54 lines
1.6 KiB
ReStructuredText
54 lines
1.6 KiB
ReStructuredText
.. _lodepng:
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===============
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LodePNG decoder
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===============
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Allow the use of PNG images in LVGL.
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Detailed introduction: `lodepng <https://github.com/lvandeve/lodepng>`__
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If enabled in ``lv_conf.h`` by :c:macro:`LV_USE_LODEPNG` LVGL will register a new
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image decoder automatically so PNG files can be directly used as any
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other image sources.
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Note that, a file system driver needs to be registered to open images from
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files. Read more about it :ref:`overview_file_system` or just
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enable one in ``lv_conf.h`` with ``LV_USE_FS_...``
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The whole PNG image is decoded, so ``width x height x 4`` bytes free RAM space is required.
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The decoded image is stored in RGBA pixel format.
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As it might take significant time to decode PNG images LVGL's :ref:`overview_image_caching` feature can be useful.
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Compress PNG files
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------------------
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PNG file format supports True color (24/32 bit), and 8-bit palette colors.
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Usually cliparts, drawings, icons and simple graphics are stored in PNG format,
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that do not use the whole color space, so it is possible to compress further
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the image by using 8-bit palette colors, instead of 24/32 bit True color format.
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Because embedded devices have limited (flash) storage, it is recommended
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to compress images.
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There is a very good and free online PNG compressor site, in which the number
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of colors can be reduced, and in the same time preview the result.
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A batch of PNG files can be uploaded also.
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Compress PNG site: https://compresspng.com/
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.. _lodepng_example:
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Example
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-------
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.. include:: ../examples/libs/lodepng/index.rst
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.. _lodepng_api:
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API
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---
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:ref:`lodepng`
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