When the counter hits e.g. 200, spam the user with notifications.
if fooOK
if barOK {
if bazOK {
// do something
}
}
}
guard fooOK else { return }
guard barOK else { return }
guard bazOK else { return }
// do something
The more important use case for guard is that 'guard let' statements can pattern-match and introduce bindings that are valid for the rest of the scope:
guard let foo = someOptional else { return }
print(foo);
With the disclaimer that I have zero knowledge of the MacBook Neo hardware, but I do know a bit about GPUs in general (including having written some GPU-accelerated drivers for Windows and the associated cursor-handling code), I'm going to make a wild guess: this lag is caused by waiting for the GPU command queue to flush.
As a bit of background information: the GPU is fed commands from a queue that the CPU writes to. These commands perform the drawing operations that the GPU is designed to accelerate. A hardware cursor is basically a small bitmap that can be positioned anywhere on the screen and moved around by simply updating position registers (which is normally done per mouse interrupt); the hardware draws it automatically. A software cursor is manually drawn by the graphics stack, which saves what was under it, draws the cursor, and then whenever it needs to be moved, writes the original data back, saves the data at the new position, and then draws the cursor there.
Flushing the command queue is necessary when switching to a software cursor, or otherwise doing software writes to the framebuffer, because you need to wait for the GPU to finish drawing what it has queued, or it may end up drawing over what software wants to draw, including the cursor. Or worse, the command is a blit (e.g. scrolling a window) and you end up with remnants of the cursor at its previous position.
If a hardware layer is not being used the cursor layer will be treated like any other layer in the compositor. Modern compositors don't try and save and write pixels like that. It will just rerender it.
>(which is normally done per mouse interrupt);
It's normally done every frame the compositor makes.
>or it may end up drawing over what software wants to draw
The compositor composites everything at that will be shown on the next refresh of the display. Things don't indepently step on each others toes since it's just the compositor rendering and synchronizing all hardware layers (planes).
the cursor could just be another small rectangle texture you position on top of the other surfaces. there is no need to read the framebuffer/write into it, its just a z-stack of 3d surfaces now
m132•2h ago
InsideOutSanta•1h ago
We showed [Gates] how the Macintosh mouse cursor moved smoothly, in a flicker-free fashion.
"What kind of hardware do you use to draw the cursor?", he asked. Many current personal computers had special hardware to draw small bitmaps called "sprites", and he thought we might be doing something similar.
Stitch4223•14m ago
The audacity of developers to restart the discussion whether the mouse should follow user input induces rage on so many levels.