如何在图片框上绘制并将其保存在Winforms C#中?

问题描述

我正在Windows窗体(C#)中创建一个简单的图形编辑器，并且我在画布上使用了 PictureBox .我想实现撤消"功能.我正在使用 System.Drawing.Graphics 进行绘制.这是我的情况:

I'm making a simple graphic editor in Windows Forms (C#), and I'm using a PictureBox for my canvas. I want to implement the "undo" functionality. I'm drawing using System.Drawing.Graphics. Here is my situation:

• 如果我使用 picturebox.CreateGraphics()，那么我将看到绘图，但实际上不会在图像上绘制(如果此后我称为 pictureBox.Image.Save(...)，保存的图像将为空白).

• If I use picturebox.CreateGraphics(), then I will see the drawing, but it won't actually be made on the image (if afterwards I called pictureBox.Image.Save(...), the saved image would be blank).

如果我使用 Graphics.FromImage(picturebox.Image)，则实际上将在图像上绘制图形，但是我什么也看不到.

If I use Graphics.FromImage(picturebox.Image), then the drawing will be actually made on the image, but I won't see anything.

我怎么都可以呢?

在那之后如何实现撤消功能?我尝试在图形上使用 Save()和 Restore()，但是它没有用，也许我误解了这些方法的含义.

And how do I implement the undo functionality after that? I tried using Save() and Restore() on graphics, but it didn't work, maybe I misunderstood what these methods mean.

推荐答案

您应该避免使用CreateGraphics，因为这是一个临时图形，可以通过最小化表单或使其他表单与图形区域重叠等方式将其擦除.

You should avoid using CreateGraphics since that is a temporary drawing that can get erased by minimizing the form or having another form overlap the graphic area, etc.

要更新PictureBox，只需在更新图形后将其无效:

To update the PictureBox, just invalidate it after you have an update to the drawing:

pictureBox1.Invalidate();

撤消重做是另一种野兽.这就要求您保留要绘制的事物的列表，并且要撤消某些任务，需要从列表中删除该项目，然后再次从活动列表中重新绘制整个事物.

The Undo-Redo is a different beast. That requires you to keep a list of things to draw and in order to undo something, you remove the item from the list and redraw the whole thing again from the active list.

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