Drucegrove DragonFly User Manual 1.4
Page 30
‘
Element Canvas
’ Root Element
Layers
All dynamic ‘Sub Elements’ that are drawn by the DragonFly must be placed in an Element Canvas. When an
individual Sub Element needs to be redrawn, the whole canvas has to be redrawn, so it is advisable to split the layout
into multiple canvases where possible, for best performance on fast updating or animated elements.
Element Canvas backgrounds are “transparent” by default (although they can be given individual solid colour
backgrounds). The transparency only works for the
background
of a canvas, so if two canvases overlap, sub elements
will only be seen on the canvas that is in front.
Canvases are drawn by the PowerVR graphics hardware in the ARM Cortex processor using OpenGLES. This allows
for animated scrolling, fading and alpha blending effects.
‘Dynamic Ticker Text’ Root Element
The DragonFly can render a smooth horizontally scrolling ‘ticker’ text. The text can either be embedded into the DFX
file, or be configured from a remote source.
Dynamic Ticket Text backgrounds are a solid colour by default, or can be configured to be “transparent”. The
transparency only works for the
background
of the element, so if two ticker or canvas elements overlap, text or sub
elements will only be seen on the canvas that is in front.
The ticker is drawn by the PowerVR graphics hardware in the ARM Cortex processor using OpenGLES. It is
automatically redrawn asynchronously to all other screen elements. This allows for smooth scrolling, but restricts
the conditional capabilities of the element (ie, it cannot be dynamically moved around the screen based on
conditional events).
‘Video’ Root Element
The DragonFly is capable of supporting a single video element. This is rendered using the hardware DSP in the ARM
Cortex processor. It is automatically rendered asynchronously to all other screen elements. This allows for smooth
playback, but restricts the conditional capabilities of the element (ie, it cannot be dynamically moved around the
screen based on conditional events). Dynamic ‘Sub Elements’ cannot be drawn onto a video element. The video
element should be the same size or larger than the video source. The video element is not recommended for rotated
displays, as performance is poor for rotated H264 playback (rotated MPEG2 performance is not affected). The video
element should not be overlapped by any other root element.
For more information on using the Video element, refer to the
Video Element
section of this manual (page 35)
