Differenze tra le versioni di "Ridimensionare un'immagine mediante le funzioni esterne del API di ImageMagick"
Da Gambas-it.org - Wikipedia.
| Riga 20: | Riga 20: | ||
<FONT Color=gray>' ''MagickWand *NewMagickWand(void)'' | <FONT Color=gray>' ''MagickWand *NewMagickWand(void)'' | ||
| − | ' Returns a wand required for all other methods in the API.''</font> | + | ' ''Returns a wand required for all other methods in the API.''</font> |
Private Extern NewMagickWand() As Pointer | Private Extern NewMagickWand() As Pointer | ||
<FONT Color=gray>' ''MagickBooleanType MagickReadImage(MagickWand *wand,const char *filename)'' | <FONT Color=gray>' ''MagickBooleanType MagickReadImage(MagickWand *wand,const char *filename)'' | ||
| − | ' Reads an image or image sequence.''</font> | + | ' ''Reads an image or image sequence.''</font> |
Private Extern MagickReadImage(wand As Pointer, filename As String) As Boolean | Private Extern MagickReadImage(wand As Pointer, filename As String) As Boolean | ||
<FONT Color=gray>' ''MagickBooleanType MagickResizeImage(MagickWand *wand, const size_t columns,const size_t rows,const FilterType filter)'' | <FONT Color=gray>' ''MagickBooleanType MagickResizeImage(MagickWand *wand, const size_t columns,const size_t rows,const FilterType filter)'' | ||
| − | ' Scales an image to the desired dimensions with a filter.''</font> | + | ' ''Scales an image to the desired dimensions with a filter.''</font> |
Private Extern MagickResizeImage(wand As Pointer, columns As Long, rows As Long, filter As Integer, blur As Float) As Boolean | Private Extern MagickResizeImage(wand As Pointer, columns As Long, rows As Long, filter As Integer, blur As Float) As Boolean | ||
<FONT Color=gray>' ''MagickBooleanType MagickWriteImages(MagickWand *wand, const char *filename,const MagickBooleanType adjoin)'' | <FONT Color=gray>' ''MagickBooleanType MagickWriteImages(MagickWand *wand, const char *filename,const MagickBooleanType adjoin)'' | ||
| − | ' Writes an image or image sequence.''</font> | + | ' ''Writes an image or image sequence.''</font> |
Private Extern MagickWriteImages(wand As Pointer, filename As String, adjoin As Boolean) As Boolean | Private Extern MagickWriteImages(wand As Pointer, filename As String, adjoin As Boolean) As Boolean | ||
<FONT Color=gray>' ''MagickWand *DestroyMagickWand(MagickWand *wand)'' | <FONT Color=gray>' ''MagickWand *DestroyMagickWand(MagickWand *wand)'' | ||
| − | ' Deallocates memory associated with an MagickWand.''</font> | + | ' ''Deallocates memory associated with an MagickWand.''</font> |
Private Extern DestroyMagickWand(wand As Pointer) As Pointer | Private Extern DestroyMagickWand(wand As Pointer) As Pointer | ||
<FONT Color=gray>' ''void MagickWandTerminus(void)'' | <FONT Color=gray>' ''void MagickWandTerminus(void)'' | ||
| − | ' Terminates the MagickWand environment.''</font> | + | ' ''Terminates the MagickWand environment.''</font> |
Private Extern MagickWandTerminus() | Private Extern MagickWandTerminus() | ||
| Riga 46: | Riga 46: | ||
'''Public''' Sub Main() | '''Public''' Sub Main() | ||
| − | + | Dim bo As Boolean | |
| − | + | Dim magickwand As Pointer | |
| − | + | Dim fileimmagine, nuovofile As String | |
fileimmagine = "<FONT Color=gray>''/percorso/del/file/immagine''</font>" | fileimmagine = "<FONT Color=gray>''/percorso/del/file/immagine''</font>" | ||
| Riga 75: | Riga 75: | ||
'''End''' | '''End''' | ||
| − | |||
'''Private''' Procedure Chiude(mw As Pointer) | '''Private''' Procedure Chiude(mw As Pointer) | ||
Versione delle 18:58, 22 feb 2022
Il sistema ImageMagick consente di creare, modificare e convertire immagini bitmap. Può altresì leggere e scrivere immagini di oltre 200 formati.
Per poter fruire in Gambas delle risorse, è necessario avere installata nel sistema e richiamare la seguente libreria condivisa: "libMagickWand-6.Q16.so.6.0.0 ".
Mostriamo di seguito un semplice esempio pratico per creare da una immagine iniziale una sua copia ridimensionata come un thumbnail:
Library "libMagickWand-6.Q16:6.0.0"
Private Enum MagickFalse = 0, MagickTrue
Private Enum UndefinedFilter = 0, PointFilter, BoxFilter, TriangleFilter, HermiteFilter,
HanningFilter, HammingFilter, BlackmanFilter, GaussianFilter, QuadraticFilter,
CubicFilter, CatromFilter, MitchellFilter, JincFilter, SincFilter, SincFastFilter,
KaiserFilter, WelshFilter, ParzenFilter, BohmanFilter, BartlettFilter, LagrangeFilter,
LanczosFilter, LanczosSharpFilter, Lanczos2Filter, Lanczos2SharpFilter, RobidouxFilter,
RobidouxSharpFilter, CosineFilter, SplineFilter, LanczosRadiusFilter, SentinelFilter
' void MagickWandGenesis(void)
' Initializes the MagickWand environment.
Private Extern MagickWandGenesis()
' MagickWand *NewMagickWand(void)
' Returns a wand required for all other methods in the API.
Private Extern NewMagickWand() As Pointer
' MagickBooleanType MagickReadImage(MagickWand *wand,const char *filename)
' Reads an image or image sequence.
Private Extern MagickReadImage(wand As Pointer, filename As String) As Boolean
' MagickBooleanType MagickResizeImage(MagickWand *wand, const size_t columns,const size_t rows,const FilterType filter)
' Scales an image to the desired dimensions with a filter.
Private Extern MagickResizeImage(wand As Pointer, columns As Long, rows As Long, filter As Integer, blur As Float) As Boolean
' MagickBooleanType MagickWriteImages(MagickWand *wand, const char *filename,const MagickBooleanType adjoin)
' Writes an image or image sequence.
Private Extern MagickWriteImages(wand As Pointer, filename As String, adjoin As Boolean) As Boolean
' MagickWand *DestroyMagickWand(MagickWand *wand)
' Deallocates memory associated with an MagickWand.
Private Extern DestroyMagickWand(wand As Pointer) As Pointer
' void MagickWandTerminus(void)
' Terminates the MagickWand environment.
Private Extern MagickWandTerminus()
Public Sub Main()
Dim bo As Boolean
Dim magickwand As Pointer
Dim fileimmagine, nuovofile As String
fileimmagine = "/percorso/del/file/immagine"
nuovofile = "/percorso/del/file/immagine/ridimensionata"
MagickWandGenesis()
magickwand = NewMagickWand()
bo = MagickReadImage(magickwand, fileimmagine)
If bo = MagickFalse Then
Error.Raise("Impossibile caricare il file immagine !")
Chiude(magickwand)
Endif
' Ridimensiona l'immagine:
MagickResizeImage(magickwand, 106, 80, LanczosFilter, 1.0)
bo = MagickWriteImages(magickwand, nuovofile, MagickTrue)
If bo = MagickFalse Then
Error.Raise("Impossibile creare il nuovo file dell'immagine ridimensionata !")
Chiude(magickwand)
Endif
Chiude(magickwand)
End
Private Procedure Chiude(mw As Pointer)
' Libera la memoria e chiude la libreria "ImageMagick":
DestroyMagickWand(mw)
Wait 0.01
MagickWandTerminus()
End
