Allow switching output image format

README.md

@@ -12,7 +12,7 @@ If you're looking for a way to render your own HTML, see my other project [hass-
 
 ## Features
 
-This tool regularly takes a screenshot of a specific page of your home assistant setup. It converts it into the PNG grayscale format which Kindles can display.
+This tool regularly takes a screenshot of a specific page of your home assistant setup. It converts it into the PNG/JPEG grayscale format which Kindles can display.
 
 Using my [own Kindle 4 setup guide](https://github.com/sibbl/hass-lovelace-kindle-4) or the [online screensaver extension](https://www.mobileread.com/forums/showthread.php?t=236104) for any jailbroken Kindle, this image can be regularly polled from your device so you can use it as a weather station, a display for next public transport departures etc.
 
@@ -47,6 +47,7 @@ Home Assistant related stuff:
 | `SCALING`                 | `1`                                   | no       | yes      | Scaling factor, e.g. `1.5` to zoom in or `0.75` to zoom out                                                                                                                                          |
 | `GRAYSCALE_DEPTH`         | `8`                                   | no       | yes      | Grayscale bit depth your kindle supports                                                                                                                                                             |
 | `COLOR_MODE`              | `GrayScale`                           | no       | yes      | ColorMode to use, ex: `GrayScale`, or `TrueColor`.                                                                                                                                                   |
+| `IMAGE_FORMAT`            | `png`                                 | no       | no       | Format for the generated images. Acceptable values are `png`, or `jpeg`.                                                                                                                                                   |
 | `DITHER`                  | `false`                               | no       | yes      | Apply a dither to the images.                                                                                                                                                                        |
 | `REMOVE_GAMMA`            | `true`                                | no       | no       | Remove gamma correction from image. Computer images are normally gamma corrected since monitors expect gamma corrected data, however some E-Ink displays expect images not to have gamma correction. |
 
@@ -109,7 +110,7 @@ Modify the following lines in the HASS Lovelace Kindle 4 extension's [`script.sh
 
 Some advanced variables for local usage which shouldn't be necessary when using Docker:
 
-- `OUTPUT_PATH=./output.png` (destination of rendered image. `OUTPUT_2`, `OUTPUT_3`, ... is also supported)
+- `OUTPUT_PATH=./output` (destination of rendered image, without extension. `OUTPUT_2`, `OUTPUT_3`, ... is also supported)
 - `PORT=5000` (port of server, which returns the last image)
 - `USE_IMAGE_MAGICK=false` (use ImageMagick instead of GraphicsMagick)
 - `UNSAFE_IGNORE_CERTIFICATE_ERRORS=true` (ignore certificate errors of e.g. self-signed certificates at your own risk)

config.js

@@ -13,10 +13,11 @@ function getPagesConfig() {
     if (!screenShotUrl) return pages;
     pages.push({
       screenShotUrl,
+      imageFormat: getEnvironmentVariable("IMAGE_FORMAT", suffix) || "png",
       outputPath: getEnvironmentVariable(
         "OUTPUT_PATH",
         suffix,
-        `output/cover${suffix}.png`
+        `output/cover${suffix}`
       ),
       renderingDelay: getEnvironmentVariable("RENDERING_DELAY", suffix) || 0,
       renderingScreenSize: {

config.yaml

@@ -35,6 +35,7 @@ options:
   ROTATION: '0'
   SCALING: '1'
   GRAYSCALE_DEPTH: '8'
+  IMAGE_FORMAT: 'png'
   COLOR_MODE: 'GrayScale'
   REMOVE_GAMMA: true
   PREFERS_COLOR_SCHEME: 'light'
@@ -54,6 +55,7 @@ schema:
   ROTATION: "int?"
   SCALING: "float?"
   GRAYSCALE_DEPTH: "int?"
+  IMAGE_FORMAT: "list(png|jpeg)?"
   COLOR_MODE: "list(GrayScale|TrueColor)?"
   REMOVE_GAMMA: "bool?"
   PREFERS_COLOR_SCHEME: "list(light|dark)?"
@@ -62,4 +64,4 @@ schema:
     - name: match(^[A-Z0-9_]+$)
       value: str
 environment:
-  output_path: "/output/cover.png"
+  output_path: "/output/cover"

docker-compose.yml

@@ -13,7 +13,7 @@ services:
       - RENDERING_SCREEN_HEIGHT=800
       - RENDERING_SCREEN_WIDTH=600
       - GRAYSCALE_DEPTH=8
-      - OUTPUT_PATH=/output/cover.png
+      - OUTPUT_PATH=/output/cover
       - LANGUAGE=en
       - ROTATION=0
       - SCALING=1

index.js

@@ -105,13 +105,14 @@ const batteryStore = {};
       const pageIndex = pageNumber - 1;
       const configPage = config.pages[pageIndex];
 
-      const data = await fs.readFile(configPage.outputPath);
-      const stat = await fs.stat(configPage.outputPath);
+      const outputPathWithExtension = configPage.outputPath + "." + configPage.imageFormat
+      const data = await fs.readFile(outputPathWithExtension);
+      const stat = await fs.stat(outputPathWithExtension);
 
       const lastModifiedTime = new Date(stat.mtime).toUTCString();
 
       response.writeHead(200, {
-        "Content-Type": "image/png",
+        "Content-Type": "image/" + configPage.imageFormat,
         "Content-Length": Buffer.byteLength(data),
         "Last-Modified": lastModifiedTime
       });
@@ -165,15 +166,15 @@ async function renderAndConvertAsync(browser) {
 
     const url = `${config.baseUrl}${pageConfig.screenShotUrl}`;
 
-    const outputPath = pageConfig.outputPath;
+    const outputPath = pageConfig.outputPath + "." + pageConfig.imageFormat;
     await fsExtra.ensureDir(path.dirname(outputPath));
 
     const tempPath = outputPath + ".temp";
 
     console.log(`Rendering ${url} to image...`);
     await renderUrlToImageAsync(browser, pageConfig, url, tempPath);
 
-    console.log(`Converting rendered screenshot of ${url} to grayscale png...`);
+    console.log(`Converting rendered screenshot of ${url} to grayscale...`);
     await convertImageToKindleCompatiblePngAsync(
       pageConfig,
       tempPath,
@@ -278,7 +279,7 @@ async function renderUrlToImageAsync(browser, pageConfig, url, path) {
     }
     await page.screenshot({
       path,
-      type: "png",
+      type: pageConfig.imageFormat,
       clip: {
         x: 0,
         y: 0,

run.sh

@@ -15,6 +15,7 @@ export BROWSER_LAUNCH_TIMEOUT=$(bashio::config 'BROWSER_LAUNCH_TIMEOUT')
 export ROTATION=$(bashio::config 'ROTATION')
 export SCALING=$(bashio::config 'SCALING')
 export GRAYSCALE_DEPTH=$(bashio::config 'GRAYSCALE_DEPTH')
+export IMAGE_FORMAT=$(bashio::config 'IMAGE_FORMAT')
 export COLOR_MODE=$(bashio::config 'COLOR_MODE')
 export REMOVE_GAMMA=$(bashio::config 'REMOVE_GAMMA')
 export PREFERS_COLOR_SCHEME=$(bashio::config 'PREFERS_COLOR_SCHEME')