cairoImageSurfaceCreateForData: cairoImageSurfaceCreateForData

Description

Creates an image surface for the provided pixel data. The output buffer must be kept around until the CairoSurface is destroyed or cairoSurfaceFinish is called on the surface. The initial contents of data will be used as the initial image contents; you must explicitly clear the buffer, using, for example, cairoRectangle and cairoFill if you want it cleared.

Usage

cairoImageSurfaceCreateForData(data, format, width, height, stride)

Arguments

data

[char] a pointer to a buffer supplied by the application in which to write contents. This pointer must be suitably aligned for any kind of variable, (for example, a pointer returned by malloc).

format

[CairoFormat] the format of pixels in the buffer

width

[integer] the width of the image to be stored in the buffer

height

[integer] the height of the image to be stored in the buffer

stride

[integer] the number of bytes between the start of rows in the buffer as allocated. This value should always be computed by cairoFormatStrideForWidth before allocating the data buffer.

Value

CairoSurface] a pointer to the newly created surface. The caller owns the surface and should call cairoSurfaceDestroy when done with it. This function always returns a valid pointer, but it will return a pointer to a "nil" surface in the case of an error such as out of memory or an invalid stride value. In case of invalid stride value the error status of the returned surface will be CAIRO_STATUS_INVALID_STRIDE. You can use cairoSurfaceStatus to check for this. See cairoSurfaceSetUserData for a means of attaching a destroy-notification fallback to the surface if necessary.

Details

Note that the stride may be larger than width*bytes_per_pixel to provide proper alignment for each pixel and row. This alignment is required to allow high-performance rendering within cairo. The correct way to obtain a legal stride value is to call cairoFormatStrideForWidth with the desired format and maximum image width value, and the use the resulting stride value to allocate the data and to create the image surface. See cairoFormatStrideForWidth for example code.