記錄一下縮圖的語法：
使用者上傳檔案時,我會先將檔案rename為xxxxxx_temp.jpg
最後縮完圖後,再將新圖存成xxxxxx.jpg
順便再刪除中介圖片xxxxxx_temp.jpg
Imports System.Drawing
Protected Sub ChangeSize(ByVal FilePath As String)
Dim imgSource As Image = Image.FromFile(FilePath)
Dim intFixLength As Integer = 750
Dim intChangedWidth As Integer = 0
Dim intChangedHeight As Integer = 0
' 設短邊為750px, 長邊等比例縮放
With imgSource
If .Width < .Height Then
intChangedWidth = intFixLength
intChangedHeight = .Height / .Width * intFixLength
Else
intChangedWidth = .Width / .Height * intFixLength
intChangedHeight = intFixLength
End If
End With
Dim bmpIntermediary As New Bitmap(intChangedWidth, intChangedHeight)
Dim gphPainter As Graphics = Graphics.FromImage(bmpIntermediary)
' 圖片繪製品質
gphPainter.CompositingQuality = Drawing2D.CompositingQuality.HighQuality
' 圖片呈現品質
gphPainter.SmoothingMode = Drawing2D.SmoothingMode.HighQuality
' 圖片插補模式
gphPainter.InterpolationMode = Drawing2D.InterpolationMode.HighQualityBilinear
' 1:要繪製的圖片 2:起始x座標 3:起始y座標 4:寬度 5:高度
gphPainter.DrawImage(imgSource, 0, 0, intChangedWidth, intChangedHeight)
bmpIntermediary.Save(Replace(FilePath, "_temp.jpg", ".jpg"), Imaging.ImageFormat.Jpeg)
bmpIntermediary.Dispose()
gphPainter.Dispose()
imgSource.Dispose()
Dim fiSource As New FileInfo(FilePath)
If fiSource.Exists Then
fiSource.Delete()
End If
End Sub
這個語法還有一個好處
就是最後完成的圖片會是 RGB 格式的圖片
即使原始圖片是 CMYK 格式也一樣 (不知不覺中就轉檔了)
參考自工頭大大的BLOG [
軟體工頭的分享BLOG]
