重新縮放圖像

Question

我正在嘗試將圖像縮小10倍並保存

System.Drawing.Bitmap bmi     
var scaleWidth = (int)(bmi.Width * 0.1);
var scaleHeight = (int)(bmi.Height * 0.1);
Rectangle f = new Rectangle(0, 0, scaleWidth, scaleHeight);
Graphics graph = Graphics.FromImage(bmi);           
graph.DrawImage(bmi, new Rectangle(
    ((int)scaleWidth - scaleWidth) / 2, 
    ((int)scaleHeight - scaleHeight) / 2, 
    scaleWidth, scaleHeight));
string a = "a.jpg";
bmi.Save(a);

但是當我這樣做時，它將保存在原始圖像上繪制的縮放圖像，並且我不確定如何更正此圖像

Answer 1

您應該將原始位圖復制到新的位圖，並隨需縮放。 示例（未試用）：

Bitmap bmpOriginal = /* load your file here */
var scaleWidth = (int)(bmi.Width * 0.1);
var scaleHeight = (int)(bmi.Height * 0.1);
Bitmap bmpScaled = new Bitmap(scaleWidth, scaleHeight);
Graphics graph = Graphics.FromImage(bmpScaled );           
graph.DrawImage(bmpOriginal, new Rectangle(0, 0, scaleWidth, scaleHeight);
bmpScaled.Save("scaledImage.bmp");

編輯：我只是在Bitmap類上注意到了這個構造函數 ，它使您可以簡化代碼：

Bitmap bmpOriginal = /* load your file here */
var scaleWidth = (int)(bmi.Width * 0.1);
var scaleHeight = (int)(bmi.Height * 0.1);
Bitmap bmpScaled = new Bitmap(bmpOriginal, new Size(scaleWidth, scaleHeight));
bmpScaled.Save("scaledImage.bmp");