在VB.NET覆盖从流的图象 [英] Overlaying images from stream in VB.NET

问题描述

我想覆盖多个图像（PNG，同样大小都与透明度）。到目前为止，我的code是如下：

I'd like to overlay a number of images (PNG, same size for all, with transparency). So far, my code is as follows.

    bg = New Bitmap(My.Resources.blue)
    g = Graphics.FromImage(bg)

    overlay = New Bitmap(tree.Image)
    g.DrawImage(overlay, 0, 0)

现在，我想覆盖多了一个形象，但是这是基于用户的，从一个文本框输入。因此，要获得这种形象，我们需要用户的输入，并获得相应的资源文件。

Now, I would like to overlay one more image, but this is based on a user's input from a textbox. So, to get that image, we need to take the user's input, and get the respective resource file.

我做如下：

Dim stream As IO.Stream = Nothing    
Dim path As String = Assembly.GetName().Name.ToString() + "." + inputbox.text + ".png"
stream = Assembly.GetManifestResourceStream(path)

这找到正确的图像流。

And this correctly finds the image stream.

现在，我尝试重叠显示图像：

Now, I try and overlay the images:

    overlay = New Bitmap(stream)
    g.DrawImage(overlay, 0, 0)

不过，这种叠加似乎并没有工作。

However, this overlay doesn't seem to work.

请注意，如果我做这样的事情：

Note that if I do something like this:

overlay = New Bitmap(My.Resources._5)
g.DrawImage(overlay, 0, 0)

叠加正常工作。

The overlay works correctly.

所以问题是：为什么是覆盖不从流工作？

So question is: Why is the overlay not working from the stream?

编辑： 事实证明，叠加不实际工作，但似乎叠加放大的图像，而不是真正的大小。会不会有任何原因？

It turns out that the overlay does actually work, but seems to overlay an enlarged image rather than the true size. Would there be any reason for this?

推荐答案

我有同样的问题 - 我已经追踪问题，以图像的DPI被覆盖和图像的DPI是叠加。检查这两个值，并尝试做的DrawImage之前改变它们

I have the same problem - I've tracked the problem to DPI of image being overlaid and DPI of image that is overlay. Check those two values, and try changing them before doing DrawImage

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