What is phps gd extension?

Image Processing and GD

• Introduction
• Installing/Configuring
  • Requirements
  • Installation
  • Runtime Configuration
  • Resource Types
• Predefined Constants
• Examples
  • PNG creation with PHP
  • Adding watermarks to images using alpha channels
  • Using imagecopymerge to create a translucent watermark
• GD and Image Functions
  • gd_info — Retrieve information about the currently installed GD library
  • getimagesize — Get the size of an image
  • getimagesizefromstring — Get the size of an image from a string
  • 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 — Output image to browser or file
  • imageaffine — Return an image containing the affine transformed src image, using an optional clipping area
  • imageaffinematrixconcat — Concatenate two affine transformation matrices
  • imageaffinematrixget — Get an affine transformation matrix
  • imagealphablending — Set the blending mode for an image
  • imageantialias — Should antialias functions be used or not
  • imagearc — Draws an arc
  • imageavif — Output image to browser or file
  • imagebmp — Output a BMP image to browser or file
  • 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
  • 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
  • imageconvolution — Apply a 3x3 convolution matrix, using coefficient and offset
  • 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
  • imagecreatefromavif — Create a new image from file or URL
  • imagecreatefrombmp — Create a new image from file or URL
  • 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
  • imagecreatefromtga — Create a new image from file or URL
  • imagecreatefromwbmp — Create a new image from file or URL
  • imagecreatefromwebp — 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
  • imagecrop — Crop an image to the given rectangle
  • imagecropauto — Crop an image automatically using one of the available modes
  • imagedashedline — Draw a dashed line
  • imagedestroy — Destroy an image
  • imageellipse — Draw an ellipse
  • imagefill — Flood fill
  • imagefilledarc — Draw a partial arc 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 a filter to an image
  • imageflip — Flips an image using a given mode
  • 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
  • imagegetclip — Get the clipping rectangle
  • imagegetinterpolation — Get the interpolation method
  • imagegif — Output image to browser or file
  • imagegrabscreen — Captures the whole screen
  • imagegrabwindow — Captures a window
  • 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 layering effects
  • imageline — Draw a line
  • imageloadfont — Load a new font
  • imageopenpolygon — Draws an open polygon
  • imagepalettecopy — Copy the palette from one image to another
  • imagepalettetotruecolor — Converts a palette based image to true color
  • imagepng — Output a PNG image to either the browser or a file
  • imagepolygon — Draws a polygon
  • imagerectangle — Draw a rectangle
  • imageresolution — Get or set the resolution of the image
  • imagerotate — Rotate an image with a given angle
  • imagesavealpha — Whether to retain full alpha channel information when saving PNG images
  • imagescale — Scale an image using the given new width and height
  • imagesetbrush — Set the brush image for line drawing
  • imagesetclip — Set the clipping rectangle
  • imagesetinterpolation — Set the interpolation method
  • 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
  • imagewebp — Output a WebP image to browser or file
  • imagexbm — Output an XBM image to browser or file
  • iptcembed — Embeds binary IPTC data into a JPEG image
  • iptcparse — Parse a binary IPTC block into single tags
  • jpeg2wbmp — Convert JPEG image file to WBMP image file
  • png2wbmp — Convert PNG image file to WBMP image file
• GdImage — The GdImage class
• GdFont — The GdFont class

mail at ecross dot nl ¶

12 years ago

hello there,
i made a function to create a gradient image.

description:
gradient(int image_width, int image_height,
int start_red, int start_green, int start_blue,
int end_red, int end_green, int end_blue,
bool vertical)

function:
function gradient($image_width, $image_height,$c1_r, $c1_g, $c1_b, $c2_r, $c2_g, $c2_b, $vertical=false)
{
// first: lets type cast;
$image_width = (integer)$image_width;
$image_height = (integer)$image_height;
$c1_r = (integer)$c1_r;
$c1_g = (integer)$c1_g;
$c1_b = (integer)$c1_b;
$c2_r = (integer)$c2_r;
$c2_g = (integer)$c2_g;
$c2_b = (integer)$c2_b;
$vertical = (bool)$vertical;// create a image
$image  = imagecreatetruecolor($image_width, $image_height); // make the gradient
for($i=0; $i<$image_height; $i++)
{
$color_r = floor($i * ($c2_r-$c1_r) / $image_height)+$c1_r;
$color_g = floor($i * ($c2_g-$c1_g) / $image_height)+$c1_g;
$color_b = floor($i * ($c2_b-$c1_b) / $image_height)+$c1_b;$color = ImageColorAllocate($image, $color_r, $color_g, $color_b);
imageline($image, 0, $i, $image_width, $i, $color);
} # Prints out all the figures and picture and frees memory
header('Content-type: image/png');

if(

herbert dot walde at googlemail dot com ¶

10 years ago

In case your script is using output-buffering-functions somewhere, then you have to clear the buffer first ( with ob_clear() ), before outputting an image with a function like imagepng().

And you should make sure that no buffer will get send after outputing an image by using the ob_end_flush()-function.

Furthermore you should check if a buffer has already been flushed somewhere before. This can be done using the headers_sent()-function.

Here is the full solution:

if(headers_sent()){
    die('Headers have been send somewhere within my script');
} ob_clean(); //Clears the buffer header('Content-type: image/png');
imagepng($img, NULL, 0,  NULL); ob_end_flush(); //Now we send the header and image plus we make sure that nothing will get send from now on (including possible shutdown-functions and __destruct()-methods) till the end of page-execution
?>

kurdtpage at gmail dot com ¶

11 years ago

When using GD, please make sure of the following things:

1. The file that is used to manipulate images is saved as ANSI format and not UTF-8
2. There is no space in front of the opening tag