refactor(scrcpy): small optimizations

libraries/scrcpy/src/control/hover-helper.ts

@@ -5,16 +5,21 @@ import {
 import { ScrcpyControlMessageType } from "./type.js";
 
 /**
- * On Android, touching the screen with a finger will disable mouse cursor.
+ * On both Android and Windows, while both mouse and touch are supported input devices,
- * However, Scrcpy doesn't do that, and can inject two pointers at the same time.
+ * only one of them can be active at a time. Touch the screen with a finger will deactivate mouse,
- * This can cause finger events to be "ignored" because mouse is still the primary pointer.
+ * and move the mouse will deactivate touch.
  *
- * This helper class injects an extra `ACTION_UP` event,
+ * On Android, this is achieved by dispatching a `MotionEvent.ACTION_UP` event for the previous input type.
+ * But on Chrome, there is no such event, causing both mouse and touch to be active at the same time.
+ * This can cause the new input to appear as "ignored".
+ *
+ * This helper class synthesis `ACTION_UP` events when a different pointer type appears,
  * so Scrcpy server can remove the previously hovering pointer.
  */
 export class ScrcpyHoverHelper {
     // AFAIK, only mouse and pen can have hover state
     // and you can't have two mouses or pens.
+    // So remember the last hovering pointer is enough.
     private lastHoverMessage: ScrcpyInjectTouchControlMessage | undefined;
 
     public process(

libraries/scrcpy/src/control/serializer.ts

@@ -40,7 +40,7 @@ export class ScrcpyControlMessageSerializer {
         this.scrollController = options.getScrollController();
     }
 
-    public getTypeValue(type: ScrcpyControlMessageType): number {
+    public getActualMessageType(type: ScrcpyControlMessageType): number {
         const value = this.types.indexOf(type);
         if (value === -1) {
             throw new Error("Not supported");
@@ -48,14 +48,24 @@ export class ScrcpyControlMessageSerializer {
         return value;
     }
 
+    public addMessageType<T extends { type: ScrcpyControlMessageType }>(
+        message: Omit<T, "type">,
+        type: T["type"]
+    ): T {
+        (message as T).type = this.getActualMessageType(type);
+        return message as T;
+    }
+
     public injectKeyCode(
         message: Omit<ScrcpyInjectKeyCodeControlMessage, "type">
     ) {
         return this.writer.write(
-            ScrcpyInjectKeyCodeControlMessage.serialize({
+            ScrcpyInjectKeyCodeControlMessage.serialize(
-                ...message,
+                this.addMessageType(
-                type: this.getTypeValue(ScrcpyControlMessageType.InjectKeyCode),
+                    message,
-            })
+                    ScrcpyControlMessageType.InjectKeyCode
+                )
+            )
         );
     }
 
@@ -63,7 +73,9 @@ export class ScrcpyControlMessageSerializer {
         return this.writer.write(
             ScrcpyInjectTextControlMessage.serialize({
                 text,
-                type: this.getTypeValue(ScrcpyControlMessageType.InjectText),
+                type: this.getActualMessageType(
+                    ScrcpyControlMessageType.InjectText
+                ),
             })
         );
     }
@@ -73,10 +85,12 @@ export class ScrcpyControlMessageSerializer {
      */
     public injectTouch(message: Omit<ScrcpyInjectTouchControlMessage, "type">) {
         return this.writer.write(
-            ScrcpyInjectTouchControlMessage.serialize({
+            ScrcpyInjectTouchControlMessage.serialize(
-                ...message,
+                this.addMessageType(
-                type: this.getTypeValue(ScrcpyControlMessageType.InjectTouch),
+                    message,
-            })
+                    ScrcpyControlMessageType.InjectTouch
+                )
+            )
         );
     }
 
@@ -86,13 +100,10 @@ export class ScrcpyControlMessageSerializer {
     public injectScroll(
         message: Omit<ScrcpyInjectScrollControlMessage, "type">
     ) {
-        (message as ScrcpyInjectScrollControlMessage).type = this.getTypeValue(
+        const data = this.scrollController.serializeScrollMessage(
-            ScrcpyControlMessageType.InjectScroll
+            this.addMessageType(message, ScrcpyControlMessageType.InjectScroll)
         );
 
-        const data = this.scrollController.serializeScrollMessage(
-            message as ScrcpyInjectScrollControlMessage
-        );
         if (!data) {
             return;
         }
@@ -103,7 +114,9 @@ export class ScrcpyControlMessageSerializer {
     public async backOrScreenOn(action: AndroidKeyEventAction) {
         const buffer = this.options.serializeBackOrScreenOnControlMessage({
             action,
-            type: this.getTypeValue(ScrcpyControlMessageType.BackOrScreenOn),
+            type: this.getActualMessageType(
+                ScrcpyControlMessageType.BackOrScreenOn
+            ),
         });
 
         if (buffer) {
@@ -115,7 +128,7 @@ export class ScrcpyControlMessageSerializer {
         return this.writer.write(
             ScrcpySetScreenPowerModeControlMessage.serialize({
                 mode,
-                type: this.getTypeValue(
+                type: this.getActualMessageType(
                     ScrcpyControlMessageType.SetScreenPowerMode
                 ),
             })
@@ -125,7 +138,9 @@ export class ScrcpyControlMessageSerializer {
     public rotateDevice() {
         return this.writer.write(
             ScrcpyRotateDeviceControlMessage.serialize({
-                type: this.getTypeValue(ScrcpyControlMessageType.RotateDevice),
+                type: this.getActualMessageType(
+                    ScrcpyControlMessageType.RotateDevice
+                ),
             })
         );
     }

libraries/scrcpy/src/options/1_16/h264-configuration.ts

@@ -55,8 +55,8 @@ class BitReader {
  * Split NAL units from a H.264 Annex B stream.
  *
  * The input is not modified.
- * The returned NAL units are views of the input (no memory allocation and copy),
+ * The returned NAL units are views of the input (no memory allocation nor copy),
- * but still contains emulation prevention bytes.
+ * and still contains emulation prevention bytes.
  *
  * This methods returns a generator, so it can be stopped immediately
  * after the interested NAL unit is found.
@@ -160,13 +160,66 @@ export function removeH264Emulation(buffer: Uint8Array) {
     let zeroCount = 0;
     let inEmulation = false;
 
-    for (let i = 0; i < buffer.length; i += 1) {
+    let i = 0;
+    scan: for (; i < buffer.length; i += 1) {
+        const byte = buffer[i]!;
+
+        if (byte === 0x00) {
+            zeroCount += 1;
+            continue;
+        }
+
+        // Current byte is not zero
+        const prevZeroCount = zeroCount;
+        zeroCount = 0;
+
+        if (prevZeroCount < 2) {
+            // zero or one `0x00`s are acceptable
+            continue;
+        }
+
+        if (byte === 0x01) {
+            // Unexpected start code
+            throw new Error("Invalid data");
+        }
+
+        if (prevZeroCount > 2) {
+            // Too much `0x00`s
+            throw new Error("Invalid data");
+        }
+
+        switch (byte) {
+            case 0x02:
+                // Didn't find why, but 7.4.1 NAL unit semantics forbids `0x000002` appearing in NAL units
+                throw new Error("Invalid data");
+            case 0x03:
+                // `0x000003` is the "emulation_prevention_three_byte"
+                // `0x00000300`, `0x00000301`, `0x00000302` and `0x00000303` represent
+                // `0x000000`, `0x000001`, `0x000002` and `0x000003` respectively
+                inEmulation = true;
+
+                // Create output and copy the data before the emulation prevention byte
+                // Output size is unknown, so we use the input size as an upper bound
+                output = new Uint8Array(buffer.length - 1);
+                output.set(buffer.subarray(0, i - prevZeroCount));
+                outputOffset = i - prevZeroCount + 1;
+                break scan;
+            default:
+                // `0x000004` or larger are as-is
+                break;
+        }
+    }
+
+    if (!output) {
+        return buffer;
+    }
+
+    // Continue at the byte after the emulation prevention byte
+    for (; i < buffer.length; i += 1) {
         const byte = buffer[i]!;
 
-        if (output) {
         output[outputOffset] = byte;
         outputOffset += 1;
-        }
 
         if (inEmulation) {
             if (byte > 0x03) {
@@ -211,15 +264,8 @@ export function removeH264Emulation(buffer: Uint8Array) {
                 // `0x000000`, `0x000001`, `0x000002` and `0x000003` respectively
                 inEmulation = true;
 
-                if (!output) {
-                    // Create output and copy the data before the emulation prevention byte
-                    output = new Uint8Array(buffer.length - 1);
-                    output.set(buffer.subarray(0, i - prevZeroCount));
-                    outputOffset = i - prevZeroCount + 1;
-                } else {
                 // Remove the emulation prevention byte
                 outputOffset -= 1;
-                }
                 break;
             default:
                 // `0x000004` or larger are as-is
@@ -227,7 +273,7 @@ export function removeH264Emulation(buffer: Uint8Array) {
         }
     }
 
-    return output?.subarray(0, outputOffset) ?? buffer;
+    return output.subarray(0, outputOffset);
 }
 
 // 7.3.2.1.1 Sequence parameter set data syntax

libraries/scrcpy/src/options/1_16/scroll.spec.ts

@@ -0,0 +1,90 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { ScrcpyControlMessageType } from "../../control/index.js";
+
+import { ScrcpyScrollController1_16 } from "./scroll.js";
+
+describe("ScrcpyScrollController1_16", () => {
+    it("should return undefined when scroll distance is less than 1", () => {
+        const controller = new ScrcpyScrollController1_16();
+        const message = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 0.5,
+            scrollY: 0.5,
+            buttons: 0,
+        });
+        expect(message).toBeUndefined();
+    });
+
+    it("should return a message when scroll distance is greater than 1", () => {
+        const controller = new ScrcpyScrollController1_16();
+        const message = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 1.5,
+            scrollY: 1.5,
+            buttons: 0,
+        });
+        expect(message).toBeInstanceOf(Uint8Array);
+        expect(message).toHaveProperty("byteLength", 21);
+    });
+
+    it("should return a message when accumulated scroll distance is greater than 1", () => {
+        const controller = new ScrcpyScrollController1_16();
+        controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 0.5,
+            scrollY: 0.5,
+            buttons: 0,
+        });
+        const message = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 0.5,
+            scrollY: 0.5,
+            buttons: 0,
+        });
+        expect(message).toBeInstanceOf(Uint8Array);
+        expect(message).toHaveProperty("byteLength", 21);
+    });
+
+    it("should return a message when accumulated scroll distance is less than -1", () => {
+        const controller = new ScrcpyScrollController1_16();
+        controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: -0.5,
+            scrollY: -0.5,
+            buttons: 0,
+        });
+        const message = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: -0.5,
+            scrollY: -0.5,
+            buttons: 0,
+        });
+        expect(message).toBeInstanceOf(Uint8Array);
+        expect(message).toHaveProperty("byteLength", 21);
+    });
+});

libraries/scrcpy/src/options/1_22/options.spec.ts

@@ -0,0 +1,13 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { ScrcpyOptions1_21 } from "../1_21.js";
+
+import { ScrcpyOptions1_22 } from "./options.js";
+
+describe("ScrcpyOptions1_22", () => {
+    it("should return a different scroll controller", () => {
+        const controller1_21 = new ScrcpyOptions1_21({}).getScrollController();
+        const controller1_22 = new ScrcpyOptions1_22({}).getScrollController();
+        expect(controller1_22).not.toBe(controller1_21);
+    });
+});

libraries/scrcpy/src/options/1_22/scroll.spec.ts

@@ -0,0 +1,23 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { ScrcpyControlMessageType } from "../../control/index.js";
+
+import { ScrcpyScrollController1_22 } from "./scroll.js";
+
+describe("ScrcpyScrollController1_22", () => {
+    it("should return correct message length", () => {
+        const controller = new ScrcpyScrollController1_22();
+        const message = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 1.5,
+            scrollY: 1.5,
+            buttons: 0,
+        });
+        expect(message).toBeInstanceOf(Uint8Array);
+        expect(message).toHaveProperty("byteLength", 25);
+    });
+});

libraries/scrcpy/src/options/1_25/options.spec.ts

@@ -0,0 +1,13 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { ScrcpyOptions1_24 } from "../1_24.js";
+
+import { ScrcpyOptions1_25 } from "./options.js";
+
+describe("ScrcpyOptions1_25", () => {
+    it("should return a different scroll controller", () => {
+        const controller1_24 = new ScrcpyOptions1_24({}).getScrollController();
+        const controller1_25 = new ScrcpyOptions1_25({}).getScrollController();
+        expect(controller1_25).not.toBe(controller1_24);
+    });
+});

libraries/scrcpy/src/options/1_25/scroll.spec.ts

@@ -0,0 +1,76 @@
+import { describe, expect, it } from "@jest/globals";
+
+import { ScrcpyControlMessageType } from "../../control/index.js";
+
+import {
+    ScrcpyFloatToInt16NumberType,
+    ScrcpyScrollController1_25,
+} from "./scroll.js";
+
+describe("ScrcpyFloatToInt16NumberType", () => {
+    it("should serialize", () => {
+        const dataView = new DataView(new ArrayBuffer(2));
+        ScrcpyFloatToInt16NumberType.serialize(dataView, 0, -1, true);
+        expect(dataView.getInt16(0, true)).toBe(-0x8000);
+
+        ScrcpyFloatToInt16NumberType.serialize(dataView, 0, 0, true);
+        expect(dataView.getInt16(0, true)).toBe(0);
+
+        ScrcpyFloatToInt16NumberType.serialize(dataView, 0, 1, true);
+        expect(dataView.getInt16(0, true)).toBe(0x7fff);
+    });
+
+    it("should clamp input values", () => {
+        const dataView = new DataView(new ArrayBuffer(2));
+        ScrcpyFloatToInt16NumberType.serialize(dataView, 0, -2, true);
+        expect(dataView.getInt16(0, true)).toBe(-0x8000);
+
+        ScrcpyFloatToInt16NumberType.serialize(dataView, 0, 2, true);
+        expect(dataView.getInt16(0, true)).toBe(0x7fff);
+    });
+
+    it("should deserialize", () => {
+        const dataView = new DataView(new ArrayBuffer(2));
+        const view = new Uint8Array(dataView.buffer);
+
+        dataView.setInt16(0, -0x8000, true);
+        expect(ScrcpyFloatToInt16NumberType.deserialize(view, true)).toBe(-1);
+
+        dataView.setInt16(0, 0, true);
+        expect(ScrcpyFloatToInt16NumberType.deserialize(view, true)).toBe(0);
+
+        dataView.setInt16(0, 0x7fff, true);
+        expect(ScrcpyFloatToInt16NumberType.deserialize(view, true)).toBe(1);
+    });
+});
+
+describe("ScrcpyScrollController1_25", () => {
+    it("should return a message for each scroll event", () => {
+        const controller = new ScrcpyScrollController1_25();
+        const message1 = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 0.5,
+            scrollY: 0.5,
+            buttons: 0,
+        });
+        expect(message1).toBeInstanceOf(Uint8Array);
+        expect(message1).toHaveProperty("byteLength", 21);
+
+        const message2 = controller.serializeScrollMessage({
+            type: ScrcpyControlMessageType.InjectScroll,
+            pointerX: 0,
+            pointerY: 0,
+            screenWidth: 0,
+            screenHeight: 0,
+            scrollX: 1.5,
+            scrollY: 1.5,
+            buttons: 0,
+        });
+        expect(message2).toBeInstanceOf(Uint8Array);
+        expect(message2).toHaveProperty("byteLength", 21);
+    });
+});

libraries/scrcpy/src/options/1_25/scroll.ts

@@ -10,17 +10,18 @@ import {
 } from "../../control/index.js";
 import { type ScrcpyScrollController } from "../1_16/index.js";
 
-const Int16Max = (1 << 15) - 1;
+export const ScrcpyFloatToInt16NumberType: NumberFieldType = {
-
-const ScrcpyFloatToInt16NumberType: NumberFieldType = {
     size: 2,
     signed: true,
     deserialize(array, littleEndian) {
         const value = NumberFieldType.Int16.deserialize(array, littleEndian);
-        return value / Int16Max;
+        // https://github.com/Genymobile/scrcpy/blob/1f138aef41de651668043b32c4effc2d4adbfc44/server/src/main/java/com/genymobile/scrcpy/Binary.java#L34
+        return value === 0x7fff ? 1 : value / 0x8000;
     },
     serialize(dataView, offset, value, littleEndian) {
-        value = clamp(value, -1, 1) * Int16Max;
+        // https://github.com/Genymobile/scrcpy/blob/1f138aef41de651668043b32c4effc2d4adbfc44/app/src/util/binary.h#L65
+        value = clamp(value, -1, 1);
+        value = value === 1 ? 0x7fff : value * 0x8000;
         NumberFieldType.Int16.serialize(dataView, offset, value, littleEndian);
     },
 };

libraries/struct/src/types/number.spec.ts

@@ -14,7 +14,7 @@ function testEndian(
     max: number,
     littleEndian: boolean
 ) {
-    test("min", () => {
+    test(`min = ${min}`, () => {
         const buffer = new ArrayBuffer(type.size);
         const view = new DataView(buffer);
         (
@@ -43,7 +43,7 @@ function testEndian(
         expect(output).toBe(input);
     });
 
-    test("max", () => {
+    test(`max = ${max}`, () => {
         const buffer = new ArrayBuffer(type.size);
         const view = new DataView(buffer);
         (
@@ -61,41 +61,30 @@ function testEndian(
 function testDeserialize(type: NumberFieldType) {
     if (type.size === 1) {
         if (type.signed) {
-            testEndian(
+            const MIN = -(2 ** (type.size * 8 - 1));
-                type,
+            const MAX = -MIN - 1;
-                2 ** (type.size * 8) / -2,
+            testEndian(type, MIN, MAX, false);
-                2 ** (type.size * 8) / 2 - 1,
-                false
-            );
         } else {
-            testEndian(type, 0, 2 ** (type.size * 8) - 1, false);
+            const MAX = 2 ** (type.size * 8) - 1;
+            testEndian(type, 0, MAX, false);
         }
     } else {
         if (type.signed) {
+            const MIN = -(2 ** (type.size * 8 - 1));
+            const MAX = -MIN - 1;
             describe("big endian", () => {
-                testEndian(
+                testEndian(type, MIN, MAX, false);
-                    type,
-                    2 ** (type.size * 8) / -2,
-                    2 ** (type.size * 8) / 2 - 1,
-                    false
-                );
             });
-
             describe("little endian", () => {
-                testEndian(
+                testEndian(type, MIN, MAX, true);
-                    type,
-                    2 ** (type.size * 8) / -2,
-                    2 ** (type.size * 8) / 2 - 1,
-                    true
-                );
             });
         } else {
+            const MAX = 2 ** (type.size * 8) - 1;
             describe("big endian", () => {
-                testEndian(type, 0, 2 ** (type.size * 8) - 1, false);
+                testEndian(type, 0, MAX, false);
             });
-
             describe("little endian", () => {
-                testEndian(type, 0, 2 ** (type.size * 8) - 1, true);
+                testEndian(type, 0, MAX, true);
             });
         }
     }

libraries/struct/src/utils.ts

@@ -55,15 +55,32 @@ export function placeholder<T>(): T {
 
 // This library can't use `@types/node` or `lib: dom`
 // because they will pollute the global scope
-// So `TextEncoder` and `TextDecoder` are not available
+// So `TextEncoder` and `TextDecoder` types are not available
 
 // Node.js 8.3 ships `TextEncoder` and `TextDecoder` in `util` module.
 // But using top level await to load them requires Node.js 14.1.
 // So there is no point to do that. Let's just assume they exist in global.
 
-// @ts-expect-error See reason above
+declare class TextEncoderType {
+    constructor();
+
+    encode(input: string): Uint8Array;
+}
+
+declare class TextDecoderType {
+    constructor();
+
+    decode(buffer: ArrayBufferView | ArrayBuffer): string;
+}
+
+interface GlobalExtension {
+    TextEncoder: typeof TextEncoderType;
+    TextDecoder: typeof TextDecoderType;
+}
+
+const { TextEncoder, TextDecoder } = globalThis as unknown as GlobalExtension;
+
 const Utf8Encoder = new TextEncoder();
-// @ts-expect-error See reason above
 const Utf8Decoder = new TextDecoder();
 
 export function encodeUtf8(input: string): Uint8Array {