.Size(264, 262);
        this.pictureBox1.TabIndex = 0;
        this.pictureBox1.TabStop = false;
        this.pictureBox1.Paint += new System.Windows.Forms.PaintEventHandler(this.pictureBox1_Paint);
        // 
        // vscrollb
        // 
        this.vscrollb.Location = new System.Drawing.Point(0, 0);
        this.vscrollb.Name = "vscrollb";
        this.vscrollb.Size = new System.Drawing.Size(20, 80);
        this.vscrollb.TabIndex = 0;
        // 
        // vScrollBar1
        // 
        this.vScrollBar1.Dock = System.Windows.Forms.DockStyle.Right;
        this.vScrollBar1.Location = new System.Drawing.Point(267, 0);
        this.vScrollBar1.Name = "vScrollBar1";
        this.vScrollBar1.Size = new System.Drawing.Size(17, 262);
        this.vScrollBar1.TabIndex = 1;
        this.vScrollBar1.Scroll += new System.Windows.Forms.ScrollEventHandler(this.HandleScroll);
        // 
        // Tools
        // 
        this.AutoScaleDimensions = new System.Drawing.SizeF(6F, 13F);
        this.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font;
        this.BackColor = System.Drawing.Color.Black;
        this.ClientSize = new System.Drawing.Size(284, 262);
        this.Controls.Add(this.vScrollBar1);
        this.Controls.Add(this.pictureBox1);
        this.Name = "Tools";
        this.Text = "Tools";
        ((System.ComponentModel.ISupportInitialize)(this.pictureBox1)).EndInit();
        this.ResumeLayout(false);

    }

推荐答案

这不是有效的C#代码。覆盖像OnPaint()这样的虚方法很好，但只能在派生自PictureBox的类中这样做。编译后，您将自动将新控件添加到工具箱中，以便可以将其放在窗体上。

但是，这不是必需的。只需实现控件的Paint事件即可。您已经这样做了，您将其命名为PictureBox1_Paint()。只需将您的代码移到那里。

其他重要提示：切勿编辑InitializeComponent()。它是由设计者自动生成的。一旦修改了表单的设计，您在那里编写的所有代码都将丢失。这也是使表单不可设计的一种非常好的方法，在设计者加载表单时触发异常。如果您确实覆盖了OnPaint()，那么调用base.OnPaint()很重要。以使正常的PictureBox管道继续工作。包括绘制图像和引发绘制事件。请务必至少阅读有关WinForms编程的教程或书籍，否则会有很多尝试，如果不这样做，大多数情况下都会出错。

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