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PineTime InfiniTime Watch Face Simulator with LVGL ported to WebAssembly

Custom PineTime Watch Face created in C++ by SravanSenthiln1: PineTime Watch Face Simulator vs Real PineTime

Custom PineTime Watch Face created in C++ by SravanSenthiln1: PineTime Watch Face Simulator vs Real PineTime

For Rust on Mynewt Watch Faces, see the mynewt branch

For Rust on RIOT Watch Faces, see the rust branch

Simulate PineTime Watch Face in Web Browser (with WebAssembly), for easier development of custom watch faces

Read the article...

Features

  1. Compiles actual PineTime Watch Face from C++ to WebAssembly: Clock.cpp was converted to WebAssembly clock

  2. Auto Convert any PineTime Watch Face from C++ to WebAssembly with sed and GitHub Actions / GitLab CD. Custom Watch Face Demo / Source Code

  3. Uses GitHub Actions Workflow to build any fork of InfiniTime Watch Face into WebAssembly

  4. Renders LVGL to HTML Canvas directly via WebAssembly, without using SDL2. See lvgl.html

  5. Includes PineTime Fonts and Symbols from LittleVgl.cpp

  6. Supports RGB565 Framebuffer Format used by PineTime Display Controller, so that bitmaps will be rendered correctly. Custom Bitmap Demo / Source Code

  7. Shows current date and time

How to Build and Preview a PineTime Watch Face with GitHub or GitLab

  1. We fork the PineTime InfiniTime Firmware repo in GitHub (or GitLab): github.com/JF002/Pinetime

  2. Enable GitHub Pages (or GitLab Pages) publishing for master branch, docs folder

  3. Add the GitHub Actions Workflow (or GitLab CD): .github/workflows/simulate.yml

  4. Enable the workflow

  5. We edit DisplayApp/Screens/Clock.cpp in the web browser via GitHub (or GitLab Web IDE)

  6. Which triggers a PineTime Firmware Build in GitHub Actions (or GitLab CD), assuming .github/workflows/main.yml has been installed

  7. Which also builds the PineTime Watch Face Simulator in WebAssembly

  8. And then pushes the generated WebAssembly files to GitHub Pages (or GitLab Pages)

  9. We preview the PineTime Watch Face through the Simulator in a web browser: https://YOUR_ACCOUNT.github.io/Pinetime (See Online Demo)

  10. If we are happy with the Watch Face, we flash the built firmware to PineTime over Bluetooth. See "Test Our PineTime Fimware"

Upcoming Features

  1. Accept Touch Input for LVGL

  2. Convert Clock.cpp from C++ to Rust with lvgl-rs

    Check out the rust branch of lvgl-asm

  3. Allow PineTime Watch Faces to be built online in Rust with online preview

References

How To Build The Simulator

To build PineTime Watch Face Simulator on Linux x64 or Arm64...

  1. Install emscripten and wabt. See instructions below.

  2. Enter...

    git clone https://github.com/AppKaki/lvgl-wasm
cd lvgl-wasm

  3. For Arm64 Only (Raspberry Pi 64, Pinebook Pro):

    We need to prevent make from running parallel builds, because the machine will freeze due to high I/O.

    Edit wasm/lvgl.sh(wasm/lvgl.sh) and change...

    make -j

    To...

    make

  4. Copy DisplayApp/Screens/Clock.cpp from our fork of the InfiniTime repo to clock/Clock.cpp...

    # Assume that our fork of InfiniTime is at ~/Pinetime
cp ~/Pinetime/src/DisplayApp/Screens/Clock.cpp clock/Clock.cpp

    This is the Watch Face that will be built into the Simulator.

  5. Build the LVGL WebAssembly app containing our Watch Face...

    # Build LVGL app: wasm/lvgl.html, lvgl.js, lvgl.wasm
wasm/lvgl.sh

    We should see...

    ...
clock/ClockTmp.cpp:172:32: warning: format specifies type 'unsigned long' but the argument has type 'unsigned int' [-Wformat]
    sprintf(stepBuffer, "%lu", stepCount.Get());
                        ~~~   ^~~~~~~~~~~~~~~
                        %u
17 warnings generated.
+ wasm-objdump -x wasm/lvgl.wasm
+ mv wasm/lvgl.html wasm/lvgl.old.html

    This produces wasm/lvgl.html, wasm/lvgl.js and wasm/lvgl.wasm

  6. Copy the generated WebAssembly files to the docs folder (used by GitHub Pages)...

    cp wasm/lvgl.js wasm/lvgl.wasm docs

    We don't need lvgl.html because docs already contains a version of lvgl.html with custom JavaScript.

  7. Start a Web Server for the docs folder, because WebAssembly doesn't work when opened from the filesystem.

    For Arm64: Use darkhttpd...

    darkhttpd docs

    For x64: Use the Chrome Extension Web Server for Chrome and set the folder to docs

  8. Launch a Web Browser and open the URL shown by darkhttpd or Web Server for Chrome.

    Enter lvgl.html in the URL bar to view the PineTime Watch Face Simulator.

In case of problems, compare with the GitHub Actions build log

How It Works

PineTime Watch Face Simulator was compiled from C and C++ to WebAssembly with emscripten...

Let's study the Build Script: wasm/lvgl.sh

Rewrite Clock.cpp to build with WebAssembly

# Rewrite Clock.cpp to build with WebAssembly:
# Change <libs/date/includes/date/date.h>
#   To "date.h"
# Change <Components/DateTime/DateTimeController.h>
#   To "DateTimeController.h"
# Change <libs/lvgl/lvgl.h>
#   To "../lvgl.h"
# Change "../DisplayApp.h"
#   To "DisplayApp.h"
# Change obj->user_data
#   To backgroundLabel_user_data
# Change backgroundLabel->user_data
#   To backgroundLabel_user_data
# Remove Screen(app),
cat clock/Clock.cpp \
    | sed 's/<libs\/date\/includes\/date\/date.h>/"date.h"/' \
    | sed 's/<Components\/DateTime\/DateTimeController.h>/"DateTimeController.h"/' \
    | sed 's/<libs\/lvgl\/lvgl.h>/"..\/lvgl.h"/' \
    | sed 's/"..\/DisplayApp.h"/"DisplayApp.h"/' \
    | sed 's/obj->user_data/backgroundLabel_user_data/' \
    | sed 's/backgroundLabel->user_data/backgroundLabel_user_data/' \
    | sed 's/Screen(app),//' \
    >clock/ClockTmp.cpp

We call sed to rewrite Clock.cpp so that it compiles with the InfiniTime Sandbox...

  1. Include paths are flattened...

    #include <Components/DateTime/DateTimeController.h>

    Becomes...

    #include "DateTimeController.h"

    The InfiniTime Sandbox header and source files are located in the clock folder, the same folder as Clock.cpp

  2. We simplify Base Classes...

    Clock::Clock(...) : 
    Screen(app),
    currentDateTime{{}}, ... {

    Becomes

    Clock::Clock(...) : 
    currentDateTime{{}}, ... {

    In the InfiniTime Sandbox, the Screen class has been replaced by a Mock Class that uses no constructor.

  3. We rewrite LVGL references like user_data.

    TODO: This may be removed, we now support user_data with the updated lv_config.h

This step creates the file ClockTmp.cpp, which is compiled instead of the original Clock.cpp.

Build LVGL app

We build the LVGL app in WebAssembly...

# Build LVGL app: wasm/lvgl.html, lvgl.js, lvgl.wasm
make -j

The make command triggers this command in the Makefile...

emcc -o wasm/lvgl.html \
	-Wl,--start-group \
  clock/ClockTmp.cpp \
	(List of C and C++ object files from LVGL and InfiniTime Sandbox) \
	-Wl,--end-group \
	-g \
	-I src/lv_core \
	-D LV_USE_DEMO_WIDGETS \
	-s WASM=1 \
    -s "EXPORTED_FUNCTIONS=[ '_main', '_get_display_buffer', '_get_display_width', '_get_display_height', '_test_display', '_init_display', '_render_display', '_render_widgets', '_create_clock', '_refresh_clock', '_update_clock' ]"

The emscripten compiler emcc generates three files in folder wasm...

  • lvgl.wasm: WebAssembly Executable Code, containing our Watch Face, LVGL and the InfiniTime Sandbox. Sample File

  • lvgl.js: Provides the JavaScript glue that's needed to load lvgl.wasm and run it in a Web Browser. Sample File

  • lvgl.html: The HTML file that calls lvgl.js to render the user interface.

    We won't be using this file, because we have a custom version of lvgl.html

EXPORTED_FUNCTIONS are the C functions that will be exposed from WebAssembly to JavaScript. See the section on "Exported Functions" below.

Dump the WebAssembly modules

For troubleshooting, we dump the text version of the WebAssembly module to lvgl.txt...

# Dump the WebAssembly modules
wasm-objdump -x wasm/lvgl.wasm >wasm/lvgl.txt

Sample lvgl.txt

Rename the HTML files

Because we use a custom lvgl.html, we rename the generated lvgl.html to prevent overwriting...

# Rename the HTML files so we don't overwrite the updates
mv wasm/lvgl.html wasm/lvgl.old.html

Mixing Rust and C WebAssembly

In future we shall be mixing C WebAssembly with Rust WebAssembly, so that the Watch Face code in Clock.cpp may be programmed in Rust instead.

Check out the rust branch of lvgl-asm

Here's a test of C WebAssembly calling Rust WebAssembly...

Here's how we build Rust and C WebAssembly: wasm/lvgl.sh

# Install Rust Toolchain for emscripten
rustup default nightly
rustup target add wasm32-unknown-emscripten

# Build Rust modules with emscripten compatibility
cargo build --target=wasm32-unknown-emscripten

# Build sample Rust app: wasm/test_rust.html, test_rust.js, test_rust.wasm
emcc \
    -g \
    wasm/test_rust.c \
    -s WASM=1 \
    -s "EXPORTED_FUNCTIONS=[ '_main', '_get_display_buffer', '_get_display_width', '_get_display_height', '_test_display', '_test_c', '_test_c_set_buffer', '_test_c_get_buffer', '_test_c_buffer_address', '_test_rust', '_test_rust2', '_test_rust3', '_test_rust_set_buffer', '_test_rust_get_buffer' ]" \
    -o wasm/test_rust.html \
	-I src/lv_core \
    target/wasm32-unknown-emscripten/debug/liblvgl_wasm_rust.a

# Dump the WebAssembly modules
wasm-objdump -x wasm/test_rust.wasm >wasm/test_rust.txt

# Rename the HTML files so we don't overwrite the updates
mv wasm/test_rust.html wasm/test_rust.old.html

InfiniTime Sandbox

PineTime Web Simulator runs in a Web Browser based on WebAssembly (somewhat similar to Java Applets). More about WebAssembly

Clock.cpp is our C++ class that contains the Watch Face code. Clock.cpp calls functions from two providers...

  1. LVGL UI Toolkit Library

  2. InfiniTime Operating System based on FreeRTOS

lvgl-wasm simulates the minimal set of InfiniTime functions needed for rendering Watch Faces. (FreeRTOS is not supported by the Simulator)

Hence lvgl-wasm works like a Sandbox. Here's how the InfiniTime Sandbox works...

Exported Functions

The Sandbox exports the following WebAssembly functions from C to JavaScript...

Clock Functions

These functions create the Clock class from Clock.cpp, render the LVGL widgets on the Watch Face, and update the time...

  • create_clock()

    Create an instance of the clock.

    From clock/ClockHelper.cpp

  • refresh_clock()

    Redraw the clock.

    From clock/ClockHelper.cpp

  • update_clock(year, month, day, hour, minute, second)

    Set the current date and time in DateTimeController. The time needs to be adjusted for the current timezone, see the JavaScript call to update_clock() below.

    From clock/ClockHelper.cpp

Display Functions

These functions initialise the LVGL library and render the LVGL Widgets to the WebAssembly Display Buffer...

  • init_display()

    Init the LVGL display.

    From wasm/lvgl.c

  • render_display()

    Render the LVGL display in 16-bit RGB565 format. From wasm/lvgl.c

    Calls the WebAssembly Display Driver defined in wasm/lv_port_disp.c

    Which calls put_display_px() to draw individual pixels to the the WebAssembly Display Buffer: wasm/lvgl.c

Display Buffer Functions

The WebAssembly Display Driver maintains a Display Buffer: 240 x 240 array of pixels, 4 bytes per pixel, in RGBA colour format: wasm/lvgl.c

///  RGBA WebAssembly Display Buffer that will be rendered to HTML Canvas
#define LV_HOR_RES_MAX          240
#define LV_VER_RES_MAX          240
#define DISPLAY_BYTES_PER_PIXEL 4
uint8_t display_buffer[LV_HOR_RES_MAX * LV_VER_RES_MAX * DISPLAY_BYTES_PER_PIXEL];

Our JavaScript code copies the Display Buffer from WebAssembly Memory and renders to HTML Canvas by calling the following functions...

  • get_display_width()

    Returns 240, the width of the WebAssembly Display Buffer.

    From wasm/lvgl.c

  • get_display_height()

    Returns 240, the height of the WebAssembly Display Buffer.

    From wasm/lvgl.c

  • get_display_buffer()

    Return the WebAssembly Address of the WebAssembly Display Buffer.

    From wasm/lvgl.c

Note that JavaScript is allowed to read and write to WebAssembly Memory (treating it like a JavaScript array of bytes). But WebAssembly can't access any JavaScript Memory.

That's why we designed the Display Buffer Functions to manipulate WebAssembly Memory.

Test Functions

For testing only...

  • test_display()

    (For Testing) Render a colour box to the WebAssembly Display Buffer.

    From wasm/lvgl.c

  • render_widgets()

    (For Testing) Render a Button Widget and a Label Widget.

    From wasm/lvgl.c

Other Functions

Sandbox API

The Sandbox simulates InfiniTime OS by exposing the following API Classes to Clock.cpp...

New Classes

The following classes were created for the Simulator...

  • ClockHelper.h, .cpp

    Exposes the Clock Functions for creating and rendering the Watch Face: create_clock(), refresh_clock() and update_clock()

Mocked Classes

The following classes from InfiniTime were mocked up (i.e. made non-functional) to run in the Simulator...

Reused Classes

The following classes were reused from InfiniTime with minor changes (e.g. include paths changed, functions stubbed out)...

Sandbox Styles

InfiniTime Sandbox exposes two LVGL Styles...

  1. Default Style defined in lv_conf.h with font jetbrains_mono_bold_20

    TODO: Use the Base Theme defined in LittleVgl.cpp. It doesn't work with LVGL Version 7 because the LVGL 7 needs Style Callback Functions.

  2. LabelBigStyle defined in LittleVgl.cpp with font jetbrains_mono_extrabold_compressed

Simulator JavaScript

The JavaScript functions here call the Exported WebAssembly Functions to render the Watch Face. From docs/lvgl.html

Initialise WebAssembly

We register a callback in the emscripten API, to be notified when the WebAssembly Module lvgl.wasm has been loaded...

//  In JavaScript: Wait for emscripten to be initialised
Module.onRuntimeInitialized = function() {
  //  Render LVGL to HTML Canvas
  render_canvas();
};

Initialise LVGL Display

When the WebAssembly Module lvgl.wasm has been loaded, we call the WebAssembly Function init_display() to initialise the LVGL display...

/// In JavaScript: Create the Watch Face in WebAssembly
function render_canvas() {
  //  Init LVGL Display
  Module._init_display();

Create Watch Face

Then we create the LVGL Watch Face Class from Clock.cpp...

  //  Create the Watch Face in WebAssembly
  Module._create_clock();

Update Watch Face Time

Every minute we update the Watch Face time in DateTimeController...

/// In JavaScript: Update the Watch Face time in WebAssembly and render the WebAssembly Display Buffer to the HTML Canvas
function updateCanvas() {
  //  Update the WebAssembly Date and Time: year, month, day, hour, minute, second
  const localTime = new Date();
  const timezoneOffset = localTime.getTimezoneOffset();  //  In mins
  //  Compensate for the time zone
  const now = new Date(
    localTime.valueOf()             //  Convert time to millisec
    - (timezoneOffset * 60 * 1000)  //  Convert mins to millisec
  );
  Module._update_clock(
    now.getFullYear(),
    now.getMonth() - 1,  //  getMonth() returns 1 to 12
    now.getDay(), 
    now.getHours(),
    now.getMinutes(),
    now.getSeconds()
  );

Note that we need to compensate for the timezone.

Redraw Watch Face

And redraw the Watch Face in Clock.cpp...

  //  Update the Watch Face time in WebAssembly
  Module._refresh_clock();

Render LVGL Widgets to WebAssembly Display Buffer

We call LVGL to render the Widgets into the WebAssembly Display Buffer...

  //  Render LVGL Widgets to the WebAssembly Display Buffer
  Module._render_display();

Resize HTML Canvas

We resize the HTML Canvas to PineTime's 240 x 240 resolution, scaled by 2 times...

  const DISPLAY_SCALE = 2;  //  Scale the canvas width and height

  //  Fetch the PineTime dimensions from WebAssembly Display Buffer
  var width = Module._get_display_width();
  var height = Module._get_display_height();

  //  Resize the canvas to PineTime dimensions (240 x 240)
  if (
    Module.canvas.width != width * DISPLAY_SCALE ||
    Module.canvas.height != height * DISPLAY_SCALE
  ) {
    Module.canvas.width = width * DISPLAY_SCALE;
    Module.canvas.height = height * DISPLAY_SCALE;
  }

Fetch HTML Canvas

We fetch the HTML Canvas...

  //  Fetch the canvas pixels
  var ctx = Module.canvas.getContext('2d');
  var imageData = ctx.getImageData(0, 0, width * DISPLAY_SCALE, height * DISPLAY_SCALE);
  var data = imageData.data;

Copy WebAssembly Display Buffer to HTML Canvas

We copy the pixels from the WebAssembly Display Buffer to the HTML Canvas (which uses 24-bit RGBA format)...

  const DISPLAY_SCALE = 2;  //  Scale the canvas width and height
  const DISPLAY_BYTES_PER_PIXEL = 4;  //  4 bytes per pixel: RGBA

  //  Copy the pixels from the WebAssembly Display Buffer to the canvas
  var addr = Module._get_display_buffer();
  Module.print(`In JavaScript: get_display_buffer() returned ${toHex(addr)}`);          
  for (var y = 0; y < height; y++) {
    //  Scale the pixels vertically to fill the canvas
    for (var ys = 0; ys < DISPLAY_SCALE; ys++) {
      for (var x = 0; x < width; x++) {
        //  Copy from src to dest with scaling
        const src = ((y * width) + x) * DISPLAY_BYTES_PER_PIXEL;
        const dest = ((((y * DISPLAY_SCALE + ys) * width) + x) * DISPLAY_BYTES_PER_PIXEL) 
          * DISPLAY_SCALE;
        //  Scale the pixels horizontally to fill the canvas
        for (var xs = 0; xs < DISPLAY_SCALE; xs++) {
          const dest2 = dest + xs * DISPLAY_BYTES_PER_PIXEL;
          //  Copy 4 bytes: RGBA
          for (var b = 0; b < DISPLAY_BYTES_PER_PIXEL; b++) {
            data[dest2 + b] = Module.HEAPU8[addr + src + b];
          }
        }
      }
    }
  }

Note that JavaScript is allowed to read and write to WebAssembly Memory (treating it like a JavaScript array of bytes in Module.HEAPU8[]). But WebAssembly can't access any JavaScript Memory.

That's why we designed the Display Buffer Functions to manipulate WebAssembly Memory.

Paint the HTML Canvas

Finally we update the HTML Canvas...

  //  Paint the canvas
  ctx.putImageData(imageData, 0, 0);
}

Install emscripten on Ubuntu x64

See the GitHub Actions Workflow...

.github/workflows/ccpp.yml

Look for the steps...

  1. "Install emscripten"

  2. "Install wabt"

Change /tmp to a permanent path like ~

Then add emscripten and wabt to the PATH...

# Add emscripten and wabt to the PATH
source ~/emsdk/emsdk_env.sh
export PATH=$PATH:~/wabt/build

Install emscripten on Arch Linux / Manjaro Arm64

Works on Pinebook Pro with Manjaro...

sudo pacman -S emscripten
sudo pacman -S wabt
source /etc/profile.d/emscripten.sh
emcc --version
# Shows emscripten version 1.39.20
wasm-as --version
# Shows binaryen version 95

For emscripten version 1.40.x and newer

emscripten and binaryen will probably work, skip the rest of this section.

For emscripten version 1.39.x and binaryen version 95 only

This will fail during the build, because emscripten 1.39 needs binaryen version 93, not 95.

We could install binaryen version 93... But emcc will fail with an error "stackSave already exists". That's because binaryen 93 generates the "stackSave" that conflicts with emscripten 1.39.20. More details here

To fix this, we install binaryen version 94, but rename it as version 93...

# Download binaryen 94
git clone --branch version_94 https://github.com/WebAssembly/binaryen
cd binaryen
nano CMakeLists.txt

Change

   project(binaryen LANGUAGES C CXX VERSION 94)

To

   project(binaryen LANGUAGES C CXX VERSION 93)

Then build and install binaryen...

cmake .
make -j 5
sudo cp bin/* /usr/bin
sudo cp lib/* /usr/lib
wasm-as --version
# Shows binaryen "version 93 (version_94)"

binaryen is now version 93, which is correct. Proceed to build the app...

cd lvgl-wasm
rm -rf ~/.emscripten_cache
make clean
make -j 5

The app build should complete successfully.

emcc Error: Unexpected binaryen version

If we see this error...

   emcc: error: unexpected binaryen version: 95 (expected 93) [-Wversion-check] [-Werror]
   FAIL: Compilation failed!: ['/usr/lib/emscripten/emcc', '-D_GNU_SOURCE', '-o', '/tmp/tmpbe4ik5na.js', '/tmp/tmpzu5jusdg.c', '-O0', '--js-opts', '0', '--memory-init-file', '0', '-Werror', '-Wno-format', '-s', 'BOOTSTRAPPING_STRUCT_INFO=1', '-s', 'WARN_ON_UNDEFINED_SYMBOLS=0', '-s', 'STRICT=1', '-s', 'SINGLE_FILE=1']

emcc Error: stackSave already exists

Then we need to install the right version of binaryen (see above)

If we see this error...

   Fatal: Module::addExport: stackSave already exists
   emcc: error: '/usr/bin/wasm-emscripten-finalize --detect-features --global-base=1024 --check-stack-overflow /tmp/emscripten_temp_84xtyzya/tmpzet09r88.wasm -o /tmp/emscripten_temp_84xtyzya/tmpzet09r88.wasm.o.wasm' failed (1)
   FAIL: Compilation failed!: ['/usr/lib/emscripten/emcc', '-D_GNU_SOURCE', '-o', '/tmp/tmpzet09r88.js', '/tmp/tmpxk8zxvza.c', '-O0', '--js-opts', '0', '--memory-init-file', '0', '-Werror', '-Wno-format', '-s', 'BOOTSTRAPPING_STRUCT_INFO=1', '-s', 'WARN_ON_UNDEFINED_SYMBOLS=0', '-s', 'STRICT=1', '-s', 'SINGLE_FILE=1']

That means binaryen 93 generates the "stackSave" that conflicts with emscripten 1.39.20. More details here

We need to install branch version_94 of binaryen, change version in CMakeLists.txt to version 93 (see above)

Install emscripten on macOS (Doesn't Work)

Enter these commands...

brew install emscripten
brew install binaryen
# Upgrade llvm to 10.0.0
brew install llvm
brew upgrade llvm
nano /usr/local/Cellar/emscripten/1.40.1/libexec/.emscripten

Change BINARYEN_ROOT and LLVM_ROOT to

BINARYEN_ROOT = os.path.expanduser(os.getenv('BINARYEN', '/usr/local')) # directory
LLVM_ROOT = os.path.expanduser(os.getenv('LLVM', '/usr/local/opt/llvm/bin')) # directory

Fails with error:

   emcc: warning: LLVM version appears incorrect (seeing "10.0", expected "12.0") [-Wversion-check]
   shared:INFO: (Emscripten: Running sanity checks)
   clang-10: error: unknown argument: '-fignore-exceptions'
   emcc: error: '/usr/local/opt/llvm/bin/clang -target wasm32-unknown-emscripten -D__EMSCRIPTEN_major__=1 -D__EMSCRIPTEN_minor__=40 -D__EMSCRIPTEN_tiny__=1 -D_LIBCPP_ABI_VERSION=2 -Dunix -D__unix -D__unix__ -Werror=implicit-function-declaration -Xclang -nostdsysteminc -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/include/compat -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/include -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/include/libc -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/lib/libc/musl/arch/emscripten -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/local/include -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/include/SSE -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/lib/compiler-rt/include -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/lib/libunwind/include -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/cache/wasm/include -DEMSCRIPTEN -fignore-exceptions -Isrc/lv_core -D LV_USE_DEMO_WIDGETS ././src/lv_core/lv_group.c -Xclang -isystem/usr/local/Cellar/emscripten/1.40.1/libexec/system/include/SDL -c -o /var/folders/gp/jb0b68fn3b187mgyyrjml3km0000gn/T/emscripten_temp_caxv1fls/lv_group_0.o -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr' failed (1)

WebAssembly Stack Trace for PineTime Watch Face

Here is a sample WebAssembly Stack Trace that appears in the web browser. It happens when we don't initialise the LVGL Style LabelBigStyle used by Clock.cpp

lvgl.js:1839 Fetch finished loading: GET "http://127.0.0.1:8887/lvgl.wasm".
instantiateAsync @ lvgl.js:1839
createWasm @ lvgl.js:1866
(anonymous) @ lvgl.js:2113
lvgl2.html:1237 In JavaScript: render_canvas()
lvgl2.html:1237 In C: Init display...
lvgl2.html:1237 Init display...
​ Uncaught RuntimeError: memory access out of bounds
    at _lv_style_get_int (http://127.0.0.1:8887/lvgl.wasm:wasm-function[229]:0x21bfb)
    at _lv_style_list_get_int (http://127.0.0.1:8887/lvgl.wasm:wasm-function[234]:0x22bf7)
    at _lv_obj_get_style_int (http://127.0.0.1:8887/lvgl.wasm:wasm-function[87]:0xe524)
    at lv_obj_get_style_shadow_width (http://127.0.0.1:8887/lvgl.wasm:wasm-function[162]:0x17d1b)
    at lv_obj_get_draw_rect_ext_pad_size (http://127.0.0.1:8887/lvgl.wasm:wasm-function[43]:0x70ae)
    at lv_obj_signal (http://127.0.0.1:8887/lvgl.wasm:wasm-function[33]:0x55e6)
    at lv_label_signal (http://127.0.0.1:8887/lvgl.wasm:wasm-function[261]:0x27804)
    at lv_obj_refresh_ext_draw_pad (http://127.0.0.1:8887/lvgl.wasm:wasm-function[45]:0x886f)
    at lv_obj_signal (http://127.0.0.1:8887/lvgl.wasm:wasm-function[33]:0x5793)
    at lv_label_signal (http://127.0.0.1:8887/lvgl.wasm:wasm-function[261]:0x27804)
_lv_style_get_int @ ​
_lv_style_list_get_int @ ​
_lv_obj_get_style_int @ ​
lv_obj_get_style_shadow_width @ ​
lv_obj_get_draw_rect_ext_pad_size @ ​
lv_obj_signal @ ​
lv_label_signal @ ​
lv_obj_refresh_ext_draw_pad @ ​
lv_obj_signal @ ​
lv_label_signal @ ​
lv_obj_refresh_style @ ​
lv_obj_add_style @ ​
Pinetime::Applications::Screens::Clock::Clock(DisplayApp*, Pinetime::Controllers::DateTime&, Pinetime::Controllers::Battery&, Pinetime::Controllers::Ble&) @ ​
create_clock @ ​
(anonymous) @ lvgl.js:1734
render_canvas @ lvgl2.html:1311
Module.onRuntimeInitialized @ lvgl2.html:1354
doRun @ lvgl.js:2496
(anonymous) @ lvgl.js:2509
setTimeout (async)
run @ lvgl.js:2505
runCaller @ lvgl.js:2411
removeRunDependency @ lvgl.js:1632
receiveInstance @ lvgl.js:1799
receiveInstantiatedSource @ lvgl.js:1816
Promise.then (async)
(anonymous) @ lvgl.js:1841
Promise.then (async)
instantiateAsync @ lvgl.js:1839
createWasm @ lvgl.js:1866
(anonymous) @ lvgl.js:2113

Migrating LVGL Version 6 to 7

PineTime runs on LVGL version 6 while our WebAssembly port runs on LVGL version 7. And programs built for LVGL version 6 will not compile with LVGL version 7.

Here's how we migrated our code from LVGL Version 6...

To LVGL Version 7...

Compare the original and converted files...

Migrating LVGL lv_label_set_style

Code that uses lv_label_set_style...

lv_label_set_style(label_time, LV_LABEL_STYLE_MAIN, LabelBigStyle);

Should be changed to lv_obj_reset_style_list and lv_obj_add_style...

//  Remove the styles coming from the theme
lv_obj_reset_style_list(label_time, LV_LABEL_PART_MAIN);
//  Then add style
lv_obj_add_style(label_time, LV_LABEL_PART_MAIN, LabelBigStyle);

Or define a macro like so...

/// Change LVGL v6 lv_label_set_style() to LVGL v7 lv_obj_reset_style_list() and lv_obj_add_style()
#define lv_label_set_style(label, style_type, style) \
{ \
    lv_obj_reset_style_list(label, LV_LABEL_PART_MAIN); \
    lv_obj_add_style(label, LV_LABEL_PART_MAIN, style); \
}
lv_label_set_style(label_time, LV_LABEL_STYLE_MAIN, LabelBigStyle);

Migrating LVGL lv_style_plain

lv_style_plain has been removed in LVGL 7. Code like this...

lv_style_copy(&def, &lv_style_plain);

Should be changed to...

lv_style_init(&def);

Migrating LVGL Themes

In LVL 6, setting the default font for a Theme used to be easy...

lv_style_init(&def);
lv_style_set_text_font(&def, LV_STATE_DEFAULT, &jetbrains_mono_bold_20);
...
lv_theme_set_current(&theme);

But in LVL 7, we need to use Theme Callback Functions to apply the style.

A simpler solution is to set the default font in lv_conf.h...

#define LV_FONT_CUSTOM_DECLARE LV_FONT_DECLARE(jetbrains_mono_bold_20)
#define LV_THEME_DEFAULT_FONT_SMALL         &jetbrains_mono_bold_20
#define LV_THEME_DEFAULT_FONT_NORMAL        &jetbrains_mono_bold_20
#define LV_THEME_DEFAULT_FONT_SUBTITLE      &jetbrains_mono_bold_20
#define LV_THEME_DEFAULT_FONT_TITLE         &jetbrains_mono_bold_20

Migrating LVGL Styles

Change LVL 6 Style...

lv_style_copy(&bg, &lv_style_plain);
bg.body.main_color = LV_COLOR_BLACK;
bg.body.grad_color = LV_COLOR_BLACK;
bg.text.color      = LV_COLOR_WHITE;
bg.text.font       = font;
bg.image.color     = LV_COLOR_WHITE;

To LVL 7 Style...

lv_style_init(&bg);
lv_style_set_bg_color(&bg, LV_STATE_DEFAULT, LV_COLOR_BLACK);
lv_style_set_bg_grad_color(&bg, LV_STATE_DEFAULT, LV_COLOR_BLACK);
lv_style_set_text_color(&bg, LV_STATE_DEFAULT, LV_COLOR_WHITE);
lv_style_set_text_font(&bg, LV_STATE_DEFAULT, font);
lv_style_set_image_recolor(&bg, LV_STATE_DEFAULT, LV_COLOR_WHITE);

Change LVL 6 Style...

lv_style_copy(&panel, &bg);
panel.body.main_color     = lv_color_hsv_to_rgb(hue, 11, 18);
panel.body.grad_color     = lv_color_hsv_to_rgb(hue, 11, 18);
panel.body.radius         = LV_DPI / 20;
panel.body.border.color   = lv_color_hsv_to_rgb(hue, 10, 25);
panel.body.border.width   = 1;
panel.body.border.opa     = LV_OPA_COVER;
panel.body.padding.left   = LV_DPI / 10;
panel.body.padding.right  = LV_DPI / 10;
panel.body.padding.top    = LV_DPI / 10;
panel.body.padding.bottom = LV_DPI / 10;
panel.line.color          = lv_color_hsv_to_rgb(hue, 20, 40);
panel.line.width          = 1;

To LVL 7 Style...

lv_style_copy(&panel, &bg);
lv_style_set_bg_color(&panel, LV_STATE_DEFAULT,       lv_color_hsv_to_rgb(hue, 11, 18)); 
lv_style_set_bg_grad_color(&panel, LV_STATE_DEFAULT,  lv_color_hsv_to_rgb(hue, 11, 18)); 
lv_style_set_radius(&panel, LV_STATE_DEFAULT,         LV_DPI / 20); 
lv_style_set_border_color(&panel, LV_STATE_DEFAULT,   lv_color_hsv_to_rgb(hue, 10, 25)); 
lv_style_set_border_width(&panel, LV_STATE_DEFAULT,   1); 
lv_style_set_border_opa(&panel, LV_STATE_DEFAULT,     LV_OPA_COVER); 
lv_style_set_pad_left(&panel, LV_STATE_DEFAULT,       LV_DPI / 10); 
lv_style_set_pad_right(&panel, LV_STATE_DEFAULT,      LV_DPI / 10); 
lv_style_set_pad_top(&panel, LV_STATE_DEFAULT,        LV_DPI / 10); 
lv_style_set_pad_bottom(&panel, LV_STATE_DEFAULT,     LV_DPI / 10); 
lv_style_set_line_color(&panel, LV_STATE_DEFAULT,     lv_color_hsv_to_rgb(hue, 20, 40)); 
lv_style_set_line_width(&panel, LV_STATE_DEFAULT,     1);

For more examples of LVL Style migration, see...

LittleVgl.cpp: LVGL Version 6 vs Version 7

Click Files Changed, then Changed Files and look for Clock/LittleVgl.cpp