Class DmabufTextureBuilder

java.lang.Object
org.javagi.base.ProxyInstance
org.gnome.gobject.TypeInstance
org.gnome.gobject.GObject
org.gnome.gdk.DmabufTextureBuilder
All Implemented Interfaces:
Proxy
@Generated("org.javagi.JavaGI") public class DmabufTextureBuilder extends GObject

Constructs Texture objects from DMA buffers.

DMA buffers are commonly called dma-bufs.

DMA buffers are a feature of the Linux kernel to enable efficient buffer and memory sharing between hardware such as codecs, GPUs, displays, cameras and the kernel drivers controlling them. For example, a decoder may want its output to be directly shared with the display server for rendering without a copy.

Any device driver which participates in DMA buffer sharing, can do so as either the exporter or importer of buffers (or both).

The memory that is shared via DMA buffers is usually stored in non-system memory (maybe in device's local memory or something else not directly accessible by the CPU), and accessing this memory from the CPU may have higher-than-usual overhead.

In particular for graphics data, it is not uncommon that data consists of multiple separate blocks of memory, for example one block for each of the red, green and blue channels. These blocks are called planes. DMA buffers can have up to four planes. Even if the memory is a single block, the data can be organized in multiple planes, by specifying offsets from the beginning of the data.

DMA buffers are exposed to user-space as file descriptors allowing to pass them between processes. If a DMA buffer has multiple planes, more than one file descriptor may be present, up to the number of planes. If the number of file descriptors is less than the number of planes, the remaining ones should be set to -1.

The format of the data (for graphics data, essentially its colorspace) is described by a 32-bit integer. These format identifiers are defined in the header file drm_fourcc.h and commonly referred to as fourcc values, since they are identified by 4 ASCII characters. Additionally, each DMA buffer has a modifier, which is a 64-bit integer that describes driver-specific details of the memory layout, such as tiling or compression.

For historical reasons, some producers of dma-bufs don't provide an explicit modifier, but instead return DMA_FORMAT_MOD_INVALID to indicate that their modifier is implicit. GTK tries to accommodate this situation by accepting DMA_FORMAT_MOD_INVALID as modifier.

The operation of GdkDmabufTextureBuilder is quite simple: Create a texture builder, set all the necessary properties, and then call build(MemorySegment) to create the new texture.

The required properties for a dma-buf texture are

  • The width and height in pixels

  • The fourcc code and modifier which identify the format and memory layout of the dma-buf

  • The file descriptor, offset and stride for each of the planes

GdkDmabufTextureBuilder can be used for quick one-shot construction of textures as well as kept around and reused to construct multiple textures.

For further information, see

Since:
4.14

  • Constructor Details

    • DmabufTextureBuilder

      public DmabufTextureBuilder(MemorySegment address)
      Create a DmabufTextureBuilder instance for the provided memory address.
      Parameters:
      address - the memory address of the native object

    • DmabufTextureBuilder

      public DmabufTextureBuilder()
      Create a new DmabufTextureBuilder.

  • Method Details

    • getType

      public static @Nullable Type getType()
      Get the GType of the DmabufTextureBuilder class.
      Returns:
      the GType

    • getMemoryLayout

      public static MemoryLayout getMemoryLayout()
      The memory layout of the native struct.
      Returns:
      the memory layout

    • asParent

      protected DmabufTextureBuilder asParent()
      Return this instance as if it were its parent type. Comparable to the Java super keyword, but ensures the parent typeclass is also used in native code.
      Overrides:
      asParent in class GObject
      Returns:
      the instance as if it were its parent type

    • build

      public @Nullable Texture build(@Nullable MemorySegment data) throws GErrorException

      Builds a new GdkTexture with the values set up in the builder.

      It is a programming error to call this function if any mandatory property has not been set.

      Not all formats defined in the drm_fourcc.h header are supported. You can use Display.getDmabufFormats() to get a list of supported formats. If the format is not supported by GTK, null will be returned and error will be set.

      The destroy function gets called when the returned texture gets released.

      It is the responsibility of the caller to keep the file descriptors for the planes open until the created texture is no longer used, and close them afterwards (possibly using the destroy notify).

      It is possible to call this function multiple times to create multiple textures, possibly with changing properties in between.

      Parameters:
      data - user data to pass to the destroy function
      Returns:
      a newly built GdkTexture or NULL if the format is not supported
      Throws:
      GErrorException - see GError
      Since:
      4.14

    • getColorState

      public @Nullable ColorState getColorState()
      Gets the color state previously set via gdk_dmabuf_texture_builder_set_color_state().
      Returns:
      the color state
      Since:
      4.16

    • getDisplay

      public Display getDisplay()
      Returns the display that this texture builder is associated with.
      Returns:
      the display
      Since:
      4.14

    • getFd

      public int getFd(int plane)
      Gets the file descriptor for a plane or -1 if none.
      Parameters:
      plane - the plane to get the fd for
      Returns:
      the file descriptor
      Since:
      4.14

    • getFourcc

      public int getFourcc()

      Gets the format previously set via gdk_dmabuf_texture_builder_set_fourcc() or 0 if the format wasn't set.

      The format is specified as a fourcc code.

      Returns:
      The format
      Since:
      4.14

    • getHeight

      public int getHeight()
      Gets the height previously set via gdk_dmabuf_texture_builder_set_height() or 0 if the height wasn't set.
      Returns:
      The height
      Since:
      4.14

    • getModifier

      public long getModifier()
      Gets the modifier value.
      Returns:
      the modifier
      Since:
      4.14

    • getNPlanes

      public int getNPlanes()
      Gets the number of planes.
      Returns:
      The number of planes
      Since:
      4.14

    • getOffset

      public int getOffset(int plane)
      Gets the offset value for a plane.
      Parameters:
      plane - the plane to get the offset for
      Returns:
      the offset
      Since:
      4.14

    • getPremultiplied

      public boolean getPremultiplied()
      Whether the data is premultiplied.
      Returns:
      whether the data is premultiplied
      Since:
      4.14

    • getStride

      public int getStride(int plane)
      Gets the stride value for a plane.
      Parameters:
      plane - the plane to get the stride for
      Returns:
      the stride
      Since:
      4.14

    • getUpdateRegion

      public @Nullable org.freedesktop.cairo.Region getUpdateRegion()
      Gets the region previously set via gdk_dmabuf_texture_builder_set_update_region() or null if none was set.
      Returns:
      The region
      Since:
      4.14

    • getUpdateTexture

      public @Nullable Texture getUpdateTexture()
      Gets the texture previously set via gdk_dmabuf_texture_builder_set_update_texture() or null if none was set.
      Returns:
      The texture
      Since:
      4.14

    • getWidth

      public int getWidth()
      Gets the width previously set via gdk_dmabuf_texture_builder_set_width() or 0 if the width wasn't set.
      Returns:
      The width
      Since:
      4.14

    • setColorState

      public void setColorState(@Nullable ColorState colorState)

      Sets the color state for the texture.

      By default, the colorstate is NULL. In that case, GTK will choose the correct colorstate based on the format. If you don't know what colorstates are, this is probably the right thing.

      Parameters:
      colorState - a GdkColorState or NULL to unset the colorstate.
      Since:
      4.16

    • setDisplay

      public void setDisplay(Display display)

      Sets the display that this texture builder is associated with.

      The display is used to determine the supported dma-buf formats.

      Parameters:
      display - the display
      Since:
      4.14

    • setFd

      public void setFd(int plane, int fd)
      Sets the file descriptor for a plane or to -1 to unset it.
      Parameters:
      plane - the plane to set the fd for
      fd - the file descriptor
      Since:
      4.14

    • setFourcc

      public void setFourcc(int fourcc)

      Sets the format of the texture.

      The format is specified as a fourcc code.

      The format must be set before calling build(MemorySegment).

      Parameters:
      fourcc - the texture's format or 0 to unset
      Since:
      4.14

    • setHeight

      public void setHeight(int height)

      Sets the height of the texture.

      The height must be set before calling build(MemorySegment).

      Parameters:
      height - the texture's height or 0 to unset
      Since:
      4.14

    • setModifier

      public void setModifier(long modifier)
      Sets the modifier.
      Parameters:
      modifier - the modifier value
      Since:
      4.14

    • setNPlanes

      public void setNPlanes(int nPlanes)
      Sets the number of planes of the texture.
      Parameters:
      nPlanes - the number of planes
      Since:
      4.14

    • setOffset

      public void setOffset(int plane, int offset)
      Sets the offset for a plane.
      Parameters:
      plane - the plane to set the offset for
      offset - the offset value
      Since:
      4.14

    • setPremultiplied

      public void setPremultiplied(boolean premultiplied)

      Sets whether the data is premultiplied.

      Unless otherwise specified, all formats including alpha channels are assumed to be premultiplied.

      Parameters:
      premultiplied - whether the data is premultiplied
      Since:
      4.14

    • setStride

      public void setStride(int plane, int stride)

      Sets the stride for a plane.

      The stride must be set for all planes before calling build(MemorySegment).

      Parameters:
      plane - the plane to set the stride for
      stride - the stride value
      Since:
      4.14

    • setUpdateRegion

      public void setUpdateRegion(@Nullable org.freedesktop.cairo.Region region)

      Sets the region to be updated by this texture. Together with Gdk.DmabufTextureBuilder:update-texture this describes an update of a previous texture.

      When rendering animations of large textures, it is possible that consecutive textures are only updating contents in parts of the texture. It is then possible to describe this update via these two properties, so that GTK can avoid rerendering parts that did not change.

      An example would be a screen recording where only the mouse pointer moves.

      Parameters:
      region - the region to update
      Since:
      4.14

    • setUpdateTexture

      public void setUpdateTexture(@Nullable Texture texture)
      Sets the texture to be updated by this texture. See setUpdateRegion(Region) for an explanation.
      Parameters:
      texture - the texture to update
      Since:
      4.14

    • setWidth

      public void setWidth(int width)

      Sets the width of the texture.

      The width must be set before calling build(MemorySegment).

      Parameters:
      width - The texture's width or 0 to unset
      Since:
      4.14

    • builder

      public static DmabufTextureBuilder.Builder<? extends DmabufTextureBuilder.Builder> builder()
      A DmabufTextureBuilder.Builder object constructs a DmabufTextureBuilder with the specified properties. Use the various set...() methods to set properties, and finish construction with DmabufTextureBuilder.Builder.build().
      Returns:
      the builder object