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.

Istallazione

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 Runtime

Questa estensione non definisce alcuna direttiva di configurazione

Resource Type

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_JPG (integer)

IMAGETYPE_PNG (integer)

IMAGETYPE_SWF (integer)

IMAGETYPE_PSD (integer)

IMAGETYPE_BMP (integer)

IMAGETYPE_TIFF_II (integer)

IMAGETYPE_TIFF_MM (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 -- Read the EXIF headers from JPEG or TIFF
exif_thumbnail -- Retrieve the embedded thumbnail of a TIFF or JPEG image
getimagesize -- Get the size of an image
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
imagearc -- Draw a partial ellipse
imagechar -- Draw a character horizontally
imagecharup -- Draw a character vertically
imagecolorallocate -- 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
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
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 to browser or file
imagegd -- Output GD image to browser or file
imagegif -- Output image to browser or file
imageinterlace -- Enable or disable interlace
imagejpeg -- Output image to browser or file
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
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
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 -- Reads header information stored in TIFF and JPEG images