c# - 旋转时调整图像大小

Question

我正在尝试旋转图像。我有一个 pictureBox 369x276。但是当我旋转时，这个尺寸会减小。

pictureBox sizeMode 是PictureBoxSizeMode.StretchImage

这是我的代码:

        Bitmap oldBitmap = (Bitmap)pictureBox1.Image;
        float angle = 90;
        var newBitmap = new Bitmap(oldBitmap.Width, oldBitmap.Height);

        var graphics = Graphics.FromImage(newBitmap);
        graphics.TranslateTransform((float)oldBitmap.Width  / 2, (float)oldBitmap.Height / 2);
        graphics.RotateTransform(angle);
        graphics.TranslateTransform(-(float)oldBitmap.Width / 2, -(float)oldBitmap.Height / 2);
        graphics.DrawImage(oldBitmap, new Point(0, 0));
        pictureBox1.Image = newBitmap;

Answer 1

只需使用 RotateFlip:

Bitmap oldBitmap = (Bitmap)pictureBox1.Image;
oldBitmap.RotateFlip(RotateFlipType.Rotate90FlipNone);
pictureBox1.Image = oldBitmap;

正如@Dan-o 所指出的，这允许旋转 System.Drawing.RotateFlipType 中的任何度数。枚举。

要在不丢失大小的情况下旋转任意角度的位图，您可以执行以下操作，但这有点复杂!

一个 - 添加 WriteableBitmapEx库到你的项目

二 - 将 XAML、WindowsBase 和 PresentationCore 库添加到您的项目

三 - 使用以下方法将位图旋转任意度数:

class Program
{
    static void Main(string[] args)
    {
        Bitmap oldBitmap = (Bitmap)pictureBox1.Image;;

        var bitmapAsWriteableBitmap = new WriteableBitmap(BitmapToBitmapImage(oldBitmap));
        bitmapAsWriteableBitmap.RotateFree(23);

        var rotatedImageAsMemoryStream = WriteableBitmapToMemoryStream(bitmapAsWriteableBitmap);
        oldBitmap = new Bitmap(rotatedImageAsMemoryStream);
    }

    public static BitmapImage BitmapToBitmapImage(Bitmap bitmap)
    {
        var memStream = BitmapToMemoryStream(bitmap);
        return MemoryStreamToBitmapImage(memStream);
    }

    public static MemoryStream BitmapToMemoryStream(Bitmap image)
    {
        var memoryStream = new MemoryStream();
        image.Save(memoryStream, ImageFormat.Bmp);

        return memoryStream;
    }

    public static BitmapImage MemoryStreamToBitmapImage(MemoryStream ms)
    {
        ms.Position = 0;
        var bitmap = new BitmapImage();

        bitmap.BeginInit();

        bitmap.StreamSource = ms;
        bitmap.CacheOption = BitmapCacheOption.OnLoad;

        bitmap.EndInit();
        bitmap.Freeze();

        return bitmap;
    }

    private static MemoryStream WriteableBitmapToMemoryStream(WriteableBitmap writeableBitmap)
    {
        var ms = new MemoryStream();

        var encoder = new JpegBitmapEncoder();
        encoder.Frames.Add(BitmapFrame.Create(writeableBitmap));

        encoder.Save(ms);

        return ms;
    }
}

屁股疼，但有效!