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Merged
rib merged 1 commit into from
Apr 2, 2026
+132 −56
Merged

Use new NativeWindow::lock() API in dummy_render() #7

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48 changes: 34 additions & 14 deletions agdk-cpal/src/lib.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,10 @@

use std::sync::OnceLock;

use android_activity::{AndroidApp, InputStatus, MainEvent, PollEvent};
use android_activity::{
ndk::{hardware_buffer_format::HardwareBufferFormat, native_window::NativeWindow},
AndroidApp, InputStatus, MainEvent, PollEvent,
};
use cpal::{
traits::{DeviceTrait, HostTrait, StreamTrait},
FromSample, Sample, SizedSample,
Expand Down Expand Up @@ -74,7 +77,7 @@ fn android_main(app: AndroidApp) {

let mut quit = false;
let mut redraw_pending = true;
let mut native_window: Option<ndk::native_window::NativeWindow> = None;
let mut native_window = None;

let host = cpal::default_host();

Expand Down Expand Up @@ -139,6 +142,16 @@ fn android_main(app: AndroidApp) {
}
MainEvent::InitWindow { .. } => {
native_window = app.native_window();
if let Some(nw) = &native_window {
// Set the backing buffer to a known format (without changing
// the size) so that we can safely draw to it in dummy_render().
nw.set_buffers_geometry(
0,
0,
Some(HardwareBufferFormat::R8G8B8A8_UNORM),
)
.unwrap()
}
redraw_pending = true;
}
MainEvent::TerminateWindow { .. } => {
Expand Down Expand Up @@ -192,17 +205,24 @@ fn android_main(app: AndroidApp) {
/// convince Android that we're drawing something and are
/// responsive, otherwise it will stop delivering input
/// events to us.
fn dummy_render(native_window: &ndk::native_window::NativeWindow) {
unsafe {
let mut buf: ndk_sys::ANativeWindow_Buffer = std::mem::zeroed();
let mut rect: ndk_sys::ARect = std::mem::zeroed();
ndk_sys::ANativeWindow_lock(
native_window.ptr().as_ptr() as _,
&mut buf as _,
&mut rect as _,
);
// Note: we don't try and touch the buffer since that
// also requires us to handle various buffer formats
ndk_sys::ANativeWindow_unlockAndPost(native_window.ptr().as_ptr() as _);
fn dummy_render(native_window: &NativeWindow) {
let mut lock = native_window.lock(None).unwrap();
let (w, h) = (lock.width(), lock.height());

assert_eq!(
lock.format(),
HardwareBufferFormat::R8G8B8A8_UNORM,
"Expected the buffer format to be R8G8B8A8_UNORM since we set that in `InitWindow` handling"
);

for (y, line) in lock.lines().unwrap().enumerate() {
let r = y * 255 / h;
for (x, pixels) in line.chunks_mut(4).enumerate() {
let g = x * 255 / w;
pixels[0].write(r as u8);
pixels[1].write(g as u8);
pixels[2].write(0);
pixels[3].write(255);
}
}
}
46 changes: 32 additions & 14 deletions agdk-mainloop/src/lib.rs
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,8 @@ use std::sync::OnceLock;

use android_activity::{
input::{InputEvent, KeyAction, KeyEvent, KeyMapChar, MotionAction},
ndk, ndk_sys, AndroidApp, InputStatus, MainEvent, OnCreateState, PollEvent,
ndk::{hardware_buffer_format::HardwareBufferFormat, native_window::NativeWindow},
AndroidApp, InputStatus, MainEvent, OnCreateState, PollEvent,
};
use jni::{
objects::{JObject, JString},
Expand Down Expand Up @@ -140,7 +141,7 @@ fn android_main(app: AndroidApp) {

let mut quit = false;
let mut redraw_pending = true;
let mut native_window: Option<ndk::native_window::NativeWindow> = None;
let mut native_window = None;

let mut combining_accent = None;

Expand Down Expand Up @@ -176,6 +177,16 @@ fn android_main(app: AndroidApp) {
}
MainEvent::InitWindow { .. } => {
native_window = app.native_window();
if let Some(nw) = &native_window {
// Set the backing buffer to a known format (without changing
// the size) so that we can safely draw to it in dummy_render().
nw.set_buffers_geometry(
0,
0,
Some(HardwareBufferFormat::R8G8B8A8_UNORM),
)
.unwrap()
}
redraw_pending = true;
}
MainEvent::TerminateWindow { .. } => {
Expand Down Expand Up @@ -401,17 +412,24 @@ fn character_map_and_combine_key(
/// convince Android that we're drawing something and are
/// responsive, otherwise it will stop delivering input
/// events to us.
fn dummy_render(native_window: &ndk::native_window::NativeWindow) {
unsafe {
let mut buf: ndk_sys::ANativeWindow_Buffer = std::mem::zeroed();
let mut rect: ndk_sys::ARect = std::mem::zeroed();
ndk_sys::ANativeWindow_lock(
native_window.ptr().as_ptr() as _,
&mut buf as _,
&mut rect as _,
);
// Note: we don't try and touch the buffer since that
// also requires us to handle various buffer formats
ndk_sys::ANativeWindow_unlockAndPost(native_window.ptr().as_ptr() as _);
fn dummy_render(native_window: &NativeWindow) {
let mut lock = native_window.lock(None).unwrap();
let (w, h) = (lock.width(), lock.height());

assert_eq!(
lock.format(),
HardwareBufferFormat::R8G8B8A8_UNORM,
"Expected the buffer format to be R8G8B8A8_UNORM since we set that in `InitWindow` handling"
);

for (y, line) in lock.lines().unwrap().enumerate() {
let r = y * 255 / h;
for (x, pixels) in line.chunks_mut(4).enumerate() {
let g = x * 255 / w;
pixels[0].write(r as u8);
pixels[1].write(g as u8);
pixels[2].write(0);
pixels[3].write(255);
}
}
}
46 changes: 32 additions & 14 deletions na-mainloop/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,8 @@ use std::sync::OnceLock;

use android_activity::{
input::{InputEvent, KeyAction, KeyEvent, KeyMapChar, MotionAction},
ndk, ndk_sys, AndroidApp, InputStatus, MainEvent, OnCreateState, PollEvent,
ndk::{hardware_buffer_format::HardwareBufferFormat, native_window::NativeWindow},
AndroidApp, InputStatus, MainEvent, OnCreateState, PollEvent,
};
use jni::{
objects::{JObject, JString},
Expand Down Expand Up @@ -140,7 +141,7 @@ fn android_main(app: AndroidApp) {

let mut quit = false;
let mut redraw_pending = true;
let mut native_window: Option<ndk::native_window::NativeWindow> = None;
let mut native_window = None;

let mut combining_accent = None;

Expand Down Expand Up @@ -176,6 +177,16 @@ fn android_main(app: AndroidApp) {
}
MainEvent::InitWindow { .. } => {
native_window = app.native_window();
if let Some(nw) = &native_window {
// Set the backing buffer to a known format (without changing
// the size) so that we can safely draw to it in dummy_render().
nw.set_buffers_geometry(
0,
0,
Some(HardwareBufferFormat::R8G8B8A8_UNORM),
)
.unwrap()
}
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@rib rib Jun 26, 2023

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It could be good to have a comment explaining what this is for.

This is intended to be a bare-bones example of how to use android-activity so it's quite likely someone looking at this isn't going to be familiar with what set_buffers_geometry does (and the name from the NDK isn't very self documenting when we're using it to set the format and not the 'geometry' as such).

Maybe we can just note that, since this example is going to clear the window from the CPU then we want to ensure the buffer is in a known format that we will be able to write to from dummy_render()

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@MarijnS95 MarijnS95 Jun 26, 2023

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Sure, still a draft as I wanted to share progress and show what's possible with the new bindings.

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@rib rib Jun 27, 2023

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Yep, I'd be happy to have a convenient way to at least show something other than a black screen, but without needing to pull in a full-blown graphics API.

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@MarijnS95 MarijnS95 Jun 27, 2023

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Cool cool, this already shows a gradient instead of a black screen, as a sign of life.

We can probably drop the draft status now, IIRC this is mostly ready.

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@rib rib Jun 27, 2023

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Yeah don't mind if it's taken out of draft and will just want to wait until it doesn't depend on [patches] before landing.

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@MarijnS95 MarijnS95 Jun 27, 2023

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Sure, expect that to take ±1month though. That should be enough time to see if there are any issues with this patch though, pretty helpful to test compatibility with the ecosystem meanwhile.

redraw_pending = true;
}
MainEvent::TerminateWindow { .. } => {
Expand Down Expand Up @@ -401,17 +412,24 @@ fn character_map_and_combine_key(
/// convince Android that we're drawing something and are
/// responsive, otherwise it will stop delivering input
/// events to us.
fn dummy_render(native_window: &ndk::native_window::NativeWindow) {
unsafe {
let mut buf: ndk_sys::ANativeWindow_Buffer = std::mem::zeroed();
let mut rect: ndk_sys::ARect = std::mem::zeroed();
ndk_sys::ANativeWindow_lock(
native_window.ptr().as_ptr() as _,
&mut buf as _,
&mut rect as _,
);
// Note: we don't try and touch the buffer since that
// also requires us to handle various buffer formats
ndk_sys::ANativeWindow_unlockAndPost(native_window.ptr().as_ptr() as _);
fn dummy_render(native_window: &NativeWindow) {
let mut lock = native_window.lock(None).unwrap();
let (w, h) = (lock.width(), lock.height());

assert_eq!(
lock.format(),
HardwareBufferFormat::R8G8B8A8_UNORM,
"Expected the buffer format to be R8G8B8A8_UNORM since we set that in `InitWindow` handling"
);

for (y, line) in lock.lines().unwrap().enumerate() {
let r = y * 255 / h;
for (x, pixels) in line.chunks_mut(4).enumerate() {
let g = x * 255 / w;
pixels[0].write(r as u8);
pixels[1].write(g as u8);
pixels[2].write(0);
pixels[3].write(255);
}
}
}
48 changes: 34 additions & 14 deletions na-subclass-jni/src/lib.rs
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,4 +1,7 @@
use android_activity::{AndroidApp, InputStatus, MainEvent, PollEvent};
use android_activity::{
ndk::{hardware_buffer_format::HardwareBufferFormat, native_window::NativeWindow},
AndroidApp, InputStatus, MainEvent, PollEvent,
};
use log::info;

#[unsafe(no_mangle)]
Expand All @@ -9,7 +12,7 @@ fn android_main(app: AndroidApp) {

let mut quit = false;
let mut redraw_pending = true;
let mut native_window: Option<ndk::native_window::NativeWindow> = None;
let mut native_window = None;

while !quit {
app.poll_events(
Expand Down Expand Up @@ -40,6 +43,16 @@ fn android_main(app: AndroidApp) {
}
MainEvent::InitWindow { .. } => {
native_window = app.native_window();
if let Some(nw) = &native_window {
// Set the backing buffer to a known format (without changing
// the size) so that we can safely draw to it in dummy_render().
nw.set_buffers_geometry(
0,
0,
Some(HardwareBufferFormat::R8G8B8A8_UNORM),
)
.unwrap()
}
redraw_pending = true;
}
MainEvent::TerminateWindow { .. } => {
Expand Down Expand Up @@ -100,18 +113,25 @@ fn android_main(app: AndroidApp) {
/// convince Android that we're drawing something and are
/// responsive, otherwise it will stop delivering input
/// events to us.
fn dummy_render(native_window: &ndk::native_window::NativeWindow) {
unsafe {
let mut buf: ndk_sys::ANativeWindow_Buffer = std::mem::zeroed();
let mut rect: ndk_sys::ARect = std::mem::zeroed();
ndk_sys::ANativeWindow_lock(
native_window.ptr().as_ptr() as _,
&mut buf as _,
&mut rect as _,
);
// Note: we don't try and touch the buffer since that
// also requires us to handle various buffer formats
ndk_sys::ANativeWindow_unlockAndPost(native_window.ptr().as_ptr() as _);
fn dummy_render(native_window: &NativeWindow) {
let mut lock = native_window.lock(None).unwrap();
let (w, h) = (lock.width(), lock.height());

assert_eq!(
lock.format(),
HardwareBufferFormat::R8G8B8A8_UNORM,
"Expected the buffer format to be R8G8B8A8_UNORM since we set that in `InitWindow` handling"
);

for (y, line) in lock.lines().unwrap().enumerate() {
let r = y * 255 / h;
for (x, pixels) in line.chunks_mut(4).enumerate() {
let g = x * 255 / w;
pixels[0].write(r as u8);
pixels[1].write(g as u8);
pixels[2].write(0);
pixels[3].write(255);
}
}
}

Expand Down
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