gd.c

void gdSetErrorMethod( gdErrorMethod  error_method )

void gdClearErrorMethod( void )

gdImagePtr gdImageCreate ( int  sx, int  sy )

gdImageCreate is called to create palette-based images, with no more than 256 colors.  The image must eventually be destroyed using gdImageDestroy().

Parameters

Returns

A pointer to the new image or NULL if an error occurred.

Example

gdImagePtr im;
im = gdImageCreate(64, 64);
// ... Use the image ...
gdImageDestroy(im);

See Also

gdImageCreateTrueColor

gdImagePtr gdImageCreateTrueColor ( int  sx, int  sy )

gdImageCreateTrueColor is called to create truecolor images, with an essentially unlimited number of colors.  Invoke gdImageCreateTrueColor with the x and y dimensions of the desired image.  gdImageCreateTrueColor returns a gdImagePtr to the new image, or NULL if unable to allocate the image.  The image must eventually be destroyed using <gdImageDestroy>().

Truecolor images are always filled with black at creation time.  There is no concept of a “background” color index.

Parameters

Returns

A pointer to the new image or NULL if an error occurred.

Example

gdImagePtr im;
im = gdImageCreateTrueColor(64, 64);
// ... Use the image ...
gdImageDestroy(im);

See Also

gdImageCreateTrueColor

void gdImageDestroy ( gdImagePtr  im )

gdImageDestroy is used to free the memory associated with an image.  It is important to invoke gdImageDestroy before exiting your program or assigning a new image to a gdImagePtr variable.

Parameters

Returns

Nothing.

Example

gdImagePtr im;
im = gdImageCreate(10, 10);
// ... Use the image ...
// Now destroy it
gdImageDestroy(im);

int gdImageColorClosest ( gdImagePtr  im, int  r, int  g, int  b )

Gets the closest color of the image

This is a simplified variant of gdImageColorClosestAlpha where the alpha channel is always opaque.

Parameters

Returns

The closest color already available in the palette for palette images; the color value of the given components for truecolor images.

See also

• gdImageColorExact

int gdImageColorClosestAlpha ( gdImagePtr  im, int  r, int  g, int  b, int  a )

Gets the closest color of the image

Parameters

Returns

The closest color already available in the palette for palette images; the color value of the given components for truecolor images.

See also

• gdImageColorExactAlpha

int gdImageColorClosestHWB ( gdImagePtr  im, int  r, int  g, int  b )

int gdImageColorExact ( gdImagePtr  im, int  r, int  g, int  b )

Gets the exact color of the image

This is a simplified variant of gdImageColorExactAlpha where the alpha channel is always opaque.

Parameters

Returns

The exact color already available in the palette for palette images; if there is no exact color, -1 is returned.  For truecolor images the color value of the given components is returned.

See also

• gdImageColorClosest

int gdImageColorExactAlpha ( gdImagePtr  im, int  r, int  g, int  b, int  a )

Gets the exact color of the image

Parameters

Returns

The exact color already available in the palette for palette images; if there is no exact color, -1 is returned.  For truecolor images the color value of the given components is returned.

See also

• gdImageColorClosestAlpha
• gdTrueColorAlpha

int gdImageColorAllocate ( gdImagePtr  im, int  r, int  g, int  b )

Allocates a color

This is a simplified variant of gdImageColorAllocateAlpha where the alpha channel is always opaque.

Parameters

Returns

The color value.

See also

• gdImageColorDeallocate

int gdImageColorAllocateAlpha ( gdImagePtr  im, int  r, int  g, int  b, int  a )

Allocates a color

This is typically used for palette images, but can be used for truecolor images as well.

Parameters

Returns

The color value.

See also

• gdImageColorDeallocate

int gdImageColorResolve ( gdImagePtr  im, int  r, int  g, int  b )

gdImageColorResolve is an alternative for the code fragment

if ((color=gdImageColorExact(im,R,G,B)) < 0)
  if ((color=gdImageColorAllocate(im,R,G,B)) < 0)
    color=gdImageColorClosest(im,R,G,B);

in a single function.  Its advantage is that it is guaranteed to return a color index in one search over the color table.

int gdImageColorResolveAlpha ( gdImagePtr  im, int  r, int  g, int  b, int  a )

void gdImageColorDeallocate ( gdImagePtr  im, int  color )

Removes a palette entry

This is a no-op for truecolor images.  The function does not alter the image data nor the transparent color or any other places where this color index could have been referenced.  The index is marked as open and will be used too for any subsequent gdImageColorAllocate or gdImageColorAllocateAlpha calls.  Other lower index may be open as well, the fist open index found will be used.

Parameters

See also

• gdImageColorAllocate
• gdImageColorAllocateAlpha

void gdImageColorTransparent ( gdImagePtr  im, int  color )

Sets the transparent color of the image

Parameter

See also

• gdImageGetTransparent

void gdImagePaletteCopy ( gdImagePtr  to, gdImagePtr  from )

int gdImageColorReplace ( gdImagePtr  im, int  src, int  dst )

int gdImageColorReplaceThreshold ( gdImagePtr  im, int  src, int  dst, float  threshold )

int gdImageColorReplaceArray ( gdImagePtr  im, int  len, int  * src, int  * dst )

int gdImageColorReplaceCallback ( gdImagePtr  im, gdCallbackImageColor  callback )

void gdImageSetPixel ( gdImagePtr  im, int  x, int  y, int  color )

int gdImageGetPixel ( gdImagePtr  im, int  x, int  y )

Gets a pixel color as stored in the image.

Parameters

See also

• gdImageGetTrueColorPixel
• gdImagePalettePixel
• gdImageTrueColorPixel

int gdImageGetTrueColorPixel ( gdImagePtr  im, int  x, int  y )

Gets a pixel color always as truecolor value.

Parameters

See also

• gdImageGetPixel
• gdImageTrueColorPixel

void gdImageAABlend ( gdImagePtr  im )

NO-OP, kept for library compatibility.

void gdImageLine ( gdImagePtr  im, int  x1, int  y1, int  x2, int  y2, int  color )

Bresenham as presented in Foley & Van Dam.

void gdImageDashedLine ( gdImagePtr  im, int  x1, int  y1, int  x2, int  y2, int  color )

int gdImageBoundsSafe ( gdImagePtr  im, int  x, int  y )

void gdImageChar ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, int  c, int  color )

Draws a single character.

Parameters

Variants

• gdImageCharUp

See also

• gdFontPtr

void gdImageCharUp ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, int  c, int  color )

void gdImageString ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, unsigned  char  * s, int  color )

Draws a character string.

Parameters

Variants

• gdImageStringUp
• gdImageString16
• gdImageStringUp16

See also

• gdFontPtr
• gdImageStringTTF

void gdImageStringUp ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, unsigned  char  * s, int  color )

void gdImageString16 ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, unsigned  short  * s, int  color )

void gdImageStringUp16 ( gdImagePtr  im, gdFontPtr  f, int  x, int  y, unsigned  short  * s, int  color )

void gdImageArc ( gdImagePtr  im, int  cx, int  cy, int  w, int  h, int  s, int  e, int  color )

void gdImageFilledArc ( gdImagePtr  im, int  cx, int  cy, int  w, int  h, int  s, int  e, int  color, int  style )

void gdImageEllipse( gdImagePtr  im, int  mx, int  my, int  w, int  h, int  c )

void gdImageFilledEllipse ( gdImagePtr  im, int  mx, int  my, int  w, int  h, int  c )

void gdImageFillToBorder ( gdImagePtr  im, int  x, int  y, int  border, int  color )

void gdImageFill( gdImagePtr  im, int  x, int  y, int  nc )

void gdImageRectangle ( gdImagePtr  im, int  x1, int  y1, int  x2, int  y2, int  color )

Draws a rectangle.

Parameters

See also

• gdImageFilledRectangle

void gdImageFilledRectangle ( gdImagePtr  im, int  x1, int  y1, int  x2, int  y2, int  color )

gdImagePtr gdImageClone ( gdImagePtr  src )

Clones an image

Creates an exact duplicate of the given image.

Parameters

Returns

The cloned image on success, NULL on failure.

void gdImageCopy ( gdImagePtr  dst, gdImagePtr  src, int  dstX, int  dstY, int  srcX, int  srcY, int  w, int  h )

Copy an area of an image to another image

Parameters

See also

• gdImageCopyMerge
• gdImageCopyMergeGray

void gdImageCopyMerge ( gdImagePtr  dst, gdImagePtr  src, int  dstX, int  dstY, int  srcX, int  srcY, int  w, int  h, int  pct )

Copy an area of an image to another image ignoring alpha

The source area will be copied to the destination are by merging the pixels.

Note

This function is a substitute for real alpha channel operations, so it doesn’t pay attention to the alpha channel.

Parameters

See also

• gdImageCopy
• gdImageCopyMergeGray

void gdImageCopyMergeGray ( gdImagePtr  dst, gdImagePtr  src, int  dstX, int  dstY, int  srcX, int  srcY, int  w, int  h, int  pct )

Copy an area of an image to another image ignoring alpha

The source area will be copied to the grayscaled destination area by merging the pixels.

Note

This function is a substitute for real alpha channel operations, so it doesn’t pay attention to the alpha channel.

Parameters

See also

• gdImageCopy
• gdImageCopyMerge

void gdImageCopyResized ( gdImagePtr  dst, gdImagePtr  src, int  dstX, int  dstY, int  srcX, int  srcY, int  dstW, int  dstH, int  srcW, int  srcH )

Copy a resized area from an image to another image

If the source and destination area differ in size, the area will be resized using nearest-neighbor interpolation.

Parameters

See also

• gdImageCopyResampled
• gdImageScale

void gdImageCopyRotated ( gdImagePtr  dst, gdImagePtr  src, double  dstX, double  dstY, int  srcX, int  srcY, int  srcWidth, int  srcHeight, int  angle )

Copy a rotated area from an image to another image

The area is counter-clockwise rotated using nearest-neighbor interpolation.

Parameters

See also

• gdImageRotateInterpolated

void gdImageCopyResampled ( gdImagePtr  dst, gdImagePtr  src, int  dstX, int  dstY, int  srcX, int  srcY, int  dstW, int  dstH, int  srcW, int  srcH )

Copy a resampled area from an image to another image

If the source and destination area differ in size, the area will be resized using bilinear interpolation for truecolor images, and nearest-neighbor interpolation for palette images.

Parameters

See also

• gdImageCopyResized
• gdImageScale

void gdImagePolygon ( gdImagePtr  im, gdPointPtr  p, int  n, int  c )

Draws a closed polygon

Parameters

See also

• gdImageOpenPolygon
• gdImageFilledPolygon

void gdImageOpenPolygon ( gdImagePtr  im, gdPointPtr  p, int  n, int  c )

Draws an open polygon

Parameters

See also

• gdImagePolygon

void gdImageFilledPolygon ( gdImagePtr  im, gdPointPtr  p, int  n, int  c )

Draws a filled polygon

The polygon is filled using the even-odd fillrule what can leave unfilled regions inside of self-intersecting polygons.  This behavior might change in a future version.

Parameters

See also

• gdImagePolygon

void gdImageSetStyle ( gdImagePtr  im, int  * style, int  noOfPixels )

Sets the style for following drawing operations

Parameters

void gdImageSetThickness ( gdImagePtr  im, int  thickness )

Sets the thickness for following drawing operations

Parameters

void gdImageSetBrush ( gdImagePtr  im, gdImagePtr  brush )

Sets the brush for following drawing operations

Parameters

void gdImageSetTile ( gdImagePtr  im, gdImagePtr  tile )

void gdImageSetAntiAliased ( gdImagePtr  im, int  c )

Set the color for subsequent anti-aliased drawing

If gdAntiAliased is passed as color to drawing operations that support anti-aliased drawing (such as gdImageLine and gdImagePolygon), the actual color to be used can be set with this function.

Example: draw an anti-aliased blue line

gdImageSetAntiAliased(im, gdTrueColorAlpha(0, 0, gdBlueMax, gdAlphaOpaque));
gdImageLine(im, 10,10, 20,20, gdAntiAliased);

Parameters

See also

• gdImageSetAntiAliasedDontBlend

void gdImageSetAntiAliasedDontBlend ( gdImagePtr  im, int  c, int  dont_blend )

Set the color and “dont_blend” color for subsequent anti-aliased drawing

This extended variant of gdImageSetAntiAliased allows to also specify a (background) color that will not be blended in anti-aliased drawing operations.

Parameters

void gdImageInterlace ( gdImagePtr  im, int  interlaceArg )

Sets whether an image is interlaced

This is relevant only when saving the image in a format that supports interlacing.

Parameters

See also

• gdImageGetInterlaced

int gdImageCompare ( gdImagePtr  im1, gdImagePtr  im2 )

Compare two images

Parameters

Returns

A bitmask of Image Comparison flags where each set flag signals which attributes of the images are different.

int gdAlphaBlend ( int  dst, int  src )

Blend two colors

Parameters

See also

• gdImageAlphaBlending
• gdLayerOverlay
• gdLayerMultiply

int gdLayerOverlay ( int  dst, int  src )

Overlay two colors

Parameters

See also

• gdImageAlphaBlending
• gdAlphaBlend
• gdLayerMultiply

int gdLayerMultiply ( int  dst, int  src )

Overlay two colors with multiply effect

Parameters

See also

• gdImageAlphaBlending
• gdAlphaBlend
• gdLayerOverlay

void gdImageAlphaBlending ( gdImagePtr  im, int  alphaBlendingArg )

Set the effect for subsequent drawing operations

Note that the effect is used for truecolor images only.

Parameters

See also

• Effects

void gdImageSaveAlpha ( gdImagePtr  im, int  saveAlphaArg )

Sets the save alpha flag

The save alpha flag specifies whether the alpha channel of the pixels should be saved.  This is supported only for image formats that support full alpha transparency, e.g.  PNG.

void gdImageSetClip ( gdImagePtr  im, int  x1, int  y1, int  x2, int  y2 )

Sets the clipping rectangle

The clipping rectangle restricts the drawing area for following drawing operations.

Parameters

See also

• gdImageGetClip

void gdImageGetClip ( gdImagePtr  im, int  * x1P, int  * y1P, int  * x2P, int  * y2P )

Gets the current clipping rectangle

Parameters

See also

• gdImageSetClip

void gdImageSetResolution( gdImagePtr  im, const unsigned  int  res_x, const unsigned  int  res_y )

Sets the resolution of an image.

Parameters

See also

• gdImageResolutionX
• gdImageResolutionY

int gdImagePaletteToTrueColor( gdImagePtr  src )

Convert a palette image to true color

Parameters

Returns

Non-zero if the conversion succeeded, zero otherwise.

See also

• gdImageTrueColorToPalette