Question

I have a PictureBox control in windows form with a movable rectangle drawing in it, my PictureBox size will increase according to the position of the rectangle, when the PictureBox size is greater than a particular size scrollbar will appear.

public void PicBox_MouseDown(object sender, MouseEventArgs e)
{

       if (rect.Contains(new Point(e.X, e.Y)))
       {
           mMove = true;
       }

       oldX = e.X;
       oldY = e.Y;
}

 public void Picbox_MouseUp(object sender , MouseEventArgs e)
 {
      mMove = false;
 }

 public void Picbox_MouseMove(object sender,MouseEventArgs e)
 {
      if (mMove)
      {
            picBox.Cursor = Cursors.Cross;
            rect.X = rect.X + e.X - oldX;
            rect.Y = rect.Y + e.Y - oldY;
      }
      oldX = e.X;
      oldY = e.Y;
      picBox.Invalidate();
 }

public void Picbox_MousePaint(object sender, PaintEventArgs e)
{
        picBox.Invalidate();
        picBox.Size = new Size((rect.Width + rect.X) + 10, (rect.Height + rect.Y) + 10);
        Draw(e.Graphics);  
}

enter image description here

On first display of form with pictureBox

enter image description here

After dragging the rectangle the size of the pictureBox increases and scroll bar appears

everything works fine here but my problems is no matter how much the size of the pictureBox is the scroll bar works fine when i drag it down,but when the rectangle is dragged up and if the edges of the pictureBox meets the form the whole scroll bar is reset to normal, by looking at the pictures below you will be able to understand what i want to say

enter image description here

How to solve this, is there another way to increase scroll according to the width of pictureBox ? i am new at this.

the rectangle is acting as if the the X and Y co-ordinates are tracked with respect to winform but not pictureBox.

Can i make pictureBox as a parent for my Drawing?

Answer 1

我担心这是不可能的。

在Winforms Scrollbars中，只会将带有溢出其容器的内容重新置于视图中。如果他们“下溢”，即如果他们的Top和/或Left值为负值，则不显示ScrollBars，即使他们这样做（因为额外的溢出）他们也不会带回来

最小滚动位置为zero。

所以你必须确保不要把事情变成负面的！

您可以通过添加虚拟控件来强制ScrollBars，但这样只会让您完全滚动PictureBox向上或向左看不见，而不是回来！

如果你真的真的真的非常想要，你可以检测到这种情况并手动添加ScrollBar控件并对其进行编码以将PictureBox向下/向右移动..

既然你在问，这是一个可以玩的例子。请注意，使用coded ScrollBars有很多陷阱..

其中一个是如何处理真实ScrollBar出现的情况？在示例中，我通过不将ScrollBar添加到Panel但通过覆盖它来解决它;因此，当编码的ScrollBar显示时，它将被隐藏。
另一个问题是数字：内容应移动多少像素？我不会让用户在任何地方滚动，但是当发生这种情况时我会一直移动PictureBox并且编码的ScrollBar会消失..
作为警告的最后一点，应该注意，编码ScrollBar可以让你对你拥有的控件做些事情;但是它不会允许你实际滚动到负面区域。我想你真正想要的是什么。但我认为这是不可能的！

所以，我建议您不要使用下面的代码，除非您只需将PictureBox.Top恢复为零即可！

// a variable at class level:
VScrollBar vScroll = null;

// move into negative for testing:
pictureBox1.Top = -15;
// now check to see if we need a VScrollBar
scrollCheck();

void scrollCheck()
{
    if (pictureBox1.Top < 0)
    {
        if (vScroll == null )
        { vScroll = new VScrollBar(); vScroll.Parent = panel1.Parent;
        vScroll.Scroll += vScroll_Scroll; vScroll.BringToFront();
        }
        vScroll.Location = new Point(panel1.Right - vScroll.Width - 2, panel1.Top + 1);
        vScroll.Height = panel1.ClientSize.Height - 2;
        vScroll.Value = vScroll.Maximum;
        vScroll.Show();
        }
    else
    { vScroll.Hide(); }
}

void vScroll_Scroll(object sender, ScrollEventArgs e)
{
    int delta = e.NewValue - e.OldValue;
    if (delta < 0)
    {
        pictureBox1.Top = 0;
        scrollCheck();
    }
}

总而言之，我真的相信避免这种情况会是最好的。

How to scroll on increasing picturebox size in windows form c#?

1 个答案: