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Create Class struct to simplify JNI calls
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@desttinghim @ikskuh
desttinghim authored and ikskuh committed Jan 10, 2023
1 parent d1a1108 commit 0ce0de7
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Showing 3 changed files with 132 additions and 127 deletions.
80 changes: 30 additions & 50 deletions examples/invocationhandler/main.zig
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Original file line number Diff line number Diff line change
Expand Up @@ -39,10 +39,9 @@ pub fn timerInvoke(data: ?*anyopaque, jni: *android.JNI, method: android.jobject

if (i == 0) {
const Button = try jni.findClass("android/widget/Button");
const setText = try jni.invokeJni(.GetMethodID, .{ Button, "setText", "(Ljava/lang/CharSequence;)V" });
var buf: [256:0]u8 = undefined;
const str = std.fmt.bufPrintZ(&buf, "Pressed {} times!", .{btn_data.count}) catch "formatting bug";
try jni.invokeJni(.CallVoidMethod, .{ object, setText, try jni.newString(str) });
try Button.callVoidMethod(object, "setText", "(Ljava/lang/CharSequence;)V", .{try jni.newString(str)});
}
}

Expand Down Expand Up @@ -94,27 +93,17 @@ pub const AndroidApp = struct {
self.uiJni = native_activity;

// Get the window object attached to our activity
const activityClass = try jni.findClass("android/app/NativeActivity");
const getWindow = try jni.invokeJni(.GetMethodID, .{ activityClass, "getWindow", "()Landroid/view/Window;" });
const activityWindow = try jni.invokeJni(.CallObjectMethod, .{ self.activity.clazz, getWindow });
const WindowClass = try jni.findClass("android/view/Window");
const ActivityClass = try jni.findClass("android/app/NativeActivity");
const activityWindow = try ActivityClass.callObjectMethod(self.activity.clazz, "getWindow", "()Landroid/view/Window;", .{});

// This disables the surface handler set by default by android.view.NativeActivity
// This way we let the content view do the drawing instead of us.
const takeSurface = try jni.invokeJni(.GetMethodID, .{ WindowClass, "takeSurface", "(Landroid/view/SurfaceHolder$Callback2;)V" });
try jni.invokeJni(.CallVoidMethod, .{
activityWindow,
takeSurface,
@as(android.jobject, null),
});
const WindowClass = try jni.findClass("android/view/Window");
try WindowClass.callVoidMethod(activityWindow, "takeSurface", "(Landroid/view/SurfaceHolder$Callback2;)V", .{@as(android.jobject, null)});

// Do the same but with the input queue. This allows the content view to handle input.
const takeInputQueue = try jni.invokeJni(.GetMethodID, .{ WindowClass, "takeInputQueue", "(Landroid/view/InputQueue$Callback;)V" });
try jni.invokeJni(.CallVoidMethod, .{
activityWindow,
takeInputQueue,
@as(android.jobject, null),
});
try WindowClass.callVoidMethod(activityWindow, "takeInputQueue", "(Landroid/view/InputQueue$Callback;)V", .{@as(android.jobject, null)});

self.thread = try std.Thread.spawn(.{}, mainLoop, .{self});
}

Expand Down Expand Up @@ -188,33 +177,23 @@ pub const AndroidApp = struct {
const native_activity = android.NativeActivity.get(self.activity);
const jni = native_activity.jni;

// We create a new Button..
std.log.warn("Creating android.widget.Button", .{});
const Button = try jni.findClass("android/widget/Button");
// methods
const buttonInit = try jni.invokeJni(.GetMethodID, .{ Button, "<init>", "(Landroid/content/Context;)V" });
const setOnClickListener = try jni.invokeJni(.GetMethodID, .{ Button, "setOnClickListener", "(Landroid/view/View$OnClickListener;)V" });
const setText = try jni.invokeJni(.GetMethodID, .{ Button, "setText", "(Ljava/lang/CharSequence;)V" });
// invocations
// init
const button = try jni.invokeJni(.NewObject, .{ Button, buttonInit, self.activity.clazz });

// .. and set its text to "Hello from Zig!"
try jni.invokeJni(.CallVoidMethod, .{ button, setText, try jni.newString("Hello from Zig!") });
// set onclick callback

// We create a new Button..
const button = try Button.newObject("(Landroid/content/Context;)V", .{self.activity.clazz});

// .. set its text to "Hello from Zig!" ..
try Button.callVoidMethod(button, "setText", "(Ljava/lang/CharSequence;)V", .{try jni.newString("Hello from Zig!")});

// .. and set its callback
const listener = try self.getOnClickListener(jni);
std.log.info("Listener {any}", .{listener});
try jni.invokeJni(.CallVoidMethod, .{ button, setOnClickListener, listener });
try Button.callVoidMethod(button, "setOnClickListener", "(Landroid/view/View$OnClickListener;)V", .{listener});

// And then we use it as our content view!
std.log.err("Attempt to call NativeActivity.setContentView()", .{});
const activityClass = try jni.findClass("android/app/NativeActivity");
const setContentView = try jni.invokeJni(.GetMethodID, .{ activityClass, "setContentView", "(Landroid/view/View;)V" });
try jni.invokeJni(.CallVoidMethod, .{
self.activity.clazz,
setContentView,
button,
});
const NativeActivityClass = try jni.findClass("android/app/NativeActivity");
try NativeActivityClass.callVoidMethod(self.activity.clazz, "setContentView", "(Landroid/view/View;)V", .{button});
}

fn mainLoop(self: *AndroidApp) !void {
Expand All @@ -229,34 +208,35 @@ pub const AndroidApp = struct {

fn getOnClickListener(self: *AndroidApp, jni: *JNI) !android.jobject {
// Get class loader instance
const activityClass = try jni.findClass("android/app/NativeActivity");
const getClassLoader = try jni.invokeJni(.GetMethodID, .{ activityClass, "getClassLoader", "()Ljava/lang/ClassLoader;" });
const cls = try jni.invokeJni(.CallObjectMethod, .{ self.activity.clazz, getClassLoader });
const ActivityClass = try jni.findClass("android/app/NativeActivity");
const cls = try ActivityClass.callObjectMethod(self.activity.clazz, "getClassLoader", "()Ljava/lang/ClassLoader;", .{});

// Class loader class object
const ClassLoader = try jni.findClass("java/lang/ClassLoader");
const findClass = try jni.invokeJni(.GetMethodID, .{ ClassLoader, "loadClass", "(Ljava/lang/String;)Ljava/lang/Class;" });
const strClassName = try jni.newString("NativeInvocationHandler");
const class = try jni.invokeJni(.CallObjectMethod, .{ cls, findClass, strClassName });
jni.invokeJniNoException(.DeleteLocalRef, .{strClassName});
defer jni.invokeJniNoException(.DeleteLocalRef, .{strClassName});
const NativeInvocationHandlerClass = try ClassLoader.callObjectMethod(cls, "loadClass", "(Ljava/lang/String;)Ljava/lang/Class;", .{strClassName});

// Get invocation handler factory
self.invocation_handler = try NativeInvocationHandler.init(jni, class);
self.invocation_handler = try NativeInvocationHandler.init(jni, NativeInvocationHandlerClass);

// Create a NativeInvocationHandler
const invocation_handler = try self.invocation_handler.createAlloc(jni, self.allocator, &self.btn_data, &timerInvoke);

// Make an object array with 1 item, the android.view.View$OnClickListener interface class
const interface_array = try jni.invokeJni(.NewObjectArray, .{
1,
try jni.findClass("java/lang/Class"),
try jni.findClass("android/view/View$OnClickListener"),
try jni.invokeJni(.FindClass, .{"java/lang/Class"}),
try jni.invokeJni(.FindClass, .{"android/view/View$OnClickListener"}),
});

// Create a Proxy class implementing the OnClickListener interface
const Proxy = try jni.findClass("java/lang/reflect/Proxy");
const newProxyInstance = try jni.invokeJni(.GetStaticMethodID, .{ Proxy, "newProxyInstance", "(Ljava/lang/ClassLoader;[Ljava/lang/Class;Ljava/lang/reflect/InvocationHandler;)Ljava/lang/Object;" });
const proxy = try jni.invokeJni(.CallStaticObjectMethod, .{ Proxy, newProxyInstance, cls, interface_array, invocation_handler });
const proxy = Proxy.callStaticObjectMethod(
"newProxyInstance",
"(Ljava/lang/ClassLoader;[Ljava/lang/Class;Ljava/lang/reflect/InvocationHandler;)Ljava/lang/Object;",
.{ cls, interface_array, invocation_handler },
);

return proxy;
}
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