The Gradient module contains the C part of the MicroVG implementation, which manages linear gradients. This module is composed of only one element: an implementation of the Low-Level APIs to create gradient elements compatible with the hardware.
The Gradient module implements the framework of the MicroVG LinearGradient. It provides Low-Level APIs that consist in creating a linear gradient in a platform-specific format. After the gradient creation and encoding, the gradient data should not change when the application draws it: the encoded format should be used by the platform-specific implementation (generally GPU).
A linear gradient is a succession of colors at different positions. The colors from the MicroVG library implementation are encoded in the 32-bit format: ARGB8888. The color encoding in the gradient is a platform-specific implementation.
The buffer where the gradient is encoded is stored in the Java heap. The MicroVG implementation on demand automatically increases the buffer size.
The low-level APIs that have to be implemented are listed in the header file
LLVG_GRADIENT_impl.h (see LLVG_GRADIENT: Vector Linear Gradient):
- MicroVG library calls the BSP functions through the header files
- The C module MicroVG provides a default implementation of
LLVG_GRADIENT_impl.h: it manages the gradient buffer creation and filling, then redirect the gradient encoding to
- The C module MicroVG-VGLte provides an implementation of
microvg_gradient.h: it encodes the gradient and implements the drawings over the Vivante VGLite library and Freetype.
- These files are automatically copied in the BSP project when fetching the C modules during the platform build.
The MicroVG Gradient APIs are available in the class