Trying to iterate over the frames in a System.Drawing.Image, throws invalid parameter exception

问题

I'm trying to use Bar Code Recognition software and need to iterate over all the frames in a tiff file. I am confused on several points: 1) What is a frame, why does it have a guid and why do I need to iterate over frames? I can't seem to find a lot of documentation.

2) The code throws an invalid parameter exception after one iteration. I'm not sure why; logically, i cannot exceed the frame count, so not sure how it could be an invalid parameter, assuming that is the problem.

System.Drawing.Image img = System.Drawing.Image.FromStream(mems);
Guid guid = img.FrameDimensionsList[0];
FrameDimension dimension = new FrameDimension(guid);
int totalFrame = img.GetFrameCount(dimension);

foreach(int i =0; i < totalFrame; i++)
{   
    img.SelectActiveFrame(dimension, i);
}

回答1:

Frames typically represent several images within the same image file. For instance, an animated GIF has several frames along the time dimension. An icon might have several frames along the resolution dimension (i.e. distinct images for different resolutions).

For instance, this code displays all frames in an animated GIF (in LinqPad):

var image = Image.FromFile(path);
int frames = image.GetFrameCount(FrameDimension.Time);
for (int i = 0; i < frames; i++)
{
    image.SelectActiveFrame(FrameDimension.Time, i);
    image.Dump();
}

In your code, you're taking the first element from FrameDimensionList, without knowing which dimension it represents. Try using FrameDimension.Page instead (assuming you need to iterate over the "page" dimension).

来源：https://stackoverflow.com/questions/11856210/trying-to-iterate-over-the-frames-in-a-system-drawing-image-throws-invalid-para

标签

.net

system.drawing