[C#] MaxHeight 및 MaxWidth 제약 조건에 비례하여 이미지 크기 조정

C# / 글쓴이

사용 System.Drawing.Image.

이미지 너비 또는 높이가 최대 값을 초과하는 경우 비례 적으로 크기를 조정해야합니다. 크기를 조정 한 후에는 너비 나 높이가 제한을 초과하지 않는지 확인해야합니다.

너비 및 높이는 자동으로 최대 및 최소를 초과하지 않을 때까지 (가능한 가장 큰 크기) 크기가 조정되고 비율도 유지됩니다.

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이렇게?

public static void Test()
{
    using (var image = Image.FromFile(@"c:\logo.png"))
    using (var newImage = ScaleImage(image, 300, 400))
    {
        newImage.Save(@"c:\test.png", ImageFormat.Png);
    }
}

public static Image ScaleImage(Image image, int maxWidth, int maxHeight)
{
    var ratioX = (double)maxWidth / image.Width;
    var ratioY = (double)maxHeight / image.Height;
    var ratio = Math.Min(ratioX, ratioY);

    var newWidth = (int)(image.Width * ratio);
    var newHeight = (int)(image.Height * ratio);

    var newImage = new Bitmap(newWidth, newHeight);

    using (var graphics = Graphics.FromImage(newImage))
        graphics.DrawImage(image, 0, 0, newWidth, newHeight);

    return newImage;
}

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작업 솔루션 :

크기가 100Kb 이하인 이미지 크기 조정

WriteableBitmap bitmap = new WriteableBitmap(140,140);
bitmap.SetSource(dlg.File.OpenRead());
image1.Source = bitmap;

Image img = new Image();
img.Source = bitmap;
WriteableBitmap i;

do
{
    ScaleTransform st = new ScaleTransform();
    st.ScaleX = 0.3;
    st.ScaleY = 0.3;
    i = new WriteableBitmap(img, st);
    img.Source = i;
} while (i.Pixels.Length / 1024 > 100);

http://net4attack.blogspot.com/ 에서 더 많은 참조

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훨씬 더 긴 솔루션이지만 다음 시나리오를 설명합니다.

  1. 이미지가 경계 상자보다 작습니까?
  2. 이미지와 경계 상자가 정사각형입니까?
  3. 이미지 사각형이고 경계 상자는 그렇지 않습니다.
  4. 이미지가 경계 상자보다 더 넓고 더 큽니까?
  5. 이미지가 경계 상자보다 더 넓습니까?

  6. 이미지가 경계 상자보다 더 큽니까?

    private Image ResizePhoto(FileInfo sourceImage, int desiredWidth, int desiredHeight)
{
    //throw error if bouning box is to small
    if (desiredWidth < 4 || desiredHeight < 4)
        throw new InvalidOperationException("Bounding Box of Resize Photo must be larger than 4X4 pixels.");
    var original = Bitmap.FromFile(sourceImage.FullName);

    //store image widths in variable for easier use
    var oW = (decimal)original.Width;
    var oH = (decimal)original.Height;
    var dW = (decimal)desiredWidth;
    var dH = (decimal)desiredHeight;

    //check if image already fits
    if (oW < dW && oH < dH)
        return original; //image fits in bounding box, keep size (center with css) If we made it bigger it would stretch the image resulting in loss of quality.

    //check for double squares
    if (oW == oH && dW == dH)
    {
        //image and bounding box are square, no need to calculate aspects, just downsize it with the bounding box
        Bitmap square = new Bitmap(original, (int)dW, (int)dH);
        original.Dispose();
        return square;
    }

    //check original image is square
    if (oW == oH)
    {
        //image is square, bounding box isn't.  Get smallest side of bounding box and resize to a square of that center the image vertically and horizontally with Css there will be space on one side.
        int smallSide = (int)Math.Min(dW, dH);
        Bitmap square = new Bitmap(original, smallSide, smallSide);
        original.Dispose();
        return square;
    }

    //not dealing with squares, figure out resizing within aspect ratios            
    if (oW > dW && oH > dH) //image is wider and taller than bounding box
    {
        var r = Math.Min(dW, dH) / Math.Min(oW, oH); //two dimensions so figure out which bounding box dimension is the smallest and which original image dimension is the smallest, already know original image is larger than bounding box
        var nH = oH * r; //will downscale the original image by an aspect ratio to fit in the bounding box at the maximum size within aspect ratio.
        var nW = oW * r;
        var resized = new Bitmap(original, (int)nW, (int)nH);
        original.Dispose();
        return resized;
    }
    else
    {
        if (oW > dW) //image is wider than bounding box
        {
            var r = dW / oW; //one dimension (width) so calculate the aspect ratio between the bounding box width and original image width
            var nW = oW * r; //downscale image by r to fit in the bounding box...
            var nH = oH * r;
            var resized = new Bitmap(original, (int)nW, (int)nH);
            original.Dispose();
            return resized;
        }
        else
        {
            //original image is taller than bounding box
            var r = dH / oH;
            var nH = oH * r;
            var nW = oW * r;
            var resized = new Bitmap(original, (int)nW, (int)nH);
            original.Dispose();
            return resized;
        }
    }
}

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