使用 GDI 旋转图像

发布于 2024-12-11 20:38:27 字数 175 浏览 0 评论 0原文

我正在使用 GDI+ 进行图像旋转。根据图像元数据，应该有 8 种不同类型的方向 (http://www.impulseadventure.com/photo/exif-orientation.html)。但我得到的所有图像都具有相同的方向，无论它们是水平方向还是垂直方向。谁能建议问题出在哪里或者我错过了什么？

谢谢！

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白况 2024-12-18 20:38:27

几天前，我将自动旋转添加到 imageresizing.net 库作为 AutoRotate 插件。我提供了相关的源代码，希望对您有所帮助。

if (!"true".Equals(settings["autorotate"], StringComparison.OrdinalIgnoreCase)) return RequestedAction.None;

int propertyId = 0x0112;
PropertyItem pi;
try {
    pi = b.GetPropertyItem(propertyId);
} catch (ArgumentException) {
    return RequestedAction.None;
}
if (pi == null) return RequestedAction.None;

int total = 0;

foreach (byte by in pi.Value) total += by; //Does not handle values larger than 255, but it doesn't need to, and is endian-agnostic.

if (total == 8) b.RotateFlip(RotateFlipType.Rotate270FlipNone);
if (total == 3) b.RotateFlip(RotateFlipType.Rotate180FlipNone);
if (total == 6) b.RotateFlip(RotateFlipType.Rotate90FlipNone);

if (total == 2) b.RotateFlip(RotateFlipType.RotateNoneFlipX);
if (total == 4) b.RotateFlip(RotateFlipType.Rotate180FlipX);
if (total == 5) b.RotateFlip(RotateFlipType.Rotate270FlipY);
if (total == 7) b.RotateFlip(RotateFlipType.Rotate90FlipY);

b.RemovePropertyItem(propertyId);

仅供参考，如果您在 ASP.NET 中调整图像大小，您应该阅读这篇文章，了解如何安全地执行此操作，或者使用 ImageResizing.Net 库。

A couple days ago I added automatic rotation to the imageresizing.net library as the AutoRotate plugin. I'm including the relevant source code, which should hopefully help you.

if (!"true".Equals(settings["autorotate"], StringComparison.OrdinalIgnoreCase)) return RequestedAction.None;

int propertyId = 0x0112;
PropertyItem pi;
try {
    pi = b.GetPropertyItem(propertyId);
} catch (ArgumentException) {
    return RequestedAction.None;
}
if (pi == null) return RequestedAction.None;

int total = 0;

foreach (byte by in pi.Value) total += by; //Does not handle values larger than 255, but it doesn't need to, and is endian-agnostic.

if (total == 8) b.RotateFlip(RotateFlipType.Rotate270FlipNone);
if (total == 3) b.RotateFlip(RotateFlipType.Rotate180FlipNone);
if (total == 6) b.RotateFlip(RotateFlipType.Rotate90FlipNone);

if (total == 2) b.RotateFlip(RotateFlipType.RotateNoneFlipX);
if (total == 4) b.RotateFlip(RotateFlipType.Rotate180FlipX);
if (total == 5) b.RotateFlip(RotateFlipType.Rotate270FlipY);
if (total == 7) b.RotateFlip(RotateFlipType.Rotate90FlipY);

b.RemovePropertyItem(propertyId);

As an FYI, if you are doing image resizing in ASP.NET, you should read this article on how to do it safely, or use the ImageResizing.Net library instead.

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在你怀里撒娇 2024-12-18 20:38:27

只是一个小改进，

我不会测试参数异常，这会消耗 CPU 周期。

   var orientation_index = Array.IndexOf(b.PropertyIdList, propertyId );

        if ( orientation_index <0) return RequestedAction.None;
        byte total =0;
        foreach (byte b in b.GetPropertyItem(OrientationId).Value)
        {
            total += b;
        }

Just a small improvement,

I would not test for an argumentexception, that costs CPU cycles.

   var orientation_index = Array.IndexOf(b.PropertyIdList, propertyId );

        if ( orientation_index <0) return RequestedAction.None;
        byte total =0;
        foreach (byte b in b.GetPropertyItem(OrientationId).Value)
        {
            total += b;
        }

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