CODEWITHSUNDEEP
c#imagebitmap
lentinant
lentinant

Reputation: 842

Add padding to bitmap programmatically

It seems, that if image, that is used for icon for Windows shortcuts, doesn't have aspect ratio 1:1, it will look stretched.

enter image description here

Left one is how it actually looks, and right one is how it should look.

I'm creating shortcut and icon programmatically from image, so I want to fix image, so it will have correct aspect ratio, but image will not look stretched. This can be achieved by adding some padding to image.

As for now, I'm simply copying image to new bitmap with correct aspect ratio, but filling new area with transparent pixels

public static Bitmap FixBitmapAspectRatio(Bitmap sourceBitmap)
{
    if (sourceBitmap.Width.Equals(sourceBitmap.Height))
        return sourceBitmap;

    int size;
    bool horizontallyOriented;
    if (sourceBitmap.Width > sourceBitmap.Height)
    {
        horizontallyOriented = true;
        size = sourceBitmap.Width;
    }
    else
    {
        horizontallyOriented = false;
        size = sourceBitmap.Height;
    }

    var sizeDifference = Math.Abs(sourceBitmap.Width - sourceBitmap.Height);

    var newBitmap = new Bitmap(size, size);

    var transparentColor = Color.FromArgb(0, 0, 0, 0);

    for (int i = 0; i < size; i++)
    {
        for (int j = 0; j < size; j++)
        {
            if (horizontallyOriented)
            {
                if (i < sizeDifference / 2 || i >= sizeDifference / 2 + sourceBitmap.Height)
                {
                    newBitmap.SetPixel(j, i, transparentColor);
                }
                else
                {
                    var originalPixel = sourceBitmap.GetPixel(j, i - sizeDifference / 2);
                    newBitmap.SetPixel(j, i, originalPixel);
                }
            }
            else
            {
                if (i < sizeDifference / 2 || i >= sizeDifference / 2 + sourceBitmap.Width)
                {
                    newBitmap.SetPixel(i, j, transparentColor);
                }
                else
                {
                    var originalPixel = sourceBitmap.GetPixel(i - sizeDifference / 2, j);
                    newBitmap.SetPixel(i, j, originalPixel);
                }
            }
        }
    }

    return newBitmap;
}

But I don't know, if I'm inventing a wheel. Is there any way to do this by means by standard libraries, or maybe easier way to achieve what I need?

Upvotes: 0

Views: 1927

Answers (1)

Luaan
Luaan

Reputation: 63772

You really don't want to set individual pixels :)

Instead, have a look at the Graphics class, in particular Graphics.FromImage (that's where you paint to) and Graphics.DrawImage (that's how you paint the scaled image).

Upvotes: 1

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