301 lines
9.3 KiB
Plaintext
301 lines
9.3 KiB
Plaintext
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Addendum to the Xv Client library documentation
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===============================================
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The following features are new to version 2.2
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1) In addition to XvInputMask and XvOutputMask masks in the type field
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of the XvAdaptorInfo there are 3 new bits defined - XvVideoMask,
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XvStillMask and XvImageMask indicating that the adaptor is capable
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of video, still or image primitives respectively.
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2) A new function and structure is defined to allow querying
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port attributes.
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typedef struct {
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int flags;
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int min_value;
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int max_value;
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char *name;
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} XvAttribute;
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flags - May be XvGettable or XvSettable or both OR'd together
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indicating the particular attribute is readable, writeable
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or readable and writeable.
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min_value, max_value - Indicate the minimum and maximum attribute
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values which are valid for the driver.
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name - A string describing the name of the attribute that may be used
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to retrieve the Atom for the particular attribute.
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extern XvAttribute* XvQueryPortAttributes(
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Display* /* display */,
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XvPortID /* port */,
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int* /* number */
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);
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XvQueryPortAttributes returns the number of attributes and an
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array of XvAttributes valid for the given port. The array may
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be freed with XFree().
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3) The X Video Extension (Xv) is extended to support client images in
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alternate colorspaces (XvImages) in the following way.
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Xv Adaptors which are capable of displaying XvImages will have
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the XvImageMask field set in the type field of the XvAdaptorInfo.
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XvImage formats supported by the port may be queried with
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XvListImageFormats().
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XvImages may be created with the help of XvCreateImage() or
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XvShmCreateImage();
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XvImages may be displayed with XvPutImage() or XvShmPutImage().
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The Port attributes of the port specified in the Xv(Shm)PutImage
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command will be valid for the image operation when applicable.
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There will be a port encoding with the name "XV_IMAGE". The
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width and height of that encoding will indicate the maximum
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source image size.
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typedef struct {
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int id; /* Unique descriptor for the format */
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int type; /* XvRGB, XvYUV */
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int byte_order; /* LSBFirst, MSBFirst */
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char guid[16]; /* Globally Unique IDentifier */
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int bits_per_pixel;
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int format; /* XvPacked, XvPlanar */
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int num_planes;
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/* for RGB formats */
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int depth;
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unsigned int red_mask;
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unsigned int green_mask;
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unsigned int blue_mask;
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/* for YUV formats */
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unsigned int y_sample_bits;
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unsigned int u_sample_bits;
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unsigned int v_sample_bits;
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unsigned int horz_y_period;
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unsigned int horz_u_period;
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unsigned int horz_v_period;
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unsigned int vert_y_period;
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unsigned int vert_u_period;
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unsigned int vert_v_period;
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char component_order[32]; /* eg. UYVY */
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int scanline_order; /* XvTopToBottom, XvBottomToTop */
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} XvImageFormatValues;
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id - A unique descriptor for the format. This is often the FOURCC
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for the format, when applicable. This id is used to describe
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the format during XvImage creation.
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type - XvRGB or XvYUV.
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byte_order - The byte order of the image. It is either LSBFirst
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or MSBFirst.
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guid - The Globally Unique IDentifier (also known as Universally Unique
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IDentifier). When not applicable, all characters are NULL.
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bits_per_pixel - The bits taken up (but not necessarily used) by each
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pixel. Note that for some planar formats which have
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fractional bits per pixel (such as IF09) this number
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may be rounded _down_.
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format - XvPacked or XvPlanar.
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num_planes - The number of planes in planar formats.
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depth - Significant bits per pixel.
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red_mask, green_mask, blue_mask - The red, green and blue bitmasks
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(RGB formats only).
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?_sample_bits - The size of each sample in bits (YUV formats only).
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horz_?_period, vert_?_period - The period (in pixels) on which samples
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occur in the horizontal and vertical
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directions (YUV formats only).
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component_order - Upper case ascii characters representing the order
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that samples are stored within packed formats.
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For planar formats this represents the ordering of
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the planes.
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scanline_order - XvTopToBottom or XvBottomToTop.
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Note: Since some formats (particularly some planar YUV formats) may not
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be completely defined by the parameters above, the guid, when
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available, should provide the most accurate description of the
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format.
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XvImageFormatValues * XvListImageFormats (
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Display *display,
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XvPortID port_id,
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int *count_return
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);
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Returns the XvImageFormatValues supported by the specified port.
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This list should be freed with XFree().
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typedef struct {
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int id;
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int width, height;
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int data_size;
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int num_planes;
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int *pitches;
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int *offsets;
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char *data;
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XPointer obdata;
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} XvImage;
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id - XvImageFormatValues id.
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width, height - The width and height of the image in pixels.
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int data_size - The size of the data buffer in bytes.
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num_planes - The number of image planes.
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pitches - An array of size num_planes indicating the scanline pitch
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in bytes. Each plane may have a different pitch.
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offsets - An array of size num_planes indicating the byte offset
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from "data" to the start of each plane.
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data - A pointer to the start of the data buffer.
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obdata - A private field for holding SHM info. This field will be
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set up by the client libraries so the programmer will
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generally need not be concerned with this field.
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XvImage * XvCreateImage (
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Display *display,
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XvPortID port,
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int id,
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char *data,
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int width,
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int height
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);
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display - Specifies the connection to the Xserver.
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port - Specifies the port the XvImage will be used with.
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id - Specifies the format of the image to be created by
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the XvImageFormatValues id.
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data - Specifies the image data.
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width
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height - Specifies the desired width and height of the image.
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This function is similar to XCreateImage. The library will
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allocate the XvImage structure and fill out all fields except for
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"data". Width and height may be enlarged in some YUV formats.
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The size of the data buffer that needs to be allocated will be
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give in the "data_size" field in the XvImage. Image data is
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not allocated by this function. The client may pass a pointer
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to the preallocated memory as "data" or may allocate the memory
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and fill in the XvImage structure's data field after the
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"data_size" field has been filled out by the server. The XvImage
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structure may be freed by XFree();
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XvImage * XvShmCreateImage (
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Display *display,
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XvPortID port,
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int id,
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char* data,
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int width,
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int height,
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XShmSegmentInfo *shminfo
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);
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This function is similar to XShmCreateImage. The library will
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allocate the XvImage structure and fill out all fields except for
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"data". Width and height may be enlarged in some YUV formats.
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The size of the data buffer that needs to be allocated will be
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give in the "data_size" field in the XvImage. Image data is
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not allocated by this function. The client may pass a pointer
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to the preallocated memory as "data" or may allocate the memory
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and fill in the XvImage structure's data field after the
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"data_size" field has been filled out by the server. The XvImage
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structure may be freed by XFree();
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XvPutImage (
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Display *display,
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XvPortID id,
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Drawable d,
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GC gc,
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XvImage *image,
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int src_x,
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int src_y,
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unsigned int src_w,
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unsigned int src_h,
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int dest_x,
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int dest_y,
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unsigned int dest_w,
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unsigned int dest_h,
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);
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XvShmPutImage (
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Display *display,
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XvPortID id,
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Drawable d,
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GC gc,
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XvImage *image,
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int src_x,
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int src_y,
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unsigned int src_w,
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unsigned int src_h,
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int dest_x,
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int dest_y,
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unsigned int dest_w,
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unsigned int dest_h,
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Bool send_event
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);
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display - The connection to the X-Server.
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id - The port id of a port on an XvImage capable adaptor.
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d - The target drawable.
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gc - the graphics context specifying the clip mask to use, if any.
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image - A pointer to the XvImage to be displayed.
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src_? - The portion of the XvImage to be displayed.
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dest_? - The portion of the destination drawable to be filled by the image.
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send_event - Indicates whether or not an XShmCompletionEvent should be
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sent. If sent, the event's major_code and minor_code
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fields will indicate the Xv extension's major code and
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XvShmPutImage's minor code.
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Shared memory segments are attached/detached with XShmAttach/Detach.
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Some of the possible Errors:
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BadDrawable - The specified drawable does not exist.
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BadContext - The specified GC does not exist.
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BadMatch - Incompatible arguments such as a port that isn't capable
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of displaying XvImages.
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XvBadPort - The specified port does not exist.
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BadAlloc - The server was unable to allocate resources required
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to complete the operation.
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BadValue - Some numeric value falls outside the range of the
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values accepted by the request.
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BadShmSegCode - An invalid shared memory segment.
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