在C++Builder中如何绘通过TPaintBox控件制出一个坐标轴

在C++Builder中，可以使用TPaintBox控件来绘制坐标轴。具体步骤如下：

1. 在Form上放置一个TPaintBox控件。

2. 在TPaintBox的OnPaint事件中进行绘制，代码如下：

void __fastcall TForm1::PaintBox1Paint(TObject *Sender)
{
    TPaintBox *paintBox = dynamic_cast<TPaintBox*>(Sender);
    TCanvas *canvas = paintBox->Canvas;

    // 画坐标轴
    canvas->Pen->Color = clBlack;
    canvas->Pen->Width = 2;
    canvas->MoveTo(50, paintBox->Height - 50);
    canvas->LineTo(50, 50);
    canvas->LineTo(paintBox->Width - 50, 50);

    // 画X轴刻度
    canvas->Pen->Color = clRed;
    canvas->Pen->Width = 1;
    for (int i = 0; i < 10; i++)
    {
        int x = 50 + (paintBox->Width - 100) / 10 * (i + 1);
        canvas->MoveTo(x, 50);
        canvas->LineTo(x, 40);
    }

    // 画Y轴刻度
    canvas->Pen->Color = clBlue;
    canvas->Pen->Width = 1;
    for (int i = 0; i < 10; i++)
    {
        int y = paintBox->Height - 50 - (paintBox->Height - 100) / 10 * (i + 1);
        canvas->MoveTo(50, y);
        canvas->LineTo(40, y);
    }
}

3. 在Form的OnResize事件中，重新计算坐标轴的位置和大小，代码如下：

void __fastcall TForm1::FormResize(TObject *Sender)
{
    PaintBox1->Left = 10;
    PaintBox1->Top = 10;
    PaintBox1->Width = ClientWidth - 20;
    PaintBox1->Height = ClientHeight - 20;
    PaintBox1->Invalidate();
}

这样就可以在TPaintBox控件上绘制出一个简单的坐标轴了。