Comment puis-je faire pivoter une image de n'importe quel degré?

Je ne comprends pas quel est votre problème, mais je pense que votre code peut être amélioré. Je pense que vous n'avez pas besoin d'utiliser directement l' Matrix classe. Il y a certaines fonctions qui fait ce travail pour vous. En effet, les seules choses dont vous avez besoin sont: définir le point de la rotation comme le centre, pivoter les graphiques et dessiner, à l'aide de certaines fonctions par le Graphics classe.
Donc pour faire pivoter une image, vous pouvez utiliser ce code simple:

private Bitmap RotateImage(Bitmap bmp, float angle) {
Bitmap rotatedImage = new Bitmap(bmp.Width, bmp.Height);
using (Graphics g = Graphics.FromImage(rotatedImage)) {
//Set the rotation point to the center in the matrix
g.TranslateTransform(bmp.Width / 2, bmp.Height / 2);
//Rotate
g.RotateTransform(angle);
//Restore rotation point in the matrix
g.TranslateTransform(- bmp.Width / 2, - bmp.Height / 2);
//Draw the image on the bitmap
g.DrawImage(bmp, new Point(0, 0));
}
return rotatedImage;
}

OriginalL'auteur Omar

Basé sur les réponses précédentes, j'ai créé ce code qui ne coupe pas l'image (d'autres exemples n'ont pas de travail pour moi)

    private Bitmap RotateImage(Bitmap bmp, float angle)
{
float height = bmp.Height;
float width = bmp.Width;
int hypotenuse = System.Convert.ToInt32(System.Math.Floor(Math.Sqrt(height * height + width * width)));
Bitmap rotatedImage = new Bitmap(hypotenuse, hypotenuse);
using (Graphics g = Graphics.FromImage(rotatedImage))
{
g.TranslateTransform((float)rotatedImage.Width / 2, (float)rotatedImage.Height / 2); //set the rotation point as the center into the matrix
g.RotateTransform(angle); //rotate
g.TranslateTransform(-(float)rotatedImage.Width / 2, -(float)rotatedImage.Height / 2); //restore rotation point into the matrix
g.DrawImage(bmp, (hypotenuse - width) / 2, (hypotenuse - height) / 2, width, height);
}
return rotatedImage;
}

OriginalL'auteur Queequeg

J'ai été en utilisant cette fonction en VB:

    Public Function RotateImage(ByRef image As Image, ByVal angle As Single) As Drawing.Bitmap
If image Is Nothing Then
Throw New ArgumentNullException("image")
End If
Dim pi2 As Single = Math.PI / 2.0
Dim oldWidth As Single = image.Width
Dim oldHeight As Single = image.Height
Dim theta As Single = angle * Math.PI / 180.0
Dim locked_theta As Single = theta
If locked_theta < 0.0 Then locked_theta += 2 * Math.PI
Dim newWidth, newHeight As Single
Dim nWidth, nHeight As Integer
Dim adjacentTop, oppositeTop As Single
Dim adjacentBottom, oppositeBottom As Single
If (locked_theta >= 0.0 And locked_theta < pi2) Or _
(locked_theta >= Math.PI And locked_theta < (Math.PI + pi2)) Then
adjacentTop = Math.Abs(Math.Cos(locked_theta)) * oldWidth
oppositeTop = Math.Abs(Math.Sin(locked_theta)) * oldWidth
adjacentBottom = Math.Abs(Math.Cos(locked_theta)) * oldHeight
oppositeBottom = Math.Abs(Math.Sin(locked_theta)) * oldHeight
Else
adjacentTop = Math.Abs(Math.Sin(locked_theta)) * oldHeight
oppositeTop = Math.Abs(Math.Cos(locked_theta)) * oldHeight
adjacentBottom = Math.Abs(Math.Sin(locked_theta)) * oldWidth
oppositeBottom = Math.Abs(Math.Cos(locked_theta)) * oldWidth
End If
newWidth = adjacentTop + oppositeBottom
newHeight = adjacentBottom + oppositeTop
nWidth = Int(Math.Ceiling(newWidth))
nHeight = Int(Math.Ceiling(newHeight))
Dim rotatedBmp As New Drawing.Bitmap(nWidth, nHeight)
Dim g As Graphics = Graphics.FromImage(rotatedBmp)
Dim points(2) As Point
If (locked_theta >= 0.0 And locked_theta < pi2) Then
points(0) = New Point(Int(oppositeBottom), 0)
points(1) = New Point(nWidth, Int(oppositeTop))
points(2) = New Point(0, Int(adjacentBottom))
ElseIf locked_theta >= pi2 And locked_theta < Math.PI Then
points(0) = New Point(nWidth, Int(oppositeTop))
points(1) = New Point(Int(adjacentTop), nHeight)
points(2) = New Point(Int(oppositeBottom), 0)
ElseIf locked_theta >= Math.PI And locked_theta < (Math.PI + pi2) Then
points(0) = New Point(Int(adjacentTop), nHeight)
points(1) = New Point(0, Int(adjacentBottom))
points(2) = New Point(nWidth, Int(oppositeTop))
Else
points(0) = New Point(0, Int(adjacentBottom))
points(1) = New Point(Int(oppositeBottom), 0)
points(2) = New Point(Int(adjacentTop), nHeight)
End If
g.DrawImage(image, points)
g.Dispose()
image.Dispose()
Return rotatedBmp
End Function

OriginalL'auteur theGD