e3dca87f23
This adds optional display list support to lws_display, using DLOs (Display List Objects). DLOs for rectangle / rounded rectangle (with circle as the degenerate case), PNGs, JPEG and compressed, antialiased bitmapped fonts and text primitives are provided. Logical DLOs are instantiated on heap and listed into an lws_display_list owner, DLOs handle attributes like position, bounding box, colour + opacity, and local error diffusion backing buffer. When the display list is complete, it can be rasterized a line at a time, with scoped error diffusion resolved, such that no allocation for the framebuffer is required at any point. DLOs are freed as the rasterization moves beyond their bounding box. Adds a platform registry binding names and other metadata to lws_display fonts / PNGs / JPEGs. Provides registration, destruction and best match selection apis. |
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| .. | ||
| ili9341-spi.c | ||
| lws-display.c | ||
| README.md | ||
| ssd1306-i2c.c | ||
lws_display
lws provides a generic "display" object that is independent of the connection to the display, i2c and spi implementations are provided.
Its purpose is to provide basic blit, backlight binding to lws_pwm, backlight / power management and display info like pixels wide and high in a generic way.
The generic display object lws_display_t can be included at the top of a
specific display implementation object, eg, binding it to additional members
to define the actual IO operations to be used, eg, i2c or spi.
When the display is instantiated, it allocates an additional structure on heap
that contains dynamic information about display state, lws_display_state_t.
Power state machine
lws_display objects have convenient power state management using a single lws sul event loop timer that is managed automatically.
| State | Meaning |
|---|---|
| OFF | The display is in sleep and not showing anything |
| BECOMING_ACTIVE | The display was asked to come out of sleep and is waiting for .latency_wake_ms befor proceeding to ACTIVE. The backlight if any is off. After the delay, the backlight is sequenced up to .bl_active using .bl_transition sequencer |
| ACTIVE | The backlight is ON and the dim timer is running |
| AUTODIMMED | The dim timer was not told the display was active for .autodim_ms, we are at .bl_dim brightness. After .off_ms we will transition to OFF |
The lws_pwm sequencers are used to provide customizable, smooth transitions for the backlight, which may be nonlinear.
Active notification
Calling lws_display_state_active(&lds) on eg, user interaction causes the
display state to transition to ACTIVE smoothly, taking care of waking the display
and waiting out a display-specific wake period, and sequencing the backlight
transition to active level as specified in the display structure.