Manuale PHP
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XLII. Funzioni per le immagini

Introduzione

In PHP puoi usare delle funzioni specifiche per sapere la dimensione di un'immagine JPEG, GIF, PNG, SWF, TIFF e JPEG2000.

Requisiti

Se hai installato le librerie GD (scaricabili su http://www.boutell.com/gd/) sarai anche in grado di creare immagini al volo e di modificarle.

I formati delle immagini sulle quali potrai agire dipendono dalla versione delle librerie GD che hai installato, e dalle altre librerie di cui GD può aver bisogno per accedere a quei formati di immagine. Versioni precedenti alla gd-1.6 supportano il formato GIF ma non quello PNG, mentre versioni superiori alla gd-1.6 supportano il formato PNG ma non il GIF.

Se hai compilato PHP con l'opzione --enable-exif sarai in grado di lavorare con le informazioni memorizzate negli header delle immagini JPEG e TIFF. Queste funzioni non richiedono le librerie GD.

Installazione

Per leggere e scrivere immagini in formato JPEG avrai bisogno di installare jpeg-6b (scaricabile da ftp://ftp.uu.net/graphics/jpeg/) e quindi ricompilare le librerie GD in modo che usino jpeg-6b. Dovrai anche compilare PHP con l'opzione --with-jpeg-dir=/percorso/per/jpeg-6b.

Per aggiungere il supporto per i Font Type 1 dovrai installare t1lib (scaricabile su ftp://sunsite.unc.edu/pub/Linux/libs/graphics/), e quindi aggiungere l'opzione --with-t1lib[=dir].

Configurazione di Runtime

Questa estensione non definisce alcuna direttiva di configurazione in php.ini

Tipi di risorse

Questa estensione non definisce alcun tipo di risorsa.

Costanti predefinite

Queste costanti sono definite da questa estensione e sono disponibili solo se l'estensione è stata compilata nel PHP o se è stata caricata dinamicamente a runtime.

IMG_GIF (integer)

IMG_JPG (integer)

IMG_JPEG (integer)

IMG_PNG (integer)

IMG_WBMP (integer)

IMG_XPM (integer)

IMG_COLOR_TILED (integer)

IMG_COLOR_STYLED (integer)

IMG_COLOR_BRUSHED (integer)

IMG_COLOR_STYLEDBRUSHED (integer)

IMG_COLOR_TRANSPARENT (integer)

IMG_ARC_ROUNDED (integer)

IMG_ARC_PIE (integer)

IMG_ARC_CHORD (integer)

IMG_ARC_NOFILL (integer)

IMG_ARC_EDGED (integer)

IMAGETYPE_GIF (integer)

IMAGETYPE_JPEG (integer)

IMAGETYPE_PNG (integer)

IMAGETYPE_SWF (integer)

IMAGETYPE_PSD (integer)

IMAGETYPE_BMP (integer)

IMAGETYPE_WBMP (integer)

IMAGETYPE_XBM (integer)

IMAGETYPE_TIFF_II (integer)

IMAGETYPE_TIFF_MM (integer)

IMAGETYPE_IFF (integer)

IMAGETYPE_JB2 (integer)

IMAGETYPE_JPC (integer)

IMAGETYPE_JP2 (integer)

IMAGETYPE_JPX (integer)

IMAGETYPE_SWC (integer)

Sommario
exif_imagetype -- Determina il tipo di un'immagine
exif_read_data -- Reads the EXIF headers from JPEG or TIFF. This way you can read meta data generated by digital cameras.
exif_thumbnail -- Retrieve the embedded thumbnail of a TIFF or JPEG image
gd_info -- Retrieve information about the currently installed GD library
getimagesize -- Get the size of an image
image_type_to_extension --  Get file extension for image type
image_type_to_mime_type -- Get Mime-Type for image-type returned by getimagesize, exif_read_data, exif_thumbnail, exif_imagetype
image2wbmp -- Rende disponibile l'immagine per il browser o la salva in un file
imagealphablending -- Set the blending mode for an image
imageantialias --  Should antialias functions be used or not
imagearc -- Draw a partial ellipse
imagechar -- Draw a character horizontally
imagecharup -- Draw a character vertically
imagecolorallocate -- Allocate a color for an image
imagecolorallocatealpha -- Allocate a color for an image
imagecolorat -- Get the index of the color of a pixel
imagecolorclosest -- Get the index of the closest color to the specified color
imagecolorclosestalpha -- Get the index of the closest color to the specified color + alpha
imagecolorclosesthwb --  Get the index of the color which has the hue, white and blackness nearest to the given color
imagecolordeallocate -- De-allocate a color for an image
imagecolorexact -- Get the index of the specified color
imagecolorexactalpha -- Get the index of the specified color + alpha
imagecolormatch --  Makes the colors of the palette version of an image more closely match the true color version
imagecolorresolve --  Get the index of the specified color or its closest possible alternative
imagecolorresolvealpha --  Get the index of the specified color + alpha or its closest possible alternative
imagecolorset -- Set the color for the specified palette index
imagecolorsforindex -- Get the colors for an index
imagecolorstotal -- Find out the number of colors in an image's palette
imagecolortransparent -- Define a color as transparent
imagecopy -- Copy part of an image
imagecopymerge -- Copy and merge part of an image
imagecopymergegray -- Copy and merge part of an image with gray scale
imagecopyresampled -- Copy and resize part of an image with resampling
imagecopyresized -- Copy and resize part of an image
imagecreate -- Create a new palette based image
imagecreatefromgd2 -- Create a new image from GD2 file or URL
imagecreatefromgd2part -- Create a new image from a given part of GD2 file or URL
imagecreatefromgd -- Create a new image from GD file or URL
imagecreatefromgif -- Create a new image from file or URL
imagecreatefromjpeg -- Create a new image from file or URL
imagecreatefrompng -- Create a new image from file or URL
imagecreatefromstring -- Create a new image from the image stream in the string
imagecreatefromwbmp -- Create a new image from file or URL
imagecreatefromxbm -- Create a new image from file or URL
imagecreatefromxpm -- Create a new image from file or URL
imagecreatetruecolor -- Create a new true color image
imagedashedline -- Draw a dashed line
imagedestroy -- Destroy an image
imageellipse -- Draw an ellipse
imagefill -- Flood fill
imagefilledarc -- Draw a partial ellipse and fill it
imagefilledellipse -- Draw a filled ellipse
imagefilledpolygon -- Draw a filled polygon
imagefilledrectangle -- Draw a filled rectangle
imagefilltoborder -- Flood fill to specific color
imagefilter --  Applies Filter an image using a custom angle
imagefontheight -- Get font height
imagefontwidth -- Get font width
imageftbbox -- Give the bounding box of a text using fonts via freetype2
imagefttext -- Write text to the image using fonts using FreeType 2
imagegammacorrect -- Apply a gamma correction to a GD image
imagegd2 -- Output GD2 image
imagegd -- Output GD image to browser or file
imagegif -- Output image to browser or file
imageinterlace -- Enable or disable interlace
imageistruecolor -- Finds whether an image is a truecolor image.
imagejpeg -- Output image to browser or file
imagelayereffect --  Set the alpha blending flag to use the bundled libgd layering effects
imageline -- Draw a line
imageloadfont -- Load a new font
imagepalettecopy -- Copy the palette from one image to another
imagepng -- Output a PNG image to either the browser or a file
imagepolygon -- Draw a polygon
imagepsbbox --  Give the bounding box of a text rectangle using PostScript Type1 fonts
imagepscopyfont --  Make a copy of an already loaded font for further modification
imagepsencodefont -- Change the character encoding vector of a font
imagepsextendfont -- Extend or condense a font
imagepsfreefont -- Free memory used by a PostScript Type 1 font
imagepsloadfont -- Load a PostScript Type 1 font from file
imagepsslantfont -- Slant a font
imagepstext -- To draw a text string over an image using PostScript Type1 fonts
imagerectangle -- Draw a rectangle
imagerotate -- Rotate an image with a given angle
imagesavealpha --  Set the flag to save full alpha channel information (as opposed to single-color transparency) when saving PNG images.
imagesetbrush -- Set the brush image for line drawing
imagesetpixel -- Set a single pixel
imagesetstyle -- Set the style for line drawing
imagesetthickness -- Set the thickness for line drawing
imagesettile -- Set the tile image for filling
imagestring -- Draw a string horizontally
imagestringup -- Draw a string vertically
imagesx -- Get image width
imagesy -- Get image height
imagetruecolortopalette -- Convert a true color image to a palette image
imagettfbbox -- Give the bounding box of a text using TrueType fonts
imagettftext -- Write text to the image using TrueType fonts
imagetypes -- Return the image types supported by this PHP build
imagewbmp -- Output image to browser or file
imagexbm --  Output XBM image to browser or file
iptcembed -- Embed binary IPTC data into a JPEG image
iptcparse --  Parse a binary IPTC http://www.iptc.org/ block into single tags.
jpeg2wbmp -- Convert JPEG image file to WBMP image file
png2wbmp -- Convert PNG image file to WBMP image file
read_exif_data -- Alias of exif_read_data()
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ob_iconv_handlerRisaliexif_imagetype