Offline version of Online convert tools

These PHP scrips are the online converter tools:

• Image converter: https://littlevgl.com/image-to-c-array
• Font converter: https://littlevgl.com/ttf-font-to-c-array

Here you you can see how they work or download them to run offline.

Get started

This guide shows how to use the converters offline in a command line on Linux

1. Install PHP: sudo apt-get install php7.2-cli
2. Intall the Image manipulator extension for PHP: sudo apt-get install php7.2-gd
3. Clone or download the lv_utils repository: git clone https://github.com/littlevgl/lv_utils.git
4. Go to the lv_utils directory.

For Mac OSX using Homebrew

Because the php version installed by xcode might not have the GD graphics library installed, you need to install the Homebrew version. Once installed, you will need to find where it was installed and reference the complete path to php when running the commands shown on this page. The example below in step 4 happened to be the installation location on my Mac for php version 7.3.3.

1. Install xcode: install via the app store
2. Install xcode CLI tools: xcode-select --install
3. Install PHP: brew install php
4. Check the install: /usr/local/Cellar/php/7.3.3/bin/php --version
5. Continue with step 3 in the installation instructions for Linux

Run the Font converter offline

1. Copy a TTF or OTF file you want to use into the lv_utils directory. (Note that OTF support has only been tested on Mac OSX with Homebrew-installed php version 7.3.3.)
2. Run the script: php font_conv_core.php "name=arial_20&font=arial.ttf&height=20&bpp=4&uni_first=32&uni_last=126"
3. Check the created C file in lv_utils directory.

The required arguments of the script:

• name name of the output file and font
• font name of font file to use (must be a *.ttf or *.otf file)
• height desired height in px
• bpp Bit-per-pixel (1, 2, 4 or 8)
• uni_first the first unicode character to convert
• uni_last the ast unicode character to convert

Optional arguments:

• built_in convert a built in font with all bpp (0 or 1)
• list list of characters to include (must be in rango of uni_first and uni_last and in ascendant order). E.g. "list=123abc"
• scale scale up/down the letters [%] E.g. "scale=120"
• base_shift shift the base line [px] E.g. "base_shift=3"
• monospace use this fixed width [px] E.g. "monospace=12"

Example with all options

Convert only the numbers and + - sign with Arial font (The plus sign is replaced with %2B): php font_conv_core.php "name=arial_num_20&font=arial.ttf&height=20&bpp=8&uni_first=32&uni_last=126&list=%2B-0123456789&built_in=1"

Using the generated font in LittlevGL

• Copy the result C file into your LittlevGL project
• In a C file of your application declare the font as: extern lv_font_t my_font_name; or simply LV_FONT_DECLARE(my_font_name);
• Set the font in a style: style.text.font = &my_font_name;

Run the Image converter offline

1. Copy a BMP, JPG or PNG file you want to use into the lv_utils directory
2. Run the script: php img_conv_core.php "name=wallpaper&img=red_flower.png"
3. Chek the created C file in lv_utils directory.

The required arguments of the script:

• name name of the output file and image
• img an image file

Optional arguments:

• cf color format. Possible values are: true_color, true_color_alpha, true_color_chroma, indexed_1, indexed_2, indexed_4, indexed_8, alpha_1, alpha_2, alpha_4, alpha_8, raw, raw_alpha, raw_chroma. The default is: true_color.
• format C array or Binary output. Possible values are: c_array, bin_332, bin_565, bin_565_swap, bin_888. Default is: c_array.

Example with all options

Convert a bunny.png with alpha for all pixels to C array: php img_conv_core.php "name=icon&img=bunny.png&format=c_array&cf=true_color_alpha"

Using the generated image in LittlevGL

• For C arrays
  • Copy the result C file into your LittlevGL project
  • In a C file of your application declare the image as: extern const lv_img_t my_image_name; or LV_IMG_DECLARE(my_image_name);
  • Set the image for an lv_img object: lv_img_set_src(img1, &my_image_name);
• For externally binary files (e.g. SD card)
  • Set up a new driver. To learn more read the Tutorial.
  • Set the image for an lv_img object: lv_img_set_src(img1, "S:/path/to/image");

Other offline tools

BDF Font Converter

utils/bdf_font_converter.py converts BDF files into a LittlevGL compatible c file. This converter is useful for generating pixel-perfect fonts, especially for monochrome displays.

Help can be printed out by:

python bdf_font_converter.py --help

Typical use case (generates crox3hb.c):

python bdf_font_converter.py win_crox3hb.bdf crox3hb