ASP.Net MVC圖像上傳通過縮小或填充來調整大小

Question

用戶將能夠上傳圖像。如果圖像大於設定的尺寸，我想將其縮小到該尺寸。很顯然，由於比例的緣故，它不必完全匹配，寬度將是關鍵尺寸，因此高度可能會變化。

如果圖像小於設置的尺寸，我想用定義顏色的背景創建一個新的圖像到設置的尺寸，然後將上傳的圖像居中，因此結果是帶有填充顏色的原始圖像。

任何的代碼示例或鏈接不勝感激

Answer 1

下面是我根據寬度快速調整大小的代碼片段。我相信你可以弄清楚如何爲Bitmap添加背景顏色。這不是完整的代碼，而只是一個如何做事的想法。

public static void ResizeLogo(string originalFilename, string resizeFilename) 
{ 
    Image imgOriginal = Image.FromFile(originalFilename); 

    //pass in whatever value you want for the width (180) 
    Image imgActual = ScaleBySize(imgOriginal, 180); 
    imgActual.Save(resizeFilename); 
    imgActual.Dispose(); 
} 

public static Image ScaleBySize(Image imgPhoto, int size) 
{ 
    int logoSize = size; 

    float sourceWidth = imgPhoto.Width; 
    float sourceHeight = imgPhoto.Height; 
    float destHeight = 0; 
    float destWidth = 0; 
    int sourceX = 0; 
    int sourceY = 0; 
    int destX = 0; 
    int destY = 0; 

    // Resize Image to have the height = logoSize/2 or width = logoSize. 
    // Height is greater than width, set Height = logoSize and resize width accordingly 
    if (sourceWidth > (2 * sourceHeight)) 
    { 
     destWidth = logoSize; 
     destHeight = (float)(sourceHeight * logoSize/sourceWidth); 
    } 
    else 
    { 
     int h = logoSize/2; 
     destHeight = h; 
     destWidth = (float)(sourceWidth * h/sourceHeight); 
    } 
    // Width is greater than height, set Width = logoSize and resize height accordingly 

    Bitmap bmPhoto = new Bitmap((int)destWidth, (int)destHeight, 
           PixelFormat.Format32bppPArgb); 
    bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); 

    Graphics grPhoto = Graphics.FromImage(bmPhoto); 
    grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; 

    grPhoto.DrawImage(imgPhoto, 
     new Rectangle(destX, destY, (int)destWidth, (int)destHeight), 
     new Rectangle(sourceX, sourceY, (int)sourceWidth, (int)sourceHeight), 
     GraphicsUnit.Pixel); 

    grPhoto.Dispose(); 

    return bmPhoto; 
} 

Answer 2

可將該文件剛剛加載到一個位圖對象：

http://msdn.microsoft.com/en-us/library/system.drawing.bitmap.aspx

然後，只需檢查對象上的寬度。對於你的問題的第二部分，我會建議使用的工具，像ImageMagick的

http://www.imagemagick.org/script/index.php

準確地調整第一圖像或創建的背景圖像和兩個圖像融合在一起。