Resize image proportionally with MaxHeight and MaxWidth constraints

Question

Using System Drawing Image   If an image width or height exceed the maximum  it need to be resized proportionally   After resized it need to make sure that neither width or height still exceed the limit   The Width and Height will be resized until it is not exceed to maximum and minimum automatically  biggest size possible  and also maintain the ratio

User · Answer

Working Solution    For Resize image with size lower then 100Kb  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  gt  100     More Reference at http   net4attack blogspot com

User · Answer

Like this   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

User · Answer

Much longer solution  but accounts for the following scenarios    Is the image smaller than the bounding box  Is the Image and the Bounding Box square  Is the Image square and the bounding box isn t Is the image wider and taller than the bounding box Is the image wider than the bounding box Is the image taller than the bounding box  private Image ResizePhoto FileInfo sourceImage  int desiredWidth  int desiredHeight          throw error if bouning box is to small     if  desiredWidth  lt  4    desiredHeight  lt  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  lt  dW  amp  amp  oH  lt  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  amp  amp  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  gt  dW  amp  amp  oH  gt  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  gt  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

[c#] Resize image proportionally with MaxHeight and MaxWidth constraints

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