从图片框中获取图像 [英] getting image from a picturebox

问题描述

如何获得我在图片框上绘制的图像?在我的应用程序中，我使用手绘图创建了一个表单.但是我无法将我绘制的图像保存为文件，有一条错误消息对象引用未设置为对象的实例".我正在使用代码

how can i get an image that i drawn on a picturebox? in my application i created a form with the freehand drawing.but i can't save the image that i drawn as a file,there have a error message that "object reference not set to an instance of an object".I am using the code

me.picturebox1.image.save(filename,sysytem.....jpeg)

谁知道请帮帮我...谢谢

any one knows please help me...thank you

推荐答案

我会假设您从不分配 PictureBox 的 Image 属性，而是直接执行绘图命令在从 PictureBox 控件检索的 Graphics 对象上.如果是这种情况，则在执行绘图时 Image 属性将保持为 Nothing/null.要解决此问题，请在初始化 PictureBox 控件时为 Image 属性分配一个空图像:

I will assume that you never assign the Image property of your PictureBox but instead perform drawing commands directly on a Graphics object retrieved from the PictureBox control. If that is the case, the Image property will remain Nothing/null when you perform the drawing. To get around this, assign an empty image to the Image property when you initialize the PictureBox control:

myPictureBox.Image =  New Bitmap(myPictureBox.ClientSize.Width, _
                                 myPictureBox.ClientSize.Height)

然后，当你想执行一些绘图时，使用 Image 中的 Graphics 对象而不是 PictureBox:

Then, when you want to perform some drawing, use a Graphics object from the Image instead of the PictureBox:

Using g As Graphics = Graphics.FromImage(myPictureBox.Image)
    ' do the drawing '
End Using

使用这种方法，您可以像在当前代码中一样保存图像，只需在 PictureBox.Image 对象上调用 Save.

With this approach you can save the image as you do in your current code, by simply calling Save on the PictureBox.Image object.

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