【发布时间】：2021-07-19 04:25:28
【问题描述】：
我有一个图片框可以在它上面绘制，没有任何图像，在白色背景上。那幅画，我想保存为pdf（作为图像）
对于图片框，我有以下代码：
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
lastPoint = e.Location;//we assign the lastPoint to the current mouse position: e.Location ('e' is from the MouseEventArgs passed into the MouseDown event)
isMouseDown = true;//we set to true because our mouse button is down (clicked)
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
isMouseDown = false;
lastPoint = System.Drawing.Point.Empty;
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (isMouseDown == true)//check to see if the mouse button is down
{
if (lastPoint != null)//if our last point is not null, which in this case we have assigned above
{
if (pictureBox1.Image == null)//if no available bitmap exists on the picturebox to draw on
{
//create a new bitmap
Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
pictureBox1.Image = bmp; //assign the picturebox.Image property to the bitmap created
}
using (Graphics g = Graphics.FromImage(pictureBox1.Image))
{//we need to create a Graphics object to draw on the picture box, its our main tool
//when making a Pen object, you can just give it color only or give it color and pen size
g.DrawLine(new Pen(Color.Black, 2), lastPoint, e.Location);
g.SmoothingMode = SmoothingMode.AntiAlias;
//this is to give the drawing a more smoother, less sharper look
}
pictureBox1.Invalidate();//refreshes the picturebox
lastPoint = e.Location;//keep assigning the lastPoint to the current mouse position
}
}
}
对于pdf的创建，我使用itext7，在内存中创建我使用的代码是：
var stream = new MemoryStream();
var writer = new PdfWriter(stream);
var pdf = new PdfDocument(writer);
var document = new Document(pdf);
document.Add(new Paragraph("Hello world!"));
MemoryStream ms = new MemoryStream();
pictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
byte[] buff = ms.ToArray();
ImageData rawImage = ImageDataFactory.Create(buff);
iText.Layout.Element.Image image = new iText.Layout.Element.Image(rawImage);
document.Add(image);
因此，我总是得到一个黑色背景的图像，而不是我实际写的。
【问题讨论】：
-
我建议您使用 .png 或 .jpg，如果您想使用位图。我很确定winforms默认使用bmp（位图），可能是转换错误？
-
使用 PictureBox 的 Paint 事件将 Bezier 曲线添加到 GraphicsPath。当您在 PictureBox 上完成绘图（用作预览）时，使用与在 PictureBox 上绘图相同的过程将结果保存到位图。这里有一个例子：How to draw a signature and save it to disc as a Bitmap?。这是一种略有不同的语言。如果你有兴趣，我可以翻译。顺便说一句，您需要在绘制形状之前指定
SmoothingMode = SmoothingMode.AntiAlias。 -
@SimpleCoder 有没有试过的解决方案，我改了pictureBox1.Image.Save(ms, System.Drawing.Imaging.ImageFormat.Png);对于 Png 而不是 Jepg，现在它显示它而不是白色背景。如果你愿意，请给出答案，我接受它
标签： c# winforms itext windows-forms-designer itext7