/**
* Warms up the electron beam in preparation for turning on or off. This method prepares a GL
* context, and captures a screen shot.
*
* @param mode The desired mode for the upcoming animation.
* @return True if the electron beam is ready, false if it is uncontrollable.
*/
public boolean prepare(int mode) {
if (DEBUG) {
Slog.d(TAG, "prepare: mode=" + mode);
}
mMode = mode;
// Get the display size and layer stack.
// This is not expected to change while the electron beam surface is showing.
DisplayInfo displayInfo = mDisplayManager.getDisplayInfo(Display.DEFAULT_DISPLAY);
mDisplayLayerStack = displayInfo.layerStack;
if (mSwapNeeded) {
mDisplayWidth = displayInfo.getNaturalHeight();
mDisplayHeight = displayInfo.getNaturalWidth();
} else {
mDisplayWidth = displayInfo.getNaturalWidth();
mDisplayHeight = displayInfo.getNaturalHeight();
}
// Prepare the surface for drawing.
if (!tryPrepare()) {
dismiss();
return false;
}
// Done.
mPrepared = true;
// Dejanking optimization.
// Some GL drivers can introduce a lot of lag in the first few frames as they
// initialize their state and allocate graphics buffers for rendering.
// Work around this problem by rendering the first frame of the animation a few
// times. The rest of the animation should run smoothly thereafter.
// The frames we draw here aren't visible because we are essentially just
// painting the screenshot as-is.
if (mode == MODE_COOL_DOWN) {
for (int i = 0; i < DEJANK_FRAMES; i++) {
draw(1.0f);
}
}
return true;
}
