gtk/docs/reference/gdk/tmpl/images.sgml

<!-- ##### SECTION Title ##### -->
Images

<!-- ##### SECTION Short_Description ##### -->
an area for bit-mapped graphics stored on the X Windows client.

<!-- ##### SECTION Long_Description ##### -->
<para>
The #GdkImage type represents an area for drawing graphics.
It has now been superceded to a large extent by the much more flexible
<link linkend="gdk-GdkRGB">GdkRGB</link> functions.
</para>
<para>
To create an empty #GdkImage use gdk_image_new().
To create a #GdkImage from bitmap data use gdk_image_new_bitmap().
To create an image from part of a #GdkWindow use gdk_image_get().
</para>
<para>
The image can be manipulated with gdk_image_get_pixel() and
gdk_image_put_pixel(), or alternatively by changing the actual pixel data.
Though manipulating the pixel data requires complicated code to cope with
the different formats that may be used.
</para>
<para>
To draw a #GdkImage in a #GdkWindow or #GdkPixmap use gdk_draw_image().
</para>
<para>
To destroy a #GdkImage use gdk_image_destroy().
</para>

<!-- ##### SECTION See_Also ##### -->
<para>
<variablelist>

<varlistentry>
<term><link linkend="gdk-Bitmaps-and-Pixmaps">Bitmaps and Pixmaps</link></term>
<listitem><para>
Graphics which are stored on the X Windows server.
Since these are stored on the server they can be drawn very quickly, and all
of the <link linkend="gdk-Drawing-Primitives">Drawing Primitives</link> can be
used to draw on them. Their main disadvantage is that manipulating individual
pixels can be very slow.
</para></listitem>
</varlistentry>

<varlistentry>
<term><link linkend="gdk-GdkRGB">GdkRGB</link></term>
<listitem><para>
Built on top of #GdkImage, this provides much more functionality,
including the dithering of colors to produce better output on low-color
displays.
</para></listitem>
</varlistentry>

</variablelist>
</para>

<!-- ##### STRUCT GdkImage ##### -->
<para>
The #GdkImage struct contains information on the image and the pixel data.
</para>

@type: the type of the image.
@visual: the visual.
@byte_order: the byte order.
@width: the width of the image in pixels.
@height: the height of the image in pixels.
@depth: the depth of the image, i.e. the number of bits per pixel.
@bpp: the number of bytes per pixel.
@bpl: the number of bytes per line of the image.
@mem: the pixel data.

<!-- ##### FUNCTION gdk_image_new ##### -->
<para>
Creates a new #GdkImage.
</para>

@type: the type of the #GdkImage, one of %GDK_IMAGE_NORMAL, %GDK_IMAGE_SHARED
and %GDK_IMAGE_FASTEST. %GDK_IMAGE_FASTEST is probably the best choice, since
it will try creating a %GDK_IMAGE_SHARED image first and if that fails it will
then use %GDK_IMAGE_NORMAL.
@visual: the #GdkVisual to use for the image.
@width: the width of the image in pixels.
@height: the height of the image in pixels.
@Returns: a new #GdkImage, or NULL if the image could not be created.


<!-- ##### ENUM GdkImageType ##### -->
<para>
Specifies the type of a #GdkImage.
</para>

@GDK_IMAGE_NORMAL: The original X image type, which is quite slow since the
image has to be transferred from the client to the server to display it.
@GDK_IMAGE_SHARED: A faster image type, which uses shared memory to transfer
the image data between client and server. However this will only be available
if client and server are on the same machine and the shared memory extension
is supported by the server.
@GDK_IMAGE_FASTEST: Specifies that %GDK_IMAGE_SHARED should be tried first,
and if that fails then %GDK_IMAGE_NORMAL will be used.

<!-- ##### FUNCTION gdk_image_new_bitmap ##### -->
<para>
Creates a new #GdkImage with a depth of 1 from the given data.
</para>

@visual: the #GdkVisual to use for the image.
@data: the pixel data.
@width: the width of the image in pixels.
@height: the height of the image in pixels.
@Returns: a new #GdkImage.


<!-- ##### FUNCTION gdk_image_get ##### -->
<para>
Gets part of a #GdkWindow and stores it in a new #GdkImage.
</para>

@window: the #GdkWindow to copy from.
@x: the left edge of the rectangle to copy from @window.
@y: the top edge of the rectangle to copy from @window.
@width: the width of the area to copy, in pixels.
@height: the height of the area to copy, in pixels.
@Returns: a new #GdkImage with a copy of the given area of @window.


<!-- ##### FUNCTION gdk_image_destroy ##### -->
<para>
Destroys a #GdkImage, freeing any resources allocated for it.
</para>

@image: a #GdkImage.


<!-- ##### FUNCTION gdk_image_put_pixel ##### -->
<para>
Sets a pixel in a #GdkImage to a given pixel value.
</para>

@image: a #GdkImage.
@x: the x coordinate of the pixel to set.
@y: the y coordinate of the pixel to set.
@pixel: the pixel value to set.


<!-- ##### FUNCTION gdk_image_get_pixel ##### -->
<para>
Gets a pixel value at a specified position in a #GdkImage.
</para>

@image: a #GdkImage.
@x: the x coordinate of the pixel to get.
@y: the y coordinate of the pixel to get.
@Returns: the pixel value at the given position.