GtkAda Reference Manual - Package Gdk.Pixbuf

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# Package Gdk.Pixbuf

This object provides image manipulation routines.

The following image formats are known, but some depend on external libraries for the proper loading of files (indicated with * in the list): PNG*, JPEG*, TIFF*, GIF, XPM, PNM, Sun raster file (ras), ico, bmp.

With this package, you can load images from file, display them on the screen, re-scale them and compose them with other images. All the functions fully support alpha channels (opacity).

Different filters are provided, depending on the quality of output you expect and the speed you need.

- Gdk.Pixbuf Types
- Gdk.Pixbuf Subprograms

## Types

    type Alpha_Mode is
        (Alpha_Bilevel, Alpha_Full);
| Alpha compositing mode. This indicates how the alpha channel (for opacity) is handled when rendering. pragma Convention (C, Alpha_Mode);
    type Alpha_Range is range 0 .. 255;
| Valid values for alpha parameters. pragma Convention (C, Alpha_Range);
    type File_Format is
        (JPEG, PNG);
| Possible formats when saving a file.
    type Gdk_Colorspace is
        (Colorspace_RGB);
| Type of the image. The only possible value is currently RGB, but extensions will exist with CMYK, Gray, Lab, ... pragma Convention (C, Gdk_Colorspace);
    type Gdk_Interp_Type is
        (Interp_Nearest,
            -- Nearest neighbor. It is the fastest and lowest quality.

         Interp_Tiles,
            -- Accurate simulation of the Postscript image operator
            -- without any interpolation enabled; each pixel is rendered as a tiny
            -- parallelogram of solid color, the edges of which are implemented
            -- with anti-aliasing. It resembles nearest neighbor for enlargement,
            -- and bilinear for reduction.

         Interp_Bilinear,
            -- Bilinear interpolation. For enlargement, it is equivalent to
            -- point-sampling the ideal bilinear-interpolated image. For reduction,
            -- it is equivalent to laying down small tiles and integrating over the
            -- coverage area.

         Interp_Hyper
            -- Filter_Hyper is the highest quality reconstruction function. It is
            -- derived from the hyperbolic filters in Wolberg's "Digital Image
            -- Warping," and is formally defined as the hyperbolic-filter sampling
            -- the ideal hyperbolic-filter interpolated image (the filter is
            -- designed to be idempotent for 1:1 pixel mapping). It is the slowest
| and highest quality. ); Interpolation methods. pragma Convention (C, Gdk_Interp_Type);
    type Gdk_Pixbuf is new Glib.C_Proxy;
| A very efficient client-side pixmap. This type can be adapted to all the possible screen depths (number of bits per pixel), and the algorithms are extremely efficient. You can also load a pixbuf directly from an external file in one of the standard image formats.
    type Gdk_Pixbuf_Animation is new Glib.C_Proxy;
| Type used for animations.
    type Gdk_Pixbuf_Animation_Iter is new Glib.C_Proxy;
| Type used to iterate through an animation.
    type Image_Quality is range 0 .. 100;
| For a JPEG image only, quality of the image in percentage.

## Subprograms

### Get_Type
    function Get_Type              return Glib.GType;
| Return the internal value associated with a Gdk_Pixbuf.
### Reference counting
    procedure Ref
      (Pixbuf             :        Gdk_Pixbuf);
| Increment the reference counting on the image. The image is destroyed when its reference counting reaches 0. Note also that most of the time you won't have to call this function yourself.
    procedure Unref
      (Pixbuf             :        Gdk_Pixbuf);
| Decrement the reference counting on the image.
### Accessing the fields
    function Get_Colorspace
      (Pixbuf             :        Gdk_Pixbuf)
       return Gdk_Colorspace;
| Query the color space of a pixbuf.
    function Get_N_Channels
      (Pixbuf             :        Gdk_Pixbuf)
       return Gint;
| Number of channels in the image.
    function Get_Has_Alpha
      (Pixbuf             :        Gdk_Pixbuf)
       return Boolean;
| Return True if the image has an alpha channel (opacity information).
    function Get_Bits_Per_Sample
      (Pixbuf             :        Gdk_Pixbuf)
       return Gint;
| Number of bits per color sample.
    function Get_Pixels
      (Pixbuf             :        Gdk_Pixbuf)
       return Gdk.Rgb.Rgb_Buffer_Access;
| Return a pointer to the pixel data of the image.
    function Get_Width
      (Pixbuf             :        Gdk_Pixbuf)
       return Gint;
| Return the width of the image in pixels.
    function Get_Height
      (Pixbuf             :        Gdk_Pixbuf)
       return Gint;
| Return the height of the image in pixels.
    function Get_Rowstride
      (Pixbuf             :        Gdk_Pixbuf)
       return Gint;
| Return the number of bytes between rows in the image data.
### Creating
    function Gdk_New
      (Colorspace         :        Gdk_Colorspace
                           := Colorspace_RGB;
       Has_Alpha          :        Boolean := False;
       Bits_Per_Sample    :        Gint := 8;
       Width              :        Gint;
       Height             :        Gint)
       return Gdk_Pixbuf;
| Create a blank pixbuf with an optimal row stride and a new buffer. The buffer is allocated, but not cleared. The reference counting is initialized to 1.
    function Copy
      (Pixbuf             :        Gdk_Pixbuf)
       return Gdk_Pixbuf;
| Copy a pixbuf.
    function Gdk_New_Subpixbuf
      (Src_Pixbuf         :        Gdk_Pixbuf;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Width              :        Gint;
       Height             :        Gint)
       return Gdk_Pixbuf;
| Create a pixbuf which points to the pixels of another pixbuf
    procedure Gdk_New_From_File
      (Pixbuf             : out    Gdk_Pixbuf;
       Filename           :        String;
       Error              : out    GError);
| Load an image from file.
    function Gdk_New_From_Xpm_Data
      (Data               :        Interfaces.C.Strings.chars_ptr_array)
       return Gdk_Pixbuf;
| Create an image from a XPM data.
    procedure Fill
      (Pixbuf             :        Gdk_Pixbuf;
       Pixel              :        Guint32);
| Fill pixbuf with a given pixel value.
    procedure Save
      (Pixbuf             :        Gdk_Pixbuf;
       Filename           :        String;
       Format             :        File_Format;
       Error              : out    GError;
       Quality            :        Image_Quality
                           := Image_Quality'Last);
| Save pixbuf to a file. Quality is only taken into account for JPEG images. Error is set to null on success, and set to a GError otherwise.
    function Add_Alpha
      (Pixbuf             :        Gdk_Pixbuf;
       Substitute_Color   :        Boolean := False;
       Red                :        Guchar := 0;
       Green              :        Guchar := 0;
       Blue               :        Guchar := 0)
       return Gdk_Pixbuf;
| Add an alpha channel. Return a newly allocated image copied from Pixbuf, but with an extra alpha channel. If Pixbuf already had an alpha channel, the two images have exactly the same contents. If Substitute_Color is True, the color (Red, Green, Blue) is substituted for zero opacity. If Substitute_Color is False, Red, Green and Blue are ignored, and a new color is created with zero opacity.
    procedure Copy_Area
      (Src_Pixbuf         :        Gdk_Pixbuf;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Width              :        Gint;
       Height             :        Gint;
       Dest_Pixbuf        :        Gdk_Pixbuf;
       Dest_X             :        Gint;
       Dest_Y             :        Gint);
| Copy a rectangular area from Src_pixbuf to Dest_pixbuf. Conversion of pixbuf formats is done automatically.
    procedure Saturate_And_Pixelate
      (Src                :        Gdk_Pixbuf;
       Dest               :        Gdk_Pixbuf;
       Saturation         :        Gfloat;
       Pixelate           :        Boolean := True);
| Brighten/darken and optionally make it pixelated-looking.
### Rendering
    procedure Render_Threshold_Alpha
      (Pixbuf             :        Gdk_Pixbuf;
       Bitmap             :        Gdk.Bitmap.Gdk_Bitmap;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Width              :        Gint;
       Height             :        Gint;
       Alpha_Threshold    :        Alpha_Range);
| Take the opacity values in a rectangular portion of a pixbuf and thresholds them to produce a bi-level alpha mask that can be used as a clipping mask for a drawable. Bitmap is the bitmap where the bilevel mask will be painted to. Alpha_Threshold are the opacity values below which a pixel will be painted as zero. All other values will be painted as one.
    procedure Render_To_Drawable
      (Pixbuf             :        Gdk_Pixbuf;
       Drawable           :        Gdk.Drawable.Gdk_Drawable;
       Gc                 :        Gdk.GC.Gdk_GC;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Width              :        Gint;
       Height             :        Gint;
       Dither             :        Gdk.Rgb.Gdk_Rgb_Dither
                           := Gdk.Rgb.Dither_Normal;
       X_Dither           :        Gint := 0;
       Y_Dither           :        Gint := 0);
| Render a rectangular portion of a pixbuf to a drawable while using the specified GC. This is done using Gdk.RGB, so the specified drawable must have the Gdk.RGB visual and colormap. Note that this function will ignore the opacity information for images with an alpha channel; the GC must already have the clipping mask set if you want transparent regions to show through. For an explanation of dither offsets, see the Gdk.RGB documentation. In brief, the dither offset is important when re-rendering partial regions of an image to a rendered version of the full image, or for when the offsets to a base position change, as in scrolling. The dither matrix has to be shifted for consistent visual results. If you do not have any of these cases, the dither offsets can be both zero.
    procedure Render_To_Drawable_Alpha
      (Pixbuf             :        Gdk_Pixbuf;
       Drawable           :        Gdk.Drawable.Gdk_Drawable;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Width              :        Gint;
       Height             :        Gint;
       Alpha              :        Alpha_Mode;
       Alpha_Threshold    :        Alpha_Range;
       Dither             :        Gdk.Rgb.Gdk_Rgb_Dither
                           := Gdk.Rgb.Dither_Normal;
       X_Dither           :        Gint := 0;
       Y_Dither           :        Gint := 0);
| Render a rectangular portion of a pixbuf to a drawable. This is done using Gdk.RGB, so the specified drawable must have the Gdk_RGB visual and colormap. When used with Alpha_Bilevel, this function has to create a bitmap out of the thresholded alpha channel of the image and, it has to set this bitmap as the clipping mask for the GC used for drawing. This can be a significant performance penalty depending on the size and the complexity of the alpha channel of the image. If performance is crucial, consider handling the alpha channel yourself (possibly by caching it in your application) and using Render_To_Drawable or Gdk.RGB directly instead. If the image does have opacity information and Alpha_Mode is Alpha_Bilevel, specifies the threshold value for opacity values
    procedure Render_Pixmap_And_Mask
      (Pixbuf             :        Gdk_Pixbuf;
       Pixmap             : out    Gdk.Pixmap.Gdk_Pixmap;
       Mask               : out    Gdk.Bitmap.Gdk_Bitmap;
       Alpha_Threshold    :        Alpha_Range);
    function Get_From_Drawable
      (Dest               :        Gdk_Pixbuf;
       Src                :        Gdk.Drawable.Gdk_Drawable;
       Cmap               :        Gdk.Color.Gdk_Colormap;
       Src_X              :        Gint;
       Src_Y              :        Gint;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Width              :        Gint;
       Height             :        Gint)
       return Gdk_Pixbuf;
| Transfer image data from a Gdk drawable and converts it to an RGB(A) representation inside a Gdk_Pixbuf. If the drawable src is a pixmap, then a suitable colormap must be specified, since pixmaps are just blocks of pixel data without an associated colormap. If the drawable is a window, the Cmap argument will be ignored and the window's own colormap will be used instead. If the specified destination pixbuf Dest is Null_Pixbuf, then this function will create an RGB pixbuf with 8 bits per channel and no alpha, with the same size specified by the Width and Height arguments. In this case, the Dest_x and Dest_y arguments must be specified as 0, otherwise the function will return Null_Pixbuf. If the specified destination pixbuf is not Null_Pixbuf and it contains alpha information, then the filled pixels will be set to full opacity. If the specified drawable is a pixmap, then the requested source rectangle must be completely contained within the pixmap, otherwise the function will return Null_Pixbuf. If the specified drawable is a window, then it must be viewable, i.e. all of its ancestors up to the root window must be mapped. Also, the specified source rectangle must be completely contained within the window and within the screen. If regions of the window are obscured by non-inferior windows, the contents of those regions are undefined. The contents of regions obscured by inferior windows of a different depth than that of the source window will also be undefined. Return value: The same pixbuf as Dest if it was non-NULL, or a newly-created pixbuf with a reference count of 1 if no destination pixbuf was specified.
### Scaling
    procedure Scale
      (Src                :        Gdk_Pixbuf;
       Dest               :        Gdk_Pixbuf;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Dest_Width         :        Gint;
       Dest_Height        :        Gint;
       Offset_X           :        Gdouble := 0.0;
       Offset_Y           :        Gdouble := 0.0;
       Scale_X            :        Gdouble := 1.0;
       Scale_Y            :        Gdouble := 1.0;
       Inter_Type         :        Gdk_Interp_Type
                           := Interp_Bilinear);
| Transform the source image by scaling by Scale_x and Scale_y then translating by Offset_x and Offset_y. The image is then rendered in the rectangle (Dest_x, Dest_y, Dest_width, Dest_height) of the resulting image onto the destination drawable replacing the previous contents.
    procedure Composite
      (Src                :        Gdk_Pixbuf;
       Dest               :        Gdk_Pixbuf;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Dest_Width         :        Gint;
       Dest_Height        :        Gint;
       Offset_X           :        Gdouble := 0.0;
       Offset_Y           :        Gdouble := 0.0;
       Scale_X            :        Gdouble := 1.0;
       Scale_Y            :        Gdouble := 1.0;
       Inter_Type         :        Gdk_Interp_Type
                           := Interp_Bilinear;
       Overall_Alpha      :        Alpha_Range := 128);
| Transform the source image by scaling by Scale_X and Scale_Y then translating by Offset_X and Offset_Y, then composite the rectangle (Dest_X, Dest_Y, Dest_Width, Dest_Height) of the resulting image onto the destination drawable.
    procedure Composite_Color
      (Src                :        Gdk_Pixbuf;
       Dest               :        Gdk_Pixbuf;
       Dest_X             :        Gint;
       Dest_Y             :        Gint;
       Dest_Width         :        Gint;
       Dest_Height        :        Gint;
       Offset_X           :        Gdouble := 0.0;
       Offset_Y           :        Gdouble := 0.0;
       Scale_X            :        Gdouble := 1.0;
       Scale_Y            :        Gdouble := 1.0;
       Inter_Type         :        Gdk_Interp_Type
                           := Interp_Bilinear;
       Overall_Alpha      :        Alpha_Range := 128;
       Check_X            :        Gint := 0;
       Check_Y            :        Gint := 0;
       Check_Size         :        Gint := 0;
       Color1             :        Guint32 := 0;
       Color2             :        Guint32 := 0);
| Transform the source image by scaling by Scale_x and Scale_y then translating by Offset_x and Offset_y, then composites the rectangle (Dest_X, Dest_Y, Dest_Width, Dest_Height) of the resulting image with a checkboard of the colors Color1 and Color2 and renders it onto the destination drawable. The origin of checkboard is at (Check_x, Check_y) Color1 is the color at the upper left of the check.
    function Scale_Simple
      (Src                :        Gdk_Pixbuf;
       Dest_Width         :        Gint;
       Dest_Height        :        Gint;
       Inter_Type         :        Gdk_Interp_Type
                           := Interp_Bilinear)
       return Gdk_Pixbuf;
| Scale the Src image to Dest_width x Dest_height and render the result into a new pixbuf.
    function Composite_Color_Simple
      (Src                :        Gdk_Pixbuf;
       Dest_Width         :        Gint;
       Dest_Height        :        Gint;
       Inter_Type         :        Gdk_Interp_Type
                           := Interp_Bilinear;
       Overall_Alpha      :        Alpha_Range := 128;
       Color1             :        Guint32 := 0;
       Color2             :        Guint32 := 0)
       return Gdk_Pixbuf;
| Scale Src to Dest_width x Dest_height and composite the result with a checkboard of colors Color1 and Color2 and render the result into a new pixbuf.
### Animation support
    function Get_Type_Animation    return Glib.GType;
| Return the internal value associated with a Gdk_Pixbuf_Animation.
    procedure Gdk_New_From_File
      (Animation          : out    Gdk_Pixbuf_Animation;
       Filename           :        String;
       Error              : out    GError);
| Create a new animation by loading it from a file. The file format is detected automatically. If the file's format does not support multi-frame images, then an animation with a single frame will be created. Possible errors are in the Pixbuf_Error and GFile_Error domains. On return, Animation is a newly created animation with a reference count of 1, or null if any of several error conditions ocurred: the file could not be opened, there was no loader for the file's format, there was not enough memory to allocate the image buffer, or the image file contained invalid data.
    procedure Ref
      (Animation          :        Gdk_Pixbuf_Animation);
| Increment the reference counting on the animation.
    procedure Unref
      (Animation          :        Gdk_Pixbuf_Animation);
| Decrement the reference counting on the animation.
    function Get_Width
      (Animation          :        Gdk_Pixbuf_Animation)
       return Gint;
| Return the width of the bounding box of a pixbuf animation.
    function Get_Height
      (Animation          :        Gdk_Pixbuf_Animation)
       return Gint;
| Return the height of the bounding box of a pixbuf animation.
    function Is_Static_Image
      (Animation          :        Gdk_Pixbuf_Animation)
       return Boolean;
| If you load a file with Gdk_New_From_File and it turns out to be a plain, unanimated image, then this function will return True. Use Get_Static_Image to retrieve the image.
    function Get_Static_Image
      (Animation          :        Gdk_Pixbuf_Animation)
       return Gdk_Pixbuf;
| If an animation is really just a plain image (has only one frame), this function returns that image. If the animation is an animation, this function returns a reasonable thing to display as a static unanimated image, which might be the first frame, or something more sophisticated. If an animation hasn't loaded any frames yet, this function will return null.
    function Get_Iter
      (Animation          :        Gdk_Pixbuf_Animation;
       Start_Time         :        GTime_Val_Access := null)
       return Gdk_Pixbuf_Animation_Iter;
| Get an iterator for displaying an animation. The iterator provides the frames that should be displayed at a given time. It should be freed after use with Unref. Start_Time would normally come from G_Get_Current_Time, and marks the beginning of animation playback. After creating an iterator, you should immediately display the pixbuf returned by Get_Pixbuf. Then, you should install a timeout (with Timeout_Add) or by some other mechanism to ensure that you'll update the image after Get_Delay_Time milliseconds. Each time the image is updated, you should reinstall the timeout with the new, possibly-changed delay time. As a shortcut, if Start_Time is equal to null, the result of G_Get_Current_Time will be used automatically. To update the image (i.e. possibly change the result of Get_Pixbuf to a new frame of the animation), call Advance. If you're using Gdk_Pixbuf_Loader, in addition to updating the image after the delay time, you should also update it whenever you receive the area_updated signal and On_Currently_Loading_Frame returns True. In this case, the frame currently being fed into the loader has received new data, so needs to be refreshed. The delay time for a frame may also be modified after an area_updated signal, for example if the delay time for a frame is encoded in the data after the frame itself. So your timeout should be reinstalled after any area_updated signal. A delay time of -1 is possible, indicating "infinite."
### Iterators
    function Get_Type_Animation_Iterreturn Glib.GType;
| Return the internal value associated with a Gdk_Pixbuf_Animation_Iter.
    procedure Ref
      (Iter               :        Gdk_Pixbuf_Animation_Iter);
| Increment the reference counting on the iterator.
    procedure Unref
      (Iter               :        Gdk_Pixbuf_Animation_Iter);
| Decrement the reference counting on the iterator.
    function Get_Delay_Time
      (Iter               :        Gdk_Pixbuf_Animation_Iter)
       return Gint;
| Return the number of milliseconds the current pixbuf should be displayed or -1 if the current pixbuf should be displayed forever. Timeout_Add conveniently takes a timeout in milliseconds, so you can use a timeout to schedule the next update.
    function Get_Pixbuf
      (Iter               :        Gdk_Pixbuf_Animation_Iter)
       return Gdk_Pixbuf;
| Return the current pixbuf which should be displayed. The pixbuf will be the same size as the animation itself (Get_Width, Get_Height). This pixbuf should be displayed for Get_Delay_Time milliseconds. The caller of this function does not own a reference to the returned pixbuf; the returned pixbuf will become invalid when the iterator advances to the next frame, which may happen anytime you call Advance. Copy the pixbuf to keep it (don't just add a reference), as it may get recycled as you advance the iterator.
    function On_Currently_Loading_Frame
      (Iter               :        Gdk_Pixbuf_Animation_Iter)
       return Boolean;
| Used to determine how to respond to the area_updated signal on Gdk_Pixbuf_Loader when loading an animation. area_updated is emitted for an area of the frame currently streaming in to the loader. So if you're on the currently loading frame, you need to redraw the screen for the updated area.
    function Advance
      (Iter               :        Gdk_Pixbuf_Animation_Iter;
       Current_Timer      :        GTime_Val_Access := null)
       return Boolean;
| Possibly advance an animation to a new frame. Chooses the frame based on the start time passed to Get_Iter. Current_Time would normally come from G_Get_Current_Time, and must be greater than or equal to the time passed to Get_Iter, and must increase or remain unchanged each time Get_Pixbuf is called. That is, you can't go backward in time; animations only play forward. As a shortcut, pass null for the current time and G_Get_Current_Time will be invoked on your behalf. So you only need to explicitly pass Current_Time if you're doing something odd like playing the animation at double speed. If this function returns False, there's no need to update the animation display, assuming the display had been rendered prior to advancing; if True, you need to call Get_Pixbuf and update the display with the new pixbuf.

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