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Functions
GdkColorspace | gdk_pixbuf_get_colorspace () |
int | gdk_pixbuf_get_n_channels () |
gboolean | gdk_pixbuf_get_has_alpha () |
int | gdk_pixbuf_get_bits_per_sample () |
guchar * | gdk_pixbuf_get_pixels () |
guchar * | gdk_pixbuf_get_pixels_with_length () |
int | gdk_pixbuf_get_width () |
int | gdk_pixbuf_get_height () |
int | gdk_pixbuf_get_rowstride () |
gsize | gdk_pixbuf_get_byte_length () |
const gchar * | gdk_pixbuf_get_option () |
gboolean | gdk_pixbuf_set_option () |
gboolean | gdk_pixbuf_remove_option () |
GHashTable * | gdk_pixbuf_get_options () |
gboolean | gdk_pixbuf_copy_options () |
const guint8 * | gdk_pixbuf_read_pixels () |
GBytes * | gdk_pixbuf_read_pixel_bytes () |
gint | gdk_pixbuf_calculate_rowstride () |
Properties
gint | bits-per-sample | Read / Write / Construct Only |
GdkColorspace | colorspace | Read / Write / Construct Only |
gboolean | has-alpha | Read / Write / Construct Only |
gint | height | Read / Write / Construct Only |
gint | n-channels | Read / Write / Construct Only |
GBytes * | pixel-bytes | Read / Write / Construct Only |
gpointer | pixels | Read / Write / Construct Only |
gint | rowstride | Read / Write / Construct Only |
gint | width | Read / Write / Construct Only |
Types and Values
enum | GdkPixbufError |
#define | GDK_PIXBUF_ERROR |
enum | GdkColorspace |
enum | GdkPixbufAlphaMode |
GdkPixbuf |
Object Hierarchy
GEnum ├── GdkColorspace ├── GdkPixbufAlphaMode ╰── GdkPixbufError GObject ╰── GdkPixbuf
Description
The GdkPixbuf structure contains information that describes an image in memory.
Image Data
Image data in a pixbuf is stored in memory in uncompressed,
packed format. Rows in the image are stored top to bottom, and
in each row pixels are stored from left to right. There may be
padding at the end of a row. The "rowstride" value of a pixbuf,
as returned by gdk_pixbuf_get_rowstride()
, indicates the number
of bytes between rows.
put_pixel() Example
The following code illustrates a simple put_pixel()
function for RGB pixbufs with 8 bits per channel with an alpha
channel. It is not included in the gdk-pixbuf library for
performance reasons; rather than making several function calls
for each pixel, your own code can take shortcuts.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 |
static void put_pixel (GdkPixbuf *pixbuf, int x, int y, guchar red, guchar green, guchar blue, guchar alpha) { int width, height, rowstride, n_channels; guchar *pixels, *p; n_channels = gdk_pixbuf_get_n_channels (pixbuf); g_assert (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB); g_assert (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8); g_assert (gdk_pixbuf_get_has_alpha (pixbuf)); g_assert (n_channels == 4); width = gdk_pixbuf_get_width (pixbuf); height = gdk_pixbuf_get_height (pixbuf); g_assert (x >= 0 && x < width); g_assert (y >= 0 && y < height); rowstride = gdk_pixbuf_get_rowstride (pixbuf); pixels = gdk_pixbuf_get_pixels (pixbuf); p = pixels + y * rowstride + x * n_channels; p[0] = red; p[1] = green; p[2] = blue; p[3] = alpha; } |
This function will not work for pixbufs with images that are other than 8 bits per sample or channel, but it will work for most of the pixbufs that GTK+ uses.
If you are doing memcpy()
of raw pixbuf data, note that the last row
in the pixbuf may not be as wide as the full rowstride, but rather
just as wide as the pixel data needs to be. That is, it is unsafe to
do memcpy (dest, pixels, rowstride * height)
to copy a whole pixbuf.
Use gdk_pixbuf_copy()
instead, or compute the width in bytes of the
last row as width * ((n_channels * bits_per_sample + 7) / 8)
.
Functions
gdk_pixbuf_get_colorspace ()
GdkColorspace
gdk_pixbuf_get_colorspace (const GdkPixbuf *pixbuf
);
Queries the color space of a pixbuf.
gdk_pixbuf_get_n_channels ()
int
gdk_pixbuf_get_n_channels (const GdkPixbuf *pixbuf
);
Queries the number of channels of a pixbuf.
gdk_pixbuf_get_has_alpha ()
gboolean
gdk_pixbuf_get_has_alpha (const GdkPixbuf *pixbuf
);
Queries whether a pixbuf has an alpha channel (opacity information).
gdk_pixbuf_get_bits_per_sample ()
int
gdk_pixbuf_get_bits_per_sample (const GdkPixbuf *pixbuf
);
Queries the number of bits per color sample in a pixbuf.
gdk_pixbuf_get_pixels ()
guchar *
gdk_pixbuf_get_pixels (const GdkPixbuf *pixbuf
);
Queries a pointer to the pixel data of a pixbuf.
Returns
A pointer to the pixbuf's pixel data. Please see the section on image data for information about how the pixel data is stored in memory.
This function will cause an implicit copy of the pixbuf data if the pixbuf was created from read-only data.
[array]
gdk_pixbuf_get_pixels_with_length ()
guchar * gdk_pixbuf_get_pixels_with_length (const GdkPixbuf *pixbuf
,guint *length
);
Queries a pointer to the pixel data of a pixbuf.
[rename-to gdk_pixbuf_get_pixels]
Returns
A pointer to the pixbuf's pixel data. Please see the section on image data for information about how the pixel data is stored in memory.
This function will cause an implicit copy of the pixbuf data if the pixbuf was created from read-only data.
[array length=length]
Since: 2.26
gdk_pixbuf_get_width ()
int
gdk_pixbuf_get_width (const GdkPixbuf *pixbuf
);
Queries the width of a pixbuf.
gdk_pixbuf_get_height ()
int
gdk_pixbuf_get_height (const GdkPixbuf *pixbuf
);
Queries the height of a pixbuf.
gdk_pixbuf_get_rowstride ()
int
gdk_pixbuf_get_rowstride (const GdkPixbuf *pixbuf
);
Queries the rowstride of a pixbuf, which is the number of bytes between the start of a row and the start of the next row.
gdk_pixbuf_get_byte_length ()
gsize
gdk_pixbuf_get_byte_length (const GdkPixbuf *pixbuf
);
Returns the length of the pixel data, in bytes.
Since: 2.26
gdk_pixbuf_get_option ()
const gchar * gdk_pixbuf_get_option (GdkPixbuf *pixbuf
,const gchar *key
);
Looks up key
in the list of options that may have been attached to the
pixbuf
when it was loaded, or that may have been attached by another
function using gdk_pixbuf_set_option()
.
For instance, the ANI loader provides "Title" and "Artist" options. The ICO, XBM, and XPM loaders provide "x_hot" and "y_hot" hot-spot options for cursor definitions. The PNG loader provides the tEXt ancillary chunk key/value pairs as options. Since 2.12, the TIFF and JPEG loaders return an "orientation" option string that corresponds to the embedded TIFF/Exif orientation tag (if present). Since 2.32, the TIFF loader sets the "multipage" option string to "yes" when a multi-page TIFF is loaded. Since 2.32 the JPEG and PNG loaders set "x-dpi" and "y-dpi" if the file contains image density information in dots per inch. Since 2.36.6, the JPEG loader sets the "comment" option with the comment EXIF tag.
gdk_pixbuf_set_option ()
gboolean gdk_pixbuf_set_option (GdkPixbuf *pixbuf
,const gchar *key
,const gchar *value
);
Attaches a key/value pair as an option to a GdkPixbuf. If key
already
exists in the list of options attached to pixbuf
, the new value is
ignored and FALSE
is returned.
Since: 2.2
gdk_pixbuf_remove_option ()
gboolean gdk_pixbuf_remove_option (GdkPixbuf *pixbuf
,const gchar *key
);
Remove the key/value pair option attached to a GdkPixbuf.
Since: 2.36
gdk_pixbuf_get_options ()
GHashTable *
gdk_pixbuf_get_options (GdkPixbuf *pixbuf
);
Returns a GHashTable with a list of all the options that may have been
attached to the pixbuf
when it was loaded, or that may have been
attached by another function using gdk_pixbuf_set_option()
.
See gdk_pixbuf_get_option()
for more details.
Since: 2.32
gdk_pixbuf_copy_options ()
gboolean gdk_pixbuf_copy_options (GdkPixbuf *src_pixbuf
,GdkPixbuf *dest_pixbuf
);
Copy the key/value pair options attached to a GdkPixbuf to another. This is useful to keep original metadata after having manipulated a file. However be careful to remove metadata which you've already applied, such as the "orientation" option after rotating the image.
Since: 2.36
gdk_pixbuf_read_pixels ()
const guint8 *
gdk_pixbuf_read_pixels (const GdkPixbuf *pixbuf
);
Provides a read-only pointer to the raw pixel data; must not be
modified. This function allows skipping the implicit copy that
must be made if gdk_pixbuf_get_pixels()
is called on a read-only
pixbuf.
Since: 2.32
gdk_pixbuf_read_pixel_bytes ()
GBytes *
gdk_pixbuf_read_pixel_bytes (const GdkPixbuf *pixbuf
);
Provides a GBytes buffer containing the raw pixel data; the data
must not be modified. This function allows skipping the implicit
copy that must be made if gdk_pixbuf_get_pixels()
is called on a
read-only pixbuf.
Returns
A new reference to a read-only copy of the pixel data. Note that for mutable pixbufs, this function will incur a one-time copy of the pixel data for conversion into the returned GBytes.
[transfer full]
Since: 2.32
gdk_pixbuf_calculate_rowstride ()
gint gdk_pixbuf_calculate_rowstride (GdkColorspace colorspace
,gboolean has_alpha
,int bits_per_sample
,int width
,int height
);
Calculates the rowstride that an image created with those values would have. This is useful for front-ends and backends that want to sanity check image values without needing to create them.
Parameters
colorspace |
Color space for image |
|
has_alpha |
Whether the image should have transparency information |
|
bits_per_sample |
Number of bits per color sample |
|
width |
Width of image in pixels, must be > 0 |
|
height |
Height of image in pixels, must be > 0 |
Since: 2.36.8
Types and Values
enum GdkPixbufError
An error code in the GDK_PIXBUF_ERROR domain. Many gdk-pixbuf operations can cause errors in this domain, or in the G_FILE_ERROR domain.
GDK_PIXBUF_ERROR
#define GDK_PIXBUF_ERROR gdk_pixbuf_error_quark ()
Error domain used for pixbuf operations. Indicates that the error code will be in the GdkPixbufError enumeration. See GError for information on error domains and error codes.
enum GdkColorspace
This enumeration defines the color spaces that are supported by the gdk-pixbuf library. Currently only RGB is supported.
enum GdkPixbufAlphaMode
GdkPixbufAlphaMode
is deprecated and should not be used in newly-written code.
it is unused since 2.42.
These values can be passed to
gdk_pixbuf_xlib_render_to_drawable_alpha()
to control how the alpha
channel of an image should be handled. This function can create a
bilevel clipping mask (black and white) and use it while painting
the image. In the future, when the X Window System gets an alpha
channel extension, it will be possible to do full alpha
compositing onto arbitrary drawables. For now both cases fall
back to a bilevel clipping mask.
Members
A bilevel clipping mask (black and white) will be created and used to draw the image. Pixels below 0.5 opacity will be considered fully transparent, and all others will be considered fully opaque. |
||
For now falls back to GDK_PIXBUF_ALPHA_BILEVEL. In the future it will do full alpha compositing. |
GdkPixbuf
typedef struct _GdkPixbuf GdkPixbuf;
This is the main structure in the gdk-pixbuf library. It is used to represent images. It contains information about the image's pixel data, its color space, bits per sample, width and height, and the rowstride (the number of bytes between the start of one row and the start of the next).
Property Details
The “bits-per-sample”
property
“bits-per-sample” gint
The number of bits per sample. Currently only 8 bit per sample are supported.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Allowed values: [1,16]
Default value: 8
The “colorspace”
property
“colorspace” GdkColorspace
The colorspace in which the samples are interpreted.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Default value: GDK_COLORSPACE_RGB
The “has-alpha”
property
“has-alpha” gboolean
Whether the pixbuf has an alpha channel.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Default value: FALSE
The “height”
property
“height” gint
The number of rows of the pixbuf.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Allowed values: >= 1
Default value: 1
The “n-channels”
property
“n-channels” gint
The number of samples per pixel. Currently, only 3 or 4 samples per pixel are supported.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Allowed values: >= 0
Default value: 3
The “pixel-bytes”
property
“pixel-bytes” GBytes *
Readonly pixel data.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
The “pixels”
property
“pixels” gpointer
A pointer to the pixel data of the pixbuf.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
The “rowstride”
property
“rowstride” gint
The number of bytes between the start of a row and the start of the next row. This number must (obviously) be at least as large as the width of the pixbuf.
Owner: GdkPixbuf
Flags: Read / Write / Construct Only
Allowed values: >= 1
Default value: 1