Add links to AUR packages in README

The SDL mouse wheel event seems inconsistent between horizontal and
vertical scrolling.

> Movements to the left generate negative x values and to the right
> generate positive x values. Movements down (scroll backward) generate
> negative y values and up (scroll forward) generate positive y values.

<https://wiki.libsdl.org/SDL_MouseWheelEvent#Remarks>

Reverse the horizontal.

Fixes <https://github.com/Genymobile/scrcpy/issues/49>.

FAQ.md

@@ -0,0 +1,84 @@
+# Frequently Asked Questions
+
+## Common issues
+
+The application is very young, it is not unlikely that you encounter problems
+with it.
+
+Here are the common reported problems and their status.
+
+### On Windows, I have no output in the console
+
+When run in `cmd.exe`, the application does not print anything. Even `scrcpy
+--help` have no output. We don't know why yet.
+
+However, if you run the very same `scrcpy.exe` from
+[MSYS2](https://www.msys2.org/) (`mingw64`), then it correctly prints output.
+
+
+### On Windows, when I start the application, nothing happens
+
+The previous problem does not help to get a clue about the cause.
+
+The most common is your device not being detected by `adb`, or is unauthorized.
+Check everything is ok by calling:
+
+    adb devices
+
+Windows may need some [drivers] to detect your device.
+
+[drivers]: https://developer.android.com/studio/run/oem-usb.html
+
+If you still encounter problems, please see [issue 9].
+
+[issue 9]: https://github.com/Genymobile/scrcpy/issues/9
+
+
+### The application does not work over `adb connect`
+
+If the device is connected using `adb connect`, then you'll get this error:
+
+    error: more than one device/emulator
+    ERROR: "adb reverse" returned with value 1
+
+We plan to support it in future versions. See [issue 5].
+
+[issue 5]: https://github.com/Genymobile/scrcpy/issues/5
+
+
+### Mouse clicks do not work
+
+On many LG devices, [mouse clicks do not work][issue 18]. We're [working][pr27]
+on it.
+
+[issue 18]: https://github.com/Genymobile/scrcpy/issues/18
+[pr27]: https://github.com/Genymobile/scrcpy/pull/27
+
+
+### I get a black screen for some applications like Silence
+
+This is expected, they requested to protect the screen.
+
+In [Silence], you can disable it in settings → Privacy → Screen security.
+
+[silence]: https://f-droid.org/en/packages/org.smssecure.smssecure/
+
+See [issue 36].
+
+[issue 36]: https://github.com/Genymobile/scrcpy/issues/36
+
+
+### Mouse clicks at wrong location
+
+On MacOS, with HiDPI support and multiple screens, input location are wrongly
+scaled. See [issue 15].
+
+[issue 15]: https://github.com/Genymobile/scrcpy/issues/15
+
+A workaround is to build with HiDPI support disabled:
+
+```bash
+meson x --buildtype release -Dhidpi_support=false
+```
+
+However, the video will be displayed at lower resolution.

README.md

@@ -2,7 +2,7 @@
 
 This application provides display and control of Android devices connected on
 USB. It does not require any _root_ access. It works on _GNU/Linux_, _Windows_
-and _Mac OS_.
+and _MacOS_.
 
 ![screenshot](assets/screenshot-debian-600.jpg)
 
@@ -37,15 +37,44 @@ The client requires _FFmpeg_ and _LibSDL2_.
 
 #### Linux
 
-Install the required packages from your package manager (here, for Debian):
+Install the required packages from your package manager.
 
-    # runtime dependencies
-    sudo apt install ffmpeg libsdl2-2.0.0
+##### Debian/Ubuntu
 
-    # build dependencies
-    sudo apt install make gcc openjdk-8-jdk pkg-config meson zip \
-                     libavcodec-dev libavformat-dev libavutil-dev \
-                     libsdl2-dev
+```bash
+# runtime dependencies
+sudo apt install ffmpeg libsdl2-2.0.0
+
+# client build dependencies
+sudo apt install make gcc pkg-config meson \
+                 libavcodec-dev libavformat-dev libavutil-dev \
+                 libsdl2-dev
+
+# server build dependencies
+sudo apt install openjdk-8-jdk
+```
+
+##### Fedora
+
+```bash
+# enable RPM fusion free
+sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm
+
+# client build dependencies
+sudo dnf install SDL2-devel ffms2-devel meson gcc make
+
+# server build dependencies
+sudo dnf install java
+```
+
+##### Arch Linux
+
+Two [AUR] packages have been created by users:
+
+ - [`scrcpy`](https://aur.archlinux.org/packages/scrcpy/)
+ - [`scrcpy-prebuiltserver`](https://aur.archlinux.org/packages/scrcpy-prebuiltserver/)
+
+[AUR]: https://wiki.archlinux.org/index.php/Arch_User_Repository
 
 
 #### Windows
@@ -65,22 +94,24 @@ project. From an MSYS2 terminal, install the required packages:
 
 [MSYS2]: http://www.msys2.org/
 
-    # runtime dependencies
-    pacman -S mingw-w64-x86_64-SDL2 \
-              mingw-w64-x86_64-ffmpeg
+```bash
+# runtime dependencies
+pacman -S mingw-w64-x86_64-SDL2 \
+          mingw-w64-x86_64-ffmpeg
 
-    # build dependencies
-    pacman -S mingw-w64-x86_64-make \
-              mingw-w64-x86_64-gcc \
-              mingw-w64-x86_64-pkg-config \
-              mingw-w64-x86_64-meson \
-              zip
+# client build dependencies
+pacman -S mingw-w64-x86_64-make \
+          mingw-w64-x86_64-gcc \
+          mingw-w64-x86_64-pkg-config \
+          mingw-w64-x86_64-meson
+```
 
 Java (>= 7) is not available in MSYS2, so if you plan to build the server,
 install it manually and make it available from the `PATH`:
 
-    export PATH="$JAVA_HOME/bin:$PATH"
-
+```bash
+export PATH="$JAVA_HOME/bin:$PATH"
+```
 
 #### Mac OS
 
@@ -88,17 +119,20 @@ Use [Homebrew] to install the packages:
 
 [Homebrew]: https://brew.sh/
 
-    # runtime dependencies
-    brew install sdl2 ffmpeg
+```bash
+# runtime dependencies
+brew install sdl2 ffmpeg
 
-    # build dependencies
-    brew install gcc pkg-config meson zip
+# client build dependencies
+brew install gcc pkg-config meson
+```
 
 Java (>= 7) is not available in Homebrew, so if you plan to build the server,
 install it manually and make it available from the `PATH`:
 
-    export PATH="$JAVA_HOME/bin:$PATH"
-
+```bash
+export PATH="$JAVA_HOME/bin:$PATH"
+```
 
 ### Common steps
 
@@ -107,21 +141,29 @@ its directory. For example:
 
 [Android SDK]: https://developer.android.com/studio/index.html
 
-    export ANDROID_HOME=~/android/sdk
+```bash
+export ANDROID_HOME=~/android/sdk
+```
 
 Then, build `scrcpy`:
 
-    meson x --buildtype release --strip -Db_lto=true
-    cd x
-    ninja
+```bash
+meson x --buildtype release --strip -Db_lto=true
+cd x
+ninja
+```
 
 You can test it from here:
 
-    ninja run
+```bash
+ninja run
+```
 
 Or you can install it on the system:
 
-    sudo ninja install    # without sudo on Windows
+```bash
+sudo ninja install    # without sudo on Windows
+```
 
 This installs two files:
 
@@ -147,12 +189,13 @@ In that case, the build does not require Java or the Android SDK.
 Download the prebuilt server somewhere, and specify its path during the Meson
 configuration:
 
-    meson x --buildtype release --strip -Db_lto=true \
-        -Dprebuilt_server=/path/to/scrcpy-server.jar
-    cd x
-    ninja
-    sudo ninja install
-
+```bash
+meson x --buildtype release --strip -Db_lto=true \
+    -Dprebuilt_server=/path/to/scrcpy-server.jar
+cd x
+ninja
+sudo ninja install
+```
 
 ## Run
 
@@ -160,28 +203,40 @@ _At runtime, `adb` must be accessible from your `PATH`._
 
 If everything is ok, just plug an Android device, and execute:
 
-    scrcpy
+```bash
+scrcpy
+```
 
 It accepts command-line arguments, listed by:
 
-    scrcpy --help
+```bash
+scrcpy --help
+```
 
 For example, to decrease video bitrate to 2Mbps (default is 8Mbps):
 
-    scrcpy -b 2M
+```bash
+scrcpy -b 2M
+```
 
 To limit the video dimensions (e.g. if the device is 2540×1440, but the host
 screen is smaller, or cannot decode such a high definition):
 
-    scrcpy -m 1024
+```bash
+scrcpy -m 1024
+```
 
 If several devices are listed in `adb devices`, you must specify the _serial_:
 
-    scrcpy -s 0123456789abcdef
+```bash
+scrcpy -s 0123456789abcdef
+```
 
 To run without installing:
 
-    ./run x [options]
+```bash
+./run x [options]
+```
 
 (where `x` is your build directory).
 
@@ -214,6 +269,11 @@ A colleague challenged me to find a name as unpronounceable as [gnirehtet].
 [`strcpy`]: http://man7.org/linux/man-pages/man3/strcpy.3.html
 
 
+## Common issues
+
+See the [FAQ](FAQ.md).
+
+
 ## Developers
 
 Read the [developers page].

app/src/convert.c

@@ -172,7 +172,10 @@ SDL_bool mouse_wheel_from_sdl_to_android(const SDL_MouseWheelEvent *from,
     to->scroll_event.position = position;
 
     int mul = from->direction == SDL_MOUSEWHEEL_NORMAL ? 1 : -1;
-    to->scroll_event.hscroll = mul * from->x;
+    // SDL behavior seems inconsistent between horizontal and vertical scrolling
+    // so reverse the horizontal
+    // <https://wiki.libsdl.org/SDL_MouseWheelEvent#Remarks>
+    to->scroll_event.hscroll = -mul * from->x;
     to->scroll_event.vscroll = mul * from->y;
 
     return SDL_TRUE;