Graphics.FromImage和DrawImage [英] Graphics.FromImage and DrawImage

问题描述

我需要编写这个示例代码，以便生成的图像与原始图像完全相同。

I need to write this sample code so that the resulting image is the exact same as the original.

Dim a = New Bitmap( _
 My.Application.Info.DirectoryPath & "\a.png")
 Dim b As New Bitmap(a.Width, a.Height, System.Drawing.Imaging.PixelFormat.Format32bppArgb )
 Dim g As Graphics = Graphics.FromImage(b)
 g.DrawImage(a, b.GetBounds(GraphicsUnit.Pixel))
 PictureBox1.Image = b
 b.Save("b.png", System.Drawing.Imaging.ImageFormat.Png)
 g.Dispose()

我不明白会发生什么当我将图像转换为图形时。 Image.FromFile保留所有图片数据，但图形会改变图片大小，以便g.DrawImage（a，0,0）可以是更大的图片，但会裁剪为原始图片的大小。 Graphics.FromImage会调整图片大小，因此会丢失一些质量。



这可以重写，以便结果与原始结果相同（不会调整大小/丢失质量） ）？

I don''t understand what happens when I convert an image to graphics. Image.FromFile preserves all of the picture data, but graphics changes the picture size so that g.DrawImage(a, 0, 0) would be a larger picture, but cropped to the original''s size. Graphics.FromImage resizes the picture and so some quality is lost.

Can this be rewritten so that the result is the same as the original (no resizing/loss of quality)?

推荐答案

你需要经过很多代码来做一些非常简单的事情。

You''re going through a lot of code to do something very simple.

Dim b As New Bitmap(a)

尝试阅读Bitmap类的文档并查看构造函数的重载。

Try reading the documentation on the Bitmap class and look at the overloads for the constructor.

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