Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height)
时间: 2024-05-24 20:10:39 浏览: 123
This line of code creates a new instance of the Bitmap class with the specified width and height, which are the dimensions of the PictureBox control named "PictureBox1". The Bitmap class is a representation of a bitmap image, which is a grid of pixels that form an image. The new instance of the Bitmap class is stored in the variable "bmp".
相关问题
Dim bmp As New Bitmap(PictureBox1.Width, PictureBox1.Height) 报错未将对象引用设置到对象的实例
这个错误通常表示您尚未实例化对象。您需要先创建一个对象,然后才能使用它。在这种情况下,您需要先创建一个PictureBox控件的实例,然后才能使用它来创建一个Bitmap对象。例如:
Dim picBox As New PictureBox
picBox.Width = 100
picBox.Height = 100
Dim bmp As New Bitmap(picBox.Width, picBox.Height)
请注意,您还需要将PictureBox控件添加到您的窗体或用户控件中,否则它将无法显示。例如:
Me.Controls.Add(picBox)
此外,您还需要在PictureBox控件中设置一些属性,如Image属性,以便在PictureBox中显示位图。例如:
picBox.Image = bmp
var point = pictureBox1.PointToClient(new Point(e.X, e.Y)); string itemName = (string)e.Data.GetData(DataFormats.Text); ListViewItem item = listView1.FindItemWithText(itemName); if (item != null) { long fileSize = new FileInfo(itemName).Length; int width = Math.Min(pictureBox1.Width, Math.Max(10, (int)(fileSize / 1024))); int height = Math.Min(pictureBox1.Height, Math.Max(10, (int)(fileSize / 1024))); Bitmap bmp = new Bitmap(width, height); using (Graphics g = Graphics.FromImage(bmp)) { g.Clear(Color.White); g.DrawString(itemName, new Font("Arial", 10), Brushes.Black, new RectangleF(0, 0, width, height), new StringFormat { Alignment = StringAlignment.Center }); } point.X = Math.Min(point.X - width / 2, pictureBox1.Width - width); point.Y = Math.Min(point.Y - height / 2, pictureBox1.Height - height); point.X = Math.Max(point.X, 0); point.Y = Math.Max(point.Y, 0); pictureBox1.BackgroundImage = bmp; pictureBox1.Location = point; }什么意思
这段代码主要是在通过鼠标拖动ListView中的项到PictureBox控件上时,根据所选项的文件大小创建一个位图,并在位图上绘制文件名,然后将位图作为PictureBox的背景图,并根据鼠标位置调整PictureBox的位置。具体实现过程如下:
- 使用PointToClient()方法将鼠标位置转换为PictureBox中的相对位置;
- 获取拖动项的文本内容,即文件名;
- 通过ListView.FindItemWithText()方法查找该文件名对应的ListViewItem对象;
- 若找到对应项,则根据文件大小计算出位图的宽度和高度,并创建一个空白的位图对象;
- 在位图上绘制文件名,然后根据鼠标位置调整位图的位置;
- 将位图作为PictureBox的背景图,并将PictureBox的位置设置为调整后的位置。