使用C#在程序中调整图像大小

Question

可能重复：
C# 中如何调整图像大小？

我该如何在 C# 中编程调整图像大小，以便它适合 WinForms 控件？

- eomeroff

Answer 1

将图像缩放到PictureBox中：

class ImageHandling
{
    public static Rectangle GetScaledRectangle(Image img, Rectangle thumbRect)
    {
        if (img.Width < thumbRect.Width && img.Height < thumbRect.Height)
            return new Rectangle(thumbRect.X + ((thumbRect.Width - img.Width) / 2), thumbRect.Y + ((thumbRect.Height - img.Height) / 2), img.Width, img.Height);

        int sourceWidth = img.Width;
        int sourceHeight = img.Height;

        float nPercent = 0;
        float nPercentW = 0;
        float nPercentH = 0;

        nPercentW = ((float)thumbRect.Width / (float)sourceWidth);
        nPercentH = ((float)thumbRect.Height / (float)sourceHeight);

        if (nPercentH < nPercentW)
            nPercent = nPercentH;
        else
            nPercent = nPercentW;

        int destWidth = (int)(sourceWidth * nPercent);
        int destHeight = (int)(sourceHeight * nPercent);

        if (destWidth.Equals(0))
            destWidth = 1;
        if (destHeight.Equals(0))
            destHeight = 1;

        Rectangle retRect = new Rectangle(thumbRect.X, thumbRect.Y, destWidth, destHeight);

        if (retRect.Height < thumbRect.Height)
            retRect.Y = retRect.Y + Convert.ToInt32(((float)thumbRect.Height - (float)retRect.Height) / (float)2);

        if (retRect.Width < thumbRect.Width)
            retRect.X = retRect.X + Convert.ToInt32(((float)thumbRect.Width - (float)retRect.Width) / (float)2);

        return retRect;
    }

    public static Image GetResizedImage(Image img, Rectangle rect)
    {
        Bitmap b = new Bitmap(rect.Width, rect.Height);
        Graphics g = Graphics.FromImage((Image)b);
        g.InterpolationMode = InterpolationMode.HighQualityBicubic;
        g.DrawImage(img, 0, 0, rect.Width, rect.Height);
        g.Dispose();

        try
        {
            return (Image)b.Clone();
        }
        finally
        {
            b.Dispose();
            b = null;
            g = null;
        }
    }
}

如何使用：

Image img = Image.FromFile(imageFilePath);
Rectangle newRect = GetScaledRectangle(img, pictureBox1.ClientRectangle);
pictureBox1.Image = ImageHandling.GetResizedImage(img, newRect);

- Amirshk

---

很抱歉，但这个方法解决了什么问题？除了与Image类的紧密耦合外，它并没有调整图片大小，只是提供了一种计算如何在调整为定义的宽度和高度（tumbRect）时保持纵横比的方法。 - Davy Landman

我正在使用这个来正确缩放在固定大小的picturebox上显示的图像，而不触及原始文件。 - Amirshk

好的，实际的调整大小操作发生在 ImageHandler.GetResizeImage 中，这是您自己的一个实用类，我猜测是吗？ - Davy Landman

哦，你说得对，忘记粘贴了...谢谢！ - Amirshk

Answer 2

缩放并居中一个ImageBox：

private void LoadAndResizeImage(string sImagepath, int iMaxHeight, int iMaxWidth, int iMinX, int iMinY)
{
    int wdt = iMaxWidth;
    int hgt = iMaxHeight;
    int partialX = iMinX;
    int partialY = iMinY;

    pictureBox1.ImageLocation = sImagepath;
    if ((pictureBox1.Image.Height > iMaxHeight) || (pictureBox1.Image.Width > iMaxWidth))
    {
        if ((pictureBox1.Image.Width / iMaxWidth) > (pictureBox1.Image.Height / iMaxHeight))
        {
            wdt = iMaxWidth;
            double ratio = (double)pictureBox1.Image.Height / (double)pictureBox1.Image.Width;
            hgt = (int)(iMaxWidth * ratio);
        }
        else
        {
            hgt = iMaxHeight;
            double ratio = (double)pictureBox1.Image.Width / (double)pictureBox1.Image.Height;
            wdt = (int)(iMaxHeight * ratio);
        }
    }
    else
    {
        hgt = pictureBox1.Image.Height;
        wdt = pictureBox1.Image.Width;
    }
    if (wdt < iMaxWidth)
    {
        partialX = (iMaxWidth - wdt) / 2;
        partialX += iMinX;
    }
    else
    {
        partialX = iMinX;
    }
    if (hgt < iMaxHeight)
    {
        partialY = (iMaxHeight - hgt) / 2;
        partialY += iMinY;
    }
    else
    {
        partialY = iMinY;
    }


    //Set size
    pictureBox1.Height = hgt;
    pictureBox1.Width = wdt;
    pictureBox1.Left = partialX;
    pictureBox1.Top = partialY;
}

- user259137